Monday, March 31, 2008

Al's Journal Update

Linear-scaling method for calculating nuclear magnetic resonance chemical shifts using gauge-including atomic orbitals within Hartree-Fock and density-functional theory
J. Chem. Phys. 127, 054103 (2007)
Jörg Kussmann and Christian Ochsenfeld
Details of a new density matrix-based formulation for calculating nuclear magnetic resonance chemical shifts at both Hartree-Fock and density functional theory levels are presented. For systems with a nonvanishing highest occupied molecular orbital–lowest unoccupied molecular orbital gap, the method allows us to reduce the asymptotic scaling order of the computational effort from cubic to linear, so that molecular systems with 1000 and more atoms can be tackled with today's computers. The key feature is a reformulation of the coupled-perturbed self-consistent field (CPSCF) theory in terms of the one-particle density matrix (D-CPSCF), which avoids entirely the use of canonical MOs. By means of a direct solution for the required perturbed density matrices and the adaptation of linear-scaling integral contraction schemes, the overall scaling of the computational effort is reduced to linear. A particular focus of our formulation is to ensure numerical stability when sparse-algebra routines are used to obtain an overall linear-scaling behavior.

Analyzing molecular properties calculated with two-component relativistic methods using spin-free natural bond orbitals: NMR spin-spin coupling constants
J. Chem. Phys. 127, 124106 (2007)

Jochen Autschbach
An analysis method for static linear response properties employing two-component (spin-orbit) relativistic density functional theory along with scalar relativistic “natural localized molecular orbitals” (NLMOs) and “natural bond orbitals” (NBOs) has been developed. The spin-orbit NLMO/NBO analysis has been applied to study the indirect spin-spin coupling (J-coupling) constants in Tl–I, PbH4, and a dinuclear Pt–Tl bonded complex with a very large Pt–Tl coupling constant (expt.: 146.8 kHz). For Tl–I it is shown that the analysis scheme based on scalar relativistic NLMOs is applicable even if spin-orbit coupling is responsible for most of the coupling's magnitude. For PbH4 it is shown that electron delocalization plays a much larger role for the Pb–H coupling than it is the case for the C–H coupling in methane. For the Pt–Tl complex the analysis clearly demonstrates the strong influence of the ligands on the Pt–Tl coupling constant and quantifies the effect of the delocalization of the Pt–Tl bond on the Pt–Tl coupling constant.

The appearance of an interval of energies that contain the whole diamagnetic contribution to NMR magnetic shieldings
J. Chem. Phys. 127, 154115 (2007)

Alejandro Maldonado and Gustavo A. Aucar
Working within relativistic polarization propagator approach, it was shown in a previous article that the electronic origin of diamagnetic contributions to NMR nuclear magnetic shielding, d, are mostly excitations that fit in a well defined interval of energies such that 2mc2 ( i− [overline s]">)<4mc2. x="Br," x="O," x="N," x="Sn" x="Br">

Theory of damped quantum rotation in nuclear magnetic resonance spectra. II. Numerical simulations for the benzene rotor
J. Chem. Phys. 127, 184504 (2007)
T. Ratajczyk and S. Szymański
In Part I of this series of papers, the damped quantum rotation (DQR) theory, formulated originally for hindered threefold molecular rotors in solids, was generalized to the N-fold case. The stochastic dynamics of such objects, evidenced in NMR line shapes, was shown to be more complicated than in the standard model of classical jumps between the wells of the N-fold torsional potential. Actually, it comprises certain quantum rate (i.e., coherence-damping) processes subject to the requirements of the Pauli principle. The jump picture is recovered only when the quantum rates fit specific patterns. In this work, one of the ways of approaching such a classical limit is identified for the benzene rotor. This is inferred from a quantum mechanical model whose validity was earlier confirmed for a methyl group. Based on that model, theoretical calculations for the benzene ring dynamics in a clathrate crystal, 1-(9-anthryloxy)anthraquinone/benzene-d6, confronted with the pertinent literature data, point to possible deviations from the classical limit. However, the predicted DQR effects are too small to be observed in solid echo 2H NMR spectra of the C6D6 isotopomer. The chances of detecting the effects are improved when Carr-Purcell echo 1H spectra of a single crystal of the isotopomer including C6H6 as a guest are considered. The substantial differences in the sensitivity to the DQR effects of the spectra of protonated and deuterated benzene are concerned with different magnitudes of the intramolecular dipolar spin couplings. The dynamic isotope effect (C6D6 vs C6H6), which is small in this case, is only of secondary importance. Legitimacy of the use of the jump model in 2H NMR line shape studies of benzene-d6 is fully confirmed by the present considerations. However, the physical significance of the dynamic parameters extracted from such studies is shown from a new perspective.

A first principles theory of nuclear magnetic resonance J-coupling in solid-state systems
J. Chem. Phys. 127, 204107 (2007)
Siân A. Joyce, Lee Maltings, Jonathan R. Yates, Chris J. Pickard, Francesco Mauri
A method to calculate NMR J-coupling constants from first principles in extended systems is presented. It is based on density functional theory and is formulated within a planewave-pseudopotential framework. The all-electron properties are recovered using the projector augmented wave approach. The method is validated by comparison with existing quantum chemical calculations of solution-state systems and with experimental data. The approach has also been applied to the silicophosphate, Si5O(PO4)6, giving 31P–29Si-couplings which are in excellent agreement with experiment.

Theoretical predictions of nuclear magnetic resonance parameters in a novel organo-xenon species: Chemical shifts and nuclear quadrupole couplings in HXeCCH
J. Chem. Phys. 127, 234314 (2007)
Michal Straka, Perttu Lantto, Markku Räsänen, and Juha Vaara
We calibrate the methodology for the calculation of nuclear magnetic resonance (NMR) properties in novel organo-xenon compounds. The available state-of-the-art quantum-chemical approaches are combined and applied to the HXeCCH molecule as the model system. The studied properties are 129Xe, 1H, and 13C chemical shifts and shielding anisotropies, as well as 131Xe and 2H nuclear quadrupole coupling constants. The aim is to obtain, as accurately as currently possible, converged results with respect to the basis set, electron correlation, and relativistic effects, including the coupling of relativity and correlation. This is done, on one hand, by nonrelativistic correlated ab initio calculations up to the CCSD(T) level and, on the other hand, for chemical shifts and shielding anisotropies by the leading-order relativistic Breit-Pauli perturbation theory (BPPT) with correlated ab initio and density-functional theory (DFT) reference states. BPPT at the uncorrelated Hartree-Fock level as well as the corresponding fully relativistic Dirac-Hartree-Fock method are found to be inapplicable due to a dramatic overestimation of relativistic effects, implying the influence of triplet instability in this multiply bonded system. In contrast, the fully relativistic second-order Møller-Plesset perturbation theory method can be applied for the quadrupole coupling, which is a ground-state electric property. The performance of DFT with various exchange-correlation functionals is found to be inadequate for the nonrelativistic shifts and shielding anisotropies as compared to the CCSD(T) results. The relativistic BPPT corrections to these quantities can, however, be reasonably predicted by DFT, due to the improved triplet excitation spectrum as compared to the Hartree-Fock method, as well as error cancellation within the five main BPPT contributions. We establish three computationally feasible models with characteristic error margins for future calculations of larger organo-xenon compounds to guide forthcoming experimental NMR efforts. The predicted 129Xe chemical shift in HXeCCH is in a novel range for this nucleus, between weakly bonded or solvated atomic xenon and xenon in the hitherto characterized molecules.

Triple oscillating field technique for accurate distance measurements by solid-state NMR
J. Chem. Phys. 128, 015103 (2008)
Navin Khaneja, Niels Chr. Nielsen
We present a new concept for homonuclear dipolar recoupling in magic-angle-spinning (MAS) solid-state NMR experiments which avoids the problem of dipolar truncation. This is accomplished through the introduction of a new NMR pulse sequence design principle: the triple oscillating field technique. We demonstrate this technique as an efficient means to accomplish broadband dipolar recoupling of homonuclear spins, while decoupling heteronuclear dipolar couplings and anisotropic chemicals shifts and retaining influence from isotropic chemical shifts. In this manner, it is possible to synthesize Ising interaction (2IzSz) Hamiltonians in homonuclear spin networks and thereby avoid dipolar truncation—a serious problem essentially all previous homonuclear dipolar recoupling experiments suffer from. Combination of this recoupling concept with rotor assisted dipolar refocusing enables easy readout of internuclear distances through comparison with analytical Fresnel curves. This forms the basis for a new class of solid-state NMR experiments with potential for structure analysis of uniformly 13C labeled proteins through accurate measurement of 13C–13C internuclear distances. The concept is demonstrated experimentally by measurement of C –C , C –C , and C –C internuclear distances in powder samples of the amino acids L-alanine and L-threonine.

Satellite transitions acquired in real time by magic angle spinning (STARTMAS): “Ultrafast” high-resolution MAS NMR spectroscopy of spin I=3/2 nuclei
J. Chem. Phys. 128, 034507 (2008
Michael J. Thrippleton, Thomas J. Ball, and Stephen Wimperis
The satellite transitions acquired in real time by magic angle spinning (STARTMAS) NMR experiment combines a train of pulses with sample rotation at the magic angle to refocus the first- and second-order quadrupolar broadening of spin I=3/2 nuclei in a series of echoes, while allowing the isotropic chemical and quadrupolar shifts to evolve. The result is real-time isotropic NMR spectra at high spinning rates using conventional MAS equipment. In this paper we describe in detail how STARTMAS data can be acquired and processed with ease on commercial equipment. We also discuss the advantages and limitations of the approach and illustrate the discussion with numerical simulations and experimental data from four different powdered solids.

A fully relativistic method for calculation of nuclear magnetic shielding tensors with a restricted magnetically balanced basis in the framework of the matrix Dirac–Kohn–Sham equation
J. Chem. Phys. 128, 104101 (2008)
Stanislav Komorovský, Michal Repiský, Olga L. Malkina, Vladimir G. Malkin, Irina Malkin Ondík, and Martin Kaupp
A new relativistic four-component density functional approach for calculations of NMR shielding tensors has been developed and implemented. It is founded on the matrix formulation of the Dirac–Kohn–Sham (DKS) method. Initially, unperturbed equations are solved with the use of a restricted kinetically balanced basis set for the small component. The second-order coupled perturbed DKS method is then based on the use of restricted magnetically balanced basis sets for the small component. Benchmark relativistic calculations have been carried out for the 1H and heavy-atom nuclear shielding tensors of the HX series (X=F,Cl,Br,I), where spin-orbit effects are known to be very pronounced. The restricted magnetically balanced basis set allows us to avoid additional approximations and/or strong basis set dependence which arises in some related approaches. The method provides an attractive alternative to existing approximate two-component methods with transformed Hamiltonians for relativistic calculations of chemical shifts and spin-spin coupling constants of heavy-atom systems. In particular, no picture-change effects arise in property calculations.

Stimulated echoes and two-dimensional nuclear magnetic resonance spectra for solids with simple line shapes
J. Chem. Phys. 128, 114506 (2008)
Burkhard Geil, Gregor Diezemann, and Roland Böhmer
Nuclear magnetic resonance (NMR) experiments on ion conductors often yield rather unstructured spectra, which are hard to interpret if the relation between the actual translational motion of the mobile species and the changes of the NMR frequencies is not known. In order to facilitate a general analysis of experiments on solids with such spectra, different models for the stochastic evolution of the NMR frequencies are considered. The treated models involve random frequency jumps, diffusive evolutions, or approximately fixed frequency jumps. Two-dimensional nuclear magnetic resonance spectra as well as stimulated-echo functions for the study of slow and ultraslow translational dynamics are calculated for Gaussian equilibrium line shapes. The results are compared with corresponding ones from rotational models and with experimental data.

Spin dynamics in the modulation frame: Application to homonuclear recoupling in magic angle spinning solid-state NMR
J. Chem. Phys. 128, 124503 (2008)
Gaël De Paëpe, Józef R. Lewandowski, and Robert G. Griffin
We introduce a family of solid-state NMR pulse sequences that generalizes the concept of second averaging in the modulation frame and therefore provides a new approach to perform magic angle spinning dipolar recoupling experiments. Here, we focus on two particular recoupling mechanisms—cosine modulated rotary resonance (CMpRR) and cosine modulated recoupling with isotropic chemical shift reintroduction (COMICS). The first technique, CMpRR, is based on a cosine modulation of the rf phase and yields broadband double-quantum (DQ) 13C recoupling using >70 kHz 1,C/2 rf field for the spinning frequency r/2=10–30 kHz and 1H Larmor frequency 0,H/2 up to 900 MHz. Importantly, for p="> 5, CMpRR recouples efficiently in the absence of 1H decoupling. Extension to lower p values (3.5 p<5) 2 ="750">

31P Magic Angle Spinning NMR Spectroscopy for Probing Local Environments in Paramagnetic Europium-Substituted Wells-Dawson Polyoxotungstates
Inorg. Chem., 46 (19), 7861 -7869, 2007
Wenlin Huang, Lynn C. Francesconi, and Tatyana Polenova
A series of europium-substituted Wells-Dawson polyoxotungstates were addressed by 31P magic angle spinning (MAS) NMR spectroscopy. The electron-nuclear dipolar interaction dominates the 31P spinning-sideband envelopes. The experimental electron-nuclear dipolar anisotropies were found to be in good agreement with those calculated based on the known crystallographic coordinates and effective magnetic moments and assuming a point-dipole approximation. These electron-nuclear dipolar anisotropies directly report on the anion stoichiometry and on the positional isomerism, indicating that 31P MAS NMR spectroscopy may be a useful and quick analytical probe of the local environment in Wells-Dawson solids containing localized europium paramagnetic centers.

Probing Lead(II) Bonding Environments in 4-Substituted Pyridine Adducts of (2,6-Me2C6H3S)2Pb: An X-ray Structural and Solid-State 207Pb NMR Study
Inorg. Chem., 46 (21), 8625 -8637, 2007
Glen G. Briand, Andrew D. Smith, Gabriele Schatte, Aaron J. Rossini, and Robert W. Schurko
The effect of subtle changes in the -electron donor ability of 4-substituted pyridine ligands on the lead(II) coordination environment of (2,6-Me2C6H3S)2Pb (1) adducts has been examined. The reaction of 1 with a series of 4-substituted pyridines in toluene or dichloromethane results in the formation of 1:1 complexes [(2,6-Me2C6H3S)2Pb(pyCOH)]2 (3), [(2,6-Me2C6H3S)2Pb(pyOMe)]2 (4), and (2,6-Me2C6H3S)2Pb(pyNMe2) (5) (pyCOH = 4-pyridinecarboxaldehyde; pyOMe = 4-methoxypyridine; pyNMe2 = 4-dimethylaminopyridine), all of which have been structurally characterized by X-ray crystallography. The structures of 3 and 4 are dimeric and have -trigonal bipyramidal S3N bonding environments, with the 4-substituted pyridine nitrogen and bridging sulfur atoms in axial positions and two thiolate sulfur atoms in equatorial sites. Conversely, compound 5 is monomeric and exhibits a -trigonal pyramidal S2N bonding environment at lead(II). The observed structures may be rationalized in terms of a simple valence bond model and the -electron donor ability of the 4-pyridine ligands as derived from the analysis of proton affinity values. Solid-state 207Pb NMR experiments are applied in combination with density functional theory (DFT) calculations to provide further insight into the nature of bonding in 4, 5, and (2,6-Me2C6H3S)2Pb(py)2 (2). The lead chemical shielding (CS) tensor parameters of 2, 4, and 5 reveal some of the largest chemical shielding anisotropies (CSA) observed in lead coordination complexes to date. DFT calculations using the Amsterdam Density Functional (ADF) program, which take into account relativistic effects using the zeroth-order regular approximation (ZORA), yield lead CS tensor components and orientations. Paramagnetic contributions to the lead CS tensor from individual pairs of occupied and virtual molecular orbitals (MOs) are examined to gain insight into the origin of the large CSA. The CS tensor is primarily influenced by mixing of the occupied MOs localized on the sulfur and lead atoms with virtual MOs largely comprised of lead 6p orbitals.

Investigating the Vanadium Environments in Hydroxylamido V(V) Dipicolinate Complexes Using 51V NMR Spectroscopy and Density Functional Theory
Inorg. Chem., 46(22); 9285-9293, 2007
Kristopher J. Ooms, Stephanie E. Bolte, Jason J. Smee, Bharat Baruah, Debbie C. Crans, and Tatyana Polenova Using 51V magic angle spinning solid-state NMR, SSNMR, spectroscopy and quantum chemical DFT calculations we have characterized the chemical shift and quadrupolar coupling parameters of a series of eight hydroxylamido vanadium(V) dipicolinate complexes of the general formula VO(dipic)(ONR1R2)(H2O) where R1 and R2 can be H, CH3, or CH2CH3. This class of vanadium compounds was chosen for investigation because of their seven-coordinate vanadium atom, a geometry for which there is limited 51V SSNMR data. Furthermore, a systematic series of compounds with different electronic properties are available and allows for the effects of ligand substitution on the NMR parameters to be studied. The quadrupolar coupling constants, CQ, are small, 3.0-3.9 MHz, but exhibit variations as a function of the ligand substitution. The chemical shift tensors in the solid state are sensitive to changes in both the hydroxylamide substituent and the dipic ligand, a sensitivity which is not observed for isotropic chemical shifts in solution. The chemical shift tensors span ~1000 ppm and are nearly axially symmetric. On the basis of DFT calculations of the chemical shift tensors, one of the largest contributors to the magnetic shielding anisotropy is an occupied molecular orbital with significant vanadium dz2 character along the V=O bond.

Structure of (NH4)3GaF6 Investigated by Multinuclear Magic-Angle Spinning NMR Spectroscopy in Comparison with Rietveld Refinement
Inorg. Chem., 47 (2), 663 -670, 2008
Thoralf Krahl, Mike Ahrens, Gudrun Scholz, Detlef Heidemann, and Erhard Kemnitz
The structure of ammonium gallium cryolite (NH4)3GaF6 was investigated by 19F and 69,71Ga magic-angle spinning (MAS) NMR in comparison with X-ray powder diffraction followed by Rietveld refinement. In agreement with previous thermodynamic measurements, NMR experiments on (NH4)3GaF6 support the model of rigid GaF6 octahedra. At high spinning speeds (30 kHz), the scalar coupling between the six equivalent 19F nuclei and 69,71Ga can be directly observed in the powder spectra. The coupling constants are J19F69Ga = 197 Hz and J19F71Ga = 264 Hz. To explain the 71Ga spectra recorded at 3 kHz a small distribution of quadrupolar frequencies has to be included. The spread of the spinning sidebands hints to a largest Q value of 28 kHz for 71Ga. This can be explained by the occurrence of highly symmetric GaF6 octahedra, which are tilted against the surrounding atoms. In addition, the incomplete motional excitation does not average out the quadrupolar effects. NMR findings are in discrepancy to those of Rietveld refinement. As result it appears that X-ray diffraction is not sensitive enough to deliver proper results.

Lead and Aluminum Bonding in Pb-Al Metaphosphate Glasses
Inorg. Chem., 47 (2), 690 -698, 2008
J. E. Tsuchida, J. Schneider, P. S. Pizani, and S. L. Oliveira
The bonding properties of cations in phosphate glasses determine many short- and medium-range structural features in the glass network, hence influencing bulk properties. In this work, Pb-Al-metaphosphate glasses (1 - x)Pb(PO3)2·xAl(PO3)3 with 0 x 1 were analyzed to determine the effect of the substitution of Pb by Al on the glass structure in the metaphosphate composition. The glass transition temperature and density were measured as a function of the Al concentration. The vibrational and structural properties were probed by Raman spectroscopy and nuclear magnetic resonance of 31P, 27Al, and 207Pb. Aluminum incorporates homogeneously in the glass creating a stiffer and less packed network. The average coordination number for Al decreases from 5.9 to 5.0 as x increases from 0.1 to 1, indicating more covalent Al-O bonds. The coordination number of Pb in these glasses is greater than 8, showing an increasing ionic behavior for compositions richer in Al. A quantitative analysis of the phosphate speciation shows definite trends in the bonding of AlOn groups and phosphate tetrahedra. In glasses with x <> 0.48 more than one nonbridging O can be linked to AlOn polyhedra. There is no corner sharing of O between AlOn and PbOn polyhedra nor between AlOn themselves throughout the compositional range. The PbOn coordination polyhedra show considerable nonbridging O sharing, with each O participating in the coordination sphere of at least two Pb. The bonding preferences determined for Al are consistent with the behavior observed in Na-Al and Ca-Al metaphosphates, indicating this may be a general behavior for ternary phosphate glasses.

Cs4P2Se10: A new compound discovered with the application of solid-state and high temperature NMR
Journal of Solid State Chemistry, Volume 180, Issue 10, October 2007, Pages 2877-2884
Matthew A. Gave, Christian G. Canlas, In Chung, Ratnasabapathy G. Iyer, Mercouri G. Kanatzidis
and David P. Weliky
The new compound Cs4P2Se10 was serendipitously produced in high purity during a high-temperature synthesis done in a nuclear magnetic resonance (NMR) spectrometer. 31P magic angle spinning (MAS) NMR of the products of the synthesis revealed that the dominant phosphorus-containing product had a chemical shift of −52.8 ppm that could not be assigned to any known compound. Deep reddish brown well-formed plate-like crystals were isolated from the NMR reaction ampoule and the structure was solved with X-ray diffraction. Cs4P2Se10 has the triclinic space group P-1 with a=7.3587(11) Å, b=7.4546(11) Å, c=10.1420(15) Å, α=85.938(2)°, β=88.055(2)°, and γ=85.609(2)° and contains the [P2Se10]4− anion. To our knowledge, this is the first compound containing this anion that is composed of two tetrahedral (PSe4) units connected by a diselenide linkage. It was also possible to form a glass by quenching the melt in ice water, and Cs4P2Se10 was recovered upon annealing. The static 31P NMR spectrum at 350 °C contained a single peak with a −35 ppm chemical shift and a 7 ppm peak width. This study highlights the potential of solid-state and high-temperature NMR for aiding discovery of new compounds and for probing the species that exist at high temperature.

MAS-NMR study of lithium zinc silicate glasses and glass-ceramics with various ZnO content
Journal of Solid State Chemistry, Volume 181, Issue 2, February 2008, Pages 269-275
Madhumita Goswami, Govind P. Kothiyal, Lionel Montagne
and Laurent Delevoye
Lithium zinc silicate glasses of composition (mol%): 17.5Li2O–(72−x)SiO2–xZnO−5.1Na2O−1.3P2O5−4.1B2O3, 5.5 x 17.7, were prepared by conventional melt-quenched technique and converted to glass-ceramic by controlled crystallization process. 29Si and 31P MAS-NMR was used to characterize the structure of both glass and glass-ceramic samples. Despite the complex glass composition, Q2, Q3 and Q4 sites are identified from 29Si MAS-NMR, which relative intensities are found to vary with the ZnO content, indicating a network depolymerization by ZnO. Moreover, well separated Q3 and Q4 resonances for low ZnO content indicates the occurrence of phase separation. From 31P MAS-NMR, it is seen that phosphorus is mainly present in the form of ortho-(Q0) and pyro-phosphate (Q1) structural units and variation of ZnO content did not have much effect on these resonances, which provides an additional evidence for phase separation in the glass. On conversion to glass-ceramics, lithium disilicate (Li2Si2O5), lithium zinc ortho-silicate (Li3Zn0.5SiO4), tridymite (SiO2) and cristobalite (SiO2) were identified as major silicate crystalline phases. Using 29Si MAS-NMR, quantification of these silicate crystalline phases is carried out and correlated with the ZnO content in the glass-ceramics samples. In addition, 31P spectra unambiguously revealed the presence of crystalline Li3PO4 and (Na,Li)3PO4 in the glass-ceramics.

Self-Assemblies Based on [Cp2Mo2(CO)4( , 2-P2)] - Solid-State Structure and Dynamic Behaviour in Solution
Chem. Eur. J., Volume 14, Issue 1, Date: December 28, 2007, Pages: 282-295
Manfred Scheer, Prof. Dr. , Laurence J. Gregoriades, Dr. , Manfred Zabel, Dr. , Junfeng Bai, Prof. Dr. , Ingo Krossing, Prof. Dr. , Gunther Brunklaus, Dr. , Hellmut Eckert, Prof. Dr.
Reaction of complex [Cp2Mo2(CO)4( , 2-P2)] (Cp=C5H5 (1)) with CuPF6, AgX (X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4) and [(Ph3P)Au(THF)][PF6] (THF=tetrahydrofuran), respectively, results in the facile formation of the dimers 3 b-h of the general formula [M2({Cp2Mo2 (CO)4( , 2: 2-P2)}2)({Cp2Mo2(CO)4 ( , 2: 1: 1-P2)}2)][X]2 (M=Cu, Ag, Au; X=BF4, ClO4, PF6, SbF6, Al{OC(CF3)3}4). As revealed by X-ray crystallography, all these dimers comprise dicationic moieties that are well-separated from the weakly coordinating anions in the solid state. If 1 is allowed to react with AgNO2 and LAuCl (L=CO or tetrahydrothiophene), respectively, the dimer [Ag2{Cp2Mo2 (CO)4( , 2: 1: 1-P2)}2( 2-NO2)2] (5) and the complex [AuCl{Cp2Mo2(CO)4( , 2: 1-P2)}] (6) are formed, which have also been characterised by X-ray crystallography. In compounds 5 and 6, the anions remain coordinated to the Group 11 metal centres. Spectroscopic data suggest that the dimers 3 b-h display dynamic behaviour in solution and this is discussed by using the comprehensive results obtained for 3 g (M=Ag; X=Al{OC(CF3)3}4) as a basis. The interpretation of the experimental results is facilitated by density functional theory (DFT) calculations on 3 g (structures, energetics, NMR shielding tensors). The 31P magic angle spinning (MAS) NMR spectra recorded for the dimers 3 b (M=Cu; X=PF6) and 3c (M=Ag; X=BF4) as well as that of the previously reported one-dimensional (1 D) polymer [Ag2{Cp2Mo2(CO)4( , 2: 1: 1-P2)}3( , 1: 1-NO3)]n[NO3]n (4) are also discussed herein and the strong dependence of the chemical shift of the phosphorus atoms within each compound on subtle structural differences in the solid state is demonstrated. Furthermore, the X-ray crystallographic and 31P MAS NMR spectroscopic characterisation of a new polymorph of 1 is reported.

Self-Assembled Amphotericin B Is Probably Surrounded by Ergosterol: Bimolecular Interactions as Evidenced by Solid-State NMR and CD Spectra
Chem. Eur. J., Volume 14, Issue 4, Date: January 28, 2008, Pages: 1178-1185
Yusuke Kasai, Dr., Nobuaki Matsumori, Dr., Yuichi Umegawa, Shigeru Matsuoka, Dr., Hiroyuki Ueno, Hiroki Ikeuchi, Tohru Oishi, Prof. Dr., Michio Murata, Prof. Dr.
Amphotericin B (AmB) is thought to exert its pharmacological effects by forming a barrel-stave assembly with ergosterol in fungal membranes. To examine the interaction between AmB and ergosterol (Erg) or cholesterol (Cho), 13C- and 19F-labelled covalent conjugates were prepared as reported previously (N. Matsumori et al. Chem. Biol. 2004, 11, 673-679). The CD spectra of the conjugates in a membrane-bound form suggested that the distance between the heptaene moieties of the ergosterol conjugates AmB-C2-(6-F)Erg 2 and AmB-C2-Erg 3 is similar to that of AmB in ergosterol-containing membranes, but significantly larger than that of AmB in nonsterol or cholesterol-containing membranes. These observations suggest that, as is the case with ergosterol-containing membranes, the conjugated sterol moiety prevents the close contact between the heptaene moieties within the membrane that would reduce channel conductivity of the AmB assemblies. To further investigate this bimolecular interaction, we recorded the solid-state NMR spectra of conjugates 2 and AmB-C2-(6-F)Cho 4, which are composed of uniformly 13C-labelled AmB and 6-fluorinated ergosterol or cholesterol; the conjugates were expected to facilitate the estimation of distances between the fluorine and carbon atoms. By using rotor-synchronous double resonance (rotational echo double resonance of X cluster; RDX) experiments, we deduced the distance between the fluorine atom and its nearest carbon atom in the heptaene moiety of 2 to be less than 8.6 Å. This indicates that the B ring of ergosterol comes close to the AmB polyene moiety. A conformational search of the AmB-ergosterol conjugate by using distance constraints derived from the RDX results suggested that ergosterol molecules possibly surround the AmB assembly, which is in contrast with the conventional image in which ergosterol is inserted into AmB molecules.

Octahedral Adducts of Dichlorosilane with Substituted Pyridines: Synthesis, Reactivity and a Comparison of Their Structures and 29Si NMR Chemical Shifts
Chem. Eur. J., Volume 14, Issue 10 , Pages 3164 - 3176
Gerrit W. Fester, Jörg Wagler, Dr. , Erica Brendler, Dr., Uwe Böhme, Dr. , Gerhard Roewer, Prof. Dr. , Edwin Kroke, Prof. Dr.
H2SiCl2 and substituted pyridines (Rpy) form adducts of the type all-trans-SiH2Cl2 2 Rpy. Pyridines with substituents in the 4- (CH3, C2H5, H2C CH, (CH3)3C, (CH3)2N) and 3-positions (Br) give the colourless solids 1 a-f. The reaction with pyrazine results in the first 1:2 adduct (2) of H2SiCl2 with an electron-deficient heteroaromatic compound. Treatment of 1 d and 1 e with CHCl3 yields the ionic complexes [SiH2(Rpy)4]Cl2 6 CHCl3 (Rpy=4-methylpyridine (3 d) and 4-ethylpyridine (3 e)). All products are investigated by single-crystal X-ray diffraction and 29Si CP/MAS NMR spectroscopy. The Si atoms are found to be situated on centres of symmetry (inversion, rotation), and the Si N distances vary between 193.3 pm for 1 c (4-(dimethylamino)pyridine complex) and 197.3 pm for 2. Interestingly, the pyridine moieties are coplanar and nearly in an eclipsed position with respect to the SiH2 units, except for the ethyl-substituted derivative 1 e, which shows a more staggered conformation in the solid state. Calculation of the energy profile for the rotation of one pyridine ring indicates two minima that are separated by only 1.2 kJ mol-1 and a maximum barrier of 12.5 kJ mol-1. The 29Si NMR chemical shifts ( iso) range from -145.2 to -152.2 ppm and correlate with the electron density at the Si atoms, in other words with the +I and +M effects of the substituents. Again, compound 1 e is an exception and shows the highest shielding. The bonding situation at the Si atoms and the 29Si NMR tensor components are analysed by quantum chemical methods at the density functional theory level. The natural bond orbital analysis indicates polar covalent Si H bonds and very polar Si Cl bonds, with the highest bond polarisation being observed for the Si N interaction, which must be considered a donor-acceptor interaction. An analysis of the topological properties of the electron distribution (AIM) suggests a Lewis structure, thereby supporting this bonding situation.

Aaron's Journal Update

J. Phys. Chem. B, 111 (45), 12977 -12984, 2007. 10.1021/jp075840f S1520-6106(07)05840-3 Web Release Date: October 25, 2007
Thermal Degradation in a Trimodal Poly(dimethylsiloxane) Network Studied by 1H Multiple Quantum NMR
Jason R. Giuliani,
Erica L. Gjersing, Sarah C. Chinn, Ticora V. Jones, Thomas S. Wilson, Cynthia T. Alviso, Julie L. Herberg, Mark A. Pearson, and Robert S. Maxwell*
Abstract: Thermal degradation of a filled, cross-linked siloxane material synthesized from poly(dimethylsiloxane) chains of three different average molecular weights and with two different cross-linking species has been studied by 1H multiple quantum (MQ) NMR methods. Multiple domains of polymer chains were detected by MQ NMR exhibiting residual dipolar coupling (<>) values of 200 and 600 Hz, corresponding to chains with high average molecular weight between cross-links and chains with low average molecular weight between cross-links or near the multifunctional cross-linking sites. Characterization of the <> values and changes in <> distributions present in the material were studied as a function of time at 250 C and indicate significant time-dependent degradation. For the domains with low <>, a broadening in the distribution was observed with aging time. For the domain with high <>, increases in both the mean <> and the width in <> were observed with increasing aging time. Isothermal thermal gravimetric analysis reveals a 3% decrease in weight over 20 h of aging at 250 C. Degraded samples also were analyzed by traditional solid-state 1H NMR techniques, and off-gassing products were identified by solid-phase microextraction followed by gas chromatography-mass spectrometry. The results, which will be discussed here, suggest that thermal degradation proceeds by complex competition between oxidative chain scissioning and postcuring cross-linking that both contribute to embrittlement.

J. Phys. Chem. B, 111 (46), 13156 -13166, 2007. 10.1021/jp073968r S1520-6106(07)03968-5 Web Release Date: October 31, 2007
High-Pressure -Al(OH)3 and -AlOOH Phases and Isostructural Hydroxides/Oxyhydroxides: New Structural Insights from High-Resolution 1H and 27Al NMR
Xianyu Xue
* and Masami Kanzaki
Abstract: In order to shed light on the proton distributions and order/disorder in high-pressure -Al(OH)3 and -AlOOH phases, two-dimensional, high-resolution 1H CRAMPS (FSLG)-MAS NMR and 27Al 3QMAS NMR spectra have been obtained. For -Al(OH)3, the 1H CRAMPS-MAS NMR revealed two peaks with an intensity ratio close to 2:1. The 27Al MAS and 3QMAS NMR suggest a single Al site with a well-defined local structure. For -AlOOH, the 1H and 27Al NMR indicate the presence of a single H and Al site each. These results are consistent with crystal structures refined from X-ray diffraction. For comparison, 1H MAS and CRAMPS-MAS NMR spectra were also obtained for several other hydroxides/oxyhydroxides, including In(OH)3 and InOOH that have similar structures to -Al(OH)3 and -AlOOH, respectively. These data not only provide additional insights into the proton distributions in these important crystal structure classes but also together provide a better defined quantitative correlation between 1H chemical shift and hydrogen-bonding O···O distance.

J. Phys. Chem. B, 111 (47), 13353 -13356, 2007. 10.1021/jp077036z S1520-6106(07)07036-8 Web Release Date: November 7, 2007
Solid-State NMR Spectroscopy Reveals That Water Is Nonessential to the Core Structure of -Synuclein Fibrils
Kathryn D. Kloepper,
Kevin L. Hartman, Daniel T. Ladror, and Chad M. Rienstra*
Abstract: Protein aggregation is implicated in the etiology of numerous neurodegenerative diseases. An understanding of aggregation mechanisms is enhanced by atomic-resolution structural information, of which relatively little is currently available. Lewy bodies, the pathological hallmark of Parkinson's disease, contain large quantities of fibrillar -synuclein (AS). Here we present solid-state NMR spectroscopy studies of dried AS fibrils. The spectra have high resolution and sensitivity, and the site-resolved chemical shifts agree very well with those previously observed for hydrated fibrils. The conserved chemical shifts indicate that bulk water is nonessential to the fibril core structure. Moreover, the sample preparation procedure yields major improvements in spectral sensitivity, without compromising spectral resolution. This advance will greatly assist the atomic-resolution structural analysis of AS fibrils

J. Phys. Chem. B, 111 (51), 14362 -14369, 2007. 10.1021/jp075531p S1520-6106(07)05531-9 Web Release Date: December 4, 2007
Crystal Polymorphism of Protein GB1 Examined by Solid-State NMR Spectroscopy and X-ray Diffraction
Heather L. Frericks Schmidt,
Lindsay J. Sperling, Yi Gui Gao, Benjamin J. Wylie, John M. Boettcher, Scott R. Wilson, and Chad M. Rienstra*
Abstract: The study of micro- or nanocrystalline proteins by magic-angle spinning (MAS) solid-state NMR (SSNMR) gives atomic-resolution insight into structure in cases when single crystals cannot be obtained for diffraction studies. Subtle differences in the local chemical environment around the protein, including the characteristics of the cosolvent and the buffer, determine whether a protein will form single crystals. The impact of these small changes in formulation is also evident in the SSNMR spectra; however, the changes lead only to correspondingly subtle changes in the spectra. Here, we demonstrate that several formulations of GB1 microcrystals yield very high quality SSNMR spectra, although only a subset of conditions enable growth of single crystals. We have characterized these polymorphs by X-ray powder diffraction and assigned the SSNMR spectra. Assignments of the 13C and 15N SSNMR chemical shifts confirm that the backbone structure is conserved, indicative of a common protein fold, but side chain chemical shifts are changed on the surface of the protein, in a manner dependent upon crystal packing and electrostatic interactions with salt in the mother liquor. Our results demonstrate the ability of SSNMR to reveal minor structural differences among crystal polymorphs. This ability has potential practical utility for studying the formulation chemistry of industrial and therapeutic proteins, as well as for deriving fundamental insights into the phenomenon of single-crystal growth.

J. Phys. Chem. B, 112 (4), 1189 -1197, 2008. 10.1021/jp077714h S1520-6106(07)07714-0 Web Release Date: January 8, 2008
Quaternary Ammonium Room-Temperature Ionic Liquid Including an Oxygen Atom in Side Chain/Lithium Salt Binary Electrolytes: Ionic Conductivity and 1H, 7Li, and 19F NMR Studies on Diffusion Coefficients and Local Motions
Kikuko Hayamizu,
* Seiji Tsuzuki, Shiro Seki, Yasutaka Ohno, Hajime Miyashiro, and Yo Kobayashi
Abstract:A room-temperature ionic liquid (RTIL) of a quaternary ammonium cation having an ether chain, N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)amide (DEME-TFSA), is a candidate for use as an electrolyte of lithium secondary batteries. In this study, the electrochemical ionic conductivity, , of the neat DEME-TFSA and DEME-TFSA-Li doped with five different concentrations of lithium salt (LiTFSA) was measured and correlated with NMR measurements of the diffusion coefficients D and the spin-lattice relaxation times T1 of the individual components DEME (1H), TFSA (19F), and lithium ion (7Li). The ion conduction of charged ions can be activated with less thermal energy than ion diffusion which contains a contribution from paired ions in DEME-TFSA. In the doped DEME-TFSA-Li samples, the and D values decreased with increasing salt concentration, and within the same sample generally DLi < DTFSA < DDEME except for the sample having the lowest salt concentration at low temperatures. Since plots of the temperature dependence of T1 of the 1H and 7Li resonances showed T1 minima, the correlation times c(H) and c(Li) were calculated for reorientational motions of DEME and the lithium jump, respectively. At the same temperature, c(Li) is longer than c(H), suggesting that the molecular motion of DEME occurs more rapidly than the lithium jump. Combining the DLi and c(Li), averaged distances for the lithium jump were estimated.

J. Phys. Chem. B, 112 (4), 1226 -1231, 2008. 10.1021/jp077396m S1520-6106(07)07396-8 Web Release Date: January 9, 2008
Probing the Porosity of Cocrystallized MCM-49/ZSM-35 Zeolites by Hyperpolarized 129Xe NMR
Yong Liu, Weiping Zhang,
* Sujuan Xie, Longya Xu, Xiuwen Han, and Xinhe Bao*
Abstract:One- and two-dimensional 129Xe NMR spectroscopy has been employed to study the porosity of cocrystallized MCM-49/ZSM-35 zeolites under the continuous flow of hyperpolarized xenon gas. It is found by variable-temperature experiments that Xe atoms can be adsorbed in different domains of MCM-49/ZSM-35 cocrystallized zeolites and the mechanically mixed counterparts. The exchange of Xe atoms in different types of pores is very fast at ambient temperatures. Even at very low temperature two-dimensional exchange spectra (EXSY) show that Xe atoms still undergo much faster exchange between MCM-49 and ZSM-35 analogues in the cocrystallized zeolites than in the mechanical mixture. This demonstrates that the MCM-49 and ZSM-35 analogues in cocrystallized zeolites may be stacked much closer than in the physical mixture, and some parts of intergrowth may be formed due to the partially similar basic structure of MCM-49 and ZSM-35.

J. Phys. Chem. B, 112 (4), 1267 -1274, 2008. 10.1021/jp075662q S1520-6106(07)05662-3 Web Release Date: January 5, 2008
NMR Chemical Shifts of the Rhodopsin Chromophore in the Dark State and in Bathorhodopsin: A Hybrid QM/MM Molecular Dynamics Study
Ute F. Röhrig
and Daniel Sebastiani*
Abstract: We investigate nuclear magnetic resonance (NMR) parameters of the rhodopsin chromophore in the dark state of the protein and in the early photointermediate bathorhodopsin via first-principles molecular dynamics simulations and NMR chemical shift calculations in a hybrid quantum/classical (QM/MM) framework. NMR parameters are particularly sensitive to structural properties and to the chemical environment, which allows us to address different questions about the retinal chromophore in situ. Our calculations show that both the 13C and the 1H NMR chemical shifts are rather insensitive to the protonation state of Glu181, an ionizable amino acid side chain located in the vicinity of the isomerizing 11-cis bond. Thus, other techniques should be better suited to establish its protonation state. The calculated chemical shifts for bathorhodopsin further support our previously published theoretical structure, which is in very good agreement with more recent X-ray data.

J. Phys. Chem. B, 112 (11), 3470 -3478, 2008. 10.1021/jp076073n S1520-6106(07)06073-7 Web Release Date: February 26, 2008
31P Chemical Shift Tensors for Canonical and Non-canonical Conformations of Nucleic Acids: A DFT Study and NMR Implications
Jana P ececht lov , Petr Padrta, Markéta L. Munzarov , and Vladimír Sklen
Abstract:31P chemical shift anisotropy (CSA) tensors have been calculated for a set of selected DNA and RNA backbone conformations using density functional theory. The set includes canonical A-RNA, A-DNA, BI-DNA, BII-DNA, ZI-DNA, and ZII-DNA as well as four A-RNA-type, seven non-A-RNA-type, and three non-canonical DNA conformations. Hexahydrated dimethyl phosphate has been employed as a model. The 31P chemical shift tensors obtained are discussed in terms of similarities in the behavior observed for gauche-gauche (gg) and gauche-trans (gt) conformations around the P-O bonds. We show that torsion angles and are major determinants of the isotropic chemical shift iso and of the component of the traceless chemical shift tensor, which is revealed in separate ranges of both iso and for gg- and gt-conformers, respectively. A clear distinction between the two conformation types has not been found for the and components, which is attributed to their different directional properties. The 31P CSA tensors exhibit considerable variations resulting in large spans of ~16 ppm for and ~22 ppm for and . We examine the consequences of the CSA variations for predicting the chemical shift changes upon partial alignment csa and for the values of CSA order parameters extracted from the analysis of 31P NMR relaxation data. The theoretical 31P CSA tensors as well as the experimental 31P CSA tensor of barium diethyl phosphate (BDEP) are used to calculate csa for two eclipsed orientations of the CSA and molecular alignment tensors. Percentage differences between the CSA order parameters obtained using the theoretical 31P CSA tensors and the experimental 31P CSA tensor of BDEP, respectively, are also determined.

J. Phys. Chem. B, 112 (6), 1586 -1593, 2008. 10.1021/jp073428u S1520-6106(07)03428-1 Web Release Date: January 23, 2008
15N and 13C High-Resolution Solid-State NMR Study of the Polymorphism of the L-Enantiomer of N-Benzoylphenylalanine
Sebastian Olejniczak,
Justyna Miku a-Pacholczyk, Colan E. Hughes, and Marek J. Potrzebowski*
Abstract:In this paper, several approaches which allow the investigation of mixtures of polymorphs, employing modern solid-state NMR (SS NMR) spectroscopy are reported. A convenient methodology for characterization of the hydrogen bonding and molecular conformation of a polymorphic sample by means of one-dimensional and two-dimensional, 13C and 15N NMR experiments as well as CSA tensor analysis and theoretical calculations is presented. Two-dimensional heteronuclear SS NMR allowed definition of the polymorphic domain of N-benzoyl-L-phenylalanine (N-Bz-Phe). The graphical method of Herzfeld and Berger was used to measure the 13C and 15N spinning sideband intensities which allowed the calculation of NMR parameters for labeled centers of N-Bz-Phe. The experimental data were compared with computed results obtained by means of the DFT hybrid method with B3PW91 functional and 6-311++G** basis set.

J. Phys. Chem. B, 112 (11), 3470 -3478, 2008. 10.1021/jp076073n S1520-6106(07)06073-7 Web Release Date: February 26, 2008
31P Chemical Shift Tensors for Canonical and Non-canonical Conformations of Nucleic Acids: A DFT Study and NMR Implications
Jana P ececht lov , Petr Padrta, Markéta L. Munzarov , and Vladimír Sklen
Abstract:31P chemical shift anisotropy (CSA) tensors have been calculated for a set of selected DNA and RNA backbone conformations using density functional theory. The set includes canonical A-RNA, A-DNA, BI-DNA, BII-DNA, ZI-DNA, and ZII-DNA as well as four A-RNA-type, seven non-A-RNA-type, and three non-canonical DNA conformations. Hexahydrated dimethyl phosphate has been employed as a model. The 31P chemical shift tensors obtained are discussed in terms of similarities in the behavior observed for gauche-gauche (gg) and gauche-trans (gt) conformations around the P-O bonds. We show that torsion angles and are major determinants of the isotropic chemical shift iso and of the component of the traceless chemical shift tensor, which is revealed in separate ranges of both iso and for gg- and gt-conformers, respectively. A clear distinction between the two conformation types has not been found for the and components, which is attributed to their different directional properties. The 31P CSA tensors exhibit considerable variations resulting in large spans of ~16 ppm for and ~22 ppm for and . We examine the consequences of the CSA variations for predicting the chemical shift changes upon partial alignment csa and for the values of CSA order parameters extracted from the analysis of 31P NMR relaxation data. The theoretical 31P CSA tensors as well as the experimental 31P CSA tensor of barium diethyl phosphate (BDEP) are used to calculate csa for two eclipsed orientations of the CSA and molecular alignment tensors. Percentage differences between the CSA order parameters obtained using the theoretical 31P CSA tensors and the experimental 31P CSA tensor of BDEP, respectively, are also determined.

J. Phys. Chem. C, 111 (45), 17146 -17154, 2007. 10.1021/jp070941z S1932-7447(07)00941-7 Web Release Date: October 18, 2007
Solid-State Characterization of the Nuclear and Electronic Environments in a Boron-Fluoride Co-doped TiO2 Visible-Light Photocatalyst
Enrique A. Reyes-Garcia, Yanping Sun, and Daniel Raftery*
Abstract:We describe the synthesis of a visible light absorbing boron-fluoride co-doped TiO2 photocatalyst by a sol-gel methodology and its structural characterization using magnetic resonance techniques. The formation of photoactive sites was induced by pyrolysis under anaerobic conditions at temperatures of 400 to 500 C, followed by a short exposure to air or oxygen gas and rapid cooling. 11B solid-state nuclear magnetic resonance analysis of B/F-TiO2 shows that the chemical environment of the photochemically active B/F co-doped TiO2 can be described as tetrahedrally coordinated BO4 units ( = -1.4 ppm). 19F NMR indicates that fluorine species form part of the Ti coordination sphere and are of the form TiO5F ( = -152 ppm). Similarly, X-ray photoelectron spectroscopy indicates that fluorine is found at lattice positions forming O-Ti-F fragments. Electron paramagnetic resonance spectroscopy, coupled to spectral simulation of the sample calcined at 485 C, shows that the radicals formed in this material are mainly located on two distinct Ti3+ species. The UV/vis characterization of B/F co-doped TiO2 shows the presence of intraband gap states likely responsible for its absorption of visible light (2.4 eV), while the indirect band gap transition remains unaltered (3.1 eV). The B/F co-doped TiO2 material shows good visible light photocatalytic activity for the photochemical oxidation of methylene blue.

J. Phys. Chem. C, 111 (47), 17564 -17569, 2007. 10.1021/jp074511k S1932-7447(07)04511-6 Web Release Date: November 7, 2007
27Al, 47,49Ti, 31P, and 13C MAS NMR Study of VX, GD, and HD Reactions with Nanosize Al2O3, Conventional Al2O3 and TiO2, and Aluminum and Titanium Metal
Abstract: Reactions of VX, GD, and HD with Al2O3, TiO2 (anatase and rutile), aluminum, and titanium metal powders have been studied by 27Al, 47,49Ti, 31P, and 13C MAS NMR. VX, GD, and HD hydrolyze on both nanosize and conventional Al2O3. A significant droplet size effect on the reaction kinetics is observed. For VX and GD, 27Al and 31P MAS NMR detect the formation of aluminum phosphonate complexes. Similarly, GD hydrolysis on TiO2 yields titanium phosphonate species as detected by 31P MAS NMR. Attempts at obtaining 47,49Ti NMR spectra of these species and those of titanium phosphonate model compounds at 14 T were marginally successful. 47,49Ti NMR spectra were obtainable for anatase and titanium metal; thus, severe second-order quadrupolar linebroadening is suspected for the titanium phosphonate complexes. 47,49Ti NMR spectra obtained for anatase at high magnetic field (17.5 and 21 T) showed anticipated improvement in peak width and resolution. GD reacted with aluminum and titanium powder in the presence of water results in acid-dissolution of the metals and the formation of their respective metal phosphonates

J. Phys. Chem. C, 111 (49), 18279 -18287, 2007. 10.1021/jp077089g S1932-7447(07)07089-6 Web Release Date: November 9, 2007
Study of the Structure of OH Groups on MgO by 1D and 2D 1H MAS NMR Combined with DFT Cluster Calculations
Céline Chizallet,
* Guylène Costentin, Hélène Lauron-Pernot, Michel Che, Christian Bonhomme, Jocelyne Maquet, Françoise Delbecq, and Philippe Sautet
Abstract: Complex 1H MAS NMR spectra of hydroxylated MgO powders have been assigned by combining DFT embedded cluster calculations and experiments using single pulse, Hahn-echo, and 2D NOESY like sequences. Chemical shifts calculations suggest the qualitative classification of protons into three main categories, characterized by different chemical shifts ranges. The highest chemical shifts ( H > -0.7 ppm) are proposed to be characteristic of hydrogen-bond donor OH groups (threefold O3C-H, fourfold O4C-H, and fivefold O5C-H localized on corners, edges, and in valleys respectively). The lowest chemical shifts ( H < -0.7 ppm) are associated to isolated and hydrogen-bond acceptor twofold O2C-H and onefold O1C-H, whereas the central signal at H = -0.7 ppm would correspond to isolated O3C-H and O4C-H on kinks and divacancies. These assignments can be refined by considering dipolar interactions between vicinal protons observed thanks to the NOESY like sequence. It is thus shown that some hydrogen bond donor OH groups are characterized by a lower chemical shift than expected from calculations and also contribute to the central signal. Calculated thermal stabilities and chemical shifts suggest that these protons correspond to O4C-H on monatomic steps. The final assignment is fully consistent with previous experimental results on CD3OH adsorption and quantitative analysis of the evolution of spectra with temperature. This study illustrates the synergism between experiments and theory, by comparison with the results obtained by either one.

J. Phys. Chem. C, 111 (50), 18615 -18623, 2007. 10.1021/jp076410s S1932-7447(07)06410-2 Web Release Date: November 29, 2007 Copyright © 2007 American Chemical Society
Solid-State NMR Studies of the Formation of Monomers and Dimers in Stearic Acid Confined in Titanate Nanotubes
Xiao-Ping Tang,
* Gregory Mogilevsky, Harsha Kulkarni, and Yue Wu
Abstract: This work employs two-dimensional solid-state NMR methods to uncover the structure and molecular arrangement of physically trapped stearic acid (SA) inside a titanate nanotube (TiNT). Thermal annealing the mixture of SA and the water-washed TiNT is shown to induce slow physical trapping of SA into the TiNT. In contrast to that the solid-state bulk exhibits only one carbonyl 13C peak of NMR and consists solely of dimer, the physically trapped SA exhibits two carbonyl 13C peaks with different chemical shifts that are assigned respectively to dimer and monomer both by the 13C homonuclear double-quantum measurement and by the 13C chemical-shift-tensor measurement. The trapped SA monomer and dimer are shown to grow simultaneously during thermal annealing with a constant number ratio between them at ~1:1. The 13C homonuclear double-quantum and the 1H-13C HETCOR spectra indicate that the trapped SA monomer and dimer do not form separated clusters but are neighbors to each other. As such, the trapped SA in the TiNT undertakes a novel molecular arrangement alternating with dimer and monomer. The carbonyl 13C chemical-shift-tensor data and the hydroxyl 1H isotropic-chemical-shift data suggest that the hydrogen bond of the dimer is stronger under nanoconfinement than in the solid bulk SA. The observed novel molecular arrangement for the fatty acid and the correlated variation of the carbonyl 13C and the hydroxyl 1H chemical shift between the different molecular arrangements are of theoretical interest.

J. Phys. Chem. C, 111 (50), 18744 -18750, 2007. 10.1021/jp0759527 S1932-7447(07)05952-3 Web Release Date: November 28, 2007
Kinetic Features of the Platinum Catalyzed Hydrolysis of Sodium Borohydride from 11B NMR Measurements
G. Guella,
* B. Patton, and A. Miotello
Abstract:A full kinetic analysis of the platinum catalyzed hydrolysis of sodium borohydride (NaBH4) in alkaline media has been performed using 11B NMR (nuclear magnetic resonance) spectroscopy with a Pt/C 5 wt % commercial powder as catalyst. By fitting the NMR data by least-square regression techniques, the rate constants of platinum catalyzed borohydride hydrolysis have been evaluated. Within the investigated [borohydride]/[catalyst] molar ratio of 200-1500, the rate law has been found to be of first-order in catalyst and zero order in borohydride. Whereas no reagent-isotope kinetic effect is observed in the NaBD4/H2O reaction system, the hydrolysis of NaBH4 in deuterated water shows a significant solvent-kinetic isotope effect. In both cases, however, 11B NMR analysis indicates that the main reaction product is the tetrahydroxyborate species (D)nH4-nBO4- (n = 1, 2, 3, 4) followed by a minor amount of the partially scrambled BH3D- species while the hydrolysis-intermediates HnB(OD)4-n- (n = 1, 2, 3) species are not detectable during all the reaction time. These results suggest that, differently from the Pd catalyzed/borohydride(borodeuteride) hydrolytic process, the hydrogen/deuterium exchange is slower than hydrolysis and that the rate-determining step of the overall process is the formation of the monohydroxy-borohydride intermediate BH3OH-. The activation energy of the overall process has been also evaluated by 11B NMR rate measurements taken at different temperatures.
J. Phys. Chem. C, 112 (1), 80 -88, 2008. 10.1021/jp7095955 S1932-7447(70)09595-X Web Release Date: December 13, 2007
Solid-State NMR Investigation of the Possible Existence of "Nanoblocks" in the Clear Solution Synthesis of MFI Materials
Colin A. Fyfe,
* Richard J. Darton, Celine Schneider, and Franziska Scheffler
Abstract: The structure of the intermediate species in the clear solution synthesis of the MFI framework (zeolite ZSM 5) has been investigated using the characteristic 13C, 14N, 15N, and 2D spectra of the tetrapropylammonium (TPA) template ions as probes as well as the 29Si spectra of the silicate species present in samples that can be isolated by centrifugation. Comparison with the corresponding spectra of the final products that can be characterized by X-ray diffraction indicates that there is no evidence for the involvement of nanospecies, as has been proposed, and that crystallization is most probably from an amorphous gel. This conclusion is supported by the lack of deuterium rotational echo double-resonance dephasing of the 29Si spectra by deuterated TPA of the earliest intermediate species obtained, while it is clearly observed in the final product. These observations indicate that any TPA ions present in the gel phase are not in intimate contact with the silicon nuclei as they would be if in the local MFI environment. This is supported by the very low amount of TPA found by 14N NMR, which is much less than needed for the proposed nano intermediates and the fact that the TPA present can be removed by simple re-suspension in water and recovery.

J. Phys. Chem. C, 112 (2), 500 -513, 2008. 10.1021/jp074816z S1932-7447(07)04816-9
Solid-State NMR Determination of the Zeolite ZSM-5/ortho-Xylene Host-Guest Crystal Structure
Colin A. Fyfe
* and J. S. Joseph Lee
Abstract: Solid-state NMR spectroscopy has been used to successfully determine the complete three-dimensional structure of the ortho-xylene-ZSM-5 zeolite complex, using complexes of three different specifically deuterated ortho-xylene molecules. The structures determined from these, at two different temperatures, using both cross polarization (CP) and CP drain experiments all agree. The ortho-xylene molecule is located at the channel intersection with one ring carbon-methyl carbon bond oriented along the straight channel while the other ring carbon-methyl carbon bond points toward the zigzag channel.

J. Phys. Chem. C, 112 (3), 860 -866, 2008. 10.1021/jp075130+ S1932-7447(07)05130-8
Probing the Local Environments of Fluorine in Ce-Based Fluorite-Type Oxyfluorides with 19F MAS NMR Spectroscopy

Laetitia Sronek,
Jérôme Lhoste, Manuel Gaudon, Christophe Legein, Jean-Yves Buzaré, Monique Body, Guillaume Crinière, Alain Tressaud, Stanislav Pechev, and Alain Demourgues*
Abstract:Ce-based oxyfluorides Ce1-xCaxO2-x-y/2Fy, with 0.13 x 0.29 and 0.03 y 0.24, adopting the fluorite structure, were prepared by coprecipitation in basic fluorinated medium followed by an annealing under air at T = 600 C. XRD profile and Rietveld analyses allowed the determination of the crystallite sizes as well as the unit cell parameters. In this series, fluorine atoms are in tetrahedral environments of cations. 19F magic angle spinning (MAS) NMR spectroscopy was used to study the local structure and fluoride ion environments. Four distinct 19F resonances were observed and assigned to four different types of environments, FCa4, FCa3Ce, FCa2Ce2, and FCaCe3, whose proportions vary with the calcium content. In these Ce-Ca oxyfluorides, F- anions have a great affinity for Ca2+ cations leading to an increase of the F amount with the Ca content. The absence of FCe4 environment is explained from a steric standpoint: the F-Ce bond lengths in the network are too short to accept fluorine ions in the vicinity of four Ce4+ cations. Finally, the increase of the average Ce-X (X = O, F) bond ionicity with the Ca and F contents was correlated to the evolution of the UV shielding properties of these new compounds, which exhibit outstanding UV absorption and scattering (in the visible range) properties.

J. Phys. Chem. C, 112 (4), 1081 -1089, 2008. 10.1021/jp076679b S1932-7447(07)06679-4 Web Release Date: January 5, 2008
Periodic DFT and High-Resolution Magic-Angle-Spinning (HR-MAS) 1H NMR Investigation of the Active Surfaces of MgCl2-Supported Ziegler-Natta Catalysts. The MgCl2 Matrix
Vincenzo Busico,
* Mauro Causà, Roberta Cipullo, Raffaele Credendino, Francesco Cutillo, Nic Friederichs, Raffaele Lamanna, Annalaura Segre, and Valeria Van Axel Castelli #
Abstract: "Classical" MgCl2-supported Ziegler-Natta catalysts (ZNCs) continue to dominate the industrial production of isotactic polypropylene. There is a growing awareness of the inherent competitive edge of these low-cost systems over single-center (primarily metallocene) catalysts and of the potential for further improvement, particularly if deeper insight into the structure of the catalytic surfaces and the mechanisms of their modification by means of electron donors can be achieved. In the framework of a project ultimately aiming at the implementation of ZNCs with known and controlled surface structures, we are revisiting this whole area by using a combination of advanced computational (periodic DFT) and spectroscopic (high-resolution magic-angle-spinning 1H NMR spectroscopy) tools. In this article, we report on the neat MgCl2 matrix and on model MgCl2/electron-donor adducts. The results indicate that the (104) surface, with five-coordinate Mg cations, is the dominant lateral termination in well-formed large crystals, as well as in highly activated MgCl2 samples prepared by ball-milling. In the latter case, a minor fraction of surface Mg sites with a higher extent of coordinative unsaturation [e.g., four-coordinate Mg cations on (110) edges and/or at crystal corners or other defective locations] also appear to be present. RMe2Si(OMe) (R = octadecyl) binds to both types of Mg sites, albeit with different strengths resulting in different mobilities. The less-electron-donating RMeSi(OMe)2, in contrast, binds to the more unsaturated Mg sites only. The approach described herein is currently being extended to MgCl2/TiCln systems, as well as to their adducts with internal and external donors of different natures, strengths, and steric demands.

J. Phys. Chem. C, 112 (6), 2215 -2221, 2008. 10.1021/jp077254s S1932-7447(07)07254-8 Web Release Date: January 23, 2008
6Li{31P} Rotational-Echo, Double-Resonance Studies of Lithium Ion Site Dynamics in Li3V2(PO4)3
L. S. Cahill,
C. W. Kirby, and G. R. Goward*
Abstract: Low-temperature 6Li{31P} rotational-echo, double-resonance (REDOR) measurements were used to study lithium mobility within each of the three Li sites in monoclinic Li3V2(PO4)3. Each of the Li ions was found to experience a different reduced dipolar coupling with the nearest 31P nucleus. Under fast magic-angle spinning (MAS) conditions (40 kHz), the three crystallographic 31P sites in Li3V2(PO4)3 were resolved. On the basis of the known Li-P internuclear distances, the 31P resonances were assigned by determining the degree of signal attenuation at each phosphorus site. The attenuation of the Li-P dipolar coupling, compared to simulations of the static case, was associated with rattling of the Li ions within the lattice. The relative mobility at each Li site is correlated with structural properties including the shortest Li-O contact within the void and bond valence calculations.

J. Phys. Chem. C, 112 (8), 2997 -3007, 2008. 10.1021/jp077687v S1932-7447(07)07687-X Web Release Date: February 6, 2008
Acidic Properties of SSZ-33 and SSZ-35 Novel Zeolites: a Complex Infrared and MAS NMR Study
Barbara Gil,
Stacey I. Zones, Son-Jong Hwang, Martina Bejblov , and Ji í ejka*
Abstract:Two novel zeolites SSZ-33 and SSZ-35 were investigated with respect to their acidic properties using different probe molecules to characterize the accessibility and acid strength of Lewis and Br nsted acid sites. Ammonia, pyridine, pivalonitrile, and acetonitrile-d3 were used as probe molecules, and the results were correlated with 27Al and 1H magic angle spinning (MAS) NMR. Both SSZ-33 and SSZ-35 zeolites were found to possess bridging Si-OH-Al groups of virtually uniform and high acid strength. For both SSZ-33 and SSZ-35, there is the typical presence of highly disturbed OH groups (IR band around 3500 cm-1), which amounts to almost half of the overall Br nsted acidity. It was found that almost all bridging Si-OH-Al groups in SSZ-33 are located in the 12-MR rings. Both acetonitrile-d3 and pyridine sorptions suggest the presence of two types of Lewis sites in SSZ-35, differing in acid strength and electron-acceptor properties, whereas in the SSZ-33 zeolite only one type is present. The relative strength of these sites is higher than that of the Br nsted type for SSZ-35 and is of comparable strength for SSZ-33. 1H and 27Al MAS NMR measurements during thermal treatment allowed the assignment of NMR peaks to different surface OH species and the establishment of their relation to IR bands. NMR spectroscopy enabled the quantitative analysis of both free and hydrogen-bonded OH groups separately, showing that for both zeolites the amount of disturbed sites is higher than the number of free OH groups.

J. Phys. Chem. C, 112 (8), 3042 -3048, 2008. 10.1021/jp076637n S1932-7447(07)06637-X Web Release Date: February 5, 2008
NMR Study of the Chemisorption and Surface Chemistry of Methylamine on Pd/SiO2
Henrik von Schenck,
Neil Kumar, Christopher A. Klug,* and John H. Sinfelt
Abstract: Results of an investigation of the interaction of methylamine with a Pd/SiO2 catalyst utilizing nuclear magnetic resonance (NMR) spectroscopy are presented. Two sets of experiments were conducted. In one set, a sample of catalyst was initially exposed to 13CH315NH2 at 77 K and then subjected to a lengthy equilibration period at 190 K. A 13C spectrum at 77 K obtained on the sample at this point exhibited a single symmetric line at a frequency very close to the resonance frequency for methylamine in the absence of the catalyst. The line is attributed to methylamine adsorbed without dissociation. In 13C spectra obtained at 77 K on the sample after each of a series of subsequent annealing periods at successively higher temperatures in the range 253-298 K, the line exhibited a gradual broadening on the downfield side. Deconvolution of the spectra resolved the original symmetric line from a very broad downfield line attributed to partially dehydrogenated surface species designated by the formula (CN)Hx. In the second set of experiments, 13CH315NH2 was adsorbed on a sample of catalyst at 298 K. The sample was then annealed at successively higher temperatures in the range 325-450 K. Deconvolution of the 13C spectra obtained at 298 K after the various annealing periods revealed extensive formation of dimethylamine, reaching a maximum after the annealing period at 400 K. Ammonia and methane were first detected in the 15N and 13C spectra, respectively, after the annealing period at 375 K. During the annealing periods at 425 and 450 K, the dimethylamine decomposed almost completely, leaving only methane, ammonia, and residual surface species.

J. Phys. Chem. C, 112 (9), 3164 -3169, 2008. 10.1021/jp710894t S1932-7447(71)00894-X Web Release Date: February 13, 2008
NMR Confirmation for Formation of [B12H12]2- Complexes during Hydrogen Desorption from Metal Borohydrides
Son-Jong Hwang,
* Robert C. Bowman, Jr. Joseph W. Reiter, Job Rijssenbeek, Grigorii L. Soloveichik, Ji-Cheng Zhao, Houria Kabbour, and Channing C. Ahn
Abstract: 11B NMR spectroscopy has been employed to identify the reaction intermediates and products formed in the amorphous phase during the thermal hydrogen desorption of metal tetrahydroborates (borohydrides) LiBH4, Mg(BH4)2, LiSc(BH4)4, and the mixed Ca(AlH4)2-LiBH4 system. The 11B magic angle spinning (MAS) and cross polarization magic angle spinning (CPMAS) spectral features of the amorphous intermediate species closely coincide with those of a model compound, closo-borane K2B12H12 that contains the [B12H12]2- anion. The presence of [B12H12]2- in the partially decomposed borohydrides was further confirmed by high-resolution solution 11B and 1H NMR spectra after dissolution of the intermediate desorption powders in water. The formation of the closo-borane structure is observed as a major intermediate species in all of the metal borohydride systems we have examined.

J. Phys. Chem. C, 112 (13), 5221 -5231, 2008. 10.1021/jp710336h S1932-7447(71)00336-4 Web Release Date: March 8, 2008
Investigations of the Phase Transition and Proton Dynamics in Rubidium Methane Phosphonate Studied by Solid-State NMR
M. Vijayakumar, Jason W. Traer, James F. Britten, and Gillian R. Goward
Abstract:In search of new solid acid proton conductors, we prepared the solid acid rubidium methane phosphonate (RMP). These crystals have a monoclinic structure (P2/c; a = 9.3452, b = 9.3142, and c = 7.5021 Å; = 101.12). The salt incorporates a hydrated lamellar structure. The 1H MAS NMR reveals two different types of acidic protons as well as the water protons in the lamella. The 1H VT MAS NMR of RMP·2H2O single crystal shows a structural phase transition around 320 K, and the high-temperature phase exhibits significant proton dynamics. The proton proximities are established by solid state 1H DQF NMR. The dehydration of RMP crystal leads to structural collapse, and the resultant RMP powder is extremely hygroscopic. The proton environment and dynamics are examined using 1H DQF NMR, which reveals that the dehydrated RMP powder has rigid lattice, in contrast with the hydrated form. Further the 1H VT MAS NMR shows that dehydrated RMP powder has no phase transition, and no significant proton dynamics are observed in the temperature range of 250-350 K. The new hydrated crystal, RMP·2H2O, shows high proton mobility at relatively low temperature (~330 K) and a proton transport mechanism that uniquely relies on crystalline water.

Macromolecules, 40 (24), 8673 -8683, 2007. 10.1021/ma071541c S0024-9297(07)01541-0 Web Release Date: November 1, 2007
Multinuclear Solid-State NMR Characterization, Ion Dissociation, and Dynamic Properties of Lithium-Doped Organic-Inorganic Hybrid Electrolytes Based on Ureasils
Hsien-Ming Kao,
* Tzu-Ti Hung, and George T. K. Fey
Abstract: Solid organic-inorganic hybrid electrolytes based on diureasils doped with LiClO4 have been obtained by the sol-gel process through the reaction of poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether) (H2N-PPG-PEG-PPG-NH2) with 3-isocyanatepropyltriethoxysilane (ICPTES), followed by co-condensation of an epoxy trialkoxysilane, 3-(glycidyloxypropyl)trimethoxylsilane (GLYMO). The structural and dynamic properties of the materials were systematically investigated by a variety of techniques including ac impedance, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), multinuclear (13C, 29Si, 7Li) solid-state NMR, 1H-13C 2D WISE (wide-line separation) NMR, and 7Li pulsed gradient spin-echo (PGSE) NMR measurements. The length of backbone PEG chain, the extent of GLYMO cross-linking, and the salt concentration were varied in order to obtain the materials with high conductivities. A maximum ionic conductivity value of 1.37 × 10-5 S/cm was obtained at 30 C for the hybrid electrolyte with a [O]/[Li] ratio of 32. This ionic conductivity value is 1 order of magnitude higher than that of previously characterized electrolytes based on ureasils without incorporation of GLYMO. The results of 13C cross-polarization magic-angle spinning (CPMAS) NMR with varying contact times and 1H-13C WISE NMR provided a microscopic view of the effects of salt concentrations on the dynamic behavior of the polymer chains. Only one distinct 7Li local environment was detected by variable temperature 7Li-{1H} MAS NMR. The temperature dependence of 7Li static line widths and self-diffusion coefficients showed that there is a strong correlation between the dynamic properties of the charge carriers and the bulk ionic conductivity.

Macromolecules, 41 (2), 372 -386, 2008. 10.1021/ma702140g S0024-9297(70)02140-X Web Release Date: December 18, 2007
Epoxy Networks Reinforced with Polyhedral Oligomeric Silsesquioxanes: Structure and Segmental Dynamics as Studied by Solid-State NMR
Jiri Brus,
* Martina Urbanov , and Adam Strachota
Abstract: The epoxy networks based on poly(propylene oxide) chains cross-linked by diglycidyl ether of Bisphenol A and reinforced by polyhedral oligomeric silsesquioxanes (POSS) provide a typical example of polymer nanocomposites with hierarchical architecture. In addition to characterizing the epoxy-POSS composites, this contribution demonstrates valuable applications of solid-state NMR spectroscopy. The size of domains in the nanocomposites was determined by high-speed MAS 1H-
1H spin-diffusion experiments, offering an alternative to the established methods like SAXS, EM, or AFM. While the latter might fail under certain circumstances (low contrast, or small domains), the 1H-1H spin-diffusion measurement yielded the size of unbroken primary domains, making also possible their distinction from "aggregates of primary domains", the size of the latter being measured by EM or SAXS. Depending on the type of the investigated network the size of the POSS aggregates arising in the nanocomposites was determined to be ca. 1-20 nm. Investigations of molecular dynamics (various "domain-selective" relaxation and recoupling solid-state NMR experiments were applied) yielded information making possible the assignment of the contribution of molecular segments to thermomechanical properties like glass transition temperature and storage shear modulus, and to predict the products' ability to absorb mechanical energy. Remarkable motional heterogeneities were found not only in the amorphous phase, where mobile polymer segments of the "free" domains coexist with the immobilized chains of the "constrained" ones, but also in the crystallites of POSS building blocks, where the amplitudes of segmental reorientations occurring in the midkilohertz frequency region remain relatively large: two-site 180 flips dominating to aromatic rings in the POSSPh crystallites are accompanied by the wobbling of the flip axes with an average fluctuation angle ca. 25 . Similarly, cyclopentyl substituents in the POSSCp crystallites undergo to ca. 35 rotational-diffusion motion.

Macromolecules, 41 (2), 387 -389, 2008. 10.1021/ma702089e S0024-9297(70)02089-2 Web Release Date: December 22, 2007
Chain Structure of Substituted Stilbene-Maleic Anhydride Alternating Copolymer Probed by Solid-State NMR
Min Mao, Chul Kim, Sungsool Wi,
* and S. Richard Turner*
Abstract: Double-quantum heteronuclear local field solid-state NMR spectroscopy (2Q-HLF solid-state NMR) has been employed to investigate the chain structure of N,N,N',N'-tetraethyl-4, 4'-diaminostilbene (TDAS) and 13C labeled maleic anhydride (MA) alternating copolymer. The torsional angle of the H-13C-13C-H part of the anhydride ring was found to be 0 , indicating an all cis configuration of the H-13C-13C-H moiety of the anhydride ring. After hydrolysis of the anhydride groups and protonation of the amino groups, the torsional angle of the H-13C-13C-H moiety of the hydrolyzed anhydride groups appears to be 60 , indicating significant rotation of the polymer backbone. Because of the predominately cis configuration of the H-13C-13C-H part of the anhydride ring, the diethylamino phenyl groups are concentrated on the two sides of the backbone plane and the anhydride groups are in the backbone plane.

Organometallics, 26 (27), 6718–6725 10.1021/om7008638
A Polystyrene-Supported Tin Trichloride Catalyst with a C11-Spacer. Catalysis Monitoring Using High-Resolution Magic Angle Spinning NMR
Vanja Pinoie,
Kevin Poelmans, Hans E. Miltner, Ingrid Verbruggen, Monique Biesemans,* Guy Van Assche, Bruno Van Mele, José C. Martins,§ and Rudolph Willem
Abstract: The cross-linked polystyrene grafted organotin [P-H](1−t)[P-(CH2)11-SnCl3]t, in which [P-H] represents the monomeric unit of the nonfunctionalized polymer and t is the functionalization degree, has been synthesized and characterized by 1D and 2D 1H, 13C, and 119Sn high-resolution magic angle spinning (HRMAS) NMR spectroscopy, elemental analysis, and IR spectrometry. Its catalytic activity was assessed in the transesterification model reaction between ethyl acetate and n-octanol. The catalyst displays an average conversion degree of 76% after 2 h and can be recycled at least nine times. The experimental concentration profiles were fitted to a mechanistic model, from which a turnover frequency in the range of 10−2 s−1 was calculated. Residual tin contents on the order of 5 ppm in the reaction products were assessed by inductively coupled plasma/atomic emission spectroscopy (ICP/AES). The combined use of 1H, 13C, and 119Sn HRMAS NMR and modulated DSC enables one to assess the chemical integrity of the catalyst upon recycling. Detailed analysis of 119Sn HRMAS NMR spectra under various chemical conditions mimicking the reaction mixtures allows gaining a better insight into the catalysis mechanism.