Accurate13C and15N Chemical Shift and14N Quadrupolar Coupling Constant Calculations in Amino Acid Crystals:  Zwitterionic, Hydrogen-Bonded Systems

2003 ◽  
Vol 107 (38) ◽  
pp. 7629-7642 ◽  
Author(s):  
Mark Strohmeier ◽  
Dirk Stueber ◽  
David M. Grant
Keyword(s):  
Amino Acid ◽  
Chemical Shift ◽  
Coupling Constant ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Hydrogen Bonded Systems ◽  
Hydrogen Bonded

scholarly journals A multinuclear NMR and quantum chemical study of solid trimethylammonium chloride

2011 ◽  
Vol 89 (9) ◽  
pp. 1036-1046 ◽  
Author(s):  
Glenn H. Penner ◽  
Renee Webber ◽  
Luke A. O’Dell
Keyword(s):  
Chemical Shift ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Spectroscopic Techniques ◽  
Trimethylammonium Chloride ◽  
Coupling Constant ◽  
High Hydrogen ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Hydrogen Position

The solid salt, trimethylammonium chloride (TMAC), is investigated by a combination of NMR spectroscopic techniques and quantum chemical calculations. Chemical shift and nuclear quadrupolar interaction parameters have been measured for 35Cl, 1H/2H, and 15N/14N. These parameters have also been calculated as a function of the hydrogen position in the N···H···Cl fragment. Overall, the measured parameters are consistent with a structure in which the hydrogen is completely transferred to the nitrogen (i.e., N–H···Cl). The high hydrogen chemical shift (10.9 ppm by 2H CP/MAS) and relatively small deuterium quadrupolar coupling constant (127 kHz) indicate a moderately strong N–H···Cl hydrogen bond. A pronounced deuterium isotope effect on the 35Cl quadrupolar coupling constant is observed.

CAN SEMIEMPIRICAL QUANTUM MODELS CALCULATE THE BINDING ENERGY OF HYDROGEN BONDING FOR BIOLOGICAL SYSTEMS?

2009 ◽  
Vol 08 (04) ◽  
pp. 691-711 ◽  
Author(s):  
FENG FENG ◽  
HUAN WANG ◽  
WEI-HAI FANG ◽  
JIAN-GUO YU
Keyword(s):  
Hydrogen Bonding ◽  
Amino Acid ◽  
Amino Acid Residue ◽  
Density Functional ◽  
Biological Systems ◽  
Binding Energies ◽  
Semiempirical Model ◽  
Hydrogen Bonded Systems ◽  
High Level ◽  
Hydrogen Bonded

A modified semiempirical model named RM1BH, which is based on RM1 parameterizations, is proposed to simulate varied biological hydrogen-bonded systems. The RM1BH is formulated by adding Gaussian functions to the core–core repulsion items in original RM1 formula to reproduce the binding energies of hydrogen bonding of experimental and high-level computational results. In the parameterizations of our new model, 35 base-pair dimers, 18 amino acid residue dimers, 14 dimers between a base and an amino acid residue, and 20 other multimers were included. The results performed with RM1BH were compared with experimental values and the benchmark density-functional (B3LYP/6-31G**/BSSE) and Möller–Plesset perturbation (MP2/6-31G**/BSSE) calculations on various biological hydrogen-bonded systems. It was demonstrated that RM1BH model outperforms the PM3 and RM1 models in the calculations of the binding energies of biological hydrogen-bonded systems by very close agreement with the values of both high-level calculations and experiments. These results provide insight into the ideas, methods, and views of semiempirical modifications to investigate the weak interactions of biological systems.

ESE-ENDOR Study and DFT Calculations on Oxovanadium Compounds:  Effect of Axial Anionic Ligands on the51V Nuclear Quadrupolar Coupling Constant

2004 ◽  
Vol 108 (19) ◽  
pp. 4310-4321 ◽  
Author(s):  
Constantino P. Aznar ◽  
Yiannis Deligiannakis ◽  
Evangelos J. Tolis ◽  
Themistoklis Kabanos ◽  
Marcin Brynda ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Coupling Constant ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Anionic Ligands ◽  
Oxovanadium Compounds

A solid-state NMR investigation of the colossal expansion material, Ag3Co(CN)6

2012 ◽  
Vol 90 (10) ◽  
pp. 891-901 ◽  
Author(s):  
Brett C. Feland ◽  
Guy M. Bernard ◽  
Roderick E. Wasylishen
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
Negative Thermal Expansion ◽  
Coupling Constant ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Field Gradients ◽  
Increasing Temperature ◽  
Nmr Properties ◽  
Expansion Behaviour

Presented here is a solid-state NMR investigation of the so-called “colossal expansion” material, Ag3Co(CN)6, a compound that exhibits some of the largest positive and negative thermal expansion properties reported. This study explores the 13C, 15N, and 59Co NMR properties of this material at room temperature and at variable temperatures with the goal of probing the effects of this colossal expansion behaviour on these properties. We found that the flexible nature of the crystal framework leads to a distribution of electric field gradients, and that, oddly enough, no strong correlation is observed between the NMR parameters of Ag3Co(CN)6 and its colossal expansion nature. The 59Co isotropic chemical shift increased and the 59Co nuclear quadrupolar coupling constant decreased with increasing temperature, but neither of these relationships were extraordinary when compared to other octahedral Co(III) complexes. The link between the colossal expansion and the NMR properties of Ag3Co(CN)6 may be the distribution of lattice parameters and hence unusually broad features in the 59Co NMR spectra. The high order of symmetry at the cobalt site resulted in a small quadrupolar coupling constant less than 1 MHz in magnitude. We also observed a |1J(107/109Ag,15N)| value of 96 Hz, the largest 107/109Ag–15N coupling constant reported to date.

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