Hydrogen bonding quantum chemical investigation

Cheng, F., Sun, H.H., Zhang, Y., Mukkamala, D., Oldfield, E. Solid state 13C NMR, crystallographic, and quantum chemical investigation of chemical shifts and hydrogen bonding in histidine dipeptides. J. Am. Chem. Soc. 2005, 127,12544-54. 

In general, quantum chemical investigation of the DNA bases in more than two base pairs requires highly accurate methods, because the system contains not only the hydrogen bonding interactions, but also the vdW interactions. 

Most studies concerning pyrimidines originate from biochemical questions. Since these systems are dominated by hydrogen-bonding and/or dispersion contributions, methods beyond the Hartree-Fock level are mandatory. The success of quantum chemical studies in this field is impressive and many effects could be explained on the basis of these theoretical investigations. 

The kinetics and mechanism of pyrrole pyrolysis were investigated by ab initio quantum-chemical calculations. It was revealed that pyrrole undergoes tautomerization to form 2H- and 37/-pyrroles prior to any thermal decomposition. It has been shown that the major product, HCN, arises from a hydrogen migration in pyrrole to form a cyclic carbene with the NH bond intact. Ring scission of the carbene leads to an allenic imine of HCN and propyne which is the lowest energy pathway. The 277-pyrrole... 

Hobza P, Sandorfy C (1984) Quantum chemical and statistical thermodynamic investigations of anesthetic activity. 3. The interaction between CH4, CH3CI, CH2CI2, CHCI3, CCI4, and an O-H- O hydrogen bond. Can J Chem 62 606—609... 

Applying ab initio quantum-chemical methods and density functional theory in the local density approximation, different (BH) spherical clusters for n — 12,20,32,42 and 92 have been investigated. Most of the clusters show nearly icosahedral symmetry. The hydrogen atoms are bonded to the spherical surface as prickles. The relative stability of the spheres measured as the binding energy per molecule has been analyzed. All the clusters studied are very stable, and the spherical (BH)32 cluster Seems to be the most stable structure. The effect of the hydrogen atoms is to increase the stability of the bare boron clusters. 

Hobza, R, Mulder, F., and Sandorfy, C., Quantum chemical and statistical thermodynamic investigations of anesthetic activity. 1. The interaction between chloroform, fluoroform, cyclopropane, and an O—H—0 hydrogen bond, J. Am. Chem. Soc. 103, 1360-1366 (1981). 

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