𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Comparison of the use of the MNDO and MINDO/3 methods with ab initio methods to study tautomerism in histamine, 2- and 4-methylhistamine

✍ Scribed by Sid Topiol

Publisher
John Wiley and Sons
Year
1987
Tongue
English
Weight
568 KB
Volume
8
Category
Article
ISSN
0192-8651

No coin nor oath required. For personal study only.

✦ Synopsis

The semiempirical MNDO and MIND013 methods are used to study the various tautomeric forms of histamine, 2-methylhistamine, and 4-methylhistamine. Comparisons of the optimized structures and tautomerization energies are made with values obtained from ab initio Hartree-Fock calculations using the 3-21G and STO-3G basis sets. Based on these results and previous comparisons of STO-3G results with x-ray structures, the present results indicate that while there are some differences in the values of the structural parameters, the changes in structure upon tautomerization and/or protonation are very similar. Further analysis of the MNDO and MIND0/3 structures by means of their utilization in 3-21G and STO-3G calculations indicates that either of these semiempirical methods provides reliable values for the structural parameters. Both methods give good qualitative agreement with the ab initio calculations for the relative energies of the various tautomers in the three compounds. In these studies the MNDO method appears to give better quantitative agreement with the 3-21G and STO-3G results than the MINDO/3 method.

📜 SIMILAR VOLUMES

Ability of empirical potentials (AMBER,
Ability of empirical potentials (AMBER, CHARMM, CVFF, OPLS, Poltev) and semi-empirical quantum chemical methods (AM1, MNDO/M, PM3) to describe H-bonding in DNA base pairs; comparison with ab initio results
✍ P. Hobza; F. Hubálek; M. Kabeláč; P. Mejzlík; J. Šponer; J. Vondrášek 📂 Article 📅 1996 🏛 Elsevier Science 🌐 English ⚖ 287 KB

Various empirical potentials (AMBER 3.0, AMBER 4.1, CHARMM 23, CVFF, OPLS, Poltev) and semi-empirical quantum chemical methods (AM1, PM3, MNDO/M) were tested to reproduce the ab initio MP2 stabilization energies of DNA H-bonded base pairs (26 different base pairs). The best performance of an empiric

Structures and Thermodynamics of the Sul
Structures and Thermodynamics of the Sulfuranes SF3CN and SF2(CN)2 as well as of the Persulfurane SF4(CN)2 − An ab initio MO Study by the G3(MP2) Method
✍ Yana Steudel; Ralf Steudel 📂 Article 📅 2003 🏛 John Wiley and Sons 🌐 English ⚖ 109 KB

## Abstract At the G3(MP2) level of theory the __trans__ isomer 1a of the hypothetical molecule SF~4~(CN)~2~ is more stable than the __cis__ isomer 1b by 8 kJ·mol^−1^. The isomerization of 1a to 1b requires an activation enthalpy of 319 kJ·mol^−1^ at 298 K. The decomposition of __trans__‐SF~4~(CN)~

A validated SIM GC/MS method for the sim
A validated SIM GC/MS method for the simultaneous determination of dextromethorphan and its metabolites dextrorphan, 3-methoxymorphinan and 3-hydroxymorphinan in biological matrices and its application to in vitro CYP2D6 and CYP3A4 inhibition study
✍ Marios Spanakis; Ioannis S. Vizirianakis; Maria Mironidou-Tzouveleki; Ioannis Ni 📂 Article 📅 2009 🏛 John Wiley and Sons 🌐 English ⚖ 347 KB 👁 2 views

## Abstract Dextromethorphan is used as a probe drug for assessing CYP2D6 and CYP3A4 activity __in vivo__ and __in vitro__. A SIM GC/MS method without derivatization for the simultaneous determination of dextromethorphan and its metabolites, dextrorphan, 3‐methoxymorphinan and 3‐hydroxymorphinan, i