Abstract

MASS SPECTRAL STUDY ON THE FRAGMENTATION OF 3-[2-(3,5- DIMETHYL-1H-PYRAZOL-1-YL)THIAZOL-4-YL]-2H-CHROMEN-2- ONE BY AM1 METHOD

Kodam Sujatha, Bojja Rajeshwar Rao and Vedula Rajeswar Rao*

Abstract

The mass spectrum of 3-[2-(3,5-dimethyl-1H-pyrazol-1-yl)thiazol-4- yl]-2H-chromen-2-one has been studied in the context of correlating fragmentation pathways with electronic charges of atoms. The atomic charges were found to be good prediction for evaluating the fragmentation mechanism and stability of fragments with the electron bombardment. In this connection, considering an isolated molecular fragments in the gas phase, which was surrounded by vacuum using semi-empirical molecular orbital AM1 method, the heats of formation (ΔHf o), dipole moment (μ), ionization potential (IP), full atomic charges and energies of frontier molecular orbitals (EHOMO and ELUMO) have been performed and discussed to evaluate stable fragments.

Keywords: AM1, mass spectrometry, fragments, 3-(2-bromoacetyl)coumarin, thiosemicarbazide, acetylacetone, 3-[2-(3,5-dimethyl-1H-pyrazol-1-yl)thiazol-4-yl]-2Hchromen- 2-one, frontier molecular orbital.