Properties of a new fluorescent coumarin derivatization reagent employing molecular modelling techniques

Coumarins are widely employed in chemical analysis due to their fluorescent properties. The conformation and the electronic properties of a newly synthesized derivatization reagent namely BrMOZPhC (4-bromomethyl-coumarin-7-phenyl[6,7-b](9,6)oxazine) was studied. The molecule was found to possess completely planar structure, which enhances the fluorescent quantum yield. Furthermore it exhibits a high degree of aromaticity, as can be depicted by the localization of the HOMO and LUMO orbitals as well as by the charge distribution between the ground and the excited state. The bond connecting the heterocyclic system of the molecule with the phenyl ring is also of significant importance because despite the fact that imposes the only degree of rotational freedom to the molecule, has been found to possess partial double bond character. The properties of the molecule were studied employing both semi-empirical and ab initio calculations whereas its fine electronic structure was explored using Bader's AIM theory.