A rational synthesis of a novel imidazo[4,5-f][1,10]phenanthroline templated Schiff base: Characterization, photoluminescence and DFT/TD-DFT study

Abstract

A new imidazo[4,5-f][1,10]phenanthroline (imp) derivative imidazo-N⁵,N⁶-bis((4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)phenyl)methylene)-1,10-phenanthroline-5,6-diamine (impap) was synthesized in five steps starting from bare phenanthroline (phen) precursors. The novel compound was fully characterized by ¹H-NMR, IR, elemental analysis and electrospray ionization mass spectroscopy (ESI-MS) techniques. Solid state emission spectrum of impap showed two distinct strong emission maxima with large Stokes shifts. The ground state gas phase geometry of impap was predicted by DFT calculations. Excited state properties of the molecule were examined through TD-DFT calculations conducted at the optimized geometry. Responsible transitions for the strong fluorescence of impap were assigned to single component charge transfer transitions with large oscillator strengths based on the ground state calculated molecular orbital contributions.

KEY WORDS: Phenanthroline, TD-DFT, Photoluminescence, Stokes shift, 1,10-phenanthroline-5,6-dione, Imidazo[4,5-f][1,10]phenanthroline

Bull. Chem. Soc. Ethiop. 2017, 31(1), 137-147. 

DOI: http://dx.doi.org/10.4314/bcse.v31i1.12