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

S Karslıoğlu,H Yılmaz,S Demir,S Gördük

doi:10.4314/bcse.v31i1.12

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

Highlights

The syntheses of imidazo[4,5-f][1,10]phenanthroline (Scheme 1) and its derivatives started with the syntheses of phenanthrimidazoles by Steck and Day [1]
In 1H-NMR spectrum of impap, a broad singlet at 13.9 ppm related to imidazolic protons and another peaks related to CH protons between 7.8-9.1 ppm were observed
A novel member of imidazo[4,5-f][1,10]phenanthroline family was prepared in five successive steps and characterized successfully by spectroscopic measurements

Summary

Introduction

The syntheses of imidazo[4,5-f][1,10]phenanthroline (imp) (Scheme 1) and its derivatives started with the syntheses of phenanthrimidazoles by Steck and Day [1]. There are numerous studies on organic compounds or metal complexes containing imp derivatives as functionalities that mainly account for the property of interest together with different groups or ancillary ligands. The resulting mixture was filtered and the pale yellow precipitate was washed with water, ethanol and ether respectively and dried in a vacuum oven at 80 °C [42].

Results

Conclusion