N-(1H-Benzo[d]imidazol-2-yl)-1-(3-Substituted phenyl)methanimines as optoelectronic and nonlinear optical materials: spectroscopic and computational approaches

OJO N. D.¹*, ADEKUSIBE O. D.¹ and OBI-EGBEDI N. O.¹

1 Department of Chemistry, Faculty of Science, University of Ibadan, Ibadan, Nigeria

* Corresponding author: dammynath@yahoo.com; nd.ojo@ui.edu.ng; Tel. +234 806 480 2584

 

ABSTRACT

Negative environmental impact of fossil fuel and ever-increasing need for renewable energy materials necessitate rigorous search for optoelectronic materials. Photon reabsorption due to small Stokes shift limits the light-emitting potentials of many optical materials. In this research, two benzimidazole Schiff bases (1H-benzo[d]imidazol-2-yl)-1-(3-nitrophenyl)methanimine (BINM) and N-(1H-benzo[d]imidazol-2-yl)-1-(3-hydroxyphenyl)methanimine (BIHM) were synthesized via one-pot single step condensation and characterized using spectrometric (1H NMR, 13C NMR, ESI-MS, FTIR) techniques. Optoelectronic and nonlinear optical (NLO) properties of BINM and BIHM were, herein, explored using spectroscopic, density functional theory (DFT) and Monte Carlo simulation approaches. Absorption, light-harvesting efficiency (LHE) and fluorescence properties were studied in different solvent. LHE, first and second hyperpolarizabilities, and parameters for power conversion efficiency (Voc and ΔGinj) were computed using time-dependent-DFT/B3LYP/6-311++G(d,p) method. Hyperpolarizabilities were compared with urea (standard). Binding properties of BINM and BIHM on TiO2 (anatase 101) were investigated using MC method. Calculated properties agree remarkably with experiment. The compounds display large Stokes shift (> 200 nm), appreciable quantum yield and low band gap. High LHE (80%) and large hyperpolarizabilities were obtained for BINM. BINM displayed higher Voc and ΔGinj than BIHM. Negative adsorption energies of BIHM-TiO₂ (-52.7 kJ/mol) and BINM-TiO₂ (-57.3 kJ/mol) interfaces indicate their strong binding interactions on anatase. The materials possess potentials for optoelectronic and nonlinear optical applications.

Key Words: Schiff base; optoelectronics; dye-sensitizer; nonlinear optical property; Stokes shift