4-(4,5-Diphenyl-1H-imidazole-2-yl)phenol: Synthesis and Estimation of Nonlinear Optical Properties using Z-Scan Technique and Quantum Mechanical Calculations

Fatemeh Mostaghni

doi:10.17344/acsi.2020.6299

Abstract

In this study, 4-(4,5-Diphenyl-1H-imidazole-2-yl) phenol is successfully synthesized, and its nonlinear optical properties (NLO) are investigated both experimentally and theoretically. Theoretical investigations have been done by using TD-DFT and B3LYP functional with usual 6-31+G(d,p) basis set. The results of HOMO-LUMO and NBO analysis show the low energy gap, high total dipole moment, and hyperpolarizabilities (β, g) as well as the presence of dipolar excited states with relatively significant dipole-moment changes which are linked to the nonlinearity. The z-scan technique confirmed the NLO properties of title compound. The nonlinear absorption coefficient, refractive index, and third-order susceptibility were found to be 4.044 × 10-1 cmW-1, 2.89 × 10-6 cm2W-1 and 2.2627 × 10-6 esu, respectively. The negative sign of n2 indicated the occurrence of self-defocusing nonlinearity. The results show that the title compound can been used as potential NLO material.

Highlights

The development of photonic technology, nonlinear optical materials have received widespread attention both from the research as well as industrial point of view.[1,2,3] In recent years, many studies have been reported by researchers to find new compounds with high nonlinear optical properties
Unlike inorganic materials in which band structure phenomena cause nonlinear phenomena, in organic materials and polymers, these phenomena arise from the transition of an electron from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO) that caused a transition of the dipole moment from the ground state to the excited state.[14,15,16,17,18]
The wide transparency of the sample in the visible region enables it for the second harmonic generation that required for all nonlinear optical properties (NLO) materials

Summary

Introduction

The development of photonic technology, nonlinear optical materials have received widespread attention both from the research as well as industrial point of view.[1,2,3] In recent years, many studies have been reported by researchers to find new compounds with high nonlinear optical properties. The essential requirements of suitable photonic materials are their high nonlinearity, fast response time, chemical stability, and ease of molecular design.[4,5,6,7,8]. In this context, π-conjugated organic materials have received more attention due to their high nonlinearity and fast response times resulting from the ease of polarizability of the extended mobile π-electron clouds across the molecule.[9,10,11,12,13]. Different types of organic compounds with extensive conjugated π system are expected to exhibit nonlinear optical properties because of π–π interactions that allow an intramolecular charge transfer (ICT).[19,20,21,22,23,24,25,26,27,28,29] ICT is responsible for the broadening of the absorption spectrum, and the reduction of the optical bandgap.[30,31,32]

Methods

Results

Conclusion