Document
Role of Delocalization, Asymmetric Distribution of π-Electrons and Elongated Conjugation System for Enhancement of NLO Response of Open Form of Spiropyran-Based Thermochromes
Linked Agent
Kanwal, S, Author
Hamid, M.H.S.A, Author
Ayub, K, Author
Gilani, M.A, Author
Imran, M, Author
Arshad, M, Author
Alkhalifah, M.A, Author
Sheikh, N.S, Author
Mahmood, T, Author
Title of Periodical
Molecules
Country of Publication
Kingdom of Bahrain
Place Published
Sakhir, Bahrain
Publisher
University of Bahrain
Date Issued
2023
Language
English
Subject
English Abstract
Abstract:
Switchable nonlinear optical (NLO) materials have widespread applications in electronics and optoelectronics. Thermo-switches generate many times higher NLO responses as compared to photo-switches. Herein, we have investigated the geometric, electronic, and nonlinear optical properties of spiropyranes thermochromes via DFT methods. The stabilities of close and open isomers of selected spiropyranes are investigated through relative energies. Electronic properties are studied through frontier molecular orbitals (FMOs) analysis. The lower HOMO-LUMO energy gap and lower excitation energy are observed for open isomers of spiropyranes, which imparts the large first hyperpolarizability value. The delocalization of π-electrons, asymmetric distribution and elongated conjugation system are dominant factors for high hyperpolarizability values of open isomers. For deep understanding, we also analyzed the frequency-dependent hyperpolarizability and refractive index of considered thermochromes. The NLO response increased significantly with increasing frequency. Among all those compounds, the highest refractive index value is observed for the open isomer of the spiropyran 1 (1.99 × 10−17 cm2/W). Molecular absorption analysis confirmed the electronic excitation in the open isomers compared to closed isomers. The results show that reversible thermochromic compounds act as excellent NLO molecular switches and can be used to design advanced electronics.
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Identifier
https://digitalrepository.uob.edu.bh/id/d5bd5a7c-59f0-4b09-bd96-c075540e85ca
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