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Kosar N, Kanwal S, Hamid MHSA, Ayub K, Gilani MA, Imran M, Arshad M, Alkhalifah MA, Sheikh NS, Mahmood T. Role of Delocalization, Asymmetric Distribution of π-Electrons and Elongated Conjugation System for Enhancement of NLO Response of Open Form of Spiropyran-Based Thermochromes. Molecules 2023; 28:6283. [PMID: 37687112 PMCID: PMC10488622 DOI: 10.3390/molecules28176283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 08/04/2023] [Accepted: 08/04/2023] [Indexed: 09/10/2023] Open
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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Affiliation(s)
- Naveen Kosar
- Department of Chemistry, University of Management and Technology (UMT), C-11, Johar Town, Lahore 54770, Pakistan
| | - Saba Kanwal
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Abbottabad 22060, Pakistan
| | - Malai Haniti S. A. Hamid
- Chemical Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei
| | - Khurshid Ayub
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Abbottabad 22060, Pakistan
| | - Mazhar Amjad Gilani
- Department of Chemistry, COMSATS University Islamabad, Lahore Campus, Lahore 45550, Pakistan
| | - Muhammad Imran
- Department of Chemistry, Faculty of Science, King Khalid University, Abha 61413, Saudi Arabia
| | - Muhammad Arshad
- Institute of Chemistry, The Islamia University of Bahawalpur, Baghdad-ul-Jadeed Campus, Bahawalpur 63100, Pakistan
| | - Mohammed A. Alkhalifah
- Department of Chemistry, College of Science, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - Nadeem S. Sheikh
- Chemical Sciences, Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, Gadong BE1410, Brunei
| | - Tariq Mahmood
- Department of Chemistry, COMSATS University Islamabad, Abbottabad Campus, Abbottabad 22060, Pakistan
- Department of Chemistry, College of Science, University of Bahrain, Sakhir P.O. Box 32038, Bahrain
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