Issue 47, 2023

Engineering TADF, mechanochromism, and second harmonic up-conversion properties in regioisomeric substitution space

Abstract

This research article explores the distinct TADF efficiency of three donor–acceptor based regio-isomers: DPAOCN (ortho-isomer), DPAMCN (meta-isomer), and DPAPCN (para-isomer). DPAPCN exhibits maximum TADF efficiency in both solution and solid-state with an impressive reverse inter-system crossing (RISC) rate of ∼106 s−1; the underlying cause being the minimum singlet-triplet splitting energy or ΔEST and maximum SOC (spin–orbit coupling) between the S1 & T1 states. Apart from TADF, differences in crystal packing of the regio-isomers result in intriguing bulk phase properties. DPAOCN, with its non-centrosymmetric P212121 space group and substantial crystal void volume, exhibits reversible tri-color mechanochromic luminescence behavior, while the meta and para isomers, due to their centrosymmetric packing and diminished crystal void volume, remain inert to mechanical pressure. Expanding the horizon of possibilities, the non-centrosymmetric nature of ortho-isomer further renders it an excellent SHG material, with a χ(2) value of 0.19 pm V−1 at 1220 nm and a laser-induced damage threshold (LIDT) value of 13.27 GW cm−2. Overall, a comprehensive investigation into the regio-isomers has been carried out, encompassing their TADF, SHG, and mechanochromic luminescent properties.

Graphical abstract: Engineering TADF, mechanochromism, and second harmonic up-conversion properties in regioisomeric substitution space

Supplementary files

Article information

Article type
Edge Article
Submitted
16 Aug. 2023
Accepted
03 Nov. 2023
First published
08 Nov. 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2023,14, 13832-13841

Engineering TADF, mechanochromism, and second harmonic up-conversion properties in regioisomeric substitution space

A. Chatterjee, J. Chatterjee, S. Sappati, R. Tanwar, M. D. Ambhore, H. Arfin, R. M. Umesh, M. Lahiri, P. Mandal and P. Hazra, Chem. Sci., 2023, 14, 13832 DOI: 10.1039/D3SC04280D

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