First hyperpolarizability of dithienylethene-based photoswitches: a structure-property relationship study.
- 1Institut für Theoretische Chemie, Universität Ulm Oberberghof 7 89081 Ulm Germany.
- 2Institut für Biologie, Humboldt-Universität zu Berlin Invalidenstraße 42 10115 Berlin Germany [email protected].
- 3Department of Chemistry, GITAM School of Science Hyderabad 502329 Telangana India [email protected] [email protected].
Abstract
Despite their considerable technological potential, structure-property relationships in intramolecular charge-transfer-based photoswitches remain poorly established. Here, we present a quantum-chemical investigation of the first hyperpolarizability (β) of a family of dithienylethene (DTE)-based photoswitches, considering static, electro-optic Pockels, and second-harmonic-generation (SHG) responses. Eight donor (D)/acceptor (A) architectures, with and without alkyne (y) π-extension, are investigated in their open- and closed-ring forms using density functional theory [CAM-B3LYP/6-31+G(d,p)/GD3BJ/(PCM)] in the gas phase and three continuum solvents, with dynamic responses evaluated at 1064 nm. Ring closure generally enhances total first hyperpolarizability (βtot) by restoring through core conjugation, while donor-acceptor asymmetry emerges as the dominant structural factor governing large NLO responses. Alkyne extension further enhances the response when coupled with a push-pull architecture. Solvation modulates both the magnitude and direction of the response, producing pronounced amplification of the closed/open βtot ratio in selected systems and a striking reorientation of the SHG response vector for Dy-yAopen. Time-dependent DFT analysis suggests that the reorientation is associated with a redistribution among nearby excited-state contribution. Importantly, βtot and the directional alignment ratio η are not necessarily correlated. We therefore introduce RNLO as a combined comparative descriptor that captures both response magnitude and directionality. RNLO identifies the closed push-pull architectures, particularly Dy-yAclosed, D-yAclosed, and Dy-Aclosed, as the most favorable systems among the considered chromophores. Overall, the results show that NLO performance is governed by the coupled effects of donor-acceptor asymmetry, ring closure, π-extension, and dielectric environment, and that optimization of both response magnitude and directionality is essential for establishing meaningful structure-property relationships in DTE photoswitches.
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BibTeX
@article{sarkar2026first,
title = {{First hyperpolarizability of dithienylethene-based photoswitches: a structure-property relationship study.}},
author = {Kanchan Sarkar and Ramprasad Misra and Axel Groß and Rudraditya Sarkar},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08114b},
url = {https://europepmc.org/article/MED/42953487},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - First hyperpolarizability of dithienylethene-based photoswitches: a structure-property relationship study.
AU - Kanchan Sarkar
AU - Ramprasad Misra
AU - Axel Groß
AU - Rudraditya Sarkar
PY - 2026
DA - 2026/10/28
JO - RSC advances
DO - 10.1039/d6ra08114b
UR - https://europepmc.org/article/MED/42953487
AB - Despite their considerable technological potential, structure-property relationships in intramolecular charge-transfer-based photoswitches remain poorly established. Here, we present a quantum-chemical investigation of the first hyperpolarizability (β) of a family of dithienylethene (DTE)-based photoswitches, considering static, electro-optic Pockels, and second-harmonic-generation (SHG) responses. Eight donor (D)/acceptor (A) architectures, with and without alkyne (y) π-extension, are investigated in their open- and closed-ring forms using density functional theory [CAM-B3LYP/6-31+G(d,p)/GD3BJ/(PCM)] in the gas phase and three continuum solvents, with dynamic responses evaluated at 1064 nm. Ring closure generally enhances total first hyperpolarizability (βtot) by restoring through core conjugation, while donor-acceptor asymmetry emerges as the dominant structural factor governing large NLO responses. Alkyne extension further enhances the response when coupled with a push-pull architecture. Solvation modulates both the magnitude and direction of the response, producing pronounced amplification of the closed/open βtot ratio in selected systems and a striking reorientation of the SHG response vector for Dy-yAopen. Time-dependent DFT analysis suggests that the reorientation is associated with a redistribution among nearby excited-state contribution. Importantly, βtot and the directional alignment ratio η are not necessarily correlated. We therefore introduce RNLO as a combined comparative descriptor that captures both response magnitude and directionality. RNLO identifies the closed push-pull architectures, particularly Dy-yAclosed, D-yAclosed, and Dy-Aclosed, as the most favorable systems among the considered chromophores. Overall, the results show that NLO performance is governed by the coupled effects of donor-acceptor asymmetry, ring closure, π-extension, and dielectric environment, and that optimization of both response magnitude and directionality is essential for establishing meaningful structure-property relationships in DTE photoswitches.
SN - 2046-2069
ER -