Work

Restriction of photoisomerization from the perspective of deviation from head-on conical deactivation: Insights from DFT-based computations with a demonstrative example

Year: 2025

Type: article

Abstract: Understanding the intricate molecular photophysics of newly synthesized Schiff base probes with structural variability and molecular flexibility often requires a comprehensive correlation between their inherent photophysical properties and spectral behavior, from both experimental and theoretical standpoints. In this study, we present DFT-based quantum chemical calculations, including potential energy curves and surfaces, to investigate the feasibility of cis↔trans isomerization in the ground and excited states using the conical deactivation model. For the purpose we employed the ESIPT-prone Schiff base, 2-((E)-(naphthalene-2-ylimino)-methyl)phenol (NMP), as a representative probe featuring a flexible double bond. Despite its apparent susceptibility to cis-trans isomerization, our detailed photophysical analysis, both experimental and theoretical, reveals that NMP's behavior is predominantly governed by prototropic processes. A subtle deviation from the ideal head-on conical deactivation, combined with a thorough analysis of potential energy curves and surfaces for the prospective cis↔trans isomerization process in the S 0 and S 1 states, reveals and justifies the non-occurrence of photoisomerization. This study highlights the effectiveness of our straightforward DFT/TDDFT based calculations, demonstrating that these methods are often sufficient to capture the trajectory of conical deactivations, without the need for more complex multiconfigurational approaches like CASPT2/CASSCF. The results underscore the critical influence of deviations from a head-on conical deactivation on the occurrence or suppression of cis-trans isomerization, a principle that extends to a wide variety of molecular systems with flexible double bonds.

Source: Heliyon

DOI: 10.1016/j.heliyon.2025.e43697

Authors: Pronab Kundu, Nitin Chattopadhyay

Institutions: Presidency University, Jadavpur University, Pandit Ravishankar Shukla University

Language: English

Topic: Photochemistry and Electron Transfer Studies

Subfield: Physical and Theoretical Chemistry

Field: Chemistry

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,270