Experimental Photophysical investigation of a new Benzodithiophene–Diisophthalate ester revealing HLCT behavior
Journal of Photochemistry and Photobiology A: Chemistry, vol.477, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 477
- Publication Date: 2026
- Doi Number: 10.1016/j.jphotochem.2026.117130
- Journal Name: Journal of Photochemistry and Photobiology A: Chemistry
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, BIOSIS, Chemical Abstracts Core, Chimica, Compendex
- Keywords: Benzodithiophene, Donor-pi-acceptor, Hybridized local and charge-transfer, Pi-conjugated small molecule
- Eskisehir Osmangazi University Affiliated: Yes
Abstract
A new quasi-planar benzodithiophene-based π-conjugated molecule, BDT-diISO , incorporating a BDT electron-donating core, phenyl π-spacers, and dimethyl ester acceptor units, has been designed, synthesized, and comprehensively characterized. Owing to its D-π-A molecular architecture, BDT-diISO exhibits high solubility and strong fluorescence in solution (ΦPL ∼ 0.51), together with observable dipole-dependent solvatochromism. Steady-state and time-resolved photoluminescence studies reveal a tunable excited-state behavior that evolves systematically from local excited (LE) → hybridized local and charge transfer (HLCT) → charge-transfer (CT) character with increasing solvent polarity. In low-to-medium polarity media, the molecule displays LE-dominant HLCT behavior with long lifetimes (τavg ≈ 4.0 ns), small Stokes shifts, and high radiative efficiency. In contrast, highly polar environments promote a CT-dominated state featuring markedly quenched fluorescence (ΦPL ∼ 0.03), a large Stokes shift (∼112 nm), broad emission (FWHM ∼95 nm), and moderate intramolecular charge separation (0.256 charge·nm). These results demonstrate, for the first time, the ability of diisophthalate-coupled BDT π-frameworks to support finely tunable LE/HLCT/CT excited states and accessible (R)ISC channels. The unique structure-property relationships unveiled here establish BDT-diISO as a promising platform for solution-processable luminescent materials and polarity-responsive optoelectronic or sensing applications.