A Blue-Green Emitting Oxadiazole: Photophysical, Solvatochromic, and FRET Studies with Core-Shell Quantum Dots.
Abstract
The development of blue-green emitting organic chromophores with excellent optoelectronic properties remains an important issue. In this context, the newly synthesized oxadiazole-based blue-green emitting chromophore, 2-(4-(2-(anthracen-10-yl)vinyl)phenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (AVBO), was accomplished via the donor-π-acceptor (D- π-A) strategy using a Wittig reaction. The integration of aryl-heteroaryl groups and the oxadiazole group was utilized to obtain efficient blue-green emission with excellent optical properties. AVBO exhibited stable and efficient PL in the range of 485-510 nm across diverse solvent environments. Solvatochromic analysis using multiple correlations (Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, and Reichardt) revealed a significantly higher excited-state dipole moment compared to the ground state ([Formula: see text]>[Formula: see text]), with a parallel orientation ([Formula: see text]). The values calculated using these empirical equations were compared with those calculated computationally. Kamlet-Taft and Catalán MLR analyses further identified dominant non-specific solvent interactions ([Formula: see text]) alongside specific hydrogen-bonding donor contributions. To explore its potential in optoelectronic applications, AVBO was integrated into hybrid systems with ZnSe/ZnS core-shell quantum dots (7-8 nm). This assembly functioned as an efficient FRET mechanism, reaching an efficiency of 88% with Förster radii of 6.14-6.16 nm. The quenching kinetics, validated by Stern-Volmer plots, showed both static and dynamic components with super-diffusion-limited rate constants (kq ≈ 1014 /MS). Time-resolved photoluminescence (TRPL) confirmed energy transfer via dipole-dipole interactions. These findings highlight the AVBO-QDs hybrid as a promising, cadmium-free, and tunable emitter for light harvesting, photosensitization, and bio-sensing applications.