Optoelectronic and NLO potential of styryl-functionalized nitroisoxazoles for OLED technologies

Abstract

Herein, we report the synthesis of eight 5-substituted-3-methyl-4-nitroisoxazoles with styryl structures (B1–B8) characterized by ¹H NMR, ¹³C NMR, FT-IR, HRMS, and XRD. Their optical properties were evaluated using UV-vis and fluorescence spectroscopy, electrochemical behavior via cyclic voltammetry, and electronic structure and nonlinear optical (NLO) properties using density functional theory (DFT) calculations. The compounds were obtained in yields ranging from 19% to 96%, with B4 and B8 being reported for the first time. Electrochemical analysis revealed quasi-reversible redox behavior, indicating chemical stability and efficient charge transfer. Notably, the low reducibility of the nitro group in B7 minimizes the formation of reactive species and enhances excitonic recombination and emission efficiency, supporting its application in functional OLEDs. All compounds exhibited strong NLO responses owing to their D–π–A configurations, with β values ranging from 71.59 to 379.95 esu and γ values from 218.02 to 1789.03 esu, significantly surpassing urea. Additionally, their high thermal stability (>200 °C) reinforces their potential for applications in optics, photonics, and optoelectronic devices, highlighting their suitability for light-emitting technologies and high-performance NLO systems.