3-Pyridylvinyl benzoxazole-derived multifunctional organic materials—from solid-state photoreactivity to photophysical and electrochemical properties

Abstract

Development of multifunctional organic materials is an area of intense research interest in organic materials chemistry. This study reports the synthesis, crystal structure elucidation and investigation of multiple properties of E-3-pyridylvinyl benzoxazole (3-PVBO) and its methylated analogue, 3-MPVBO. With Z′ = 2, 3-PVBO belongs to a rare class of crystals for which Z′ > 1. Upon methylation, fascinating material properties were observed. [3-MPVBO]I exhibited strong emission spectra and readily available redox states. It exhibited stronger emission at 474 nm, with a larger Stokes shift of 8900 cm⁻¹, than the emission of 3-PVBO at 386 nm, with a Stokes shift of 5450 cm⁻¹. Upon exposure to UV light, crystals of 3-PVBO underwent a solid-state photodimerization reaction in a head-to-tail fashion (HT), leading to the formation of the HT-rctt isomer of the dimer, i.e., 1,3-bis(benzoxazole)-2,4-bis(3-pyridyl)cyclobutane (PBOCB). Herein, the crystal structure, solid-state photoreactivity, and multiple material properties, e.g., photophysical and electrochemical properties, are presented.