Synthesis, structure, photoluminescence and photochromism of phosphindole oxide and benzo[b]thiophene S,S-dioxide derivatives

Luminogens with aggregation-induced emission (AIE) characteristics have attracted much attention because of their broad applications in optoelectronics, bioprobes and environmental monitoring. Herein, two family of luminogens based on phosphindole oxide (PIO) and benzo[b]thiophene S,S-dioxide (BTO) cores and thiophene substituents are prepared and fully characterized. Their structures and optical properties are comparatively investigated by crystallography, spectroscopy, theory calculation, etc. These luminogens with different connection patterns between thiophene and PIO/BTO cores exhibit different torsion angles and thus diverse photophysical properties. The luminogens show faint emissions in dilute solutions but enhanced emissions in the aggregated state, displaying good AIE feature. Reversible photochromism is observed for the luminogens, and the PIO-based luminogens show better photochromism properties than BTO-based ones. The interesting photoluminescence and photochromism properties endow these new luminogens with good potential in optoelectronic devices and molecular switches.