All-visible-light triggered photochromic fluorescent dithienylethene-phenanthroimidazole dyads: Synthesis, crystal structure, multiple switching behavior and information storage

A novel all-visible-light controlled photochromic dithienylethene (DTE) derivatives bearing phenanthroimidazole (PI) unit were synthesized (DTE-PI). Upon alternating irradiation with 420/540 nm light, effective photochromic and fluorescent switches were demonstrated in solution, PMMA film, single crystal and solid powder. Remarkably, multi-stimuli responsive chromism and fluorescence switches were demonstrated by modulation of protonation. The effect of adding trifluoroacetic acid (TFA) on the performance of DTE-PI were carefully investigated. Interestingly, multi-stimuli responsive chromism and fluorescent switches were achieved with good reversibility when treated with excessive TFA. Neutralization by triethylamine (TEA) could restore it to the initial state. Notably, the photoswitchable dual-mode patterning application was developed successfully.