Toward High Contrast and Noninvasive Fluorescence Switches via an O-Fused Ring...

An unprecedented O-fused ring 5,7-dihydroxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one (3) was first time synthesized. Further, a series of novel dialkyl/fluoroalkyl derivatives of compound 3, 5,7-dialkoxy/fluoroalkoxy-4-methyl-2,2,3-triphenylbenzofuran-6(2H)-one, were obtained with noninvasive fluorescence switching characteristics and aggregation-induced emission properties. Compared with fluoroalkyl derivatives, the alkyl analogs exhibited a significant bathochromic shift in solid-state fluorescence emission. Notably, these noninvasive fluorescent molecular switches could be facilely tuned through light and heat stimulation, which successfully achieved high contrast and reversible fluorescent emission between orange and yellow endowing them with potential applications in data encryption materials. In addition, the single crystal data of compounds 3 and 7-CF displayed weak intermolecular interactions in different directions, resulting in twisted conformation and antiparallel slip stacking. Interestingly, the polymer dimethyl silicone film doped with 7-CF also showed an evident light-responsive behavior, meeting the criterion for fluorescent materials in the optical field.