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Near-infrared (NIR) photochromic materials, especially with aggregation-induced emission (AIE) features, have lately aroused great research interest for their wide application potential in the fields of functional biomaterials and optical electronics. In this contribution, a new donor-acceptor-type (D-A-type) dithienylethene (TDC) appended by triphenylethene and dicyanovinyl fragments at both ends of dithienylethene was rationally constructed and prepared. The chemical structure of TDC has been well analyzed by HRMS (ESI), 1H NMR, 13C NMR, and XRD. TDC displayed NIR-like photochromic properties with strong fatigue resistance in toluene, THF and 1,4-dioxane when exposed to UV/NIR light. The ring-open isomer TDC (o) showed typical luminescent and AIE-like behaviors in the solid state before illumination with UV light. Furthermore, effective photochromic properties and fluorescent switching behavior was observed in the solid and aggregated states. Interestingly, TDC displayed unexpected aggregation-controlled photochromism in the mixtures of H 2 O/DMSO. Accordingly, TDC represents a new multi-state NIR photochromic dithienylethene and can be further applied in smart optoelectronics and functional biomaterials. [Display omitted] • A novel donor-acceptor type dithienylethene was successfully developed. • It displayed NIR photochromic properties in toluene, THF and 1,4-dioxane. • The ring-open isomer showed typical aggregation-induced emission. • Effective photoswitching behavior was observed in the aggregated and solid states. • It showed aggregation-controlled photochromism in the mixtures of H 2 O/DMSO. [ABSTRACT FROM AUTHOR]

Developing new visible light-triggered fluorescent molecular photoswitches is highly desirable for potential application in the fields of photoresponsive optoelectronics and photopharmacology. In this contribution, two novel tetra-/triphenylethene-dithienylethene-BF 2 bdk triads (TDB1 and TDB2) have been designed and prepared by appending tetra-/triphenylethene and BF 2 bdk moieties at the termini of dithienylethene unit. Before irradiation with blue light at 460–470 nm, they showed an intense emission in solution and in the PMMA film state, suggesting that the AIE effect of tetra-/triphenylethene was inhibited, and functioned only as electron-donating groups. Moreover, upon alternating irradiation with blue/NIR light, TDB1 and TDB2 displayed effective fluorescent switching behaviors and NIR photochromism in toluene and the PMMA film. Therefore, they would be utilized as novel visible light-triggered switches integrated in smart optoelectronic materials. The DFT calculations further validate the differences for their optical properties in the experiments. Image 1 • Two novel tetra-/triphenylethene-dithienylethene-BF 2 bdk triads were developed. • They showed an intense emission in solution and the PMMA film state before irradiation. • AIE effect of tetra-/triphenylethene was inhibited, and functioned only as electron-donating groups. • They displayed visible light-triggered optical switching behaviors in toluene and the PMMA film. [ABSTRACT FROM AUTHOR]