Mechanochromic organic molecules (MOMs) that exhibit a large difference of fluorescence wavelength between two states have important potential applications, but few such compounds are known. Here, we report a new MOM, cis-ABPX01(0), which shows switchable near-IR and blue fluorescence responses. Detailed spectrophotometric and single-crystal X-ray analyses revealed that the near-IR fluorescence is attributable to fluorescence from slip-stacked dimeric structures in crystals, while the blue fluorescence is attributable to fluorescence from the monomer. Switching between the two is achieved by dynamic structural interconversion between the two molecular packing arrangements in response to mechanical grinding and solvent vapor-fuming.
We report synthesis and characterization of near-infrared (NIR)-absorbing/emitting Thiele's hydrocarbon derivatives, in which four aryl groups are bridged to a quinodimethane skeleton. The quinoid structure of the bridged-tetra-aryl-p-quinodimethanes (BTAQs) was confirmed by spectroscopic, X-ray crystallographic, and computational methods. Although quinodimethane derivatives with a small HOMO−LUMO energy gap often exhibit biradical character, BTAQs showed no biradical character. Instead, they exhibited two-step near-infrared electrochromism. The donor/acceptor properties of the aryl groups were found to play a key role in the unique properties of BTAQs.
An unprecedented boron-containing fluorophore, π-extended cis-stilbene, obtained via alkynylboration reaction of alkynamide is reported. Boron-containing πextended cis-stilbenes emit fluorescence with high quantum yields in the solid state and exhibit aggregation-induced emission enhancement. The broad substrate scope of the alkynylboration reaction offers facile access to electronically diverse structures, enabling fine-tuning of light absorption/ emission characteristics. The boron-containing π-extended cisstilbene with a diphenylamino group displays solvatofluorochromism via an intramolecular charge-transfer transition.
New derivatives of aminobenzopyrano-xanthene (ABPX) dyes have been designed and synthesized with high fluorescence quantum yields in the visible and far-red regions. It was kinetically demonstrated that the structurally rigid conjugation of the xanthene moiety, which is closely related to the reduction of the nonradiative deactivation process, is an effective molecular design for the drastic enhancement of fluorescence emission efficiency.
One molecule, three faces: A new aminobenzopyranoxanthene (ABPX)‐based colorimetric sensor allows determination of changes in Cu2+ concentration by spectrophotometry and the naked eye. This quantitative, colorful, and simple method takes advantage of the unique protolytic reaction of ABPX in response to Cu2+.
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