Mechanochromic fluorescence based on a combination of acceptor and bulky donor moieties: tuning emission color and regulating emission change direction

Abstract

Mechanochromic fluorescence based on a conventional strategy using a donor–acceptor structure bearing nonplanar three-dimensional donor moieties was studied.

Regulation of Multicolor Fluorescence Changes Found in Donor‐acceptor‐type Mechanochromic Fluorescent Dyes

“…The BTD‐pCHO(O) dye exhibited a crystal packing feature similar to that of BTD‐pOMe reported in a previous study (Figure 2). [28] Specifically, two independent molecules formed a dimeric structure in a parallel arrangement along the long molecular axis, in which four intermolecular C−H⋅⋅⋅π interactions (2.68–2.96 Å) between the triphenylamine moieties and one C–H⋅⋅⋅π interaction (2.91 Å) among the formyl‐substituted benzene moieties cooperatively stabilized the dimeric structure (Figures 5a and S16b). Additionally, the dimeric structure is organized one‐dimensionally through three intermolecular C−H⋅⋅⋅π interactions (2.80, 2.91, and 2.94 Å) among the triphenylamine moieties.…”

“…Triphenylamine–benzothiadiazole‐based donor‐acceptor‐type dyes were employed, which exhibit MCF due to their twisted conformations and the continuous internal space created by the steric demand of their donor moieties (Figure 1). [28] These dyes can be used to produce multicolor fluorescence changes. The crystal polymorphs, which arose from the introduction of formyl functional groups to the dyes, responded to mechanical grinding to provide multicolor fluorescence changes.…”

Wood‐Derived Carbon Materials and Light‐Emitting Materials

“…[ 83–85 ] However, most of these chromophores lose their fluorescent emission when they aggregate via π–π stacking, which compromises their performance in these applications. [ 86,87 ] Several methods have been proposed to conquer this challenge, such as designing molecules with aggregation‐induced emission (AIE), [ 88,89 ] introducing moieties with high steric bulk, [ 90,91 ] and dispersing the chromophores in a matrix. [ 92,93 ] Wood‐derived components such as cellulose and lignin have shown great promise for the preparation of chromophores without ACQ.…”

Recent Advances in Mechanochromic Luminescence of Organic Crystalline Compounds

“…In 2019, Ishi-i and coworkers reported both bathochromically and hypsochromically shifted MCL of triphenylamine-based donor-acceptor dyes 18 (Figure 4e). 33 The direction of the emission-color shift was changed depending on the central acceptor moiety of 18. Benzothiadiazole derivative 18a exhibited a bathochromic shift of the emission, whereas thiazolothiazole derivative 18b showed a hypsochromic shift.…”