Carbazole-modified thiazolo[3,2-c][1,3,5,2]oxadiazaborinines exhibiting aggregation-induced emission and mechanofluorochromism

Abstract

Two novel AIE-active donor–acceptor organoboron complexes with a carbazole donor unit are developed and their morphology-dependent solid-state fluorescence properties are established.

Aggregation‐Induced Emission‐Active Carbazolyl‐Modified Benzo[4,5]thiazolo[3,2‐c]oxadiazaborinines as Mechanochromic Fluorescent Materials

“…Starting materials -4-(9H-carbazol-9-yl)benzoic acid ( 5) and 4- (3,6-di-tert-butyl-9H-carbazol-9-yl)benzoic acid ( 6) -were synthesized as described in our previous work. [17] Acids 5 and 6 were treated with thionyl chloride in hot dry toluene giving corresponding chlorides 7 and 8, which were immediately introduced into reaction with benzo [d]thiazole-2-amine (9) in the presence of triethylamine and catalytic amount of 4-dimethylaminopyridine (DMAP). Amides 10 and 11 were isolated with good yields (72 and 66 %, respectively) after two steps.…”

“…These parameters indicate the remarkable thermal stability of both compounds, which is even higher than those of analogues 1 and 2 (T d = 313 and 316°C, respectively). [17] DSC experiments showed that during heating and cooling first cycle, organoboron complex 3 demonstrated single melting and crystallization peaks at 263 and 168°C, respectively. The second heating demonstrate almost not-changed melting peak (258°C) (Figure S2 in the ESI).…”

“…This observation indicates that benzothiazole-based complexes 3 and 4 exhibited more pronounced AIE than thiazole analogues 1 and 2. [17] Solid-state photophysical properties. The solid-state photoluminescence properties of benzothiazole analogues 3 and 4 were investigated using both crystalline and thin-film samples.…”

“…Moreover, complex 2 with 3,6-di-tert-butyl-9H-carbazole donor unit demonstrated MFC properties, in contrast to almost MFC-inactive derivative 1 with unsubstituted carbazolyl group. [17] In the current work, we present our result of the investigation of N,O-coordinated organoboron complexes 3 and 4, based on benzothiazole-amide ligands. We demonstrate that the benzene ring fusion to the thiazole unit of compounds 1 and 2 results in enhancement of solid-state fluorescence efficiency (up to 0.48).…”

“…Moreover, compound 3 crystalize in two polymorphs with the different fluorescent properties, while thiazole derivative 1 is MFC-inactive. [17]…”