Tuning the Solid State Emission of the Carbazole and Cyano‐Substituted Tetraphenylethylene by Co‐Crystallization with Solvents

Abstract

Solid state emissive materials with high quantum yields and tunable emissions are desirable for various applications. A new TPE derivative (1) with two carbazole moieties and two cyano groups is reported, which shows typical aggregation induced emission behavior. Four crystals 1a, 1b, 1c, and 1d are obtained after crystallization from N,N-dimethylformamid (DMF), trichloromethane (CHCl ), tetrahydrofuran (THF), and dichloromethane (CH Cl ), respectively. Crystal structural analyses reveal that (i) molecules of 1 co-crystallize with DMF, CHCl , THF, and CH Cl in 1a, 1b, 1c, and 1d, respectively, and (ii) conformations of 1 are different within 1a, 1b, 1c, and 1d, and compound 1 within crystal 1a adopts the most twisting conformation. Crystalline solids 1a, 1b, 1c, and 1d exhibit high emission quantum yields up to 0.65, but their emission colors are varied from blue to green. In comparison, the amorphous solid of 1 is yellow-emissive with emission maximum at 542 nm. Moreover, the blue- or green-emissive crystalline solids and the yellow-emissive amorphous solid can be inter-converted by the grinding of crystalline solids and exposure of the amorphous solid to vapors of appropriate solvents. It is also demonstrated that microrods of 1a, 1b, and 1d show typical optical waveguiding behavior.

Tricolor Luminescence Switching by Thermal and Mechanical Stimuli in the Crystal Polymorphs of Pyridyl‐substituted Fluorene

“…[1,2] The luminescence properties of organic solids dependo nn ot only the molecular chemical structure, but also on moleculars tacking. [3,4] In recent years, a number of stimuli-responsive organic fluorescent materials have been reported, [5,6] in which switching to the solid luminescent color is achieved by alteringt he mode of molecularly assembled structures upon externals timulus, [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] such as grinding, heating, and exposure to chemicalv apor.T his smart approacht oc hanging the luminescence properties of organic solids is thought to be more promising and easier than switching molecularly chemical structures by chemical reactions. To date, most of the reported examples display ar eversible twocolor luminescence switching, [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] and multicolor switched materials remaine xtremelyl acking due to the un-designability of this kind of smart materials.…”

Multistimuli Response and Polymorphism of a Novel Tetraphenylethylene Derivative

“…These three different states of 1 can be interconverted into each other rapidly with simple treatments. This property is rarely reported and it provides more promising application potentials than other known molecules …”

Construction of Luminogen Exhibiting Multicolored Emission Switching through Combination of Twisted Conjugation Core and Donor-Acceptor Units

“…Therefore, the reason of 1YC to 1OC is indeed the loss of THF molecules; when the THF molecules accessed into 1OC again, 1YC was obtained again. Therefore, we can draw the conclusion that the THF molecules can change molecular conformation and packing mode of 1YC and 1OC [ 54 ] . Inspired by above phenomenon, we also obtained 1YC by fuming 1GC with THF vapor ( Figure 2 A, (h) to (i)), while we got 1OC by fuming 1GC with DCM ( Figure 2 A, (h) to (j)), which was verified by the PL spectra ( Figure 2 B).…”