Blue multi-functional emitters with a perfluorobiphenyl moiety exhibiting polymorphism and changing emission colour.

A family of highly emissive benzo[4,5]thiazolo[3,2- c][1,3,5,2]oxadiazaborinines, conjugated with the donor 4-dimethylaminophenyl group, was designed and synthesized. Their photophysical, both in solution and in the solid state, and structural properties were investigated. The influence of donor and acceptor substituents (R) in the benzothiazole unit on photophysical properties of complexes was found out. The tetrafluorobenzothiazole analogue exhibits nonbonded nuclear spin-spin coupling between fluorines from the BF group and α-fluorine atom at the benzene ring. Additionally, this boron complex demonstrates a comparatively high solid-state fluorescence quantum yield (Φ = 0.34).

A series of 1,3-thiazole-based organoboron complexes has been designed and synthesized by acylation of 2-amino 4-subsituted 1,3-thiazoles with (4-dimethylamino)benzoyl chloride and the subsequent BF complexation reaction. The influence of substituents in position 4 of the thiazole ring on photophysical properties of the complexes has been investigated. Synthesized thiazolo[3,2-c][1,3,5,2]oxadiazaborinines mainly showed intensive fluorescence in solutions. Complex with a 4,5-unsubstituted thiazole unit demonstrated an aggregation induced emission (AIE) effect and a very high fluorescent quantum yield (94%) in the solid state because of the inhibition of π-π/π-n interactions in the molecular packing.

Three new quinoline and di‐tert‐butyl phenothiazine isomeric derivatives were synthesized and characterized towards applications for oxygen sensing and optical information multicoding. The compounds with phenylene linker showed outstanding phase‐dependent reversibility between ON/OFF states (low and high emission intensity, drastic shifting of emission colors, short‐ and long‐lived fluorescence) in systematic grinding/fuming cycles, as required for multichannel memory devices based on optical information multicoding. The conformational diversity of the phenothiazine unit resulted in dual emission of the doped films implemented by the different luminescence mechanisms with peaks located at 414/530, 416/540, and 440/582 nm. The presence of a phenylene linker and thus two rotational degrees of freedom resulted in quenching of the delayed fluorescence of quasi‐equatorial conformers in the solid state. The compound containing no phenylene bridge was characterized by two different driving photoluminescence mechanisms of the doped films: short fluorescence of the quasi‐axial conformer and thermally activated delayed fluorescence of the quasi‐equatorial form. This compound showed oxygen sensitivity with a Stern–Volmer constant of 7.5×10−4 ppm−1.

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