We report a series of thermally activated delayed fluorescence (TADF) molecules with mechanochromic luminescence properties and reversible TADF turn on/off properties in solid state that are induced by the transition between amorphous and crystalline states. Additionally, multicolor altering through external stimulus is demonstrated. All of the studied compounds exhibited recovery of the initial states associated with narrower emission spectra. TADF organic light-emitting diodes fabricated by solution processing rendered high external quantum efficiency up to 10.9% and luminance of 16 760 cd m.

Thianthrenes have been nearly forgotten as phosphors in recent years, but are now coming back, showing their strong potential in luminescent applications. Here, we present a comprehensive photophysical study of a carbazolyl derivative of thianthrene in different matrices and environments. The diffusion of oxygen is slowed down in the rigid environment of thianthrene organic crystals suppressing their phosphorescence quenching, as well as triplet-triplet annihilation. This facilitates the observation of simultaneous fluorescence and phosphorescence emissions at room temperature, in air, giving origin to strong white luminescence. Moreover, the color coordinates of the dual fluorescence-phosphorescence white emission, which is observed only in rigid amorphous media and in crystals, can be tuned.

Dual emission (TADF + RTP) and mechanochromism have been obtained using an iminodibenzyl–quinoxaline–iminodibenzyl scaffold.

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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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α-Ketoimidoyl chlorides, obtained from α-addition of acyl chlorides onto alkyl isocyanides, are treated with enamines to afford 5-(alkylimino)-4-hydroxy-4,5-dihydro-1H-pyrrole-2,3,4-tricarboxylates and 2-(alkylimino)-3-hydroxy-2,3-dihydro-1H-pyrrole-3,4-dicarboxylates in good to excellent yields.