Reversibly Switchable Phase‐Dependent Emission of Quinoline and Phenothiazine Derivatives towards Applications in Optical Sensing and Information Multicoding

Abstract

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.

Amphiphilic di-cationic methylene blue for improving antibacterial photodynamic efficiency through high accumulation and low aggregation on bacterial cell surfaces

“…The chemical shis at 6.72-7.94 ppm belongs to the hydrogen atoms of the benzene ring in phenothiazine. 24 From 13 C NMR results shown in Fig. 1(C), the chemical shis at 27.28 ppm symbolize the carbon atoms of long alkyl chain, and those around 115 ppm, 122 ppm and 135 ppm could be attributed to the carbon atoms on aromatic ring.…”

Conformational isomeric thermally activated delayed fluorescence (TADF) emitters: mechanism, applications, and perspectives

“…1.76). 25,37,51–56 Furthermore, when linking such a segment to an A segment via a phenyl bridge, two stable conformations, i.e. , QA and QE conformations, with distinctly different twist degrees will coexist in ground states.…”

“…Therefore, the overall properties are actually determined by their combined effect. [34][35][36][37][38] It is noteworthy that, unlike the mechanisms of excited-state intramolecular proton transfer (ESIPT), [39][40][41][42] vibration-induced emission (VIE), [43][44][45] and twisted intramolecular charge transfer (TICT), [46][47][48][49][50] which are all caused by photophysical properties in excited states, conformational isomerism is a phenomenon that naturally occurs in the ground states.…”

Hexagon and network structured organic geometrical isomers with distinct intramolecular H-bonding and stimuli-induced self-reversible fluorescence switching

“…Developing organic fluorescent materials with tunable and switchable emission has been of great interest in academic research as well as optoelectronic device applications. [1][2][3][4][5] Unlike the solution properties, supramolecular interactions, molecular conformation and packing exert a significant influence on the fluorescence properties in the solid state. [6][7][8][9] Extensive structure-property studies revealed that a donor (D)-acceptor (A) molecular structure with a twisted nonplanar conformation is an ideal platform for generating solid state fluorescence materials.…”