Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non‐radiative Decay Pathway

Uncovering Integrated Dual-State ESIPT-Conductivity, Redox-Capacity, and Opto-Electronic Responses Toward Hg(II)/ Cr(III) of Aliphatic Fluorescent Polymers

Excited-state intramolecular proton transfer (ESIPT)-associated dual-state emissive aliphatic dual-light emitting conducting polymers (DLECPs) having oxidation-reduction capacities are prepared polymerizing 2-acrylamido-2-methylpropane-1-sulfonic acid, methacrylic acid, and 2-methyl-3-(N-(2-methyl-1-sulfopropan-2-yl)acrylamido)propanoic acid monomers. Of as-synthesized DLECPs, nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies, fluorescent enhancements (I/I0), and computational investigation indicate intriguing photophysical features in DLECP3 (optimum composition). In DLECP3, ─CONH─, ─CON<, and ─COOH subluminophores are recognized by density-functional theory (DFT)/time-dependent-DFT calculations and experimental investigations. ESIPT-associated dual-state emission/conductivity, aggregation-enhanced emissions, selective opto-electronic responses toward Hg(II)/Cr(III) at 437/574 nm, and redox properties of DLECP3 are supported by solid-state/solution spectroscopies, time-correlated single photon counting (TCSPC) measurements, dual-state excitation dependent emissions, microscopic images, electrochemical measurements, and DFT calculations. Here, preferential interaction of Hg(II)/Cr(III) with DLECP3 (amide)/DLECP3 (imidol) and reduction/oxidation of Hg(II)/Cr(III) to Hg(I)/Cr(VI) are substantiated by UV-vis, FTIR, and X-ray photoelectron spectroscopies; TCSPC measurements; NMR-titration; electrochemical studies; alongside computational calculations. The proton-electrical conductivities of DLECP3, Hg(II/I)-DLECP3, and Cr(III/VI)-DLECP3 in solids/solutions are 15.27 × 10-5/6.16 × 10-5, 19.60 × 10-5/25.52 × 10-5, and 26.69 × 10-5/27.60 × 10-5 S cm-1, respectively.

Solid-State Emission and Aggregate Emission of Aroyl- S,N-Ketene Acetals Are Controlled and Tuned by Their Substitution Pattern

Aroyl-S,N-ketene acetals are a novel highly diverse class of aggregation-induced emission fluorogens (AIEgens) with a plethora of interesting properties. An expanded compound library of more than 110 dyes set the stage for the first qualitative control and tuneability of all aspects of their photophysical properties. The interplay of substituents not only allows tuning and prediction of the emission color, but also of the intensity, and quantum yields both in solids and in the aggregated state; these can be rationalized by scrutinizing intermolecular interactions in the crystalline solid state.

Donor-Acceptor Molecule Based High-Performance Photothermal Organic Material for Efficient Water Purification and Electricity Generation

In this contribution, a unique donor-acceptor conjugated organic-small-molecule photothermal material, namely GDPA-QCN, is presented. Bulky dendritic triphenylamine (GDPA) was grafted onto quinoxaline-6,7-dicarbonitrile (QCN) with a phenyl ring as a bridge to form an "umbrella" architecture. Benefited from the particular molecular structure, in solid state, GDPA-QCN molecules adopted a loose packing mode due to the steric effect of "umbrella head" dendritic triphenylamine and flexible molecular structure feature, which allows efficient intramolecular motions and consequently elevates energy dissipation by taking the pathway of thermal deactivation within broad absorption range. The GDPA-QCN solid has high solar-thermal conversion efficiency with an absorption range from 300 to 1100 nm, which can promote superior water purification and electricity generation performance.

Linked Rotaxane Structure Restricts Local Molecular Motions in Solution to Enhance Fluorescence Properties of Tetraphenylethylene

The restriction of local molecular motions is critical for improving the fluorescence quantum yields (FQYs) and the photostability of fluorescent dyes. Herein, we report a supramolecular approach to enhance the performance of fluorescent dyes by incorporating a linked rotaxane structure with permethylated α-cyclodextrins. Tetraphenylethylene (TPE) derivatives generally exhibit low FQYs in solution due to the molecular motions in the excited state. We show that TPE with linked rotaxane structures on two sides displays up to 15-fold higher FQYs. Detailed investigations with variable temperature ¹ H NMR, UV-Vis, and photoluminescence spectroscopy revealed that the linked rotaxane structure rigidifies the TPE moiety and thus suppresses the local molecular motions and non-radiative decay. Moreover, the linked rotaxane structure enhances the FQY of the dye in various solvents, including aqueous solutions, and improves the photostability through the inhibition of local molecular motions in the excited TPE.