Jianlei Han

Micro-cocrystals of the intermolecular charge-transfer (CT) complex formed from pyrene and tetracyanobenzene can be fabricated via a solution-based method. Intersystem crossing of the directly excited CT exciton in the cocrystal is observed, yielding a CT triplet exciton that undergoes efficient triplet-triplet energy transfer to a diphenylanthracence (DPA)-based triplet acceptor. For the first time, we demonstrate that these micro-cocrystals can act as triplet sensitizers to upconvert the emission of liquid-state DPA triplet acceptors, enabling highly efficient triplet-triplet annihilation photon upconversion (TTA-UC) from 532 to 430 nm. This work demonstrates the utilization of CT excitons as triplet sensitizers in a TTA-UC process, providing a novel approach for efficient and heavy-atom-free UC systems.

A family of chiral perylene diimides (PDIs) was newly developed as excellent circularly polarized luminescence (CPL) materials. They are asymmetrically derivatized with a double‐alkyl‐chained L‐ or D‐glutamate unit and a linear or branched alkyl chain. When water is added to the tetrahydrofuran (THF) solution of glutamate‐PDI‐linear‐alkyl chain compounds, kinetically formed H‐aggregates are formed in globular nanoparticles (NPs). These NPs undergo spontaneous transformation into thermodynamically stable nanotubes via helical nanostructures, which showed structured broad spectra originating from the strong coupling of delocalized Frenkel excitations (FE) and charge transfer excitations (CTE). Significant enhancement of circular dichroism (CD), fluorescence quantum yield, and circularly polarized luminescence (CPL) with luminescence dissymmetry factor (g_lum) are observed during the transformation of NPs to the FE/CTE‐coupled helical and tubular structures. This transformation process is significantly accelerated by applying physical stimuli, i.e., ultrasonication or adding helical aggregates as seed crystals, a feature unique to living supramolecular polymerization. Meanwhile, the branched chain‐containing PDIs only form H‐aggregates and did not show FE/CTE hybrid exciton states with living supramolecular polymerization properties. This study unveils that suitably designed chiral PDI derivatives show FE/CTE coupling accompanied by high fluorescence quantum yields, enhanced chiroptical properties, and supramolecular living polymerization characteristics.

A family of chiral perylene diimides (PDIs) was newly developed as excellent circularly polarized luminescence (CPL) materials. They are asymmetrically derivatized with a double‐alkyl‐chained L ‐ or D ‐glutamate unit and a linear or branched alkyl chain. When water is added to the tetrahydrofuran (THF) solution of glutamate‐PDI‐linear‐alkyl chain compounds, kinetically formed H‐aggregates are formed in globular nanoparticles (NPs). These NPs undergo spontaneous transformation into thermodynamically stable nanotubes via helical nanostructures, which showed structured broad spectra originating from the strong coupling of delocalized Frenkel excitations (FE) and charge transfer excitations (CTE). Significant enhancement of circular dichroism (CD), fluorescence quantum yield, and circularly polarized luminescence (CPL) with luminescence dissymmetry factor ( g _lum ) are observed during the transformation of NPs to the FE/CTE‐coupled helical and tubular structures. This transformation process is significantly accelerated by applying physical stimuli, i.e., ultrasonication or adding helical aggregates as seed crystals, a feature unique to living supramolecular polymerization. Meanwhile, the branched chain‐containing PDIs only form H‐aggregates and did not show FE/CTE hybrid exciton states with living supramolecular polymerization properties. This study unveils that suitably designed chiral PDI derivatives show FE/CTE coupling accompanied by high fluorescence quantum yields, enhanced chiroptical properties, and supramolecular living polymerization characteristics.

Correction for ‘Signal transmission encryption based on dye-doped chiral liquid crystals via tunable and efficient circularly polarized luminescence’ by Chengxi Li et al. , Mater. Adv. , 2021, 2 , 3851–3855, DOI: https://doi.org/10.1039/D1MA00368B.

In situ instant crystallization significantly boosts the CPL performance in which both large circular polarization and high luminescence efficiency are achieved due to the chiral supramolecular arrangement of chromophores in the crystalline state.

An external efficiency of triplet–triplet annihilation based photon upconversion of up to 0.42 was achieved from bichromophoric annihilators sensitized by a metallic porphyrin sensitizer.

Photofluorochromic diarylethene (DAE) molecules have been widely investigated due to their excellent fatigue resistance and thermal stability. However, the poor water solubility of DAEs limits their biological applications to some extent. Herein, we reported two kinds of water-dispersible DAE nanoparticles (DAEI-NPs and DAEB-NPs), in which DAE molecules were stabilized by the amphiphilic polymer DSPE-mPEG2000 using the nanoprecipitation approach. The fabricated nanoparticles retain well-controlled luminescence and fluorescence photoswitching properties in aqueous solution, which could be reversibly switched on and off under the alternating irradiation of ultraviolet (UV) and visible light. In addition, the closed-ring isomers of DAEB-NPs performed hot-band-absorption-based photon upconversion when excited by a 593.5 nm laser. Bearing excellent photophysical properties and low cytotoxicity, DAEB-NPs were applicable for upconversion cell imaging without high-excitation power density and free from oxygen removal. Additionally, the imaging process could be switched on by regulating the photofluorochromic nanoparticles.

Multi-channel adjustable CPL in chiral liquid crystals was investigated, where a well-organized structure distributed in double thin layers exhibits a high |g_lum| for the input signal to encrypt information transmission.