Synergism between covalent and non-covalent bonds is employed to fix an organic phosphor guest in a rigid inorganic framework, simulating the stiffening effect seen in the glassy state and realizing efficient and ultralong roomtemperature phosphorescence (RTP). Twelve heavy-atom-free composites have been obtained through introducing arylboric or arylcarboxylic acid derivatives into the inorganic boric acid matrix by solid-phase synthesis. Owing to the stiffening effect of multiple bonds, all the composites show highly efficient and persistent RTP of guest molecules with a quantum yield ranging from 39.8 % to ca. 100 % and a lifetime up to 8.74 s, which results in a 55 s afterglow visible to the naked eye after exposure to a portable UV lamp. Interestingly, it is found that the substitution position and quantity of carboxyl in the guest have a great influence on the phosphorescent properties, and that the heavy-atom effect is invalid in such host-guest hybrid systems. The 100 g grade composite is easily prepared because of the solvent-free, green, and simple synthesis method. These results provide an important way for the development of RTP materials with ultrahigh quantum yield and ultralong lifetime, as well as their practical applications in the fields of anti-counterfeiting and information storage, among others.

Advanced electrocatalysts for complete oxidation of ethylene glycol (EG) in direct EG fuel cells are strongly desired owing to the higher energy efficiency. Herein, Pd-PdSe heterostructural nanosheets (Pd-PdSe HNSs) have been successfully fabricated via a one-step approach. These Pd-PdSe HNSs feature unique electronic and geometrical structures, in which unconventional p-d hybridization interactions and tensile strain effect co-exist. Compared with commercial Pd/C and Pd NSs catalysts, Pd-PdSe HNSs display 5.5 (6.6) and 2.5 (2.6) fold enhancement of specific (mass) activity for the EG oxidation reaction (EGOR). Especially, the optimum C1 pathway selectivity of Pd-PdSe HNSs reaches 44.3 %, illustrating the superior CÀ C bond cleavage ability. Electrochemical in situ FTIR spectroscopy and theoretical calculations demonstrate that the extraordinary p-d hybridization interaction and tensile strain effect could effectively reduce the activation energy of CÀ C bond breaking and accelerate CO* oxidation, boosting the complete oxidation of EG and improving the catalytic performance.

Fluorescent single crystals that respond to multiple external stimuli are of great interest in molecular machines, sensors, and displays. The integration of photo-or acidinduced fluorescence enhancement and bending in one organic crystal, however, has not been reported yet. Herein, we report the interesting plastic photomechanical bending and switching on of the fluorescence of an azine crystal in a single-crystal transformation, due to extended p-conjugation and molecular slippage. Moreover, the fluorescent plastic bending driven by multiple volatile acid vapors was firstly observed, and attributed to the synergistic effect of push-pull electronic structure and hydrogen bonding. The single crystal also shows high elasticity under external force. In addition, reversible fluorescence switching can be triggered by grinding and solvent fuming, as well as by the adsorption and desorption of HCl vapor. The integration of plastic, elastic bending and switch-on fluorescence into one single crystal provides a new strategy for next-generation smart materials.

Unique luminescence of non-conventional luminophores derived from space conjugation (SC) has recently attracted extensive interest. However, it is difficult to achieve highly efficient emission (especially white light one) from SC,...

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Herein, two maleimide derivatives substituted by Br (DBM) and I (DIM) with a two-dimensional (2D) layered structure are found to have highly efficient red roomtemperature phosphorescence (RTP) at 660 nm in solid state, which is independent of their morphology (crystal, powder, and film). The red RTP of DBM and DIM is closely related to the synergism of n π -ct-π* transitions and the 2D halogen-bonded network. Interestingly, the red RTP can be excited by visible light of 500 nm, which should be ascribed to the forbidden absorption from the ground state to the triplet state activated in the layered halogen-bonded framework. Due to the rich intermolecular interactions in the rigid layered structure, the red RTP of DBM is very stable under water or external force stimulation. Notably, Hg(II) and Cd(II) ions in a pure aqueous solution result in an opposite change in the RTP intensity of the DBM film. The detection limit of Hg(II) ion is as low as 2.5 × 10 −5 nM, lesser than all reported values. The above results not only provide a new idea for the design of simple and efficient red RTP materials but also make it possible to develop solid-state phosphorescent probes for toxic heavy metal ions in environmental sewage with high sensitivity and selectivity.

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