Fluorescence Switching and Photoisomerization of a Spiropyran Molecular Photoswitch through Confined Spaces Regulation in Crystals

Spiropyran (SP) and its derivatives are highly attractive owing to their distinctive merits in high contrast and fast response read-out systems. However, the realization of photoswitching properties of SP is hindered in the aggregate state, particularly in crystals owing to the dense packing of molecules leading to insufficient study of the relationship between the molecular structure/stacking mode and photoswitching behavior. Herein, we report three SP derivatives: different flexible chains (carboxyl group for SP-0 and ester group for SP-1) are attached to the indoline moiety, while the ester group is attached to the chromene moiety for SP-2. SP-1 exhibits fluorescent photoswitching properties in crystals due to the weak intermolecular interactions resulting in enough free space for the photoisomerization. The presence of hydrogen bonds in SP-0 enhances the molecular interactions to restrict the photoisomerization, and the ester group of SP-2 impacts the thermodynamic properties, thereby limiting the realization of photoswitching of SP-2.

Ultrafast Photocatalytic Detoxification of Mustard Gas Simulants by a Mesoporous Metal-Organic Framework with Dangling Porphyrin Molecules

Developing effective catalysts to degrade chemical warfare agents is of great significance. Herein, a mesoporous MIL-101(Cr) composite material dangled with porphyrin molecules (denote as TCPP@MIL-101(Cr), TCPP = tetra(4-carboxyphenyl)porphyrin) is reported, which can be used as a heterogeneous photocatalyst for detoxification of mustard gas simulants 2-chloroethyl ethyl sulfide (CEES) to 2-chloroethyl ethyl sulfoxide (CEESO) with a half-life of 1 min. The catalytic performance of TCPP@MIL-101(Cr) is comparable to that of homogeneous molecular porphyrin. Mechanistic studies reveal that both 1 O2 and O2 •- are efficiently generated and play vital roles in the oxidation reaction. Gold nanoparticles (AuNPs) are attached to the TCPP@MIL-101(Cr) to further enhance the catalytic activity with a benchmark half-life of 45 s, which is the fastest record so far. A medical mask loaded TCPP@MIL-101(Cr) is fabricated for practical applications, which can selectively photoxidize CEES to CEESO under sunlight and air atmosphere, exhibiting the best degradation performance among the reported fabric-like composite materials.

Photothermal healing of a glass fiber reinforced composite interface by gold nanoparticles

Scheme of interfacial healing process.