By combination of heteropolymolybdates and metal–Schiff-base complexes, two new organic–inorganic hybrid compounds {Mn(salen)₂(H₂O)₂[AlMo₆(OH)₆O₁₈]}[arg]·16H₂O (1) and {Mn(salen)₂(H₂O)₂[CrMo₆(OH)₆O₁₈]}[arg]·11H₂O (2) (salen = N,N′-ethylene-bis(salicylideneiminate) have been successfully isolated. Compounds 1 and 2 were structurally characterized by elemental analyses, IR spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. To the best of our knowledge, compounds 1 and 2 represent the first single-crystal structures of metal–Schiff-base decorated polyoxometalates (POMs) compounds. Photocatalytic experiments indicated that both 1 and 2 exhibit high catalytic activity for photodegradation of RhB with UV irradiation. In addition, the magnetic properties of 1 were also investigated.

Optical signals of pH probes mainly driven from the formation or rupture of covalent bonds, whereas the changes in covalent bonds usually require higher chemical driving forces, resulting in limited sensitivity and reversibility of the probes. The exploration of high-performance pH probes has been a subject of intense investigation. Herein, a new pH probe has been developed, with optical property investigation suggesting the probe has excellent signal-to-noise ratio, and fluorescence intensity shows exponential growth, combined with a visible color change, as pH increased from 5.1 to 6.0; Moreover, the probe has outstanding stability and reversibility, with more than 90% of the initial signal intensity remaining after 30 cycles. In order to better understand the special fluorescence behavior of the reported probe, the non-halogenated isomer is introduced for comparison, combined with the results of structural analysis, quantitative calculation and optical experiments, and the possible mechanism of the special supramolecular aggregation-caused quenching effect induced by the halogen atom is discussed.

The introduction of [Mn(salen)(H₂O)]₂(ClO₄)₂·H₂O ({Mn^III ₂}) into the polyoxometalate (POM) systems Na₃[XMo₆(OH)₆O₁₈] (X = Al and Cr) led to the isolation of new {Mn^III ₂}–POM composite materials with single-molecule magnetic behaviour.