Development of hybrid nanoparticles based on Zr(iv) and perylene-3,4,9,10-tetracarboxylic acid with visible-light photoredox activity.

Herein, we investigate perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) as a linker in Zr-clusters. The photostable, 3D metal-organic nanomaterial obtained by a solvothermal synthesis procedure in the presence of formic acid as modulator, named ZIPER, shows strong absorption in the visible (400-560 nm) and an intense photoluminescence (PL) in the 600-700 nm range. PL quenching experiments strongly indicate that the ZIPER excited state (ZIPER*) behaves primarily as a strong oxidant and a mild reductant with redox couples E(ZIPER*/ZIPER˙-) = 1.8-1.2 V and E(ZIPER˙+/ZIPER*) = -0.44--0.48 V (vs. NHE). Amine quenching of ZIPER* PL led to a strong reductant (ZIPER˙-) with E(ZIPER/ZIPER˙-) <-0.6 V vs. NHE. This reactivity was exploited to drive the reductive dehalogenation of model polychlorinated compounds, such as carbon tetrachloride and trichloroacetic acid, through visible-light photoredox catalysis in aqueous suspension. In contrast, under air-saturated conditions, the system predominantly produces substantial amounts of H2O2. A detailed analysis of the results suggests that photoexcitation of the organic linkers is followed by electron transfer to the Zr cluster. Charge-separated states are mainly stabilized in the presence of suitable electron donors or acceptors; otherwise, the system relaxes radiatively, emitting strong orange fluorescence.