Chiral {Ni6PW9} Cluster–Organic Framework: Synthesis, Structure, and Properties

A chiral three-dimensional polyoxometalate cluster-organic framework (POMCOF) H3[(btc)Ni6(μ3-OH)3(H2O)5(B-α-PW9O34)]·17H2O (1, btc = 1,2,4-benzenetricarboxylate) has been made under hydrothermal conditions in the absence of amine or chiral starting reagents. 1 shows high stability in CH3CN/DMF (1:3), acidic, and basic solutions with the pH ranging from 2 to 12 for 5 days. The UV-vis reflectance spectra and Mott-Schottky measurements reveal that 1 could be a suitable catalyst for photocatalysis. Visible-light-driven H2 evolution studies have demonstrated that 1 is an ecofriendly, efficient, and recyclable catalyst with a H2 evolution rate of 1058.24 μmol h-1g-1. Nonlinear optical (NLO) measurement reveals that 1 exhibits a second-harmonic generation (SHG) response of about 1.4 times that of KH2PO4 (KDP), indicating that 1 is a potential NLO material as well.