A 3D rare cubane-like tetramer Cu(II)-based MOF with 4-fold dia topology as an efficient photocatalyst for dye degradation

A three dimensional (3D) rare cubane-like tetrameric Cu(II)-based MOF 1 having formula [Cu4(O)(OH)3(bb)4(NO3)30.3 H2O·3CH3CN]n (bb = 4,4'-bis (imidazolyl) biphenyl) has been synthesized and characterized. The MOF 1 possess 4-fold dia topology and effectively catalyzes the photodegradation of basic green (BG), rhodamine B (RhB), methyl blue (MB) and methyl orange (MO) dyes under UV light irradiation. The effects of initial solution pH, concentration of dyes, and photocatalyst dose have been monitored on the photocatalytic performance of 1. The photocatalytic results suggest that MOF 1 exhibits best photocatalytic activity for BG amongst all the four dyes investigated. Under the optimal reaction condition, ∼96.8 % photodegradation of BG has been observed at pH 5, at 40 ppm concentration of BG and 30 mg photocatalyst concentration in 120 min time span. The radical trapping experiments suggest that O2·− and·OH are the main active species that catalyzes the photodecomposition of dyes. The possible mechanism for the BG degradation of 1 is proposed using density of states (DOS) calculations and Hirshfeld surface analysis.