Fe(Cu)-containing coordination polymers: Syntheses, crystal structures, and applications as benzyl alcohol oxidation catalysts

In this paper three coordination polymers, {[Fe(fcz)(2)Cl-2]center dot 2CH(3)OH}(n) (1), {[Cu(fcz)(2)(H2O)]center dot SO4 center dot DMF center dot 2CH(3)OH}(n) (2), and {[Cu(fcz)(2)Cl-2]center dot 2CH(3)OH}(n) (3) [fcz = 1-(2,4-difluorophenyl) -1,1-bis[(1H-1,2,4-triazol-1-yl)methyl)ethanol), were synthesized. Crystallographic analysis reveals that polymer 1 exhibits a 2-D rhombohedral grid structure with (4, 4) nets, while polymer 2 has a 1-D double-chain framework. The structure of polymer 3 is similar to that of 1. We found that polymers 1-3 could effectively catalyze the oxidation of benzyl alcohol to benzaldehyde with H2O2 (30 mass-%) as oxidant in aqueous medium. Various reaction conditions were studied, and optimal reaction conditions were obtained. Under the optimal conditions, the selectivity to benzaldehyde was almost up to 100 % and the conversion of benzyl alcohol was 87 % for 1, 79 % for 2, and 68 % for 3. The results of the recycling test showed that the catalytic activity decreased by only about 7 % after three consecutive reaction cycles. However, under similar conditions, when we used the corresponding metal salt instead of the polymer as catalyst, or replaced the water with acetonitrile as solvent, neither the selectivity nor the conversion was the same.