Zinc-based coordination polymer as a highly effective photocatalyst for the degradation of dyes in water

A zinc-based coordination polymer, namely [Zn-3(L)(2)(H2O)(6)] (n) (1) (L = 5-(2',5'-dicarboxylphenyl) picolinic acid), was synthesized by the solvothermal method. Under visible light irradiation for 80 or 90 min, complex 1 exhibited a photodegradation efficiency of 98 % and 82 % towards methyl blue (MB) and saffron T (ST), respectively. After 5 cycles, the degradation performance of complex 1 did not decrease significantly, and the structure of complex 1 was consistent with that of fresh 1, demonstrating excellent stability. Meanwhile, free radical capture experiments and electron spin resonance (ESR) spectroscopy confirmed that the free radical active species center dot OH, center dot O-2 and h+ produced during photocatalytic degradation improved the degradation efficiency of complex 1.