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

A zinc-based coordination polymer, namely [Zn3(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 minutes, 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 ⋅OH, ⋅O2− and h+ produced during photocatalytic degradation improved the degradation efficiency of complex 1.