Two diverse temperature-directed cobalt-based coordination polymers: environmentally friendly photocatalysts for degradation of organic dyes

Abstract

Two new cobalt-based coordination polymers (CPs) based on a semirigid naphthalene-bridged bis-pyridyl-bis-amide ligand, namely [Co(4-bmnpd)(5-HNIP)2(H2O)2] (1) and [Co4(4-bmnpd)4(5-NIP)4]·2H2O (2) (4-bmnpd = N,N′-bis(4-methylenepyridin-4-yl)-2,6-naphthalenedicarboxamide, 5-H2NIP = 5-nitroisophthalic acid), have been prepared under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction analyses, infrared (IR) spectroscopy, and powder X-ray diffraction (PXRD). The structural analyses show that 1 has a one-dimensional (1D) chain structure while 2 exhibits a two-dimensional (2D) network. The effect of temperature on the structures of the CPs is discussed. The solid-state fluorescent properties of 1 and 2 were determined at room temperature. Furthermore, their photocatalytic degradation properties were also studied. Photocatalysts 1 and 2 are environmentally friendly and can effectively degrade organic dye Congo Red (CR) under ultraviolet (UV) light. In addition, the possible degradation mechanism was also investigated.