A series of porous 3D inorganic–organic hybrid framework crystalline materials based on 5-aminoisophthalic acid for photocatalytic degradation of crystal violet

Abstract

This work designed and synthesized seven novel complexes by using transition-metal salts 5-aminoisophthalic acid (5-aip) and 4,4′-bipyridine (4,4′-bipy) by the hydrothermal synthetic method, they were [Zn(5-aip)(4,4′-bipy)_0.5]·2H₂O (1), [Cu(5-aip)(4,4′-bipy)_0.5]·CH₃OH (2), [Ni_0.25Zn_0.75(5-aip)(4,4′-bipy)_0.5]·2H₂O (3), [Cr(5-aip)(4,4′-bipy)_0.5]·2H₂O (4), [Co(5-aip)(4,4′-bipy)_0.5]·2H₂O (5), [Fe(5-aip)(4,4′-bipy)_0.5]·2H₂O (6), and [Mn(5-aip)₂(H₂O)₂] (7). Complexes 1–7 were characterized by elemental analysis, infrared spectroscopy, UV-vis spectroscopy, powder X-ray diffraction analysis, and thermogravimetric analysis (TG). X-ray single crystal diffraction analysis showed that complexes 1–7 could form a porous three-dimensional network structure through covalent bonding, π–π interaction or hydrogen bonding. In addition, the photodegradation ability of Crystal Violet (CV) solution under natural light was also investigated with complexes 1–4 as the photocatalysts. The results showed that all four complexes had photocatalytic degradation behavior in CV solution. The relationship of the distance between the active sites and the photocatalytic activity was also explored firstly from the fluorescence spectra. The results showed that there was a linear correlation between the photocatalytic activity and the reciprocal of the distance between active sites. The shorter the distance between active sites, the better the photocatalytic degradation effect. And it was found that the photocatalytic degradation process was confirmed to be suitable for the pseudo-first-order kinetic model.