The synthesis and characterization of Zn(ii)/Cd(ii) based MOFs by a mixed ligand strategy: a Zn(ii) MOF as a dual functional material for reversible dye adsorption and as a heterogeneous catalyst for the Biginelli reaction

Abstract

Two mixed ligand MOFs, {[Zn₂(5NO₂-IP)₂(L)₂](H₂O)}_n (ADES-1) and {[Cd₂(5NO₂-IP)₂(L)₂(H₂O)₄](L)(H₂O)(CH₃OH)₆}_n (ADES-2) (where 5NO₂-IP = 5-nitroisophthalate and L = (E)-N′-(pyridin-3-ylmethylene)nicotinohydrazide), have been synthesized and characterized via various analytical methods, including SXRD analysis. SXRD analysis revealed that both MOFs adopt an identical two-dimensional network topology. ADES-1 with bulk phase purity has been synthesized via a conventional reflux method and its potential applications as a functional material for reversible dye adsorption and as an efficient heterogeneous catalyst for the Biginelli reaction were exploited. ADES-1 exhibited the rapid and efficient adsorption of both cationic and anionic dye molecules with a slight preference for methyl violet (86%) compared to the other dyes that were investigated. A separation study involving a mixture of dyes and the application of ADES-1 as a column filler for the separation of organic dyes from water are also demonstrated. Moreover, the catalytic performance of ADES-1 towards a multi-component Biginelli reaction to yield 3,4-dihydropyrimidin-2(1H)-ones (DHPM) derivative has been studied. Finally, studies of the utilization of ADES-1 for dye adsorption and its catalytic activity revealed good stability and reusability, enabling it to be a potential functional material, and possible dye adsorption and Biginelli reaction mechanisms are also proposed.