Combination effect of ionic liquid components on the structure and properties in 1,4-benzene-dicarboxylate based zinc metal-organic frameworks

Two types of 2D [RMI](2)[Zn-3(BDC)(3)X-2] ( Type A) and 3D [Zn(BDC)(H2O)] (Type B) (H2BDC = 1,4-benzene-dicarboxylate acid) compounds were synthesized with three kinds of 1-alkyl-3-methyl imidazolium halide ([RMI]X) ionic liquids. Type A is the primary structure model showing a ( 3,6) network. Type B can be obtained from [BMI]Cl, [AMI]Cl and [AMI]Br media, showing a 4,4-connected {4(2).8(4)} network. The structure, TG, and fluorescence analyses demonstrate the combination effect of the RMI+ templating effect and X- controlling the structure types. The boundary between Types A and B is from [PMI]Cl, via [BMI]Br, to [AMI]I as the reaction media. The decomposition temperatures of the compounds in Type A decrease with increased RMI+, while X- anions exert the influence that compounds containing Br- supply the highest thermal stability. Similarly, with increased RMI+, or X = I-, the compounds show red shifts compared to the emissions of the ligand.