Syntheses, structures, surface analysis, DFT and fluorescence properties of three new Cd(II)-MOFs assembled with semi-rigid polycarboxylate

Three Cd(II)-based metal-organic frameworks (MOFs), namely, [Cd(HL1)(4,4'-bipb)](n) (1), [Cd-2(L-2)(4,4'-bipb)(2) (H2O)(3)](n) (2), {[Cd-2(L-3)(4,4'-bipb)(H2O)(2)]center dot(4,4'-bipb)(0.5)}(n) (3), where H3L1, H4L2, H4L3, and 4,4'-bipb are semi-rigid 2-(4-carboxyphenoxy) terephthalic acid, 3-(2,4-dicarboxyphenoxy)phthalic acid, 3,3'-(1,3-phenylenebis(oxy))diphthalic acid, and 1,4-bis(pyridin-4-yl)benzene, respectively, are synthesized in the presence of 4,4'-bipb and Cd(II) ions by hydrothermal method. 1 displays a 2,6-connected 3D topological structure. 2 features a 3D framework with 4,5,5-connected topology. 3 shows a 4,4,4-connected 3D topology. The fluorescence properties of 1-3 were determined in a dilute aqueous suspension at room temperature. The initial fluorescence intensity of 1 and 2 was almost completely quenched after the addition of Fe(NO3)(3) solution. It is confirmed that after the addition of AgNO3 solution, the fluorescence intensity of 3 was quenched significantly, but the fluorescence intensity is increased after the Al(NO3)(3) and Fe(NO3)(3) solutions are added. (C) 2021 Published by Elsevier B.V.

Automated summary

The synthesis and characterization of three Cd(II)-based metal-organic frameworks with different topological structures and fluorescence properties were studied, showing the influence of metal ions on their properties.