A multifunctional Cd(II)-based metal-organic framework with amide groups exhibiting luminescence sensing towards multiple substances

A solvothermal reaction of an amide-functionalized tetracarboxylate linker (H4L) with Cd(II) leads to an anionic metal-organic framework, (Me2NH2)(2)[Cd-3(L)(2)]center dot 7H(2)O (1). Incorporating the flexible amide group into the skeleton of H4L causes the entire molecule to be twisted. Consequently, H4L can behave as a tetrahedral node and further combine with cubic trinuclear [Cd-3(COO)(8)] nodes to afford a rare (4,8)-connected fluorite (flu) net. More importantly, 1 contains an anionic framework featuring a channel decorated with amide groups, and thus exhibits a multi-responsive behavior towards Fe3+, Cu2+ and Cr2O72- ions in water as well as nitroaromatics in acetonitrile based on the turn-off effect. The possible quenching mechanism inferred that the amide groups decorated in the framework facilitate effective interactions through the formation of hydrogen bonds with analytes causing a change in luminescence signals.