A multifuctional Cd(II)-based metal−organic framework with amide groups exhibiting luminescent sensing towards multiple substances

Solvothermal reaction of a amide-functionalized tetracarboxylate linker (H4L) with Cd(II) leads to a anionic metal-organic framework, (Me2NH2)2[Cd3(L)2]∙7H2O (1). Incorporated flexible amide group into the skeleton of H4L causes the entire molecule to be twisted. Consequently, H4L can behave as tetrahedral nodes and further combine cubic trinuclear [Cd3(COO)8] nodes to afford a rare (4,8)-connected fluorite (flu) net. More importantly, 1 contains anionic framework featuring amide groups decorated channel, and thus exhibits multi-responsive behavior towards Fe3+, Cu2+ and Cr2O72- ions in water as well as nitroaromatics in acetonitrile based on turn-off effect. The possible quenching mechanism was inferred and revealed that the amide groups decorated in framework facilitate the effective interactions through the formation of hydrogen bonding with analytes and incur the change of luminescence signals.