3-D indium(III)-btc channel frameworks and their ion-exchange properties (btc=1,3,5-benzenetricarboxylate)

Assembly of InCl3 with 1,3,5-benzenetricarboxylic acid (H3btc) and pyridine or pyridine derivatives under hydrothermal conditions produces a series of isostructural coordination polymers with the interesting frameworks: {(HL)[In4(OH)4(btc)3]·L·3H2O}n, L=pyridine (1); L=2-picoline (2); L=4-picoline (3) and {(Hdpea)[In4(OH)4(btc)3]·3H2O}n (4) (dpea=1,2-di(4-pyridyl)ethane). In these four complexes, carboxyl and hydroxyl oxygen atoms bridge indium(III) centers to form octahedral chain-like sinusoidal curves, which are further interlinked by btc3− moieties to generate 3-D frameworks with 1-D channels. The protonated guests HL in 1–3 located at the channels can be fully exchanged by K+ ion or partially exchanged by Sr2+, and Ba2+ ions.