Series of Lanthanide-Alkali Metal-Organic Frameworks Exhibiting Luminescence and Permanent Microporosity

A series of permanently porous luminescent lanthanide frameworks of the general formula, [Na 6 (H 2 O) 6 ][Ln(L) 4 ](H 2 O) n Cl, Ln = Sm ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), and Dy ( 5 ), have been prepared by the reaction of trivalent lanthanide salts with sodium-4,4‘-disulfo-2,2‘-bipyridine- N, N ‘-dioxide, L. The structures are formed via the one-pot self-assembly of the anionic cubic metalloligand, [Ln(L) 4 ] 5-, and subsequent cross-linking with sodium cations and chloride to afford a three-dimensional network with two-dimensional channels. The cross-linking units involve [Na 4 Cl] 3+ clusters which resemble ideal faces of the halite structure. Both coordinated and uncoordinated water molecules, up to ∼80%, can be reversibly removed from 1 − 5 as identified using thermal gravimetric analysis/differential scanning calorimetry (TGA/DSC) leaving a rigid and porous framework with a Dubinin−Radushkevich (DR) surface area of 426 m 2 /g determined using CO 2 adsorption. The permanent microporosity of the framework is also supported by the energy level splitting in the luminescence spectra which are maintained in both the hydrated and mostly dehydrated frameworks. Compounds 1 − 5 were each characterized by X-ray crystallography, TGA/DSC, water and CO 2 sorption analyses, and luminescence spectroscopy.