A series of three-dimensional lanthanide(iii) coordination polymers of 2,5-dihydroxy-1,4-benzenedicarboxylic acid based on dinuclear lanthanide unitsElectronic supplementary information (ESI) available. CCDC reference numbers 823998–824002. For ESI and crystallographic data in CIF or other electronic format, see DOI: 10.1039/c1ce05069a

The reactions of Ln(NO3)3with 2,5-dihydroxy-1,4-benzenedicarboxylic acid (H2-DHBDC) under solvothermal conditions produce a series of isomorphous lanthanide coordination polymers with the empirical formula {[Ln2(DHBDC)3(DMF)4](DMF)2}n(Ln = La(1), Nd(2), Sm(3), Gd(4), and Er(5)). Compound {[Ln2(DHBDC)3(DMF)4](DMF)2}ncontains dinuclear Ln2(COO)6units, which are linked by the –C6H2(OH)2– spacers to form a three-dimensional framework exhibiting α-Po topology (pcu-(412·63) net) based on dinuclear Ln2(COO)6nodes. The three-dimensional framework shows one-dimensional open channels that accommodate the coordinated and guest DMF molecules. Gas adsorption measurements on compound 4indicate that the desolvated solid of 4adsorbs CO2and shows nonporous behavior toward N2. The adsorption favoring CO2over N2may arise from the chemical environments of the host framework, which contains the polar –OH groups of the phenyl and the π-electrons of the ligands. Magnetic measurements on compound 4indicate that there is an antiferromagnetic interaction between Gd3+ions. [ABSTRACT FROM AUTHOR]