A three-dimensional gadolinium organic framework based on a pyridinedicarboxylic acid organic linker with a paddle-wheel-type network structure.

A new gadolinium(III)-pyridine-2,5-dicarboxylic acid (Gd III -2,5-H 2 pdc)-based three-dimensional coordination polymer, namely, poly[dimethylazanium [bis(μ-pyridine-2,5-dicarboxylato)gadolinium(III)]], {[(CH 3 ) 2 NH 2 ][Gd(C 7 H 3 NO 4 ) 2 ]} n , CP-1, has been synthesized via a typical solvothermal method. The as-synthesized material was characterized in the solid state using single-crystal X-ray diffraction, powder X-ray diffraction, thermogravimetric analysis and FT-IR spectroscopy. During the synthesis of CP-1, the in situ dimethylformamide (DMF) promotes the formation of a dimeric unit and these act as secondary building blocks in the assembly of a three-dimensional anionic {[Gd(pdc) 2 ] - } ∞ framework. The framework has channels along the c axis which are filled by dimethylazanium cations. Interestingly, the framework shows a helical-type assembly running down the a axis. A Hirshfeld surface analysis of CP-1 suggests that extra stability is provided by hydrogen-bonding interactions. The magnetic properties of CP-1 showed weak antiferromagnetic couplings between adjacent Gd 3+ ions.