A thermally stable three-dimensional cobalt(II) coordination polymer based on the V-shaped ligand 4-(4-carboxyphenoxy)isophthalate.

A new cobalt(II) coordination polymer (CP), poly[[bis[μ6-4-(4-carboxylatophenoxy)benzene-1,3-dicarboxylato-κ6O1:O1:O3:O3':O4:O4']bis(1,10-phenanthroline-κ2N,N')tricobalt(II)] 0.72-hydrate], {[Co3(C15H7O7)2(C12H8N2)2]·0.72H2O}n, (I), is constructed from CoII ions and 4-(4-carboxyphenoxy)isophthalate (cpoia3-) and 1,10-phenanthroline (phen) ligands. Based on centrosymmetric trinuclear [Co3(phen)2(COO)6] secondary building units (SBUs), the structure of (I) is a three-dimensional CP with a (3,6)-connected net and point symbol (42.6)2(44.62.87.102). The positions of four [Co3(phen)2(COO)6] SBUs and four cpoia3- ligands reproduce a Chinese-knot-shaped arrangement along the ab plane. (I) has been characterized by single-crystal X-ray diffraction, IR spectroscopy, powder X-ray diffraction (PXRD) and thermostability analysis. It shows a good thermal stability from room temperature to 673 K. In addition, the temperature dependence of the magnetic properties was measured.