Pyridinium/imidazolium-triggered modulation of structure and properties of cobalt naphthalene-diphosphates

By the introduction of protonated 1,3-di(4-pyridyl)propane (1,3-dppH(2)(2+)) and protonated bis(imidazol-1- ylmethyl)benzene (1,4-bixH(2)(2+)) as a cationic template, three new cobalt naphthalene-diphosphate coordination polymers based on 1,4-naphthalenediphosphonic acid (1,4-ndpaH(4)), namely (1,3-dppH(2))(2)[Co-4(1,4-ndpa)(1,4-ndpaH)(2)(1,4- ndpaH(2))]center dot 6H(2)O (1), (1,4-bixH(2))(0.5)[Co(1,4-ndpaH)] (2), and (1,4-bixH(2))(0.5)[Co-2(1,4-ndpaH)(1,4-ndpaH(2))(H2O)(2)] (3), have been hydrothermally synthesized. Complexes 1-3 were characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric analysis, respectively. In complexes 1 and 2, inorganic chains of corner-sharing {CoO4} and {PO3C} tetrahedron are cross-linked by naphthalene ligands into 3D open-framework structures. The protonated di-pyridinium/imidazolium moieties, 1,3-dppH(2)(2+) for 1 and 1,4-bixH(2)(2+) for 2, lie inside the skeletal voids of the crystal structure, respectively. Interestingly, complex 3 with similar chemical composition to 2 except for an additional 1,4-ndpaH(2)(2-) ligand and two coordinated water molecules shows a 2D undulating layer structure, where the chains of corner-sharing {CoO5} trigonal bipyramid, {CoO6} octahedron, and {PO3C} tetrahedron are cross-linked by naphthalene groups. Adjacent layers are packed in AB stacking into the supramolecular structure, in which 1,4-bixH(2)(2+) ions fill and balance the charge of 3. Magnetic studies reveal that dominant antiferromagnetic interactions between the magnetic centers are propagated in complexes 1 and 2. CCDC: 2202596, 1; 2202597, 2; 2202598, 3.

Automated summary

Three new cobalt naphthalene-diphosphate coordination polymers, (1,3-dppH(2))(2)[Co-4(1,4-ndpa)(1,4-ndpaH)(2)(1,4- ndpaH(2))]center dot 6H(2)O (1), (1,4-bixH(2))(0.5)[Co(1,4-ndpaH)] (2), and (1,4-bixH(2))(0.5)[Co-2(1,4-ndpaH)(1,4-ndpaH(2))(H2O)(2)] (3), were synthesized using protonated 1,3-di(4-pyridyl)propane and protonated bis(imidazol-1- ylmethyl)benzene as cationic templates. Complexes 1 and 2 have 3D open-framework structures, while complex 3 has a 2D undulating layer structure. Magnetic studies show dominant antiferromagnetic interactions in complexes 1 and 2.