Structures, Magnetic Properties, and Photoluminescence of Dicarboxylate Coordination Polymers of Mn, Co, Ni, Cu Having <i>N</i>-(4-Pyridylmethyl)-1,8-naphthalimide

Abstract

Supramolecular interactions of N -(4-pyridylmethyl)-1,8-naphthalimide ( L ) and flexibility of intervening units of dicarboxylate ligands contribute to formation of different types of coordination polymers such as [Mn L 2 (Adp)(H 2 O) 2 ] n ·2 n H 2 O ( 1 ), [Co L 2 (Fum)(H 2 O) 2 ] n ·2 n H 2 O ( 2 ), [Co L 2 (Adp)(H 2 O) 2 ] n ·2 n H 2 O ( 3 ), [Ni L (Fum)(H 2 O) 3 ] n ·H 2 O ( 4 ), [Cu L 2 (Fum)] n · n H 2 O ( 5 ), [Cu L (Mal)] n ( 6 ), and [Cu 3 L 6 (Adp) 3 (H 2 O) 3 ] n ( 7 ) (where Adp = adipate, Fum = fumarate, and Mal = malonate). These coordination polymers are structurally characterized. Coordination polymers 1 and 3 are isostructural having three-dimensional (3D) supramolecular layer-like structures. Coordination polymer 2 forms a two-dimensional (2D) supramolecular network through C–H···π and O···π interactions. Coordination polymer 4 forms H-bonded 3D chainlike supramolecular architecture. Coordination polymer 5 forms a 3D supramolecular sheet-like structure, whereas coordination polymer 6 and coordination polymer 7 forms a 2D lamellar structure through π···π and C–H···π interactions. Manganese coordination polymer 1 shows weak antiferromagnetic interactions between chains at low temperature and also exhibits single chain magnetic behavior. Coordination polymers 2 and 3 show saturation value of magnetic moment at 2 K and 7 T, which are lower than the spin-only Co(II) ion. Coordination polymer 4 show spin-only values for Ni(II) ion. The room-temperature χ M T value for coordination polymer 5 is close to the spin-only value for two Cu(II) ions. With lowering of the temperature, the χ M T value remains constant to 35 K, from where the value begins to decrease to a minimum at 2 K. For copper coordination polymer 6 value of χ M T smoothly decreases with lowering of the temperature to attain a quasi plateau between 80 K and 35 K, and it further sharply increases at 2 K. Coordination polymer 7 shows spin-only Cu(II) ion. These coordination polymers in solid state show quenching of fluorescence emission of ligand L, as well as a shift of emission toward a shorter wavelength.