Structures, Magnetic Properties, and Photoluminescence
of Dicarboxylate Coordination Polymers of Mn, Co, Ni, Cu Having N‑(4-Pyridylmethyl)-1,8-naphthalimide
posted on 2014-09-03, 00:00authored byJayanta
K. Nath, Abhishake Mondal, Annie K. Powell, Jubaraj B. Baruah
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 [MnL2(Adp)(H2O)2]n·2nH2O (1), [CoL2(Fum)(H2O)2]n·2nH2O (2), [CoL2(Adp)(H2O)2]n·2nH2O (3), [NiL(Fum)(H2O)3]n·H2O (4), [CuL2(Fum)]n·nH2O (5), [CuL(Mal)]n (6), and [Cu3L6(Adp)3(H2O)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 χMT value for coordination polymer 5 is close to the spin-only value for two Cu(II) ions. With lowering
of the temperature, the χMT 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 χMT 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.