Coordination polymers of manganese(II), cobalt(II), nickel(II) and cadmium(II) decorated with rigid pyrazine-2,3-dicarboxylic acid linker: Synthesis, structural diversity, DFT study and magneto-luminescence properties

摘要

Single crystal diffraction analysis shows the formation of four new coordination polymers (CPs), viz. {[Mn(PYzdc)(H2O)(2)]center dot 2H(2)O}(n) (1), [Co(Pyzdc)(H2O)(2)](n) (2), [Ni(PYzdc)(H2O)(2)](n) (3) and [Cd(Pyzdc)](n) (4) (where Pyzdc(2) stands for the fully-deprotonated pyrazine-2,3-dicarboxylic acid), by the solvothermal selfassembly of the four titled metal(II) nitrates with rigid pyrazine-2,3-dicarboxylic acid. CP 1 crystallizes in the monoclinic P2(1)/c space group, whereas CPs 2, 3 and 4 have orthorhombic Pcca, Pcca and Pnna space groups respectively. CPs 1-4 consist of dinuclear secondary building units (SBUs) [Mn2O10N2 (1), M2O8N4 (where M=Co (2) and Ni (3)) and Cd2O6 N-4 (4)]. In CPs 1-3 (Mn, Co and Ni), covalent interactions foster into one-dimensional structures, whereas CP 4 (Cd) exhibits a three-dimensional architecture. The Pyzdc linker exhibits three different coordination modes (mu 3-kappa O:kappa O:kappa O:kappa N for CP 1, mu(2)-kappa O:kappa O:kappa N:kappa N for CPs 2 and 3, and mu(4)-kappa O,O:kappa O,O:kappa N:kappa N for CP 4). DFT calculations reveal that in one compound (CP 1), interesting it-hole interactions exist, which have been evaluated energetically (at the PBE1PBE-D3/def2-TZVP level of theory) and characterized using the quantum theory of "atoms-in-molecules" (QTAIM). Magnetic studies reveal that the Weiss constant, based on the equation chi(m) = g(T-theta), is negative (theta = -34.37, -50.46 and -37.09 K for CPs 1, 2 and 3 respectively). This suggests weak antiferromagnetic interactions between adjacent M(II) centers. Lastly, the ligand based photoluminescence of CP 4 has been explored. (C) 2020 Elsevier Ltd. All rights reserved.