Substituent groups from aromatic dicarboxylates modulated structural diversification in the assembly of Co(II) complexes based on the bis-pyridyl-bis-amide ligands

Abstract

Four coordination polymers based on two bis-pyridyl-bis-amide ligands and three aromatic dicarboxylates with different substituent groups, namely, [Co(3-bpcb)1.5(NPH)(H2O)]·4H2O (1), [Co(3-bpcb)(NIPH)] (2), [Co(3-bpcb)0.5(5-H2AIP)]·2H2O (3), [Co(3-bpcd)0.5(5-H2AIP)(H2O)]·2H2O (4) [3-bpcb = N,N′-bis(3-pyridinecarboxamide)-1,4-benzene, 3-bpcd = N,N′-bis(3 pyridine)cyclohexane-1,4-dicarboxamide, H2NPH = 3-nitrophthalic acid, H2NIPH = 5-nitroisophthalic acid, 5-H4AIP = 5-aminoisophthalic acid] have been synthetized under hydrothermal conditions. Complex 1 displays a one dimensional (1D) chain based on the binuclear [Co2(NPH)2] units and 3-bpcb ligands, which is extended into a three dimensional (3D) supramolecular framework through hydrogen bonding and π-π stacking interactions. In complex 2, the (3,5)-connected two dimensional (2D) layers are constructed from 1D Co-NIPH chains and bidentate-bridging 3-bpcb ligands. Complex 3 is a 2D double layer based on Co-5-H2AIP 2D layers and 3-bpcb pillars. Complex 4 also displays a 2D network, which is constructed from the Co-5-H2AIP 1D double chains and 3-bpcd ligands. Finally, complexes 2-4 are extended into 3D supramolecular frameworks by hydrogen bonding or π-π stacking interactions. The substituent groups of dicarboxylates play an important role in the assembly and structures of the title complexes. In addition, the fluorescent properties of complexes 1–4 and the electrochemical behaviors of 3 and 4 at room temperature have been investigated.