Synthesis and characterizations of Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate

Abstract

Seven Zn(II) and Co(II) coordination polymers based on 5-acetamidoisophthalate (AcAIP) and flexible bis(imidazolyl) ligands, [Zn(H2O)0.5(AcAIP)]n (1), [Zn(AcAIP)(o-BIMB)]n·3nH2O (2), [Co(AcAIP)(o-BIMB)]n·3nH2O (3), [Zn(AcAIP)(m-BIMB)]n·3nH2O (4), [Co(AcAIP)(m-BIMB)]n·3nH2O (5), [Zn(AcAIP)(p-BIMB)]n (6) and [Co(AcAIP)(p-BIMB)]n (7) (o-BIMB=1,2-bis(imidazol-1-yl-methyl)benzene, m-BIMB=1,3-bis(imidazol-1-yl-methyl)benzene and p-BIMB=1,4-bis(imidazol-1-yl-methyl)benzene), were synthesized and well characterized. In complex 1, AcAIP serves as a μ4-bridge through μ2,η2-carboxylate, monodentate carboxylate and acetamido, and connects Zn(II) ions into a 3-D network, while acetamido group of AcAIP in 2–7 is not involved in coordination with metal ions owing to the presence of bis(imidazolyl) ligands. Notably, AcAIP in 2–6 bridges two metal ions through two monodentate carboxylate groups. AcAIP in 2–5 connects Zn(II) and Co(II) ions into 1-D chain, subsequent bridge by o-BIMB generates a 2-D corrugated layer, while m-BIMB connects two intra-chained metal ions to form [Zn2(AcAIP)(m-BIMB)] macrocycles. Interestingly, AcAIP in 6 links two Zn(II) ions into a 16-membered [Zn2(AcAIP)2] macrocycle, and subsequent bridge by anti-conformationed p-BIMB forms a 2-D layer. However, two carboxylate groups of AcAIP in 7 function in μ2,η2-bridging and chelating modes, AcAIP and gauche-conformationed p-BIMB bridge Co(II) ions to form a twofold interpenetrating framework consisting of dinuclear Co(II)-carboxylate units. Magnetic analysis of complex 7 shows that the existence of antiferromagnetic interactions. Fluorescent properties of Zn(II) coordination polymers in solid state were also investigated.