N-donor auxiliary ligand-directed assembly of CoII compounds with a 2,2′-dinitro-biphenyl-4,4′-dicarboxylate ligand: structures and magnetic properties?

CrystEngComm Pub Date: 2017-02-21 DOI: 10.1039/C7CE00046D

Abstract

To explore the influence of different N-donor auxiliary ligands on the self-assembly and structures of CoII-based coordination polymers (CPs), six coordination compounds, formulated as {Co(dnpdc)(bipy)}n (1), {[Co3(dnpdc)3(bipy)3(H2O)2]·2H2O}n (1s), {[Co5(OH)2(dnpdc)4(bpp)2(H2O)2]·2H2O}n (2), {[Co5(OH)2(dnpdc)4(bpp)2(H2O)2]·2H2O}n (3), {Co(dnpdc)(bcim)·(H2O)0.5}n (4) and {Co2(dnpdc)2(bpee)(bpim)}n (5) where bipy = 4,4′-bipyridine, bpee = bis(4-pyridyl)ethene, bpp = 1,3-bis(4-pyridyl)propane, bimb = 1,4-bis(imidazolyl)benzene, bcim = 4-bis(imidazol-1-ylmethyl)benzene and bpim = 4,4′-bis(imidazolyl)biphenyl, have been rationally designed and generated through the hydrothermal reaction of the dicarboxylate derivative ligand (H2dnpdc), Co(NO3)2, and a series of different N-donor co-ligands. These N-donor ligands were employed in the crystal preparation of these CPs as structure-directing ligands owing to their structural specialties and size-matching fashions. X-ray analyses revealed that these compounds exhibit two- or three-dimensional architectures. Compounds 1 and 5 are iso-structural, and both exhibit 3D “pillared” frameworks based on 1D [Co(OCO)2]n chains. Compound 1s, prepared at higher temperature, displays unusual (4,6)-connected and three-fold interpenetrated frameworks based on mononuclear and dinuclear nodes. Compound 2 features a new 10-connected 3D topology net based on a novel Co5(μ-OH)2(μ-OCO)6 pentanuclear cluster linked by mixed bpp and dnpdc ligands. Compound 3 exhibits a 6-fold interpenetrated diamond net. Compound 4 shows 2D sheets constructed from flexible bcim and dnpdc ligands. The magnetic properties of compounds 1, 2 and 5 have also been investigated to help us tentatively understand their structure–property relationships.

Graphical abstract: N-donor auxiliary ligand-directed assembly of CoII compounds with a 2,2′-dinitro-biphenyl-4,4′-dicarboxylate ligand: structures and magnetic properties
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