Ligand-directed assembly of tetranuclear cobalt clusters: structural modulation via a lactate derivative and azacyclic linkers
Year: 2025
Type: article
Abstract: The semi-rigid lactic acid derivative 5-(1-carboxyethoxy)isophthalic acid (H3CIA) demonstrates inherent cluster-forming propensity through its carboxylate groups and ether oxygen donors. Leveraging these features, three cobalt-based coordination polymers were synthesized via solvothermal assembly of H3CIA with Co(II) ions in the presence of azacyclic linkers pyrazine, 1,3-dib and 4,4’-dib: [Co4(CIA)2(OH)2(pyrazine)(H2O)]·(H2O)(MeOH)0.5 (HU1), [Co2(CIA)(OH)(1,3- dib)]·(H2O)2(DMF)0.5 (HU2), and [Co2(CIA)(OH)(4,4’-dib)]·xGuest (HU3). Notably, all architectures incorporate tetranuclear [Co4(μ3-OH)2]6+ clusters formed by means of the distinct coordination preferences of CIA3- anion. The clusters interconnect to generate analogous two-dimensional layers with kdg net among HU1-3, which are further pillared by azacyclic ligands into three-dimensional frameworks. Structural variations arise from divergent linker geometries: HU1 contains two discrete [Co4(μ3-OH)2]6+ units bridged by two pyrazine ligands per cluster, while HU2 and HU3 feature a single [Co4(μ3-OH)2]6+ unit coordinated by four 1,3-dib or 4,4’-dib ligands, respectively. Although there are obvious structural differences among complexes HU1-3, their frameworks can all be simplified to the same 3,8-connected tfz-d net from the perspective of topological analysis. Furthermore, optical characterization demonstrates broad absorption bands across UV-vis regions and magnetic studies confirm antiferromagnetic coupling within all three complexes. In the presence of pyrazine, 1,3-dib, and 4,4′-dib, H3CIA assembled with Co(II) ions to result in three CPs with tetranuclear [Co4(μ3-OH)2]6+ units, two-dimensional CIA-Co metal-organic layers and pillared-layer frameworks with a 3,8-connected topological network.
Source: Figshare
Authors: Zheng, Ya-Jia, Xu, Zhong-Xuan
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W6902373271
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