Two different heterometallic supramolecular compounds based on the ligands salicylhydroxamic acid (H3shi) and 5-nitroisophthalic acid (5-NO2-H2iph) have been characterized by single-crystal X-ray analysis. One structure is a 12-MC-4 dimer {LnNa[12-MCAl(III)N(shi)-4]}2(5-NO2-iph)4, where LnIII = Gd (1) and Dy (2), and the second is a molecular parallelogram [Ln4Al12(shi)8(H2shi)4(5-NO2-iph)10(H2O)16(DMF)2], where LnIII = Gd (1a) and Dy (2a). When the synthesis is performed in N,N-dimethylformamide (DMF), both the 12-MC-4 dimer and molecular parallelogram co-crystallize. In one instance when the synthesis is performed in a N,N-dimethylacetamide (DMA):methanol mixture (50:50), the only product was the 12-MC-4 dimer. For the dimeric structure, two LnNa[12-MCAl(III)N(shi)-4] units are connected by four 5-NO2-iph2− linkers. Each 12-MC-4 unit contains four ring AlIII ions and four triply deprotonated shi3− ligands in a square arrangement, which generates a central metallacrown cavity. This cavity binds both a LnIII and Na+ ion on opposite faces. The LnIII-LnIII distances across the dimer for 1 and 2 are 7.05 and 7.08 Å, respectively. The molecular parallelogram contains two Ln2Al6(shi)4(H2shi)2(5-NO2-iph)5 units that are similar to the 12-MC-4 dimers. The presence of singly deprotonated H2shi− ligands though prevent formation of true 12-MC-4 units and thus the dimer. The LnIII-LnIII distances across the dimer-like units of 1a and 2a, 7.29 and 7.31 Å, respectively, are comparable to the equivalent distances of 1 and 2. The two Ln2Al6(shi)4(H2shi)2(5-NO2-iph)5 units of 1a and 2a are connected by two 5-NO2-iph2− linkers to generate the supramolecular parallelogram [Ln4Al12(shi)8(H2shi)4(5-NO2-iph)10(H2O)16(DMF)2]. Graphical abstract

Utilizing 5-Nitroisophthalate to Construct 12-Metallacrown-Dimers and Molecular Parallelograms

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发表日期：

2026年6月20日

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Lee B. Garman,
Matthias Zeller,
Curtis M. Zaleski

摘要

Two different heterometallic supramolecular compounds based on the ligands salicylhydroxamic acid (H₃shi) and 5-nitroisophthalic acid (5-NO₂-H₂iph) have been characterized by single-crystal X-ray analysis. One structure is a 12-MC-4 dimer {LnNa[12-MC_{Al(III)N(shi)}-4]}₂(5-NO₂-iph)₄, where Ln^III = Gd (1) and Dy (2), and the second is a molecular parallelogram [Ln₄Al₁₂(shi)₈(H₂shi)₄(5-NO₂-iph)₁₀(H₂O)₁₆(DMF)₂], where Ln^III = Gd (1a) and Dy (2a). When the synthesis is performed in N,N-dimethylformamide (DMF), both the 12-MC-4 dimer and molecular parallelogram co-crystallize. In one instance when the synthesis is performed in a N,N-dimethylacetamide (DMA):methanol mixture (50:50), the only product was the 12-MC-4 dimer. For the dimeric structure, two LnNa[12-MC_{Al(III)N(shi)}-4] units are connected by four 5-NO₂-iph²⁻ linkers. Each 12-MC-4 unit contains four ring Al^III ions and four triply deprotonated shi³⁻ ligands in a square arrangement, which generates a central metallacrown cavity. This cavity binds both a Ln^III and Na⁺ ion on opposite faces. The Ln^III-Ln^III distances across the dimer for 1 and 2 are 7.05 and 7.08 Å, respectively. The molecular parallelogram contains two Ln₂Al₆(shi)₄(H₂shi)₂(5-NO₂-iph)₅ units that are similar to the 12-MC-4 dimers. The presence of singly deprotonated H₂shi⁻ ligands though prevent formation of true 12-MC-4 units and thus the dimer. The Ln^III-Ln^III distances across the dimer-like units of 1a and 2a, 7.29 and 7.31 Å, respectively, are comparable to the equivalent distances of 1 and 2. The two Ln₂Al₆(shi)₄(H₂shi)₂(5-NO₂-iph)₅ units of 1a and 2a are connected by two 5-NO₂-iph²⁻ linkers to generate the supramolecular parallelogram [Ln₄Al₁₂(shi)₈(H₂shi)₄(5-NO₂-iph)₁₀(H₂O)₁₆(DMF)₂].

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