Heterometallic Cu(II)-M(II) (M = Mg, Ca and Sr) complexes with a N,O-donor ligand in situ generated from topiroxostat

Abstract

By introducing alkaline-earth metal ions (Mg²⁺, Ca²⁺, and Sr²⁺) as structure-directing agents, three new heterometallic complexes, Mg(H₂O)₆·[Cu₂Mg(L)₄(H₂O)₄]·4H₂O (1), [CuCa(L)₂(H₂O)₄]_n (2) and [CuSr(L)₂(H₂O)₄]_n (3) [H₂L = 4-(3-(pyridine-4-yl)-1H-1,2,4-triazol-5-yl)picolinic acid], have been synthesized under hydrothermal conditions and structurally characterized. H₂L was in situ generated from hydrolysis of the well-known selective xanthine oxidase inhibitor topiroxostat. Complex 1 crystallizes in the space group P2₁/c and exhibits a zero-dimensional (0-D) structure containing the discrete [Mg(H₂O)₆]²⁺ cationic and [Cu₂Mg(L)₄(H₂O)₄]^2– dianionic moieties. Complexes 2 and 3 are isostructural and crystallize in the space group C2/c, with one-dimensional (1-D) polymeric structure with infinite Cu(II)–Ca/Sr–carboxylate chains. The results reveal the significant influence of the alkaline-earth metal ions on the molecular structure. Their spectroscopic, thermal and solid-state luminescent properties have also been investigated.

Graphical Abstract

Keywords:

• Topiroxostat
• Heterometallic complex
• Alkaline-metal-regulated assembly
• Crystal structure
• Luminescent property

Additional information

Funding

This research was supported by the National Natural Science Foundation of China (grant no. 21676030), a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), the Advanced Catalytic and Green Manufacturing Collaborative Innovation Center, Changzhou University and Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology (grant nos. ZZZD201807 and BM2012110).