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Journal of Synthetic Crystals ›› 2026, Vol. 55 ›› Issue (2): 314-324.DOI: 10.16553/j.cnki.issn1000-985x.2025.0198

• Research Articles • Previous Articles     Next Articles

Synthesis, Crystal Structure and Binding CT-DNA/HSA of [LaL3(H2O)2] n Complex

HUANG Qiuping(), YANG Siming, ZHENG Yanfei, PANG Huayu, HUANG Qiuchan(), ZHANG Haiquan()   

  1. Guangxi Key Laboratory for High-Value Utilization of Manganese Resources,Chongzuo Key Laboratory of Comprehensive Utilization Technology of Manganese Resources,Guangxi Minzu Normal University,Chongzuo 532200,China
  • Received:2025-09-10 Online:2026-02-20 Published:2026-03-06

Abstract: Using the solvothermal method,with 4-methyl-1,2,3-thiadiazole-5-carboxylic acid (HL) as the ligand and reacting with lanthanum nitrate hexahydrate,the thiadiazole lanthanum complex [LaL3(H2O)2n was synthesized. The structure of the complex was characterized by single crystal X-ray diffraction,infrared spectroscopy and elemental analysis. The interaction of the lanthanum complex with calf thymus DNA (CT-DNA) and human serum albumin (HSA) was investigated by ultraviolet (UV) and fluorescence spectroscopy. Single crystal structure tests show that,the complex belongs to the triclinic crystal system,space group P1,unit cell parameters a=0.979 88(5) nm,b=1.057 26(6) nm,c=1.103 62(5) nm,α=105.134(5)°,β=109.816(4)°,γ=94.221(4)°,Z=2,V=1.021 65(10) nm3Dc=1.974 g·cm-3F(000)=598.0,Rint=0.057 3. The lanthanum complex is formed by La3+ coordinating with six 4-methyl-1,2,3-thiadiazole-5-carboxylate anions and two water molecules,resulting in a nine-coordinated distorted three-capped trigonal prism structure. It forms a one-dimensional chain through carboxylate oxygen bridges,and the one-dimensional chains are further assembled into a three-dimensional network through N—H,S—H hydrogen bonds and π…π stacking of the thiadiazole rings.UV and fluorescence spectroscopic analysis indicates that,the complex interacts with CT-DNA and HSA. The quenching constant Ksv of the complex with CT-DNA is 4.75×104 L·mol-1,the quenching rate constant Kq is 4.75×1012 L·mol-1·s-1,the binding rate constant Ka is 2.45×105 L·mol-1,and the binding site n is 1.18. Therefore,it can be concluded that the fluorescence quenching of CT-DNA by the complex is static quenching. The quenching constant Ksv of the complex with HSA is 9.83×104 L·mol-1,the quenching rate constant Kq is 9.83×1012 L·mol-1·s-1,the binding rate constant Ka is 67.61 L·mol-1,and the binding site n is 0.39. The fluorescence quenching of HSA by the complex is static quenching. Hirshfeld analysis shows that there is a strong H…H interaction between molecules.

Key words: lanthanum (III) complex; thiadiazole; crystal structure; Hirshfeld; CT-DNA; HSA

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