Four novel lanthanide complexes with 4‐ethylbenzoic acid and 5,5′‐dimethy‐2,2′‐bipyridine: Structures, luminescent, thermal properties and bacteriostatic activities

Abstract

Four new lanthanide complexes [Ln(4-EBA) 3 (5,5′-DM-2,2′-bipy)] 2 ·2C 2 H 5 OH (Ln = Ho (1), Tb (2), Er (3)); [Ln(4-EBA) 3 (4-EBAH)(5,5′-DM-2,2′-bipy)] 2 (Ln = Eu(4); 4-EBA =4-ethylbenzoate; 5,5′-DM-2,2′-bipy =5,5′-dimethy-2,2′bipyridine; 4-EBAH = 4-ethylbenzoic acid) have been synthesized and characterized by elemental analysis and IR spectra. The single crystal results reveal that complexes 1-3 are isostructural. It is worth noting that the mole ratios of the carboxylate ligands and neutral ligands is 4:1 in complex 4, which is different from the former and has been rarely reported. Nevertheless, all complexes are connected to form 1D chain by π···π wake staking interactions. Additionally, the complexes 2 (Tb(III)) and 4 (Eu(III)) exhibit characteristic luminescent properties, indicating that ligands can be used as sensitizing chromophore in these systems. The thermal decomposition mechanism of the complexes has been investigated by TG/DSC-FTIR technology. Stacked plots of the FTIR spectra of the evolved gases show complexes broken down into H 2 O, CO 2 , and other gaseous molecules as well as the gaseous organic fragments. The studies on bacteriostatic activities of complexes show that four complexes have good bacteriostatic activities against Candida albicans but no bacteriostatic activity on Escherichia coli, and Staphylococcus aureus. Additionally, the complexes 1 to 3 have better bacteriostatic activities on Candida albicans than complex 4.

Crystal structures, thermal decomposition kinetics and thermodynamic properties of lanthanide Ho(III) complex with 2,5-dichlorobenzoic acid and 5,5′-dimethyl-2,2′-bipyridine

“…2015 年, 宗广才 [17] 以2-溴-5-甲氧基苯甲酸和1,10-邻菲罗啉 为配体与稀土离子合成了系列稀土配合物, 并对其中 Ho(III)和Er(III)配合物进行了磁性研究. 2017年, 申盼 盼 [18] 通过使用有机羧酸和5,5′-二甲基-2,2′-联吡啶合成 了系列稀土配合物, 并进行了抑菌活性测试, 结果显示 此类配合物对白色念珠菌具有很好的抑制作用. 2017 年, 赵青青 [19] Table 5 Conversion degrees measured at the same temperatures given on four curves of [Ho(2,5-DClBA) 3 (5,5′-DM-2,2′-bipy)] 2 at different heating rates for the second step Table 9 Thermodynamic parameters for complex 表 8 用改进的双等双步法 [26] 计算配合物第二步热分解反应的动力学参数的值 Table 8 The values of the kinetics parameters computed by the Flynn-Wall-Ozawa method [26] α…”