Bhattacharyya Arunasis, Gadly Trilochan, Pathak Priyanath, Ghosh Sunil K, Mohapatra Manoj, Ghanty Tapan K, Mohapatra Prasanta K
Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.
Dalton Trans. 2014 Aug 28;43(32):12422-9. doi: 10.1039/c4dt01342e.
A systematic study on the Ln(3+) complexation behaviour with two terdentate 'N' donor ligands of varying structural rigidity, viz. 5,6-dimethyl-(1,2,4)-triazinylbipyridine (Me2TBipy) and 5,6-dimethyl-(1,2,4)-triazinylphenanthroline (Me2TPhen), is performed in the present work by UV-Vis spectrophotometry, time resolved fluorescence spectroscopy (TRFS) and electrospray ionization mass spectrometric (ESI-MS) studies. These studies indicate the formation of a 1 : 1 complex of La(3+), 1 : 2 complexes of Eu(3+) and Er(3+) with both the ligands. Density functional theoretical (DFT) study is carried out to determine the solution phase structure of the Eu(3+) complex considering the species (from UV-Vis spectrophotometry) and C2v site symmetry around the Eu(3+) ion (from TRFS study). Me2TPhen is found to be a stronger complexing ligand as compared to Me2TBipy irrespective of the Ln(3+) ions. The solid state crystal structure of the La(3+) complex of Me2TPhen is determined using the single crystal X-ray diffraction (SCXRD) technique. The complexation of the trivalent Am(3+) ion is also studied with both these ligands using UV-Vis spectrophotometric titrations which show the formation of 1 : 2 complexes with higher complexation constant values as compared to all the Ln(3+) ions studied, indicating the selectivity of these ligands for the trivalent actinides over the lanthanides.
本工作通过紫外可见分光光度法、时间分辨荧光光谱法（TRFS）和电喷雾电离质谱法（ESI-MS），对具有不同结构刚性的两种三齿“N”供体配体，即5,6-二甲基-(1,2,4)-三嗪基联吡啶（Me2TBipy）和5,6-二甲基-(1,2,4)-三嗪基菲咯啉（Me2TPhen）与Ln(3+)的络合行为进行了系统研究。这些研究表明，La(3+)形成了1:1的络合物，Eu(3+)和Er(3+)与这两种配体均形成了1:2的络合物。进行了密度泛函理论（DFT）研究，以根据紫外可见分光光度法得到的物种以及TRFS研究得到的Eu(3+)离子周围的C2v位点对称性，确定Eu(3+)络合物的溶液相结构。无论Ln(3+)离子如何，发现Me2TPhen与Me2TBipy相比是更强的络合配体。使用单晶X射线衍射（SCXRD）技术确定了Me2TPhen的La(3+)络合物的固态晶体结构。还使用紫外可见分光光度滴定法研究了三价Am(3+)离子与这两种配体的络合情况，结果表明形成了1:2的络合物，其络合常数高于所研究所有Ln(3+)离子的络合常数，表明这些配体对三价锕系元素比对镧系元素具有选择性。
