Ruprecht-Karls-Universität Heidelberg, Institut für Physikalische Chemie, Im Neuenheimer Feld 253, 69120 Heidelberg, Germany.
Dalton Trans. 2013 Sep 14;42(34):12139-47. doi: 10.1039/c3dt50536g. Epub 2013 Apr 4.
Two BTP-type N-donor ligands with different numbers of aromatic nitrogen atoms (2,6-bis(4-ethyl-pyridazin-1-yl)pyridine, Et-BDP and 2,6-bis(4-(n)propyl-2,3,5,6-tetrazine-1-yl)pyridine, (n)Pr-Tetrazine) have been synthesized and characterized by NMR and MS techniques. The complexation with Cm(III) in 2-propanol-water (1 : 1, vol.) is studied for both ligands using time resolved laser-induced fluorescence spectroscopy (TRLFS) and the complexation properties are compared to (n)Pr-BTP. With increasing the ligand concentration three different species, the 1 : 1-, 1 : 2- and 1 : 3-complex, were found. Log β3 values of 7.6 for the formation of Cm(Et-BDP)3 and 9.2 for the formation of Cm((n)Pr-Tetrazine)3 are determined. The complexation with (n)Pr-Tetrazine shows slow kinetics. Thermodynamic data of the complexation reactions are determined in a temperature range of 25 °C-60 °C. The complexation with Et-BDP is exothermic (ΔH = -16.3 ± 1.2 kJ mol(-1)) and exergonic (ΔG = -43.8 ± 2.6 kJ mol(-1)) whereas the complexation with (n)Pr-Tetrazine is endothermic (ΔH = 43.9 ± 3.1 kJ mol(-1)) and exergonic (ΔG = -51.7 ± 2.2 kJ mol(-1)). In the case of the latter the complexation is driven by a highly positive reaction entropy change (ΔS = 320.6 ± 15.4 J mol(-1) K(-1)). In comparison to (n)Pr-BTP, less negative ΔG values were found for the complexation of Cm(III) with both ligands.
两种不同含氮原子数目的 BTP 型 N-供体配体（2,6-双（4-乙基-1,2,3,4-四嗪-1-基）吡啶，Et-BDP 和 2,6-双（4-（正）丙基-2,3,5,6-四嗪-1-基）吡啶，（n）Pr-Tetrazine）已通过 NMR 和 MS 技术合成并进行了表征。使用时间分辨激光诱导荧光光谱法（TRLFS）研究了这两种配体在 2-丙醇-水（1：1，体积比）中与 Cm（III）的络合情况，并将络合性质与（n）Pr-BTP 进行了比较。随着配体浓度的增加，发现了三种不同的物种，即 1：1-、1：2-和 1：3-配合物。确定了 Cm（Et-BDP）3 的形成的 Logβ3 值为 7.6，而 Cm（（n）Pr-Tetrazine）3 的形成的 Logβ3 值为 9.2。（n）Pr-Tetrazine 的络合反应动力学较慢。在 25°C-60°C 的温度范围内确定了络合反应的热力学数据。与 Et-BDP 的络合是放热的（ΔH = -16.3 ± 1.2 kJ mol(-1)）和放能的（ΔG = -43.8 ± 2.6 kJ mol(-1)），而与（n）Pr-Tetrazine 的络合是吸热的（ΔH = 43.9 ± 3.1 kJ mol(-1)）和放能的（ΔG = -51.7 ± 2.2 kJ mol(-1)）。在后一种情况下，络合是由非常正的反应熵变（ΔS = 320.6 ± 15.4 J mol(-1) K(-1)）驱动的。与（n）Pr-BTP 相比，发现 Cm（III）与这两种配体的络合的ΔG 值不那么负。
