The complexation of the betadiketone,1,1,1,2,2,3,3-heptafluoro-7,7-dimethyl-4,6-octanedione (HFOD) was studied with trivalent lanthanide ions, viz. Nd³⁺, La³⁺, and Eu³⁺ in several methylimidazolium-based ionic liquids (C_nmim•NTf₂, where, n = 4,6,8). In C₆mim•NTf₂, predominant formation of ML₂⁺ and ML₄^– species was evidenced from the UV–vis absorption (Nd³⁺) as well as luminescence (Eu³⁺) spectral studies with log β₂ ≈ 5.88 ± 0.04, log β₄ ≈ 10.95 ± 0.06. The formation constants followed the trend C₄mim•NTf₂ > C₆mim•NTf₂ > C₈mim•NTf₂. The asymmetry factors for the ML₂⁺ and ML₄^– species were found to be 1.2 and 1.59, respectively. The ML₄^– complex was found to have one primary coordination sphere water molecule with enhanced covalency between Eu³⁺ and O from HFOD (Judd Offelt constants Ω₂ and Ω₄ ≈ 17.2 and 2.35) compared to Eu³⁺_aq, yet comparable to other β diketones. Complexation-induced temperature increase was confirmed by calorimetric measurements, indicating the exothermic complexation reaction (ΔH_complexation ≈ −13.7 kJ mol^–1), which is also spontaneous in nature (ΔG ≈ −68.1 kJ mol^–1), with an enhancement in the entropy values. Due to complexation, the shifts in the peak positions (1686.66 cm^–1, 1633.53 cm^–1) associated with β diketone/ketone functional groups were evidenced. Density functional theory (DFT) calculation was performed to optimize the structural parameters including bond distance, bond angles, and energetics associated with the complexation.

中文翻译：

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离子液体辅助三价镧系元素与氟化β二酮的放热络合：具有理论洞察力的多技术方法

研究了 β二酮,1,1,1,2,2,3,3-七氟-7,7-二甲基-4,6-辛二酮 (HFOD) 与三价镧系离子的络合，即。几种甲基咪唑基离子液体中的Nd ³⁺、La ³⁺和Eu ^{3+ (C} _n mim•NTf ₂，其中n = 4,6,8)。在C ₆ mim•NTf _{2中，ML 2} ⁺和ML ₄ ^–物质的主要形成通过紫外可见吸收（Nd ³⁺）以及发光（Eu ³⁺）光谱研究得到证实，log β ₂ ≈ 5.88 ± 0.04，log β ₄ ≈ 10.95 ± 0.06。形成常数的趋势为C ₄ mim•NTf ₂ > C ₆ mim•NTf ₂ > C ₈ mim•NTf ₂。_{ML 2} ⁺和 ML ₄ ^–物种的不对称因子分别为 1.2 和 1.59。与 Eu 3+ aq 相比， ML ₄ ^–配合物被发现具有一个一级配位层水分子，并且来自 HFOD 的 Eu ³⁺和 O 之间的共价性增强（Judd Offelt 常数 Ω ₂和 Ω ₄ ≈ 17.2 和 2.35），但与 Eu ³⁺ _aq相比，仍可与其他β二酮。通过量热测量证实了络合引起的温度升高，表明放热络合反应（Δ H_络合≈ -13.7 kJ mol ^–1），这也是自发的（Δ G ≈ -68.1 kJ mol ^–1），并且增强在熵值中。由于络合作用，与β二酮/酮官能团相关的峰位置（1686.66 cm ^–1、1633.53 cm ^{–1 ）发生了移动。}进行密度泛函理论（DFT）计算以优化结构参数，包括键距、键角和与络合相关的能量学。