Terminal Ligand (L) Effects on Zero-Magnetic-Field Splitting in the Excited Triplet States of [{Mo6Br8}L6]2- (L = Aromatic Carboxylates)
Terminal Ligand (L) Effects on Zero-Magnetic-Field Splitting in the Excited Triplet States of [{Mo6Br8}L6]2- (L = Aromatic Carboxylates)
复制标题
末端配体 (L) 对 [{Mo6Br8}L6]2- 激发三重态中零磁场分裂的影响（L = 芳香族羧酸盐）
DOI：
10.1021/acs.inorgchem.8b02881
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发表时间：
2019
影响因子：
4.6
通讯作者：
and N. Kitamura
中科院分区：
文献类型：
--
作者：
S. Akagi;T. Horiguchi;S. Fujii;and N. Kitamura
本文报道了以六溴化钼（II）（{Mo 6 Br 8}4+）为核心，末端含有一系列芳香羧酸配体（RCOO）[{Mo 6 Br 8}（RCOO）6]2-的八面体簇合物在溶液和晶相的发光性质。RCOOH的酸解离常数（pKa（L））被证明是控制簇的氧化还原和发射性质的。温度（T）控制的发射实验（3-300 K）表明，由于发射激发三重态（T1）的零磁场分裂，团簇表现出大的依赖于T的发射能量（V_（em））和寿命（τem）。T1态的自旋子能级（Φn，n= 1-4）模型很好地解释了与T相关的发射特性（ν ε em和τem），与所研究的团簇无关。此外，我们还发现最低能量（Φ1）与能量较高的第三或第四自旋子能级（Φ3或Φ4）之间的能量差Δ E13或ΔE14分别与pKa（L）有很好的相关性.根据[{Mo 6 Br 8}（RCOO）6]2-中Mo金属中心的有效核电荷随pKa（L）的变化对结果进行了讨论。
We report the emission properties of the octahedral hexamolybdenum(II) bromide-core ({Mo6Br8}4+) clusters having a series of terminal aromatic carboxylate ligands (RCOO), [{Mo6Br8}(RCOO)6]2–, in solution and crystalline phases. The acid dissociation constant of RCOOH (pKa(L)) was shown to govern the redox and emission properties of the clusters. Temperature (T)-controlled emission experiments (3–300 K) demonstrated that the clusters showed largeT-dependent emission energies (ν̃em) and lifetimes (τem) because of zero-magnetic-field splitting in the emissive excited triplet (T1) states. The spin sublevel (Φn,n= 1–4) model in the T1state of the cluster explained very well theT-dependent emission characteristics (ν̃emand τem), irrespective of the clusters studied. Furthermore, we revealed that the energy difference between the lowest-energy (Φ1) and energetically upper-lying third (Φ3) or fourth spin sublevels (Φ4), ΔE13or ΔE14, respectively, correlated very well with pKa(L). The results are discussed in terms of the variation of the effective nuclear charge of the Mo metal center(s) in [{Mo6Br8}(RCOO)6]2–with that of pKa(L).