Section of Inorganic and Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
Department of Chemistry, University of Cyprus, Nicosia 2109, Cyprus.
Molecules. 2021 Sep 15;26(18):5588. doi: 10.3390/molecules26185588.
The siderophore organic ligand ,2-dihydroxybenzamide (Hdihybe) incorporates the hydroxamate group, in addition to the phenoxy group in the ortho-position and reveals a very rich coordination chemistry with potential applications in medicine, materials, and physical sciences. The reaction of Hdihybe with TiCl in methyl alcohol and KOH yielded the tetranuclear titanium oxo-cluster (TOC) [Ti(μ-O)(HOCH)(-Hdihybe)(Hdihybe)]Cl∙10HO∙12CHOH (). The titanium compound was characterized by single-crystal X-ray structure analysis, ESI-MS, C, and H NMR spectroscopy, solid-state and solution UV-Vis, IR vibrational, and luminescence spectroscopies and molecular orbital calculations. The inorganic core Ti(-O) of constitutes a rare structural motif for discrete Ti oxo-clusters. High-resolution ESI-MS studies of in methyl alcohol revealed the presence of isotopic distribution patterns which can be attributed to the tetranuclear clusters containing the inorganic core {Ti(-O)}. Solid-state IR spectroscopy of showed the presence of an intense band at ~800 cm which is absent in the spectrum of the Hdihybe and was attributed to the high-energy ν(Ti--O) stretching mode. The (C=O) in is red-shifted by ~10 cm, while the (N-O) is blue-shifted by ~20 cm in comparison to Hdihybe. Density Functional Theory (DFT) calculations reveal that in the experimental and theoretically predicted IR absorbance spectra of the ligand and Ti-complex, the main bands observed in the experimental spectra are also present in the calculated spectra supporting the proposed structural model. H and C NMR solution (CDOD) studies of reveal that it retains its integrity in CDOD. The observed NMR changes upon addition of base to a CDOD solution of , are due to an acid-base equilibrium and not a change in the Ti coordination environment while the decrease in the complex's lability is due to the improved electron-donating properties which arise from the ligand deprotonation. Luminescence spectroscopic studies of in solution reveal a dual narrow luminescence at different excitation wavelengths. The TOC exhibits a band-gap of 1.98 eV which renders it a promising candidate for photocatalytic investigations.
铁载体有机配体 2-二羟基苯甲酰胺 (Hdihybe) 除了在邻位具有苯氧基外，还包含羟肟酸基团，具有丰富的配位化学性质，在医学、材料和物理科学领域具有潜在的应用。Hdihybe 与 TiCl 在甲醇和 KOH 中的反应生成了四核钛氧簇 (TOC) [Ti(μ-O)(HOCH)(-Hdihybe)(Hdihybe)]Cl∙10HO∙12CHOH ()。该钛化合物通过单晶 X 射线结构分析、ESI-MS、C 和 H NMR 光谱、固态和溶液紫外可见光谱、IR 振动光谱和发光光谱以及分子轨道计算进行了表征。构成的无机核心 Ti(-O) 为离散 Ti 氧簇提供了一种罕见的结构基元。在甲醇中对 的高分辨率 ESI-MS 研究表明存在同位素分布模式，可归因于含有无机核心{Ti(-O)}的四核簇。的固态 IR 光谱显示在 ~800 cm 处存在一个强带，而在 Hdihybe 的光谱中不存在该带，这归因于高能 ν(Ti--O)伸缩模式。与 Hdihybe 相比，中的 (C=O) 红移约 10 cm，而 (N-O) 蓝移约 20 cm。密度泛函理论 (DFT) 计算表明，在配体和 Ti 配合物的实验和理论预测 IR 吸收光谱中，实验光谱中观察到的主要谱带也存在于计算光谱中，这支持了所提出的结构模型。在 CDOD 溶液中进行的 H 和 C NMR 研究表明，它在 CDOD 中保持完整。向 的 CDOD 溶液中加入碱时观察到的 NMR 变化是由于酸碱平衡，而不是 Ti 配位环境的变化，而复合物的不稳定性降低是由于配体去质子化导致的电子供体性质的提高。在溶液中的发光光谱研究表明，在不同的激发波长下存在双重窄发光。TOC 具有 1.98 eV 的带隙，使其成为光催化研究的有前途的候选者。
