Gao Mei-Yan, Wang Zirui, Li Qiao-Hong, Li Dejing, Sun Yayong, Andaloussi Yassin H, Ma Chao, Deng Chenghua, Zhang Jian, Zhang Lei
State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China.
Department of Chemical Sciences, Bernal Institute, University of Limerick, Limerick V94 T9PX, Republic of Ireland.
J Am Chem Soc. 2022 May 11;144(18):8153-8161. doi: 10.1021/jacs.2c00765. Epub 2022 Apr 27.
A series of catecholate-functionalized titanium-oxo clusters (TOCs), to , with atomically precise structures were synthesized and characterized, including distinctive "boat" and "chair" conformations in and , respectively. These cluster compounds are prominent for their ultralow optical band gaps, as is visually evident from the rather unusual black TOCs (B-TOCs), to . The cluster structures were found to be ultrastable with respect to air, water, organic solvents, and even acidic or basic aqueous solutions in a wide pH range (pH 0-13), owing to the stabilizing effects of catecholate and its derivatives, as well as the carboxylate ligands. Another prominent feature is the occurrence of third-order nonlinear optical (NLO) performance, which has previously been unreported in the field of homometallic titanium-oxo clusters. Open-aperture Z-scan experiments show significant solid-state optical limiting (OL) applications of these B-TOCs, with high laser irradiation stability and low minimum normalized transmittance () of as ∼0.17. Meanwhile, theoretical calculations indicate that the smaller band gaps of B-TOCs were beneficial for strengthening the NLO response. This work not only represents a significant milestone in the construction of stable low-band gap black titanium oxide materials but also contributes to the mechanism insights into their optical applications.
合成并表征了一系列具有精确原子结构的儿茶酚官能化钛氧簇（TOCs），从 到 ，其中 和 分别具有独特的“船型”和“椅型”构象。这些簇化合物因其超低的光学带隙而引人注目，从相当不寻常的黑色 TOCs（B-TOCs），从 到 ，视觉上就很明显。由于儿茶酚及其衍生物以及羧酸盐配体的稳定作用，发现这些簇结构在空气、水、有机溶剂甚至宽 pH 范围（pH 0 - 13）的酸性或碱性水溶液中都具有超稳定性。另一个突出特点是出现了三阶非线性光学（NLO）性能，这在同金属钛氧簇领域此前尚未见报道。开孔 Z 扫描实验表明这些 B-TOCs 在固态光学限幅（OL）方面有显著应用，具有高激光辐照稳定性，最低归一化透过率（）低至约 0.17。同时，理论计算表明 B-TOCs 较小的带隙有利于增强 NLO 响应。这项工作不仅代表了稳定的低带隙黑色氧化钛材料构建中的一个重要里程碑，也有助于深入了解其光学应用的机理。
