标题：Functionalization of Titanium Oxide Cluster Ti17O24((OC3H7)-C-i)(20) with Catechols: Structures and Ligand-Exchange Reactivities
作者：Liu, Caiyun; Hu, Junyi; Zhu, Feng; Zhan, Jinhua; Du, Lin; Tung, Chen-Ho; Wang, Yifeng
作者机构：[Liu, Caiyun; Hu, Junyi; Zhu, Feng; Zhan, Jinhua; Tung, Chen-Ho; Wang, Yifeng] Shandong Univ, Sch Chem & Chem Engn, Shanda South Rd 27, Jinan 250100, 更多
通讯作者地址：[Wang, YF]Shandong Univ, Sch Chem & Chem Engn, Shanda South Rd 27, Jinan 250100, Shandong, Peoples R China.
来源：CHEMISTRY-A EUROPEAN JOURNAL
关键词：binding modes; cluster compounds; catechols; ligand exchange;; post-functionalization; titanium
摘要：The functionalization of Ti17O24((OC3H7)-C-i)(20) (Ti-17) with substituted catechols is studied by using crystallography, Raman spectroscopy, and stopped-flow kinetics. The knowledges on the number of accessible functionalities, their exact location correlated with their Raman assignment, and the kinetic parameters are acquired. A catecholate ligand binds to a five-coordinated surface Ti of Ti-17 (denoted as Ti-a site) adopting the mono-protonated, chelate-bidentate binding mode, whereas it binds to a six-coordinated surface-Ti (denoted as Ti-b site) adopting the mono-dentate mode. With low numbers of equivalents of added catechols the Ti-a sites show higher reactivity than the Ti-b sites toward functionalization. Two binding modes may co-exist and equilibrate in solution. Our results also imply that at most eight of the twenty (OC3H7)-C-i ligands of Ti-17 are exchangeable without damage of the core structure. The kinetic studies point out that the ligand-exchange reaction is second order and occurs very fast. The current findings are helpful for the controlled functionalization of Ti-17 and other Ti oxide clusters, and the further application of them as building blocks in supramolecular chemistry for the assembly of well-defined organic-inorganic hybrid materials.