A Thiol-Michael Approach Towards Versatile Functionalized Cyclic Titanium-Oxo Clusters

In expanding our research activities of superlattice engineering, designing new giant molecules is the necessary first step. One attempt is to use inorganic transition metal clusters as building blocks. Efficient functionalization of chemically precise transition metal clusters, however, remains a great challenge to material scientists. Herein, we report an efficient thiol-Michael addition approach for the modifications of cyclic titanium-oxo cluster (CTOC). Several advantages, including high efficiency, mild reaction condition, capability of complete addition, high atom economy, as well as high functional group tolerance were demonstrated. This approach can afford high yields of fully functionalized CTOCs, which provides a powerful platform for achieving versatile functionalization of precise transition metal clusters and further applications.

Threefold Collaborative Stabilization of Ag14 -Nanorods by Hydrophobic Ti16 -Oxo Clusters and Alkynes: Designable Assembly and Solid-State Optical-Limiting Application

Ag nanoclusters have received increasing attention due to their atomically precise and diverse structures and intriguing optical properties. Nevertheless, the inherent instability of Ag nanoclusters has seriously hindered their practical application. In this work, for the first time, Ag clusters are collaboratively protected by hydrophobic Ti-oxo clusters and alkyne ligands. Initially, a pyramidal Ag₅ cluster terminated with ^t BuC≡C^- and CH₃ CN was inserted into the cavity of a Ti₈ -oxo nanoring to form Ag₅ @Ti₈ . To overcome the instability of acetonitrile-terminated silver site, such two Ag₅ @Ti₈ clusters could sandwich an Ag₄ unit to form Ag₁₄ -nanorod@Ti₁₆ -oxo-nanoring (Ag₁₄ @Ti₁₆ ), which is peripherally protected by fluorophenyl groups and alkyne caps. This threefold protected (hydrophobic fluorinated organic layer, Ti-O shell, and terminal alkyne ligands) Ag₁₄ @Ti₁₆ exhibits superhydrophobicity and excellent ambient stability, endowing it with solid-state optical limiting characteristics.