Self-Assembly of a Ti4(embonate)6 Cage toward Silver

Stepwise assembly of thiacalix[4]arene-protected Ag/Ti bimetallic nanoclusters: accurate identification of catalytic Ag sites in CO2 electroreduction

The accurate identification of catalytic sites in heterogeneous catalysts poses a significant challenge due to the intricate nature of controlling interfacial chemistry at the molecular level. In this study, we introduce a novel strategy to address this issue by utilizing a thiacalix[4]arene (TC4A)-protected Ti-oxo core as a template for loading Ag1+ ions, leading to the successful synthesis of a unique Ag/Ti bimetallic nanocluster denoted as Ti8Ag8. This nanocluster exhibits multiple surface-exposed Ag sites and possesses a distinctive "core-shell" structure, consisting of a {Ti4@Ag8(TC4A)4} core housing a {Ti2O2@Ag4(TC4A)2} motif and two {Ti@Ag2(TC4A)} motifs. To enable a comprehensive analysis, we also prepared a Ti2Ag4 cluster with the same {Ti2O2@Ag4(TC4A)2} structure found within Ti8Ag8. The structural disparities between Ti8Ag8 and Ti2Ag4 provide an excellent platform for a comparison of catalytic activity at different Ag sites. Remarkably, Ti8Ag8 exhibits exceptional performance in the electroreduction of CO2 (eCO2RR), showcasing a CO faradaic efficiency (FECO) of 92.33% at -0.9 V vs. RHE, surpassing the FECO of Ti2Ag4 (69.87% at -0.9 V vs. RHE) by a significant margin. Through density functional theory (DFT) calculations, we unveil the catalytic mechanism and further discover that Ag active sites located at {Ti@Ag2(TC4A)} possess a higher εd value compared to those at {Ti2O2@Ag4(TC4A)2}, enhancing the stabilization of the *COOH intermediate during the eCO2RR. This study provides valuable insights into the accurate identification of catalytic sites in bimetallic nanoclusters and opens up promising avenues for efficient CO2 reduction catalyst design.

Enhancing Third-Order Nonlinear Optical Property by Regulating Interaction between Zr4(embonate)6 Cage and N, N-Chelated Transition-Metal Cation

Herein, the combination of anionic Zr₄L₆ (L = embonate) cages and N, N-chelated transition-metal cations leads to a series of new cage-based architectures, including ion pair structures (PTC-355 and PTC-356), dimer (PTC-357), and 3D frameworks (PTC-358 and PTC-359). Structural analyses show that PTC-358 exhibits a 2-fold interpenetrating framework with a 3,4-connected topology, and PTC-359 shows a 2-fold interpenetrating framework with a 4-connected dia network. Both PTC-358 and PTC-359 can be stable in air and other common solvents at room temperature. The investigations of third-order nonlinear optical (NLO) properties indicate that these materials show different degrees of optical limiting effects. It is surprising that increasing coordination interactions between anion and cation moieties can effectively enhance their third-order NLO properties, which can be attributed to the formation of coordination bonds that facilitate charge transfer. In addition, the phase purity, UV-vis spectra, and photocurrent properties of these materials were also studied. This work provides new ideas for the construction of third-order NLO materials.

Synthesis of a Zr4(embonate)6-cobalt based superstructure for photocatalytic hydrogen production

Herein, we report an efficient method to construct cage-based MOF materials with exposed metal active sites for catalysis. By employing Zr₄L₆ (L = embonate) cages as precursors for assembly with N-containing ligands and Co²⁺ ions, a new Zr₄L₆-Co based chain structure (PTC-318) has been generated through two-step reactions. Interestingly, in the absence of a photosensitizer, PTC-318 exhibits notable photocatalytic activity for H₂ evolution under visible-light irradiation.

Tunable Third-Order Nonlinear Optical Effect via Modifying Ti4(embonate)6 Cage-Based Ionic Pairs

Benefiting from the strong inherent π-conjugation properties, the integration of Ti4L6 (L = embonate) cages and various N, N-chelated transition-metal cations into tightly packed structures accurately lead to the high-performance...

Coordination Assembly of Tetrahedral Zr4(embonate)6 Cages with Eu3+ Ions

Herein we systematically investigated the coordination assembly behavior of Zr₄L₆ cages with Eu³⁺ ions at room temperature. Through adjustment of the concentration of Eu salt and changes of the type and molar ratio of the solvent, a series of Zr₄L₆-Eu structures with different structure dimensionalities have been synthesized and structurally characterized. In addition, we also studied the optical properties of these materials in detail, including the fluorescent and third-order nonlinear-optical properties. Most notably, a 2D layer structure with a strong aromatic π···π-stacking force exhibits a good optical-limiting effect.

Co-crystal of Ti4Ni2 and Ti8Ni4 clusters with enhanced photochemical properties

A heterometallic cluster with co-crystal arrangement, {Ti₈Ni₄+ Ti₄Ni₂}, which exhibits enhanced photocurrent response and photocatalytic hydrogen evolution activity, has been synthesized.