Fujian Institute of Research on the Structure of Matter

Rare-earth boron-oxo clusters, which combine the structural diversity of borates with the unique chemical properties of rare-earth ions, represent a promising platform for advanced functional materials. Herein, we report the synthesis and characterization of a series of heteronuclear rare-earth boron-oxo clusters (BOCs), [RE3B9(μ3-O)12Pz6HPz6Cl6] (BOC-9, Pz = pyrazolate, HPz = pyrazole), [RE3B9(μ3-O)12Pz7HPz6(MeO)2Cl3] (BOC-10), and [RE(NO3)6RE5B18(μ3-O)24Pz18]n (BOC-11), where RE = Dy3 +/Y3 +. Structural evolution from discrete to 2-dimensional (2D) architectures was achieved through systematic variation of boron sources and rare-earth salts. These clusters exhibit a well-defined stability gradient correlated with increasing organic ligands and structural dimensionality. Spectroscopic characterizations uncover two distinct photoluminescence emission mechanisms in the boron-oxo based functional materials. Dy3 +-based BOCs exhibit typical f-f transition emissions, which are effectively sensitized by the ligand-to-metal charge transfer (LMCT) process, whereas closed-shell Y3 +-based BOCs show exclusive photoluminescence derived from the ligand-to-boron charge transfer pathway. Dynamic B─N bond cleavage, as evidenced by electrospray ionization mass spectrometry (ESI-MS), enables isolation of cluster cores, providing mechanistic insights into structural rearrangements. This work establishes design principles for next-generation luminescent materials based on rare-earth boron-oxo clusters.

Supramolecular polymers have attracted considerable attention owing to their potential applications in biomedicine, molecular machines, sensing, and self-healing materials. Precise evaluation of hydrogen-bond energies is crucial for the rational design of these materials. Here, the experimental electron densities (EEDs) of three representative quadruple hydrogen-bonded dimers, ureidopyrimidinone (DDAA, DADA. D: donor; A: acceptor) and ureidotriazine (DADA), are investigated using high-resolution single-crystal X-ray diffraction. Comparative energy decomposition analyses (EDA) of the experimental and theoretical electron densities are performed. The total interaction energies from the EDA of EEDs are in good agreement with the experimentally determined binding constants, correcting the discrepancies observed in theoretical EDA and in the typical secondary electrostatic interaction model. Our results confirm the pivotal role of long-range electrostatic interactions in governing multiple hydrogen-bonded systems, and the EDA-EED approach provides a benchmark for theoretical methods that accurately describe long-range electrostatic interactions, which are fundamentally important for the development of supramolecular systems.

In this study, a remote-control strategy for tuning the electronic structures of atomically precise Cu nanoclusters (Cu NCs) was developed, aiming to enhance the selectivity of the CO2RR toward high-value hydrocarbons. Two Cu7 NCs protected by tridentate N-heterocyclic carbene (NHC) ligands with distinct functional groups on the remote benzimidazole ring, NHCH-Cu7 and NHCMe-Cu7, were synthesized via a green and efficient ball-milling approach. The main product obtained with NHCMe-Cu7 is CO, with a selectivity of 82.8%, whereas the Faradaic efficiency (FE) for hydrocarbon production using NHCH-Cu7 is 74.0%, affording 50.4% CH4 and 23.6% C2H4 at -1.5V versus the reversible hydrogen electrode (RHE). Comprehensive theoretical calculations and operando spectroscopic analyses demonstrate that the effect of the remote substituent on the NHC ligand provides a greater population of active electrons in the highest occupied d-orbital of NHCH-Cu7 compared to that in NHCMe-Cu7, thus effectively regulating the binding strength of the *CO intermediate. This in turn promotes stabilization and further activation of the intermediate, ultimately steering the product selectivity from CO toward targeted hydrocarbons. This study establishes an atomic-level paradigm for ligand engineering of Cu NCs, enabling remote tuning of the electronic structure of the active sites to realize highly selective hydrocarbon generation.

Photocatalysts are usually in powder form, which makes it difficult to expand the scale of photocatalysis. Here, we report a Newtonian fluid photocatalyst, which consists of an internal nano-hollow imidazole framework and an external light-excitable liquid chain striking a pose on the stage. Due to the intermolecular interaction at the solid-liquid interface and significant steric hindrance effect, the Newtonian fluid catalyst with higher surface tension can firmly adhere to different kinds of scaffolds via simple printing, such as curved surfaces, inclined walls, and grids. In addition to the easier scale-up, the pore structure of frameworks favors faster CO2 mass transfer, and the liquid chain with a co-catalytic effect serves as the electron donor for efficient CO2 photoreduction. In this work, the Newtonian fluid photocatalyst achieves a 57.8-fold increase in CO overflow efficiency (100% selectivity), and this universal synthesis method can convert common organic/inorganic photocatalysts into similar Newtonian fluid photocatalysts.

Effective removal of organic contaminants present in water is of vital importance for water remediation, public health, and economic benefits. Photodegradation has been recognized as a low‐energy consumption, recyclable, and mild treatment method for the rapid, efficient, and complete removal of organic contaminants. Among various photocatalytic materials, metal‐free covalent organic frameworks (COFs) have gained considerable attention to serve as photocatalytic materials in water remediation owing to their highly ordered structures, high specific surface areas, tunable pore environment, superior light absorption, and adjustable electronic structures. This article presents a comprehensive review of design strategies and applications of photocatalytic metal‐free COFs for organic contaminants degradation. Specifically, strategies for enhancing the photocatalytic performance of metal‐free COFs are discussed spanning from monomer design to framework construction in detail. Then, an analysis of reported metal‐free COFs for the photodegradation of organic contaminants is summarized. Finally, the current challenges and future opportunities for metal‐free COFs are highlighted. This review is expected to provide guidance for the rational design of photocatalytic metal‐free COFs and serve as a useful reference for future studies in water remediation.