Yue Zhao

Divalent rare-earth solids with a 4fn+1 configuration provide access to electronic structures in which localized 4f states coexist with low-lying, structurally responsive 5d states, yet the combined magnetic, electrical, and optical manifestations of these states remain underexplored in extended Tm2+ compounds. Here, we investigate layered TmI2 as an extended Tm2+ solid and employ Cs4TmI6 with isolated TmI6 units and dilute SrI2:Tm2+ as targeted reference systems. Structural, spectroscopic, and X-ray photoelectron spectroscopic measurements support Tm2+ as the dominant oxidation state, while electronic-structure calculations reveal narrow, localized, occupied Tm 4f-derived bands and low-lying Tm 5d-derived unoccupied states, with substantially greater 5d dispersion in TmI2 than in Cs4TmI6. Magnetic measurements establish localized 4f13 Kramers-ion behavior on the triangular Tm2+ lattice of TmI2, together with a small negative low-temperature Weiss temperature and no evidence of long-range magnetic ordering down to 2 K. Comparative luminescence, photothermal, and photocurrent measurements reveal distinct photoresponses across the three systems within a shared electronic-level framework encompassing 4f–5d and 4f–4f transitions. Relative to Cs4TmI6 and SrI2:Tm2+, TmI2 exhibits a lower-energy optical absorption onset, weaker photoluminescence, and a more pronounced light-induced current response despite its high electrical resistivity. Its wavelength-dependent photothermal response broadly follows the 4f–5d absorption profile. Together, these results establish layered TmI2 as a distinctive rare-earth platform that combines the 4f13 magnetic characteristics familiar from Yb3+ systems with low-energy 4f–5d excitations, expanding the scope for investigating rare-earth magnetic solids with optical excitation channels beyond 4f–4f transitions.

Achieving abrupt, hysteretic spin crossover (SCO) requires strong cooperativity, typically engineered through supramolecular interactions. In this work, we designed a dual-halogenated Hqsal ligand, 5-F-Hqsal-5-Iq, strategically incorporating both bulky iodine and electronegative fluorine moieties. This design modulates the ligand field and, more importantly, induces strong halogen-mediated supramolecular interactions. Three FeIII complexes, [Fe(5-F-qsal-5-Iq)2]A·CH3OH (A = ClO4− (1), BF4− (2), and OTf− (3)), were synthesized and characterized, all adopting a similar Chain-Layer packing motif. The steric demand of the iodine atom forces the fluorine atoms on adjacent chains into closer proximity, which enhances hydrogen bonds and fluorine-mediated interactions within the 2D layers, thereby enhancing cooperativity. Notably, complex 3 exhibits enhanced cooperativity driven by extensive and intensified supramolecular interactions involving the iodine atoms and the OTf− anion. Magnetically, 1 and 2 exhibit abrupt SCO with narrow hysteresis, while 3 exhibits a two-step transition with a remarkably wide and stable 57 K hysteresis (1 K/min) that expands to 64 K at 15 K/min. All complexes exhibit the LIESST effect, with 3 showing the most pronounced response. This study underscores how steric and electronic effects from dual-halogen substitution can be employed to modulate SCO properties, offering a rational design route to high-performance SCO materials.

In recent years, numerous photocatalytic systems have been developed to promote a wide range of organic transformations mediated by singlet oxygen. However, conventional blue-light photosensitizers encounter significant challenges in large-scale synthesis, primarily due to the limited penetration depth of high-energy photons. Herein, we report an atomically precise Au27 nanocluster featuring a novel superatomic core built from an icosahedral Au13 and a tetrahedral Au4, allowing for highly efficient singlet oxygen generation under far-red-light irradiation. While its overall structure closely resembles that of Au25 nanoclusters with a single icosahedral Au13 core, the incorporation of a tetrahedral Au4 building unit through ligand engineering markedly enhances intersystem crossing efficiency and aligns transition energies for effective O2 sensitization, affording an internal quantum yield of 0.37% at 740 nm. Compared with previous light-driven systems, our ten-gram-scale, cluster-based photochemical process reduces catalyst loading by four orders of magnitude (10,000-fold), requiring only 13 nmol of photocatalyst, and achieves turnover numbers greater than one million. This study establishes a new paradigm in photocatalyst design, demonstrating how atomic-level structural control can enable far-red-light-driven organic transformations with substantially enhanced catalytic performance.

This work addresses the detection of nitroaromatic compounds (NACs) and antibiotics in water by developing two isomeric fluorescent metal–organic framework (MOFs) Cd-1 and Cd-2, with the formula [Cd2(Tipe)(ABD)2]·solvent (Tipe = 1,1,2,2-tetrakis(4-(1-imidazolyl)phenyl)ethylene, H2ABD = 4,4′-azodibenzoic acid). By modulating the reaction solvent, two interpenetrated isomeric MOFs with distinct space groups and fluorescence properties were obtained. Interestingly, Cd-1 and Cd-2 exhibit high selectivity and rapid response (<10 s) toward 2,4,6-trinitrophenol (TNP) and nitrofurazone (NFZ) with distinct response behaviors. Namely, Cd-1 shows fluorescence quenching at both 423 and 485 nm, whereas Cd-2 exhibits quenching only at 423 nm but remains unchanged at 485 nm, implying a ratiometric fluorescence sensor (I423/I485). Both Cd-1 and Cd-2 possess low detection limits (0.32 and 0.24 μM for TNP and 0.34 and 0.15 μM for NFZ), strong anti-interference ability, good reusability, and structural stability. Spectroscopic overlapping and fluorescence lifetime shortening imply a dynamic quenching mechanism. X-ray photoelectron spectroscopy (XPS) analysis further suggests electron transfer from the MOF skeleton to analytes of TNP/NFZ. This study provides an example of solvent-regulated interpenetration isomerism in MOFs, reveals its modulatory role in fluorescence response behaviors, and offers new insights for designing ratiometric fluorescence sensors.

The stereodivergent construction of C(sp³)-C(sp³) bonds between two prochiral radicals remains a formidable challenge. Here, we report the engineering of a thiamine-diphosphate-dependent radical enzyme to catalyze redox-neutral and stereodivergent cross-coupling of two electrophilic C(sp³) precursors. This new-to-nature enzyme reactivity was achieved via light-accelerated single-electron transfer from an unprecedented enzymatic vinyl Breslow intermediate, generating two distinct prochiral radicals whose stereoselective recombination forges the new C(sp³)-C(sp³) bond. Through systematic protein engineering, we developed four enzyme variants that collectively deliver all four stereoisomers with high efficiency (up to 82% yield, 99% enantiomeric excess (ee) and >20:1 diastereomeric ratio (d.r.)). This work establishes a platform for enzymatic, reductant-free radical cross-coupling with simultaneous control over two C(sp³) stereocenters.

Incorporating a perylene diimide (PDI)-based ligand into metal-organic frameworks (MOFs) is an effective but scarcely studied strategy for fabricating high-performance photocatalysts. In this work, three isostructural PDI-based MOFs with a formula of [M₃(HTCPDI)₂(H₂O)₄]·2DMF·H₂O (M-TCPDI, where M = Ni(II), Co(II), or Mg(II), H₄TCPDI = N,N'-bis(3,5-dicarboxyphenyl)-1,6,7,12-tetrachloroperylene-3,4,9,10-tetracarboxylic diimide, and DMF = N,N-dimethylformamide) were successfully synthesized under solvothermal conditions. Crystal structure analysis demonstrated that these three MOFs are isostructural three-dimensional (3D) frameworks. In addition to retaining absorption features similar to those of H₄TCPDI in the visible region, these materials exhibit additional pronounced and extended absorption spanning the range of 600-900 nm. To study their capability as photocatalysts, the oxidative coupling of benzylamine to imine was employed as a model reaction and the results revealed that the performance of Ni-TCPDI is slightly better than that of Co-TCPDI, but significantly better than that of Mg-TCPDI, under 50 W white light LED irradiation in air without any other additives. More impressively, Ni-TCPDI could deliver appreciable photocatalytic reactivity under simulated sunlight at a light intensity of 50 mW cm^-2. This study expands the scope of PDI-based MOFs in photocatalysis and offers an effective strategy for light-driven oxidative reactions through rational metal-node modulation.

The emergence of functional hydrogen-bonded organic frameworks (HOFs) has created new opportunities in materials science. However, the development of functional metallo-HOFs (MHOFs) featuring switchable magnetic properties remains a significant challenge. Herein, we report three new magnetic MHOFs built from spin-crossover (SCO)-active [Fe(2-pic)₃]²⁺ cation and two sulfonate anions, 1,5-naphthalenedisulfonate (NDS^2-) and 1,3,6,8-pyrenetetrasulfonate (PTS^4-). These compounds, formulated as [Fe(2-pic)₃]·NDS·2H₂O (1·2H₂O) and [Fe(2-pic)₃]·0.5PTS·nH₂O (n = 2, 3; denoted as 2·2H₂O and 3·3H₂O), were fully characterized by single-crystal X-ray diffraction, magnetic measurements, and proton conduction studies. Notably, complex 1·2H₂O undergoes a single-crystal-to-single-crystal transformation upon dehydration, which directly modifies its hydrogen-bonded network, thereby switching its gradual and complete SCO to a fully HS state. Complexes 2·2H₂O and 3·3H₂O exhibit distinct SCO profiles due to their different Fe²⁺ coordination geometries (meridional in 2·2H₂O, facial in 3·3H₂O) and hydrogen-bonded networks. While 2·2H₂O exhibits a gradual two-step SCO, 3·3H₂O displays hysteresis SCO with a loop width of approximately 10 K. Proton conduction studies revealed that these complexes show moderate proton conduction (with σ up to 2.70 × 10^-3 S cm^-1 at 95% RH and 45 °C), with 3·3H₂O performing the best. These complexes represent rare multifunctional MHOFs integrating switchable SCO and proton transport.

Extending π electron delocalization to encompass f-block actinides within a carbon-based framework constitutes a fundamental challenge because of the inherently poor spatial overlap between contracted actinide 5f and carbon 2p orbitals. Here we report the synthesis and isolation of a diuranacyclobutadiene complex, which represents the first example of an actinide metallacycle featuring a fully delocalized π system. Single-crystal X-ray diffraction reveals a symmetric, planar U₂C₂ core with four essentially equivalent U-C bonds (averaging 2.23 Å). These bond lengths fall distinctly between typical U-C single (ca. 2.45 Å) and double (ca. 2.01 Å) bonds, providing structural evidence for multicenter π delocalization. Comprehensive theoretical analyses demonstrate that uranium 5f/6d orbital participation enables two symmetry-required phase inversions within the cyclic conjugation pathway, transforming the classical four-π-electron antiaromatic cyclobutadiene framework into a stabilized four-π-electron Möbius aromatic system. This work fundamentally expands the frontier of electron delocalization in metal-carbon rings to encompass the heaviest elements, validating the unique and previously unrealized capacity of actinide orbitals to participate in extended π systems.

The stereoselective synthesis of allylic alcohols bearing both a hydroxyl stereocenter and defined olefin geometry remains a significant challenge. While traditional methods predominantly furnish thermodynamically favored ( E )‐isomers, efficient access to enantiomerically enriched ( Z )‐configured counterparts is severely underdeveloped. Herein, we report an asymmetric addition of β‐borylenamides to aldehydes by rhodium catalysis, enabling the synthesis of ( Z )‐hydroxy enamides with excellent stereocontrol. The requisite β‐borylenamides are stereoconvergently prepared from mixed‐olefin starting materials through directed electrophilic C−H borylation. A key innovation lies in the development of late‑stage modified ligands, readily accessible via direct arylation of phosphoramidites. This modular strategy circumvents traditional de novo ligand synthesis, thereby significantly accelerating the discovery and optimization of privileged ligands. The resulting allylic alcohol products undergo smooth reduction to furnish γ‐amino alcohols with exceptional enantio‐ and diastereocontrol. The influence of the modified ligands on enantioselectivity was elucidated through density functional theory (DFT) calculations.

The stereoselective synthesis of allylic alcohols bearing both a hydroxyl stereocenter and defined olefin geometry remains a significant challenge. While traditional methods predominantly furnish thermodynamically favored ( E )‐isomers, efficient access to enantiomerically enriched ( Z )‐configured counterparts is severely underdeveloped. Herein, we report an asymmetric addition of β‐borylenamides to aldehydes by rhodium catalysis, enabling the synthesis of ( Z )‐hydroxy enamides with excellent stereocontrol. The requisite β‐borylenamides are stereoconvergently prepared from mixed‐olefin starting materials through directed electrophilic C−H borylation. A key innovation lies in the development of late‑stage modified ligands, readily accessible via direct arylation of phosphoramidites. This modular strategy circumvents traditional de novo ligand synthesis, thereby significantly accelerating the discovery and optimization of privileged ligands. The resulting allylic alcohol products undergo smooth reduction to furnish γ‐amino alcohols with exceptional enantio‐ and diastereocontrol. The influence of the modified ligands on enantioselectivity was elucidated through density functional theory (DFT) calculations.