Li-Min Zheng

Metal–organic framework (MOF) nanosheets have emerged as promising platforms for catalytic applications, yet the controlled exfoliation of bulk MOFs into monolayer nanosheets remains challenging. Herein, a cluster-based [Co3.5L3{N(CN)2}H2O]·7H2O (Co7-DCA) MOF, where H2L refers to the phosphonate ligand and its bimetallic derivatives M@Co7–DCA (M = Cu, Zn) were rationally synthesized via a hydrothermal strategy to introduce synergistic heterometal sites and enhanced oxidase–mimic activity. Remarkably, these bimetallic MOFs can be efficiently exfoliated into monolayer nanosheets in methanol, a rare phenomenon for structurally rigid MOFs, enabling in situ formation of ultrathin nanosheets during catalysis. The resulting monolayer nanosheets act as highly efficient oxidase mimics, catalyzing the aerobic C–H oxidation of substituted aminophenols and diamines in aqueous media under air atmosphere. High-resolution mass spectrometry (HRMS) revealed key reaction intermediates, while electron paramagnetic resonance (EPR) confirmed the generation of radical species. Overall, this work reveals a rare example of methanol-triggered, in situ exfoliation of a bimetallic MOF into monolayer nanosheets, offering a powerful strategy to significantly improve oxidase-like activity from intact bulk MOFs.

The crystallization pathways of metal phosphonate frameworks (MPFs) remain poorly understood because the strong coordination ability of phosphonate ligands often leads to rapid precipitation, making the isolation of transient intermediates challenging. Herein, we report two 3D Cu‐based MPFs, [Cu ₂ (amp ₂ H ₂ )]·2H ₂ O·DMF ( Cu‐3D ) and [Cu ₂ (INA) ₂ (amp ₂ H ₂ )(H ₂ O) ₂ ] ( Cu‐INA‐3D ), where amp ₂ H ₄ is photodimerized 9‐anthracenemethylphosphonic acid and INAH is isonicotinic acid. By shortening the reaction time, we isolated a metastable intermediate, [Cu ₂ (INA) ₂ (amp ₂ H ₂ )]·2H ₂ O ( Cu‐INA‐2D ), which can gradually transform into the thermodynamically more stable Cu‐INA‐3D phase via reconstruction of the Cu–PO ₃ connectivity and reorganization of the {Cu(INA)} chains. The crystals of Cu‐INA‐2D can undergo solvent‐assisted cleavage to yield an accordion‐like morphology. Further, thermal de‐dimerization of the dianthracene units in Cu‐3D and Cu‐INA‐3D induces framework transformation, generating new phases containing anthracene moieties. We studied the photothermal properties of Cu‐3D , Cu‐INA‐3D and their de‐dimerized products. All exhibited near‐infrared (NIR) photothermal responses under 808 nm laser irradiation. Benefiting from its photothermal conversion capability and the redox activity of Cu ^II centers, Cu‐INA‐3D was employed to serve as a photothermally driven catalyst for pyrrole polymerization. These findings provide insight into the crystallization mechanism of copper diphosphonate frameworks and demonstrate the potential of dianthracene‐based MPFs as multifunctional photothermal materials.

Enantiomeric complexes Dy( R / S -L _N6 )(mapp) ₃ ·3H ₂ O (1R/1S) and their racemate Dy( RS -L _N6 )(mapp) ₃ ·3H ₂ O exhibited distinct photothermal conversion efficiencies, which can be further enhanced by applying an external magnetic field.

Metal-organic coordination materials have emerged as promising candidates for electrocatalytic nitrate reduction reaction (NITRR), but the molecular-level engineering required for constructing high-efficiency electrocatalysts remains challenging. This study addresses this gap by developing a class of metal-organic coordination nanotubes (MONTs) as atomically precise single-site electrocatalysts, including Fe-MONTs, Co-MONTs, and Ni-MONTs. Benefited from the unique coordination structure, the Co-MONT electrode exhibited superior electrocatalytic performances for the NITRR, achieving an ammonia production Faradaic efficiency of 89.9% at −0.7 V (vs reversible hydrogen electrode) and an ammonia yield rate of 231.3 mmol h−1 g−1cat. in pure nitrate solution. Through combining in situ characterizations and theoretical simulations, the electrocatalysis mechanisms and active site configurations were elucidated. This work establishes MONTs as an intriguing platform for electrochemical wastewater purification and sustainable ammonia synthesis, providing promising design principles for advanced electrocatalysts.

Hydrothermal reaction of Ln(NO ₃ ) ₃ and R -pempH ₂ yields the isomorphous compound Ln( R -pempH) ₃ ·2H ₂ O (R-1h-Ln, Ln = Sm, Eu, Gd, Tb, Dy, Ho) with a macroscopic helical structure. The helical chirality depends on the specific Ln ³⁺ ion.

The investigation of helical coordination polymers (CPs) with integrated molecular and mesoscale chirality as high-performance liquid chromatography (HPLC) chiral selectors is a crucial endeavor. Nevertheless, the related study has not been reported. Herein, we prepared a set of CPs that exhibited distinct morphologies, including nanofiber, twist ribbon, and superhelix with varying helical pitches. Subsequently, a series of new chiral stationary phases (CSPs) based on these chiral CPs were successfully fabricated by coating them onto the spherical aminated silica gel matrix. A systematic investigation into the separation performances of these CSPs was conducted via HPLC. By comparing the relationship between chiral CPs with different morphologies and their chromatographic separation abilities, we found that the superhelix possessing both molecular and mesoscale chirality exhibited the most superior chiral separation performance, capable of efficiently resolving nine racemic compounds with a maximum resolution of 3.62. However, the CSPs prepared from chiral CPs with nanofiber or twist ribbon morphologies displayed comparatively poor chromatographic separation abilities. Meanwhile, the chiral separation performance was markedly diminished for the dehelical polymer obtained through the thermal treatment of the superhelix, underscoring that mesoscale superhelical chirality is crucial for chiral recognition and separation. Additionally, we also found that the pitch sizes of the mesoscale superhelices have a significant internal connection with their chiral separation performances. This work not only identifies hierarchical chiral CPs with dual molecular and mesoscale helical chirality as promising chiral materials for chromatographic enantioseparation but also establishes that the introducing mesoscale superhelices and controlling their pitches precisely are key to boosting chiral separation efficiency.

Chiral lanthanide phosphonate R -Dy(pempH) ₃ ·H ₂ O with a chain structure can be obtained in both crystalline ( R -1c ) and helical forms ( R -1h ). R -1h shows significantly enhanced stability in halomethane.

Lanthanide-based single-molecule magnets (Ln-SMMs) showing stimuli-responsive changes in photoluminescence (PL) and magnetic properties are attractive for their potential applications in information storage and molecular devices. In this work, we report two mononuclear complexes, namely, Dy(SCN)₂(NO₃)(Cl-depma)₂(4-hpy)₂ (Dy-Cl) and Dy(SCN)₂(NO₃)(Br-depma)₂(4-hpy)₂ (Dy-Br), where X-depma represents 10-X-9-diethylphosphinomethylanthracene (X = Cl, Br) and 4-hpy is 4-hydroxypyridine. Both contain face-to-face π-π-interacted anthracene rings and exhibit yellow-green excimer emission. Unlike the other related Dy–anthracene complexes without a halogen substituent, Dy-Cl and Dy-Br cannot undergo photocycloaddition reaction under UV-light irradiation. However, they exhibited remarkable grinding-induced changes in luminescence. Magnetic studies revealed that Dy-Cl and Dy-Br show SMM behavior under zero dc field with the effective energy barriers (U_eff/k_B) of 259 K and 264 K, respectively. We also investigated the effect of pressure on the magnetic properties of Dy-Br and observed a reduction in the magnetization value, narrowing of the butterfly-shaped hysteresis loop, and acceleration of the magnetic relaxation under 1.09 GPa. The results demonstrate that introducing a halogen substituent into an anthracene group may pose significant influences on the photophysical and photochemical properties of the complexes. In addition, pressure may be a promising external stimulus to modulate the PL and SMM behaviors of Dy–anthracene complexes.

Lanthanide-anthracene complexes that can undergo reversible photocycloaddition reaction are attractive for the development of photoresponsive luminescent single-molecule magnets (SMMs). However, how to regulate the de-dimerization temperature of in situ formed dianthracenes remains an open question. Here, we report two binuclear dysprosium-anthracene complexes [Dy₂(SCN)₄(L)₂(depma)₂(DEPP)₂] (1) and [Dy₂(SCN)₄(L^Me)₂(depma)₂(DEPP)₂] (2), where L is 2,6-dimethoxyphenol, L^Me is 4-methyl-2,6-dimethoxyphenol, depma is 9-diethyl-phosphonomethylanthracene, and DEPP is diethylpropylphosphonate. Both undergo single-crystal-to-single-crystal (SC-SC) photocycloaddition reactions to form the 1D coordination polymers [Dy₂(SCN)₄L₂(depma₂)(DEPP)₂]_n (1UV) and [Dy₂(SCN)₄(L^Me)₂(depma₂)(DEPP)₂]_n (2UV), where depma₂ is photo-dimerized depma, concomitant with changes in photoluminescence and magnetic properties. Interestingly, the de-dimerization temperatures of 1UV (80 °C) and 2UV (71 °C) are much lower than those of the known lanthanide-dianthracene complexes (³ 100 °C). We found that the stability of in situ formed dianthracene depends largely on the spacing and slip angle of the anthracene pair in the original complex, with spacing being more important, and these parameters can be modulated by choosing suitable co-ligands. In addition, we investigated the kinetics of the photocycloaddition reaction of 1 at different temperatures and found that the rate of the reaction reached a maximum at the temperature of complete de-dimerization.

Co₂(OH)(5-cnapp)(H₂O) (1) and [Co₈(OH)(4-cnapp)₅(H₂O)₁₀]·12H₂O (2) were obtained using positionally isomeric phosphonic acids. Compound 1 contains distorted Co₃(μ₃-OH) kagomé layers and shows long-range weak ferromagnetic ordering below 30 K.