Creating ordered two-dimensional (2D) metal–organic framework (MOF) nanomaterials is conducive to understanding the structure–property relationship for rationally designing high-efficiency electrocatalysts. However, the controllable synthesis of ultrathin MOF nanosheets with predesigned structures and anticipative properties is still a great challenge. Here, we reported an electrolyte-assisted electrochemical approach to in situ exfoliate the intrinsic 2D MOF crystals with the Ni4Ln cluster as a secondary building unit (SBU) into ultrathin metal–organic nanosheets. Notably, the electric current density of the oxygen evolution reaction rapidly increases from 9.4 to 31.0 mA cm–2 at 1.8 V and the Tafel slope reduces from 150 to 87 mV dec–1, originating from electrochemically delaminating the thick 2D MOF precursors into ultrathin (∼4 nm) nanosheets to expose more catalytic active sites. Furthermore, the electrocatalytic oxygen evolution reaction (OER) activity of these 2D heterometallic MOF nanosheets can be effectively manipulated through precisely altering the lanthanide component of the Ni4Ln SBU in the layered MOFs. Density functional theory calculations reveal that the lanthanide ion of the SBU affects the adsorption and desorption capacity of active nickel centers to OER-relevant species, leading to the difference of the catalytic activity.

Three one‐dimensional ladder‐like coordination polymers consisting of Cd6 metalloring as the building unit, {[Cd4LCl4]·3H2O}n (1), {[Cd3L(ClO4)(H2O)]ClO4·3H2O}n (2), and {[Cd6(L)2(NO3)2(CH3OH)(H2O)](NO3)2·2CH3OH·5H2O}n (3), were solvothermally constructed from a carboxylic functionalized bisazamacrocyclic ligand 4,4′‐bis((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐1,1′‐biphenyl (H4L). These compounds dispersed in ethanol show the multiple emissions originating from the monomeric and intramolecularly overlapping biphenyl moieties which could be sensitively quenched by picric acid (PA) and 4‐nitrophenol (4‐NP) through the effective fluorescence resonance energy transfer process. The differential fluorescent responses of each compound on exposure to PA and 4‐NP individually make the convenient ratiometric discrimination of two analytes based on the fluorescent intensity ratio (I320/I360) attainable, and 1 and 2 as ratiometric chemosensors for PA present a broad linear detection range from 4 to 300 μM with detection limits of 0.84 and 0.93 μM, respectively. Furthermore, the blue light emission of 1 under an ultraviolet lamp could be selectively quenched by PA even in the presence of all other interfering nitroaromatic pollutants, which empowers the fast visual detection of PA by naked eye.

Two LnIII ions are sandwiched by dinuclear CoII building blocks derived from a tris‐triazamacrocyclic ligand bearing pendant carboxylic acid functionality, 1,3,5‐tris((4,7‐bis(2‐carboxyethyl)‐1,4,7‐triazacyclonon‐1‐yl)methyl)‐benzene (H6L), giving rising to two nanoscale heterometallic metal–organic cages formulated as [Co4Ln2(LH2.5)2(H2O)4]·(ClO4)6·NO3·nH2O [Ln = Dy, n = 12 (1); Ln = Yb, n = 9 (2)], whose internal cavity accommodates a guest NO3− anion. Their hexanuclear cage‐like architectures are maintained both in solution and solid states as confirmed by mass spectrum as well as X‐ray diffraction experiments. These two cages display ligand‐based fluorescence emissions and therefore both were chosen to be operated as fluorescent chemosensors for the detection of nitroaromatic compounds. Attractively, these metal–organic cages allow highly selective and sensitive detection of picric acid (PA) over other nitroaromatics in solution and suspension, and the fluorescence resonance energy transfer (FRET) between the cage probes and PA is mainly responsible for the remarkable detection efficiency.

Three new dinuclear Cu(II) complexes with the formulas [Cu 2 (pxdmbtacn)Cl 4 ] (1), [Cu 2 (pxdmbtacn)Cl 0.7 (NO 3 ) 1.3 (OH) 2 (H 2 O) 1.3 ]⋅6H 2 O (2) and [Cu 2 (pxdiprbtacn)Cl 4 ] (3) together with one previously reported complex, [Cu 2 (pxbtacn)Cl 4 ] (4), were obtained from Cu(II) salts with three p-xylylene-bridged bis-tacn ligands bearing pendant alkyl substituents or without pendant group. Complex 2 was structurally characterized as a centrosymmetric dinuclear molecule with each metal center being coordinated to some labile ligands in addition to one tacn ring. Based on the results of mass spectrometry and UVvisible spectroscopy, complexes 1 and 3 are capable of existing in aqueous solution as dinuclear species but 4 can partially form a dimer of the original dinuclear motif. Complexes 1, 3 and 4 can all effectively cleave supercoiled DNA oxidatively in the presence of hydrogen peroxide. The superoxide dismutase (SOD) activities of 1 and 3 measured under physiological conditions are comparable to that of the native CuZnSOD enzyme but the enzymatic activity of 4 is about three-to fourfold lower. Furthermore, complexes 1, 3 and 4 demonstrate moderate scavenging effect on hydrogen peroxide and their catalase activities are in the decreasing order of 3 > 1 > 4.