Rational Design of a Highly Sensitive Carboxylesterase Probe and Its Application in High-Throughput Screening for Uncovering Carboxylesterase Inhibitors.

Tracking carboxylesterases (CESs) through noninvasive and dynamic imaging is of great significance for diagnosing and treating CES-related metabolic diseases. Herein, three BODIPY-based fluorescent probes with a pyridine unit quaternarized via an acetoxybenzyl group were designed and synthesized to detect CESs based on the photoinduced electron transfer process. Notably, among these probes, BDPN2-CES exhibited a remarkable 182-fold fluorescence enhancement for CESs within 10 min. Moreover, BDPN2-CES successfully enabled real-time imaging of endogenous CES variations in living cells. Using BDPN2-CES, a visual high-throughput screening method for CES inhibitors was established, culminating in the discovery of an efficient inhibitor, WZU-13, sourced from a chemical library. These findings suggest that BDPN2-CES could provide a new avenue for diagnosing CES-related diseases, and WZU-13 emerges as a promising therapeutic candidate for CES-overexpression pathological processes.

Strategic design of an NIR probe for viscosity imaging in inflammatory and non-alcoholic steatohepatitis mice.

Two novel near-infrared (NIR) fluorescent probes Cy-Vis1 and Cy-Vis2 with large Stokes shifts (>100 nm) were constructed using a "symmetry collapse" strategy. Notably, Cy-Vis2 was significantly more sensitive to viscosity than Cy-Vis1 through an enhanced intramolecular interaction strategy. The fluorescence intensities of Cy-Vis1 and Cy-Vis2 exhibited increases, by 7.6- and 19.9-fold, respectively, across the viscosity range from 0.8 cp to 359.9 cp. Cy-Vis2 was successfully used to visualize viscosity abnormalities in lipopolysaccharide (LPS)-induced inflammatory and NASH model mice.

Two Stable Bifunctional Zinc Metal-Organic Frameworks with Luminescence Detection of Antibiotics and Proton Conduction.

Functionalized crystalline solids based on metal-organic frameworks (MOFs) enable efficient luminescence detection and high proton conductivity, making them crucial in the realms of environmental monitoring and clean energy. Here, two structurally and functionally distinct zinc-based MOFs, [Zn(TTDPa)(bodca)]·H2O (1) and [Zn(TTDPb)(bodca)]·H2O (2), were successfully designed and synthesized using 3,6-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPa) and 2,5-di(pyridin-4-yl)thieno[3,2-b]thiophene (TTDPb) as ligands, in the presence of bicyclo[2.2.2]octane-1,4-dicarboxylic acid (H2bodca). Both 1 and 2 display a three-dimensional (3D) structure with 5-fold interpenetration, and notably, 2 forms a larger one-dimensional pore measuring 17.16 × 10.81 Å2 in size. Fluorescence experiments demonstrate that 1 and 2 can function as luminescent sensors for nitrofurantoin (NFT) and nitrofurazone (NFZ) with low detection limits, remarkable selectivity, and good recyclability. A comprehensive analysis was conducted to investigate the differing sensing effects of compounds 1 and 2 and to explore potential sensing mechanisms. Additionally, at 328 K and 98% relative humidity, 1 and 2 exhibit proton conductivity values of 2.13 × 10-3 and 4.91 × 10-3 S cm-1, respectively, making them suitable proton-conducting materials. Hence, the integration of luminescent sensing and proton conductivity in monophasic 3D Zn-MOFs holds significant potential for application in intelligent multitasking devices.

Multicomponent hydroxides supported Cu/Cu2O nanoparticles for high efficient photocatalytic ammonia synthesis.

Environmentally friendly photocatalytic N2 fixation process has attracted considerable attention. Developing efficient photocatalysts with high electron-hole separation rates and gas adsorption capacities remains quite challenging. Herein, a facile fabrication strategy of Cu-Cu2O and multicomponent hydroxide S-scheme heterojunctions with carbon dot charge mediators is reported. The rational heterostructurebrings excellent N2 absorption ability and high photoinduced electron/hole separation efficiency, and the ammonia produced yield reach above 210 µmol·gcal-1·h-1 during the nitrogen photofixation process. More superoxide and hydroxyl radicals are generated simultaneously in the as-prepared samples under light illumination. This work offers a reasonable construction method to further develop suitable photocatalysts for ammonia synthesis.

CeO2-CDs clusters decorated Co(OH)2 nanosheets for improved photocatalytic ammonia synthesis.

The green synthesis process of photocatalytic ammonia production has received more and more attentions. Herein, a Z-scheme heterojunction with all-solid-state structures is constructed, in which carbon dots can act as electron transferring mediators. The photocatalytic measurement shows that the modified photocatalysts exhibit much higher activities, in which the ammonia production rates can reach above 232 µmol·gcal-1·h-1 under the light irradiation. The improved catalytic properties can be credited to the significantly increased number of photoinduced oxygen vacancies, the excellent visible-light adsorption abilities and photogenerated electron-hole separation efficiencies for the carbon dots bridged heterostructures. More hydroxyl and superoxide radicals can be simultaneously produced in the composites. This work provides reasonable guidance for applications in photocatalytic ammonia synthesis and a promising construction strategy of efficient Z-scheme photocatalysts.

Synthesis of 1-Aminoisoquinolines and Their Application in a Host-Guest Doped Strategy To Construct Ultralong Room-Temperature Phosphorescence Materials for Bioimaging.

Organic ultralong room-temperature phosphorescence (RTP) materials have attracted great attention for their wide applications in optoelectronic devices and bioimaging. However, the development of these materials remains a challenging task, partially due to the lack of rational molecular design strategies and unclear luminescence mechanisms. Herein, we present a method for facile access to structurally diverse substituted 1-aminoisoquinoline derivatives through a copper-catalyzed one-pot three-component coupling reaction that provides a promising approach to rapidly assemble a library of 1-aminoisoquinolines for exploring the regularity of the host-guest doped system. A series of host-guest RTP materials with wide-ranging lifetimes from 4.4 to 299.3 ms were constructed by doping various substituted isoquinolines derivatives into benzophenone (BP). Furthermore, 4 r/BP nanoparticles could be used for in-vivo imaging with a signal-to-noise ratio value as high as 32, revealing the potential of the isoquinoline framework for the construction of high-performance RTP materials.

Syntheses, structures, and magnetic properties of acetate-bridged lanthanide complexes based on a tripodal oxygen ligand.

Four homodinuclear lanthanide complexes, Dy2 (LOEt)2(OAc)4 (1), Tb2 (LOEt)2(OAc)4 (2), Ho2(LOEt)2(OAc)4 (3), and Gd2 (LOEt)2(OAc)4 (4), have been synthesized and characterized based on a tripodal oxygen ligand Na [(η5-C5H5)Co(P(O)(OC2H5)2)3] (NaLOEt). Structural analyses show that the acetate anions bridge two symmetry-related Ln3+ ions in the µ2:η1:η1 and µ2:η1:η2 coordination patterns, and each lanthanide (III) ion owns a twisted square antiprism (SAPR) conformation. Static magnetic measurements reveal the weak intramolecular ferromagnetic interaction between dysprosium (III) ions in 1 and antiferromagnetic Ln3+···Ln3+ couplings in the other three complexes. Through the analysis of the ligand-field effect and magnetic anisotropy axis orientation, the reasons for the lack of dynamic magnetic behavior in 1 were identified.

Rational Design of a Near-Infrared Ratiometric Probe with a Large Stokes Shift: Visualization of Polarity Abnormalities in Non-Alcoholic Fatty Liver Model Mice.

Tracking liver polarity with noninvasive and dynamic imaging techniques is helpful to better understand the non-alcoholic fatty liver (NAFL). Herein, a novel near-infrared (NIR) fluorescent probe Cy-Mp is constructed using a "symmetry collapse" strategy. The structure modification leads to the conversion of locally excited state fluorescence to charge transfer state fluorescence. Cy-Mp emits at near-infrared (NIR) wavelengths with high photostability as well as a large Stokes shift. Cy-Mp exhibits a ratiometric response to polarity, providing more accurate analysis of intracellular polarity via the built-in internal reference correction. Most importantly, the in vivo studies indicate that Cy-Mp can accumulate in the liver and the decreased polarity in the liver of mice with NAFL is verified by the ratiometric imaging, implying the great potential of Cy-Mp in the diagnosis of NAFL.

Two-dimensional dysprosium(III) coordination polymer: Structure, single-molecule magnetic behavior, proton conduction, and luminescence.

A new dysprosium (III) coordination polymer [Dy(Hm-dobdc) (H2O)2]·H2O (Dy-CP), was hydrothermal synthesized based on 4,6-dioxido-1,3-benzenedicarboxylate (H4m-dobdc) ligand containing carboxyl and phenolic hydroxyl groups. The Dy(III) center adopts an octa-coordinated [DyO8] geometry, which can be described as a twisted square antiprism (D 4d symmetry). Neighboring Dy(III) ions are interconnected by deprotonated Hm-dobdc3- ligand to form the two-dimensional infinite layers, which are further linked to generate three-dimensional structure through abundant hydrogen bonds mediated primarily by coordinated and lattice H2O molecules. Magnetic studies demonstrates that Dy-CP shows the field-induced slow relaxation of magnetization and the energy barrier U eff/k B and relaxation time τ 0 are 35.3 K and 1.31 × 10-6 s, respectively. Following the vehicular mechanism, Dy-CP displays proton conductivity with σ equal to 7.77 × 10-8 S cm-1 at 353 K and 30%RH. Moreover, luminescence spectra reveal that H4m-dobdc can sensitize characteristic luminescence of Dy(III) ion. Herein, good magnetism, proton conduction, and luminescence are simultaneously achieved, and thus, Dy-CP is a potential multifunctional coordination polymer material.

Synthesis of Diverse γ-Lactams via Rh-Catalyzed C(sp2)-H Addition to Aliphatic Nitriles.

We herein report an unprecedented pathway to access γ-lactams using acetonitrile analogues as coupling partners without oxidants, ligands, and Lewis acids. The reaction undergoes Rh-catalyzed C(sp2)-H addition to carbon-bound nitriles with the aid of an amide traceless auxiliary followed by an annulation sequence, featuring a broad substrate scope, good functional group tolerance, and excellent chemo/stereoselectivity. Scale-up reactions and late-stage derivatizations highlight the potential synthetic utility of this methodology. A plausible mechanism is proposed based on mechanistic investigations.

Dysprosium(III) Metal-Organic Framework Demonstrating Ratiometric Luminescent Detection of pH, Magnetism, and Proton Conduction.

A multifunctional metal-organic framework, (Hdmbpy)[Dy(H2dobdc)2(H2O)]·3H2O (Dy-MOF, H4dobdc = 2,5-dihydroxyterephthalic acid, dmbpy = 4,4'-dimethyl-2,2'-bipyridine), was synthesized and structurally characterized. The metal center DyIII is connected by four carboxyl groups to form the [Dy2(CO2)4] binuclear nodes, which are further interconnected by eight separate H2dobdc2- ligands to form a three-dimensional (3D) framework including hydrophilic triangular channels and abundant hydrogen-bonding networks. Dy-MOF has good stability in aqueous solution as well as in harsh acidic or alkaline solutions (pH range: 2.0-12.0). Furthermore, the luminescence signal of Dy-MOF undergoes a visualized color change as the acidity of the solution alters, which is the typical behavior of pH ratiometric probe. At a 100% relative humidity, Dy-MOF exhibits a high proton conductivity σ (1.70 × 10-4 S cm-1 at 303 K; 1.20 × 10-3 S cm-1 at 343 K) based on the proton hopping mechanism, which can be classified as a superionic conductor with σ exceeding 10-4 S cm-1. Additionally, the ferromagnetic interaction and magnetic relaxation behavior are simultaneously achieved in Dy-MOF. Herein, the combination of luminescence sensing, magnetism, and proton conduction in a single-phase 3D MOF may offer great potential applications in smart multitasking devices.

Cu-Based Conductive MOF Grown in situ on Cu Foam as a Highly Selective and Stable Non-Enzymatic Glucose Sensor.

A non-enzymatic electrochemical sensor for glucose detection is executed by using a conductive metal-organic framework (MOF) Cu-MOF, which is built from the 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) ligand and copper acetate by hydrothermal reaction. The Cu-MOF demonstrates superior electrocatalytic activity for glucose oxidation under alkaline pH conditions. As an excellent non-enzymatic sensor, the Cu-MOF grown on Cu foam (Cu-MOF/CF) displays an ultra-low detection limit of 0.076 µM through a wide concentration range (0.001-0.95 mM) and a strong sensitivity of 30,030 mA µM-1 cm-2. Overall, the Cu-MOF/CF exhibits a low detection limit, high selectivity, excellent stability, fast response time, and good practical application feasibility for glucose detection and can promote the development of MOF materials in the field of electrochemical sensors.

Iron(II) Spin Crossover Coordination Polymers Derived From a Redox Active Equatorial Tetrathiafulvalene Schiff-Base Ligand.

Two polymorphic FeII coordination polymers [FeIIL (TPPE)0.5] 1) and [(FeII 3L3 (TPPE)1.5)] 2), were obtained from a redox-active tetrathiafulvalene (TTF) functionalized ligand [H2L = 2,2'-(((2-(4,5-bis-(methylthio)-1,3-dithiol-2-ylidene)benzo(d) (1,3) dithiole-5,6-diyl)bis-(azanediyl))bis-(meth anylylidene)) (2E,2E')-bis(3-oxobutanoate)] and a highly luminescent connector {TPPE = 1,1,2,2-tetrakis[4-(pyridine-4-yl)phenyl]-ethene}. Complex 1 has a layered structure where the TPPE uses its four diverging pyridines from the TPPE ligand are coordinated by the trans positions to the flat TTF Schiff-base ligand, and complex 2 has an unprecedented catenation of layers within two interpenetrated frameworks. These coordination polymers reserved the redox activity of the TTF unit. Complex 1 shows gradual spin transition behavior without hysteresis. And the fluorescence intensity of TPPE in 1 changes in tandem with the spin crossover (SCO) transition indicating a possible interplay between fluorescence and SCO behavior.

Rare-Earth Metal Tetrathiafulvalene Carboxylate Frameworks as Redox-Switchable Single-Molecule Magnets.

Using the redox-active tetrathiafulvalene tetrabenzoate (TTFTB4- ) as the linker, a series of stable and porous rare-earth metal-organic frameworks (RE-MOFs), [RE9 (µ3 -OH)13 (µ3 -O)(H2 O)9 (TTFTB)3 ] (1-RE, where RE=Y, Sm, Gd, Tb, Dy, Ho, and Er) were constructed. The RE9 (µ3 -OH)13 (µ3 -O) (H2 O)9 ](CO2 )12 clusters within 1-RE act as segregated single-molecule magnets (SMMs) displaying slow relaxation. Interestingly, upon oxidation by I2 , the S=0 TTFTB4- linkers of 1-RE were converted into S= 1 / 2 TTFTB.3- radical linkers which introduced exchange-coupling between SMMs and modulated the relaxation. Furthermore, the SMM property can be restored by reduction in N,N-dimethylformamide. These results highlight the advantage of MOFs in the construction of redox-switchable SMMs.

Magnetic Relaxation Dynamics of a Binuclear Diluted Er(III)/Y(III) Compound Influenced by Lattice Solvent.

It is crucial to investigate the slow relaxation mechanisms of binuclear ErIII -based single-molecule magnets (SMMs) and explore strategies for optimizing their magnetic properties. Herein, a doped compound, [Y1.75 Er0.25 (thd)4 Pc] ⋅ 2C6 H6 (YEr ⋅ 2C6 H6 , Hthd=2,2,6,6-tetramethylheptanedione, H2 Pc=phthalocyanine), was synthesized by doping the paramagnetic erbium(III) compound Er2 ⋅ 2C6 H6 in the diamagnetic yttrium(III) matrix Y2 ⋅ 2C6 H6 . The doping effect was studied using SQUID magnetization measurements. The results suggest that magnetic-site dilution improves the magnetic property from a fast relaxation of the pure ErIII compound to a typical SMM relaxation process of the doped sample. In this binuclear system, the dominant single-ion relaxation is entangled with the neighboring ErIII ion through the intramolecular ErIII ⋅⋅⋅ErIII interaction, which plays an important role in suppressing the quantum tunneling of the magnetization (QTM) process. Furthermore, the influence of lattice solvents on single-ion relaxation was studied. By releasing the benzene molecules, compound YEr ⋅ 2C6 H6 can be successfully transformed to a desolvated sample YEr accompanied by structural alteration and improved SMM performance.

Modulating Magnetic Property of Phthalocyanine Supported MII-DyIII (M = Ni, Zn) Heterodinuclear Complexes.

Three heterometallic dinuclear compounds, [MIIDyIII(L)(Pc)(ROH)]·ROH (R = CH3, M = Ni (1), Zn (2); R = C2H5, M = Zn (3)), were stepwise synthesized based on phthalocyanine (H2Pc) and one tripodal Schiff-base ligand 1,1,1-tris[(salicylideneamino)methyl]ethane (H3L). All of them have been studied structurally and magnetically. The six-coordinate MII ion and the seven-coordinate DyIII ion are bridged by two phenolic oxygen atoms to form an MII-LnIII heterodinuclear unit. Magnetic measurements indicate that the ferromagnetic NiII-DyIII interaction is operative in compound 1 and all three compounds exhibit the field-induced slow relaxation of magnetizations. In particular, compounds 2 and 3 have the improved magnetic performance. Ab initio calculations indicate that the weak NiII-DyIII interaction decreases the energy barrier, while the replacement of the paramagnetic NiII ion by the diamagnetic ZnII in compound 2 and 3 not only controls the magnetic interaction but also alters the local magnetic axes of DyIII ions to optimize the magnetic relaxation behavior.

A Two-Dimensional Iron(II) Coordination Polymer with Synergetic Spin-Crossover and Luminescent Properties.

A composite material, {[Fe(L)(TPPE)0.5 ]⋅3 CH3 OH}n , has been constructed by integrating the spin-crossover (SCO) subunit FeII {diethyl(E,E)-2,2'-[1,2-phenyl-bis(iminomethylidyne)]bis(3-oxobutanoate)-(2-)-N,N',O3 ,O3 '} and the highly luminescent connector 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)-ethene. Its structure contains four staggered 4×4 layers and intercalated methanol. The packing is dominated by considerable H-bonds either between adjacent layers and between layers and guests. A crystal-structure transformation was detected upon removal of the guest molecules. The SCO transition of the solvated crystals is centered at ca. 215 K with a non-symmetrical hysteresis of 25 K wide, and the desolvated [Fe(L)(TPPE)0.5 ]n exhibits gradual SCO without hysteresis. Intriguingly, the intensity of the fluorescence at 460 nm for the latter is maximized at the SCO transition. The energy transfer between luminescent and SCO entities is achievable as confirmed by theoretical calculations.

Enhancing low-field magnetoresistance in magnetite nanoparticles via zinc substitution.

We report a strategy to enhance the room temperature low-field magnetoresistance (LFMR) behavior of Fe3O4 nanoparticle (NP) assemblies by controlled Zn-substitution. The Zn-substituted 7 nm ZnxFe3-xO4, (x = 0 to 0.4) NPs are prepared by thermal decomposition of metal acetylacetonates (M(acac)n, M = Fe2+, Fe3+, and Zn2+). The substitution increases NP magnetic susceptibility (χ) and makes the magnetic moment more sensitive to low magnetic fields. As a result, the Zn0.3Fe2.7O4 NP assembly with NPs separated by tridecanoate exhibits a large magnetoresistance (MR) ratio of -14.8% at 300 K under a 4.5 kOe magnetic field. The demonstrated approach to control NP substitution to enhance low-field magnetoresistance of the NP assemblies provides an attractive new strategy to fabricate Fe3O4-based magnetic NP assemblies with desirable transport properties for sensitive spintronic applications.

Modulating the Magnetic Interaction in New Triple-Decker Dysprosium(III) Single-Molecule Magnets.

A new type of dinuclear dysprosium(III) complex based on phthalocyanine and salicylaldehyde derivatives (HL-R), [Dy2(Pc)2(L-R)2(H2O)]·2THF (R = OCH3 (1), OC2H5 (2); H2Pc = phthalocyanine; HL-OCH3 = 2-hydroxy-3-methoxybenzaldehyde; HL-OC2H5 = 3-ethoxy-2-hydroxybenzaldehyde), was successfully synthesized and structurally characterized. Complex 1 features a sandwich-type triple-decker structure, where two coplanar L-OCH3 ligands lie in the middle layer shared by two eight-coordinated DyIII ions and two Pc ligands are located in the outer layer. In 2, the introduction of an ethoxy group generates a noncoordination mode for the Oalkoxy atom. Magnetic studies indicate that complex 1 behaves as a zero-field single-molecule magnet with a higher energy barrier, while 2 exhibits a fast tunneling relaxation process. Theoretical calculations revealed that changes in the ligand field environment around DyIII ions can significantly affect the arrangement of the main magnetic axes and further result in distinct magnetic interactions as well as different relaxation behaviors.

Redox-switchable breathing behavior in tetrathiafulvalene-based metal-organic frameworks.

Metal-organic frameworks (MOFs) that respond to external stimuli such as guest molecules, temperature, or redox conditions are highly desirable. Herein, we coupled redox-switchable properties with breathing behavior induced by guest molecules in a single framework. Guided by topology, two flexible isomeric MOFs, compounds 1 and 2, with a formula of In(Me2NH2)(TTFTB), were constructed via a combination of [In(COO)4]- metal nodes and tetratopic tetrathiafulvalene-based linkers (TTFTB). The two compounds show different breathing behaviors upon the introduction of N2. Single-crystal X-ray diffraction, accompanied by molecular simulations, reveals that the breathing mechanism of 1 involves the bending of metal-ligand bonds and the sliding of interpenetrated frameworks, while 2 undergoes simple distortion of linkers. Reversible oxidation and reduction of TTF moieties changes the linker flexibility, which in turn switches the breathing behavior of 2. The redox-switchable breathing behavior can potentially be applied to the design of stimuli-responsive MOFs.