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Atherosclerosis (AS) is a crucial contributor to various cardiovascular diseases (CVDs), which seriously threaten human life and health. Early and accurate recognition of AS plaques is essential for the prevention and treatment of CVD. Herein, we introduce an AS-targeting nanoprobe based on near-infrared (NIR) persistent luminescence nanoparticles (PLNPs), developing a highly sensitive NIR persistent luminescence (PersL) AS plaque imaging technique and successfully realizing early AS plaque detection. The nanoprobe exhibits good monodispersity and regular spherical morphology and also owns exceptional NIR PersL performance upon repetitive irradiation by biological window light. The surface-conjugated antibody (anti-osteopontin) endowed nanoprobe excellent targeting ability to foam cells within plaques. After intravenously injected nanoprobe into AS model mice, the highly sensitive PersL imaging technique can accurately detect AS plaques prior to ultrasonography (US) and magnetic resonance imaging (MRI). Specifically, the NIR PersL imaging reveals AS plaques at the earliest within 2 weeks, with higher signal-to-background ratio (SBR) up to 5.72. Based on this technique, the nanoprobe has great potential for applications in the prevention and treatment of CVD, the study of AS pathogenesis, and the screening of anti-AS drugs.

High-performance bi-functional materials are in urgent demand for the next-generation integrated optical devices. In this work, we successfully synthesized the first tricyanomelaminate with bi-functional optical responses, namely Cs3C6N9•H2O (I), from its analogue Na3C6N9•3H2O by a facile ion exchange method. In contrast to Na3C6N9•3H2O, Irealizes an optimal arrangement of π-conjugated (C6N9)3−anion groups in its crystal structure. As a result, the second-order nonlinear optical (NLO) response is greatly enhanced from nearly zero of Na3C6N9•3H2O to ∼9.8 × KH2PO4of I. Furthermore, Iexhibits a giant linear optical anisotropic response (i.e. birefringence) of 0.52 at the wavelength of 550 nm. Both responses are almost the largest among the inorganic compounds of π-conjugated rings, which indicates that Ihas great potential as a bi-functional optical crystal. Structural and theoretical analyses reveal the microscopic origin of excellent optical properties. This work would attract a lot of interest to the persistently neglected potential of tricyanomelaminates as linear optical and NLO crystals.

Homochiral metal–organic frameworks (HMOFs) have been widely investigated in the application of enantiomeric separation. Nonetheless, it remains a significant challenge to explore the effect of multiple weak interactions between HMOF adsorbents and chiral adsorbates on enantiomeric separation performance still. In this work, robust chiral amine-alcohol-functionalized UiO-68-typed Zr-HMOFs 1–3with the same hydrogen-bonding sites but slightly different π-binding sites were prepared for the enantioseparation of amino acid derivatives (Fmoc-AAs) with large π-binding groups. As a consequence of multiple host–guest interactions, these Zr-HMOFs exhibit speedy adsorption and high adsorption capacity for Fmoc-L/D-AAs and dissimilar enantioselectivity for the adsorption of their enantiomers. Materials 1and 2exhibit excellent enantioselective separation performance for Fmoc-valine with a single terminal π-binding group, while material 3displays excellent enantioselective separation performance for Fmoc-phenylalanine and Fmoc-tryptophan with π-binding groups at both ends. As evidently demonstrated by our experimental and density functional theory (DFT) computational results, when the number of π-binding groups preset in the confined chiral space of adsorbents matches the number of π-binding groups of chiral adsorbates, the synergism of π–π or σ–π interactions will increase enantioselectivity; otherwise, the competition interactions from redundant identical binding sites will weaken enantioselectivity. Our case not only provides a tremendously typical system for investigating the collaborative discrimination of multiple weak interactions and exploring the impact of relatively excessive binding sites of HMOF adsorbents or chiral adsorbates on the enantioselective separation performance but also provides guidance for targeted functional modifications of high-performance chiral porous materials.

Benefiting from superior semiconducting properties and the angle-dependence of the bulk photovoltaic effect (BPVE) on polarized light, the two-dimensional (2D) hybrid perovskite ferroelectrics are developed for sensitive self-powered polarized photodetection. Most of the currently reported ferroelectric-driven polarized photodetection is restricted to the shortwave optical response, and expanding the response range is urgently needed. Here we report the first instance of a FAPbI3-derived (2D) perovskite ferroelectric, (BA)2(FA)Pb2I7(1, BA is n-butylammonium, FA is formamidinium). It exhibited a notably high thermostability and broad-spectrum adsorption extending to around 650 nm. Significantly, 1demonstrated ferroelectricity-driven self-powered polarized photodetection under 637 nm with an anisotropic photocurrent ratio of ∼1.96, ultrahigh detectivity of 3.34 × 1012Jones, and long-term repetition. This research will shed light on the development of new ferroelectrics for potential application in broad-spectrum polarization-based optoelectronics.

Considering the importance of C2H2in industry, it is of great significance to develop porous materials for efficient C2H2/CO2separation. Besides the high selectivity, the C2H2adsorption capacity is another vital factor in C2H2/CO2separation. However, the “trade-off” between these two factors is still perplexing. Rational pore design of metal–organic frameworks (MOFs) has been proven to be an effective way to solve the above problem. In this work, we have appropriately combined three kinds of strategies in the design of the MOF (FJI-H33), i.e., the introduction of open metal sites, construction of cage-like cavities, and adjustment of moderate pore size. As anticipated, FJI-H33exhibits both outstanding C2H2adsorption capacity and high C2H2/CO2selectivity. At 298 K and 100 kPa, the C2H2storage capacity of FJI-H33is 154 cm3/g, while the CO2uptake is only 80 cm3/g. The ideal adsorbed solution theory (IAST) selectivity of C2H2/CO2(50:50) is calculated as high as 15.5 at 298 K. More importantly, the excellent practical separation performance was verified by breakthrough experiments. In addition, the calculation of adsorption sites and relevant energy by density functional theory (DFT) provides a good explanation for the excellent separation performance and pore design strategy.

As structural variants of famous hexagonal tungsten bronzes, hexagonal tungsten oxides (HTO) represent an important family with fascinating functional properties, such as piezoelectric, ferroelectric, pyroelectric, and nonlinear optical (NLO) properties. However, none of them are transparent in the deep-UV spectral region, which limits their applications. Herein, we report the first HTO-type monofluorophosphate K3Sc3(PO4)(PO3F)2F5(I) with deep-UV transparency. Such a monofluorophosphate is NLO-active with a phase-matchable powder second harmonic generation efficiency of 0.9 times that of KH2PO4at 1064 nm. Importantly, the UV-Vis reflectance spectrum indicates that it is deep-UV transparent down to 200 nm. This work pushes the transparent window of NLO materials with HTO-type structures down to the deep-UV spectral region for the first time and opens up a new door for HTO materials.

Epoxy resin (EP) is widely used in various industries. However, its inherent flammability characteristics limit its application, so there is an urgent need to develop bio-based flame retardants for efficient flame retardant EP. Chitosan (CS) is one of the most commonly used bio-based raw materials, but most chitosan-based flame retardants are synthesised using large amounts of organic solvents, with low yields and not in line with the theme of green and sustainable development. In this paper, we report a facile, eco-friendly, and solvent-free approach to chitosan-based flame retardants. A novel full biomass flame retardant, chitosan-based ammonium phytate (PUCS), was synthesised without the organic solvent by using chitosan and phytanic acid as raw materials and the electrostatic adsorption interaction between them and urea, and it was used as a flame retardant additive for EP. The results showed that the EP samples with 7.5 wt% PUCS added increased the limiting oxygen index from 22.2 % to 32.2 % and the vertical burning rating from no rating to V-0. Moreover, the cone calorimeter test results showed that the EP/PUCS composites with adding PUCS showed a significant decrease in the peak heat release rate, and it has excellent flame retardancy. It is worth mentioning that the mechanical property test results showed that the mechanical properties of EP/PUCS composites with adding PUCS could still reach the scope of the needs for engineering applications. This work provides an economical, convenient, and eco-friendly feasible route for bio-based flame retardants.

Luminescent stability is a vital factor that dictates the application of lanthanide luminescent materials. Designing luminescent lanthanide cluster nodes that form an extended framework with predictable linking patterns may help enhance the structural stability of the lanthanide complexes and hence lead to improved luminescent stability. Herein, we report a series of one-dimensional (1D) rare-earth metal–organic framework compounds, {Ln4(μ4-OH)(TC4A)2(H2O)2(CH3O)(HCOO)2(HCOOH)}·xCH3OH (Ln = Sm (1), Eu (2), Tb (3), Dy (4); x= 1–5), based on double thiacalix[4]arene-capped Ln4(μ4-OH)(TC4A)2nodes. The axially capped Ln4(μ4-OH)(TC4A)2nodes are connected equatorially by formate bridges to form zigzag 1D-metal–organic framework (MOF) chains, which further assemble into a quasi-two-dimensional (2D) structure via hydrogen bonding. These unique features result in a stable structure and therefore superior luminescent stability. For example, the Tb-based 1D-MOF (3) exhibits intensive green photoluminescence with a quantum yield of 53% and an average decay time of 1.33 × 106ns. It maintains its integrated emission intensity at 96.5, 94.5, and 89.4% of the original value after being exposed to moisture (soaking in water for 10 days), elevated temperature (150 °C), and UV (15 days of continuous radiation), respectively, demonstrating excellent luminescent stability. We adopt the Tb-based 1D-MOF (3) as the green phosphor and successfully fabricate a prototype white-light-emitting diode (LED) with stable emission under long-term operation. Our synthetic strategy allows control over the linking pattern of lanthanide nodes, providing a predictive route to obtain lanthanide MOFs with improved luminescent stability.

Trivalent lanthanide (Ln3+)-doped luminescent nanoparticles (NPs) have been extensively investigated as deep-tissue-penetration visual bioimaging agents owing to their exceptional upconversion and near-infrared (NIR) luminescence upon irradiation of NIR light. However, in most cases, the power density of irradiation used for in vivobiological imaging is much higher than that of the reported maximum permissible exposure (MPE) value of NIR light, which inevitably does great damage to the living organisms under study and thus impedes the plausible clinical applications. Herein, by using a facile syringe pump-aided shell epitaxial growth method, we construct for the first time a new class of Ln3+-doped KMgF3:Yb/Er@KMgF3core-shell NPs that can be activated by utilizing a 980-nm xenon lamp or diode laser with an ultralow excitation power density down to 0.08 mW cm−2, a value that is approximately 4 orders of magnitude lower than the MPE value set by the American National Standards Institute (ANSI) for safe bioimaging in vivo.By combining the comparative spectroscopic investigations with atomic-resolved spherical aberration corrected transmission electron microscopy (AC-TEM) characterization, we find that the reduced crystallographic defects are the primary cause underlying such an ultralow-power-excitable feature of the KMgF3: Yb/Er@KMgF3core-shell NPs. And, by the same token, the resultant KMgF3:Yb/Er@KMgF3core-shell NPs also exhibit an anomalous thermo-enhanced photoluminescence (PL) behavior coupled with an excellent photothermal stability that cannot occur in other Ln3+-doped core-shell NPs. These findings described here unambiguously pave a new way to prepare high-quality Ln3+-doped luminescent NPs with desirable ultralow-power-excitable capability and photothermal stability for future biomedical applications.

Accurately designing and synthesizing new deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals that are limited by the so-called “200 nm wall” on their transparency windows remain challenging. On the basis of a bandgap-directed computer-aided material design approach, two new NLO sulfates, KMgSO4F and KZnSO4F, are designed and successfully synthesized. They feature three-dimensional frameworks closely related to the commercial NLO crystal, KTiOPO4(KTP). Remarkably, the transmittance spectrum based on a single crystal indicates that the transparency window of KZnSO4F is significantly blue-shifted to <190 nm from 350 nm for KTP. The microscopic origin of this significant transparent window blue shift is illustrated well by first-principles calculations. This work pushes the transparency windows of KTP-like NLO sulfates into the deep-UV spectral region for the first time and will pave a prospective way to the accurate design and synthesis of new deep-UV NLO materials.

It remains a challenge to develop UV nonlinear optical (NLO) crystals that can achieve a desirable trade-off on UV absorption edge, second harmonic generation (SHG), and birefringence. Here we report a thiosulfate UV NLO crystal of a 2D van der Waals layered structure, [C(NH2)3]2SO3S. Remarkably, this thiosulfate realizes the desired trade-off, with a short absorption edge of 254 nm, a strong SHG response of approximately 2.8 times that of the benchmark KH2PO4, and a sufficient birefringence of 0.073 at the wavelength of 546 nm. In addition, it exhibits strong in-plane anisotropy of the SHG intensity. According to the first-principles calculations, the non-π-conjugated [SO3S]2–anion is the dominant SHG functional gene, while the π-conjugated [C(NH2)3]+cation serves as the functional gene of birefringence. This is different from common UV NLO materials whose functionals of SHG and birefringence are the same. These findings indicate that combining different function genes may be an effective strategy to develop outstanding NLO materials with the desirable property trade-off.

Constructing supramolecular cages with multiple subunits via weak intermolecular interactions is a long-standing challenge in chemistry. So far, π-stacked supramolecular cages still remain unexplored. Here, we report a series of π-stacked cage based hierarchical self-assemblies. The π-stacked cage (π-MX-cage) is assembled from 16 [MXL]+ions (M = Mn2+, Co2+; X = Br–, SCN–, Cl–; and L = tris(2-benzimidazolylmethyl)amine) via 18 intermolecular π-stacking interactions. The tetrahedral cage, consisting of four [MXL]+ions as the vertexes and six pairs of [MXL]+ions as the edges, features 48 exterior N–H hydrogen bond donors for hydrogen bond formation with guest molecules. By variation of the M2+/X–pair, the π-MX-cage demonstrates unique versatility for incorporating a wide variety of species via different hydrogen-bonding modes during the assembly of hierarchical superstructures. In specific, the π-MnBr-cages encapsulate acetonitrile (CH3CN) or cis-1,3,5-cyclohexanetricarbonitrile (cis-HTN) molecules in the central voids, while a core–shell tetrahedral inorganic cluster [Mn(H2O)6]@([Mn(H2O)4]4[Br42–]6) (Mn@Mn4-cage) is captured within the interstitial regions between cages. The π-CoSCN-cages are capable of stabilizing reactive sulfur-containing species, such as S2O42–, S2O62–, and HSO3–ions, in the hierarchical superstructure. Finally, H2PO4–ions are incorporated between π-CoCl-cages, resulting in an inorganic mesoporous framework. These results provide insights into further exploring the chemistry and hierarchical assembly of supramolecular cages based on π–π stacking intermolecular interactions.

As a functional material, conductive hydrogel has been widely used due to its stretchability and flexibility, especially in the field of flexible wearable sensors. However, preparing a hydrogel sensor with high elasticity, fatigue resistance, and low-temperature resistance is still challenging. In this work, a novel hydrogel was synthesized with acrylic acid and sodium p-styrene sulfonate in an acidic solution of chitosan under ultraviolet light. Then, the hydrogel was immersed in the sodium chloride solution to obtain a chitosan/poly(acrylic acid-sodium p-styrene sulfonate)/sodium chloride (CS/P(AA-co-SS)/NaCl) dual network (DN) hydrogel. The sodium chloride caused the molecular chains of the hydrogel to entangle. The hydrogel shows excellent mechanical properties (tensile strength is as high as 532.2 kPa, elongation at break is as high as 620%, energy to break is 1200 kJ/m3, compressive strength at 80% is 661 kPa, and compressive toughness is 83.5 kJ/m3) and high electrical conductivity (up to 4.5 S/m). At the same time, the hydrogel possesses excellent resilience and fatigue resistance due to hydrogen bonds, electrostatic interactions, and the existence of hydrophobic domains. Moreover, the hydrogel also exhibits outstanding frost resistance, excellent mechanical properties, and electrical conductivity even at −20 °C. The wearable sensor made of the CS/P(AA-co-SS)/NaCl DN hydrogel will have high sensitivity (under 100% strain, gauge factor = 2.4) and repeatability, which can accurately detect various movements of the human body.

All-inorganic cesium lead halide perovskite (CsPbX3, X = Cl, Br, and I) quantum dots (QDs), possessing high photoluminescence quantum yields and tunable color output, have recently been endowed great promise for high-performance solar cells and light-emitting diodes (LEDs). Although moisture stability has been greatly improved through separating QDs with a SiO2shell, the practical applications of CsPbX3QDs are severely restricted by their poor thermal stability, which is associated with the intrinsically low formation energies of perovskite lattices. In this regard, enhancing the formation energies of perovskite lattices of CsPbX3QDs holds great promise in getting to the root of their poor thermal stability, which hitherto remains untouched. Herein, we demonstrate an effective strategy through Mn2+substitution to fundamentally stabilize perovskite lattices of CsPbX3QDs even at high temperatures up to 200 °C under ambient air conditions. We employ first-principle calculations to confirm that the significantly improved thermal stability and optical performance of CsPbX3:Mn2+QDs arise primarily from the enhanced formation energy due to the successful doping of Mn2+in CsPbX3QDs. Benefiting from such an effective substitution strategy, these Mn2+-doped CsPbX3QDs can function well as efficient light emitters toward the fabrication of high-performance perovskite LEDs.

Ligands with flexible conformations add to the structural diversity of metal–organic frameworks but, at the same time, pose a challenge to structural design and prediction. Representative examples include Zr-tetracarboxylate-based MOFs, which afford assorted structures for a wide range of applications, but also complicate the structural control. Herein, we systematically studied the formation mechanism of a series of (4,8)-connected Zr-tetracarboxylate-based MOFs by altering the substituents on different positions of the organic linkers. Different ligand rotamers give rise to three types of structures with flu, scu, and csqtopologies. A combination of experiment and molecular simulation indicate that the steric hindrance of the substituents at different positions dictates the resulting MOF structures. Additionally, the controllable formation of different structures was successfully implemented by a combination of linkers with different steric effects at specific positions.

A high efficiency of laser-light conversion and short cutoff edge is essential to an ultraviolet (UV) nonlinear-optical (NLO) material. Previous researches on phosphates were mainly centered on alkali-metal or alkali-earth-metal phosphate systems, resulting in relatively weak NLO responses. Through the introduction of transition-metal cadmium and alkali-metal cesium elements with large radii into the phosphate system, a new UV NLO pyrophosphate, CsLiCdP2O7, has been synthesized. It exhibits a high second-harmonic-generation (SHG) efficiency of 1.5KH2PO4and is transparent down to 200 nm. This work provides a new path for the design of UV NLO materials with high SHG efficiencies and short cutoff edges by introducing a transition metal with a d10electron configuration and an alkali metal with a large radius into phosphate systems.

Crystal growth in China has a long history and is developing rapidly at the present time. In the past decade, significant efforts have been directed toward the research of structure−property relationships and high quality crystal growth, which has brought to fruition many fields covering nonlinear optical, laser, ferro-/piezo-electric, and wide band gap semiconductor crystals. In this contribution, selected research work accomplished by Chinese scientists in crystal engineering and growth is reviewed.

A novel molecular electric ordered compound [(Hdabco)+ClF2CCOO–] (complex 1, dabco = 1,4-diazabicyclo[2.2.2]octane) has been discovered as a switchable dielectric material, in which the N–H···O hydrogen bonds connect the anions and cations together to form a dimer structure. It undergoes a reversible second order solid state phase transition at 165 K (Tc), which was confirmed by thermal analyses including differential scanning calorimetry (DSC) and specific heat (Cp) and dielectric measurements. Variable temperature single crystal X-ray diffraction analyses revealed its order–disorder transformation of twisting motion characteristic behaviors for the phase transition. Owing to the ordering of twisting motions of the chlorodifluoroacetate anions, the structure of 1demonstrates a phase transition from high crystallographic symmetry with space group of Pnmato the low state with space group of P21/c; that is, an Aizu notion of mmmF2/moccurs. Emphatically, the dielectric constant of 1displays a distinctive step-like anomaly; namely, it possesses a high dielectric state in the room temperature phase (RTP) and a low state in the low temperature phase (LTP). Such distinctive dielectric performances disclose that 1might be considered as a potential switchable dielectric material. We believe that all the findings would afford a useful strategy in exploring new electric ordering materials.

Lanthanide ions (Ln3+) doping provides a potential strategy to control over the luminescent properties of lead-free halide double perovskite nanocrystals (DP NCs). However, due to the low energy transfer efficiency between self-trapped exciton (STE) and Ln3+ions, the characteristic emissions of Ln3+ions are not prominent. Furthermore, the energy transfer mechanism between STE and Ln3+ions is also elusive and requires in-depth study. We chose trace Bi3+-doped Cs2Ag0.6Na0.4InCl6–xBrxas a representative DP matrix to demonstrate that by tuning the bromide concentration, the Ln3+emission can be greatly enhanced. Such enhanced STE and Ln3+ions energy transfer originates from the high covalency of Ln–Br bond, which contributes to improvement of the characteristic emission of Ln3+ions. Furthermore, optical spectroscopy reveals that the energy transfer mechanism from DP to Eu3+ions is different from all the other doped Ln3+ions. The energy transfer from DP to Eu3+ions is mostly through Eu–Br charge transfer while the other Ln3+ions are excited by energy transfer from STE. The distinct energy transfer mechanism has resulted from the energy separation between the excited energy level of Ln3+ions and the bottom of conduction band of DP. With increasing the energy separation, the energy transfer from STE to Ln3+ions is less efficient because of the generation of a larger number of phonons and finally becomes impossible for Eu3+ions. Our results provide new insight into tuning the energy transfer of Ln3+-doped DP NCs.

Six three-dimensional (3D) lanthanide coordination polymers with formula [Ln(TDC)(ox)0.5(H2O)2]·(H2O) (1Ln) (Ln = Pr 1, Nd 2, Sm 3, Gd 4) and [Ln(TDC)(ox)0.5(H2O)2]·(H2O) (2Ln) (Ln = Dy 5, Er 6) have been synthesized by hydrothermal reactions of thiophene-2,5-dicarboxylate (TDC) and oxalate (ox) with corresponding lanthanide nitrate. X-ray crystal structure analyses reveal that 1Lnand 2Lnare isomers that may be produced by lanthanide contraction. Compounds 1–4are isostructural and possess binodal (4,5)-connected 3D framework of tcj/hc topology with triangular channels along the [101] direction. Isostructural compounds 5and 6present trinodal (4,4,6)-connected 3D framework of sqc254 topology with rectangular channels along the baxis. The magnetic properties reveal that compound 2has antiferromagnetic behavior, while compound 4has ferromagnetic behavior. The luminescent property shows that compound 5displays intense yellow luminescence and exhibits the typical Dy3+ion emission. Furthermore, infrared (IR), thermogravimetric analyses (TGA), elemental analyses (EA), powder X-ray diffraction (PXRD), magnetic and luminescent properties of these compounds are also investigated.

Two-dimensional (2D) hybrid perovskites of Ruddlesden–Popper (RP) lattices are recently booming as a vigorous class of ferroelectrics, whereas their intrinsic van der Waals gaps exert weak interactions that destabilize the layered motifs. Thus, it is an urgent challenge to reduce interlayered energy gaps to allow an exploration of stable RP ferroelectrics. Here, we propose hydrogen bonds to reduce van der Waals gaps of 2D RP-type perovskites while the ferroelectricity is retained. For the first time, a homoconformational transisomer has been alloyed as the spacing cation of the 2D ferroelectric (t-ACH)2(EA)2Pb3Br10(1, where t-ACH is 4-aminomethyl-1-cyclohexanecarboxylate and EA is ethylammonium). Strikingly, the strong O–H···O hydrogen bonds link adjacent spacing sheets to build a quasi-RP motif with a lower energy gap. In terms of ferroelectricity, the mixed-cation alloying has a crucial role in spontaneous polarization (Ps), as verified by structure analyses, quadratic optical nonlinearity, and electric hysteresis loops. The ordering of t-ACH+and EA+cations induces mmmFmsymmetry breaking, along with an unusual in-plane Psvalue of ∼2.9 μC/cm2in the acplane. In combination with the anisotropic nature of its 2D motif, this ferroelectricity creates strong linearly polarized light sensitivity with a large dichroism ratio of ∼3.2, far beyond those of most of the inorganic 2D systems. As far as we know, a 2D RP-type ferroelectric with a transisomer cationic spacer is unprecedented, and the concept of reducing energy gaps via H-bonding interactions will strengthen the layered perovskite structure and shed light on the rational design of stable ferroelectrics toward photoelectric applications.

Exploring the application potentials of metal-organic frameworks(MOFs) in the field of light hydrocarbons storage and separation is of great significance for solving the critical energy problem. However, designing porous materials with efficient separation capacity is still a challenging task. In this work, we synthesized a cage-based porous materiel(FJI-H32) with a large surface area. After activation, FJI-H32exhibits the feature of high C2H2storage capacity(113 cm3/g) and promising C2H2/CO2separation ability at 298 K and under 100 kPa. More importantly, the C2H2/CO2separation was verified by actual breakthrough experiments.

Lanthanide-doped inorganic upconversion nanocrystals (UCNCs) are promising as fluorescent diagnostic and therapeutic agents for in vivoapplications ranging from biological imaging to disease theranostics. However, all currently available lanthanide-doped inorganic UCNCs are not biodegradable and thus cannot be harmlessly eliminated from the body of living organism during a reasonable period of time, making their clinical translations nearly impossible. Here, we report a class of red-emitting biodegradable UCNCs based on Yb3+/Er3+-doped inorganic potassium heptafluozirconate (K3ZrF7:Yb/Er) that features a dynamically “soft” crystal lattice containing water-soluble [ZrF7]3–cluster and a K+cation. The red-emitting K3ZrF7:Yb/Er UCNCs exhibit a pH-dependent biodegradation capability upon exposure to water both in vitroand in vivo, and the rapid biodegradation rate, monitored using the intrinsic red upconversion luminescence, can be tuned particularly in a mild acidic tumor microenvironment (pH ∼5–6). More importantly, the final biodegradation products of K3ZrF7:Yb/Er UCNCs can be excreted from the body of mice in a short period of time with no evidence of toxicity, in stark contrast to the nondegradable β-NaYF4:Yb/Er UCNCs that primarily accumulate in the main organs of mice. These findings described here unambiguously would benefit the future biomedical applications and clinical translations of lanthanide-doped inorganic UCNCs.

The development of a practical Hg(II) adsorbent is highly important for both environmental protection and public health. Herein, an adaptive metal–organic framework (MOF; FJI-H30) has been prepared from a highly flexible ligand [tris(pyridin-4-ylmethyl)amine] and Co(SCN)2with cheap Hg(II) adsorption sites (SCN–groups) that not only has excellent chemical stability but also can capture Hg(II) from aqueous solution with high adsorption capacity (705 mg g–1). Moreover, it also has good anti-interference ability and can be used repeatedly and large-scale prepared. Further researches demonstrate that the relatively high Hg(II) adsorption capacity originates from the adsorbed Hg(II)-induced deformation of FJI-H30, and such an adaptive deformation will reduce the potential repulsive forces between the adsorbed Hg(II) ions, enabling almost all Hg(II) absorption sites to adsorb Hg(II) ions. Finally, how to induce the deformation of FJI-H30by adsorbed Hg(II) also has been studied in detail. Our work not only provides a practical Hg(II) adsorbent for wastewater treatment but also offers a novel strategy for the design of novel MOFs for efficient heavy-metal-ion removal.

Antiferroelectric materials, characterized by an antiparallel array of adjacent dipoles, are holding a bright future for solid-state refrigeration based on their electrocaloric (EC) effects. Despite great advances of inorganic oxides and some organic soft polymers, their EC effects are achieved under quite high electric fields that result in too low EC strengths for practical application. Currently, it is a challenge to exploit soft antiferroelectric with strong EC strengths. Here, by the mixed-cation alloying, we present a new perovskite-type soft antiferroelectric, (isopentylammonium)2CsPb2Br7(1), which incorporates both an organic spacing cation and an inorganic perovskitizer Cs+moiety. Remarkably, the synergic cooperativity between the reorientation of the organic spacer and atomic displacement of Cs+cation triggers its multiple ferroelectric–antiferroelectric–paraelectric phase transitions at 321 and 350 K. Their natural polarization vs electric field hysteresis loops are characterized to confirm ferroelectric and antiferroelectric orders of 1, respectively. It is emphasized that, under a low electric field of 13 kV/cm, the antipolar dipole realignment in 1endows a giant near-room-temperature EC strength (ΔTEC/ΔE) of 15.4 K m MV–1at antiferroelectric phase. This merit is on par with the record-high value of BaTiO3(∼16 K m/MV) but far beyond the state-of-the-art soft polymers. The underlying EC mechanism for 1is ascribed to the extremely low critical field to switch dipoles, involving the reorientation of the organic spacer and the shift of the Cs+cation. Besides, notable EC entropy change (∼4.1 J K–1kg–1) and temperature change (∼2 K) reveal potentials of 1for solid-state refrigeration. As far as we know, this discovery of near-room-temperature EC strengths is unprecedented in the hybrid perovskite family, which sheds light on the exploration of new soft antiferroelectrics toward high-efficiency refrigeration devices.

Halide double perovskites have emerged as remarkable semiconductors owing to their nontoxicity and superior optoelectronic features. Despite recent exciting progress, halide double perovskites with bulk ferroelectricity are still sparse. Herein, we report the discovery of a multiaxial layered halide double perovskite ferroelectric, BA2CsAgBiBr7(1, BA = n-butylammonium), which exhibits a fascinating ferroelectric feature with a Curie temperature of ∼273 K and unique semiconducting nature. Particularly, for 1, the dimensional reduction reduced strong coupling of octahedral rotations and cation ordering leads to a notable spontaneous polarization of 5.2 μC/cm2and an extremely high fatigue resistance (over 107switching), which are comparable to those of oxide perovskites. As far as we are aware, this is the first example of a multiaxial ferroelectric in the booming family of halide double perovskites. Another fascinating feature is that 1also possesses a biaxial ferroelastic order with a high Curie temperature of 375 K. Such discovery of a halide double perovskite ferroelectric with multiple ferroic orders signifies an important step toward designing multifunctional ferroelectric materials as well as inspires their further applications in optoelectronic devices.

The development of practical porous materials for the selective capture of CO2from flue gas and crude biogas is highly critical for both environment protection and energy safety. Here, a novel metal–organic framework (FJI-H29) has been prepared, which not only has excellent acid–base resistance but also possesses polar micropores (3.4–4.3 Å) that can match CO2molecules well. FJI-H29can selectively capture CO2from N2and CH4with excellent separation efficiency and suitable adsorption enthalpy under ambient conditions. Breakthrough experiments further confirm its practicability for both CO2/N2and CO2/CH4separation. All of these confirm FJI-H29is a practical CO2adsorbent. Modeling calculations reveal that the confinement effect of micropores and the polar environment synergistically promotes the selective adsorption of CO2, which will provide a potential strategy for the synthesis of a practical metal–organic framework for CO2capture.

The pore engineering of microporous metal–organic frameworks (MOFs) has been extensively investigated in the past two decades, and an expansive library of functional groups has been introduced into various frameworks. However, the reliable procurement of MOFs possessing both a targeted pore size and preferred functionality together is less common. This is especially important since the applicability of many elaborately designed materials is often restricted by the small pore sizes of microporous frameworks. Herein, we designed and synthesized a mesoporous MOF based on Zr6clusters and tetratopic carboxylate ligands, termed PCN-808. The accessible coordinatively unsaturated metal sites as well as the intrinsic flexibility of the framework make PCN-808 a prime scaffold for postsynthetic modification via linker installation. A linear ruthenium-based metalloligand was successfully and precisely installed into the walls of open channels in PCN-808 while maintaining the mesoporosity of the framework. The photocatalytic activity of the obtained material, PCN-808-BDBR, was examined in the aza-Henry reaction and demonstrated high conversion yields after six catalytic cycles. Furthermore, thanks to the mesoporous nature of the framework, PCN-808-BDBR also exhibits exceptional yields for the photocatalytic oxidation of dihydroartemisinic acid to artemisinin.

Structures composed of SiOxF6–x(x= 1, 2, 3, 4, 5) or SiOxF4–x(x= 1, 2, 3) species have thus far been observed in only a few compounds, and their functional properties are completely unknown in silicate chemistry. By introducing the least electronegative element, cesium, and the most electronegative element, fluorine, into the silicophosphate system, we successfully designed the first noncentrosymmetric fluorooxosilicophosphate with Si–F bonds, CsSiP2O7F, whose structure consists of an unprecedented SiP2O10F moiety containing hexacoordinate SiO5F species. The experimental results highlight CsSiP2O7F as the first fluorooxosilicophosphate deep-UV nonlinear optical (NLO) material. The first-principles calculations reveal that the SiP2O10F moiety is a new type of NLO-active unit and that both cesium and fluorine increase the deep-UV transparency of CsSiP2O7F. This work provides a new source of deep-UV NLO materials and insights into obtaining noncentrosymmetric structures that are indispensable to functional materials in nonlinear optics, piezoelectricity, ferroelectric, pyroelectricity, etc.

Benefiting from their structural flexibility and solution processability, organic–inorganic metal halide hybrids with efficient white-light emission present a great promise for solid-state lighting and display applications. However, most of these reported high-performance single-component white-light materials contain lead. Herein, we report a “green” organic zinc halide, [(N-AEPz)ZnCl4]Cl (1; N-AEPz = N-aminoethylpiperazine), exhibiting prominent bluish-white-light emission with a photoluminescence quantum efficiency as high as 11.52%. Such a value is among the highest in the reported metal halide white-light emitters. Mechanism studies disclose that the broad-band emission is ascribed to the synergistic work of organic salts and inorganic clusters. This work would incent research on single-component white-light materials for next-generation display and lighting technologies.

The second harmonic generation (SHG) responses of nonisostructural nonlinear optical (NLO) compounds, β-BaB2O4, LiB3O5, CsB3O5, CsLiB6O10, KBe2BO3F2, and LiCs2PO4, were examined by density functional theory (DFT) calculations, and the contributions of their individual cations and anions were determined by performing atomic response theory analyses. In all of these compounds, the contribution of all metal cations lies in the range of ∼9.3 to ∼29.7% of the total SHG responses, and that of all anions lies between ∼57.4 and ∼72.3%. However, in terms of individual atom contribution, a large metal cation can contribute more than does an anion to the total SHG response. Our work shows that the SHG contribution of an individual anion (e.g., O2–) is weakened when it forms covalent bonds with its surrounding cations (e.g., O–B). The contribution of an individual cation is further affected by the homogeneity of its surrounding anion distribution and also by how strongly the polarizabilities of its surrounding anions are weakened by covalent bonding with other cations. The SHG response increases with αsum/(NEg), an important parameter useful in searching for new NLO materials, where αsumis the sum of the polarizabilities of all of the ions in the primitive unit cell, Nis the total number of atoms per primitive cell, and Egis the band gap.

Ferroelectric semiconductors, combining semiconduction, spontaneous polarization, and photoinduced excitation, show great promise to enhance the performance of solar cells, pressure sensors, and photodetectors. Particularly, organic–inorganic lead halide perovskite ferroelectrics have been explored for their prominent carrier transport properties and structural tunability. However, a high concentration of toxic Pb is a stumbling block for their further application. Here, we present a lead-free hybrid perovskite semiconductor, (C4H9NH3)2(NH3CH3)2Sn3Br10(1), which exhibits a large spontaneous polarization of 11.76 μC cm–2at room temperature. Significantly, 1presents a spontaneous polar ordering transition, similar to the better-known perovskite ferroelectrics, and exhibits ferroelectric phase transition behaviors. To our best knowledge, 1is the first example of a Sn-based hybrid perovskite semiconductor featuring ferroelectric performance. Mechanistic studies reveal that such ferroelectricity can be attributable to the synergistic effects of ordering of organic cations and stereochemically active lone-pair electrons inducing distortion of inorganic octahedra. This work provides an effective way to explore “green” ferroelectric semiconductors with potentially enhanced energy conversion efficiency.

Perovskite ferroelectrics, in which the spontaneous polarization (Ps) is conducive to the separation of photoexcited charge carriers, have shown great potential for self-powered photodetection. Nevertheless, such self-powered ferroelectric photodetectors are mostly dominated by traditional inorganic oxides and exhibit relatively small zero-bias photocurrent, which limit their further application. Herein, we present a wide-bandgap 2D trilayered lead chloride hybrid perovskite ferroelectric, EA4Pb3Cl10(1, EA = ethylammonium), which shows a notable Psof ∼4.5 μC/cm2and a high Curie temperature (415 K) beyond that of BaTiO3(393 K). Significantly, benefiting from the wide bandgap of 3.39 eV, a self-powered visible-blind ultraviolet (UV) photodetector has been successfully realized, with a zero-bias photocurrent as high as 18.6 μA/cm2, which is nearly 2 orders of magnitude larger than those of mostly conventional inorganic ferroelectrics. As a pioneering study, this work offers an efficient approach for exploring wide-bandgap perovskite ferroelectrics and will excavate their application in the field of self-powered visible-blind UV photodetection.

Metal–organic frameworks (MOFs) have been excellent platforms for the research of solid-state porous materials in response to external stimuli. Herein, we have designed and synthesized two mesoporous, flexible MOFs on the basis of trigonal-prismatic [M3O(RCOO)6] clusters and 4-connected tetratopic carboxylate ligands, which show remarkable structural transformation upon heating. The intermediate states of these stimuli-responsive processes can be visualized by in situ X-ray diffraction analyses, and the mechanisms of the structural transformations can be elucidated unambiguously. The flexibility of the indium MOF PCN-167 mainly derives from the twisting of the ligands. However, for the iron analogue PCN-168, the elasticity of the inorganic clusters in addition to the deformation of the organic ligands play an important role in the significant increase of axial expansion/contraction coefficients. Furthermore, guest molecules in the pores are also very important for the structural transformation of the frameworks.

We report a multifunction lanthanide-based metal organic framework (Eu-SPFF) constructed by a hexanuclear Eu(III) cluster and a tetracarboxylate ligand 4,4′,4″,4‴-(9,9′-spirobi[fluorene]-2,2′,7,7′-tetrayl)tetrakis(2-fluorobenzoic acid) (H4SPFF). The (4,12)-connected ftwtopological three-dimensional structure contains octahedral and cubic cages with permanent porosity (BET: 1891.3 m2g–1). Eu-SPFFnot only exhibits high performance for the separation of light hydrocarbons but also shows highly selective recognition of 4-nitrophenol and Cu2+ions.

Herein, a microporous NbO-type framwork (FJI-H23) that showed outstanding surface area (3740.4 m2·g–1) was fabricated by utilizing an azobenzene-derived carboxylate ligand. As anticipated, FJI-H23can store 2.35 wt % H2at 77 K up to 1 bar. Furthermore, FJI-H23exhibits high-capacity storage of C2 and C3 hydrocarbons at room temperature. Especially, the uptake amount of C3H8is 325.76 cm3·g–1at 298 K, which represents the new record of C3H8adsorption capacity in the MOFs materials. In addition, FJI-H23exhibits excellent gravimetric total uptake of 332 cm3·g–1at 298 K and 65 bar.

Antiferroelectrics, characterized by the natural polarization-electric field (P–E) double hysteresis loops, has been developed as a promising branch for energy storage. Here, we present the first antiferroelectric in the booming family of lead iodide hybrid perovskites, (BA)2(EA)2Pb3I10(1, where BA = n-butylammonium and EA = ethylammonium), which exhibits one of the highest Curie temperatures (∼363 K) for the majority of known molecular systems. Strikingly, its high-temperature antiferroelectricity, triggered by an antipolar alignment of adjacent dipoles, is confirmed by the characteristic double P–Ehysteresis loops, thus enabling remarkable energy storage efficiencies in the range of 65%–83%. This merit is almost comparable to those of many inorganic counterparts, suggesting the great potential of 1for energy storage. Another fascinating attribute is that 1also acts as a room-temperature biaxial ferroelectric with spontaneous polarization of 5.6 μC·cm–2. As far as we know, this study on the high-temperature antiferroelectric, along with room-temperature biaxial ferroelectricity, is unprecedented for the versatile lead iodide hybrid perovskites, which sheds light on the design of new electric-ordered materials and facilitates their application of high-performance devices.

The second-harmonic generation (SHG) coefficients of 12 nonlinear optical chalcopyrites, ABC2(A= Zn, Cd; B= Si, Ge, Sn; C= P, As) were calculated by first-principles methods to find that given the primitive cell volume Vand the band gap Egof ABC2, the SHG coefficients davof ABC2increase almost linearly with increasing value of V/Eg. This suggests that a noncentrosymmetric crystal has a large SHG response when it consists of large atoms, leading to a small band gap.

A novel multifunctional chiral In-MOF (InOF-18) was synthesized by a solvothermal method. The compound simultaneously contains exposed N groups and three kinds of chiral channels with different window sizes, chiral screw axes, and helicities as measured by single-crystal X-ray diffraction. Luminescence measurements demonstrate that InOF-18exhibits high sensitivity and ultrafast response (less than 5 s) for Cu2+ion detection. Moreover, InOF-18shows a high H2uptake of 179.77 cm3g–1(1.60 wt %) at 77 K and 1.0 bar and also had excellent selective gas sorption behaviors with IAST selectivity values of 10.44 and 37.83 at 273 K and 1.0 bar for CO2/CH4and CO2/N2, respectively.

In this work, a microporous Pb(II)-based framework (FJI-H22) has been synthesized upon solvothermal reaction, which is constructed from two kinds of rarely seen tetranuclear Pb(II) clusters. FJI-H22has two kinds of one-dimensional microporous channels (ca. 12.80 Å × 15.08 and 6.05 Å × 11.83 Å) along the crystallographic baxis. Interestingly, when immersed in methanol FJI-H22can undergo reverse single-crystal-to-single-crystal transformations to form FJI-H22-MeOH. In particular, high stability (stable up to 300 °C in atmosphere), large Brunauer–Emmett–Teller (BET) surface area (483 m2·g–1), and the nature of microporosity enable desolvated FJI-H22to be a good candidate for purification of natural gas. As anticipated, desolvated FJI-H22can selectively adsorb C2/C3 hydrocarbons over CH4at 298 K and 1 bar. Furthermore, ideal adsorbed solution theory calculations reveal that FJI-H22shows highly selective separation of higher hydrocarbons over CH4under ambient conditions.

Multiaxial molecular ferroelectrics, in which multiple-directional switching of spontaneous polarization creates diverse properties, have shown many intriguing advantages, making them indispensable complements to conventional inorganic oxides. Despite recent blooming advances, multiaxial molecular ferroelectric with bulk photovoltaic effects still remains a huge blank. Herein, we report a biaxial lead halide ferroelectric, EA4Pb3Br10(1, EA = ethylammonium), which adopts the unique trilayered perovskite motif with a high Curie temperature of ∼384 K. Particularly, for 1, the distinct symmetry breaking with 4/mmmFmm2 species leads to the emergence of four equivalent polarization directions in the ferroelectric phase. Based on its biaxial nature, the bulk photovoltaic effect of 1can be facilely tuned between such multiple directions through electric poling. As far as we know, this is the first report on biaxial hybrid perovskite ferroelectric showing directionally tunable photovoltaic activity. This work provides an avenue to control the bulk physical properties of multiaxial molecular ferroelectrics, and highlights their potential for further applications in the field of smart devices.

Trivalent Lanthanide (Ln3+)-doped fluoride nanocrystals (NCs) in the category of ALn2F7(A = Li, Na, and K) have recently emerged as an attractive alternative to the well-developed ALnF4-type fluorides owing to their unique crystallographic structures. In this paper, we reported for the first time the controlled synthesis of monodisperse Ln3+-doped monoclinic-phase KGd2F7NCs via a facile thermal decomposition method. Characteristic downshifting and upconverting luminescence (UCL) of Ln3+ion ranging from the visible to near-infrared spectral regions were readily tuned in the KGd2F7:Ln3+NCs. Moreover, we have also fabricated a series of KGd2F7:Yb3+/Er3+core/shell NCs with different architectures of inert KGd2F7or active KGd2F7:Yb3+shells, which thereby allowed us to carry out a comparative spectroscopic investigation of the optimum core/shell architecture for highly enhanced UCL of Ln3+. Specifically, the KGd2F7:Yb3+/Er3+core/shell NCs with optimized thickness of inert KGd2F7shell were found to outperform their counterparts with active KGd2F7:Yb3+shell in terms of UCL intensity and lifetime. These results would unambiguously provide new fundamental insights into the rational design of complicated core/shell nanostructures with highly enhanced UCL of Ln3+, and would further push forward the development of novel luminescent nanomaterials based on Ln3+-doped KGd2F7NCs for versatile applications.

Antiferroelectric materials have been regarded as a promising candidate for electronic energy storage devices, due to their natural double polarization versus electric field (P–E) hysteresis loops. Currently, two-dimensional organic–inorganic hybrid perovskites with structural diversity and tunability, have received blooming interests, whereas above-room-temperature antiferroelectrics are still unreported in this perovskite system. Herein, for the first time, we successfully acquire a two-dimensional Ruddlesden–Popper hybrid perovskite antiferroelectric, ((CH3)2CHCH2NH3)2CsPb2Br7(1), which shows an above-room-temperature Curie temperature at 353 K, trigging by the synergistic dynamic motion of inorganic Cs atoms and organic isobutylammonium cations. Intriguingly, the antiferroelectricity of 1existing over a wide temperature range of 298–353 K are revealed by the distinct double P–Ehysteresis loops. Besides, 1possesses remarkable energy storage efficiency up to 69%, comparable to those of some reported inorganic antiferroelectric ceramics, promoting 1potential application in energy storage devices. This work provides an avenue to construct novel antiferroelectric materials for high-performance electronic device applications.

The non-π-conjugated sulfate system has long been overlooked as potential deep-UV nonlinear optical (NLO) materials. Here we report two asymmetric anhydrous sulfates, namely, NH4NaLi2(SO4)2(Ι) and (NH4)2Na3Li9(SO4)7(Π), which consist of non-π-conjugated [SO4]2–anions. Their single crystals can be readily grown by a facile evaporation method from water solution. Both sulfates are transparent down to the deep-UV region. Interestingly, there is a large NLO gap between Iand Π, with phase-matching NLO responses of 1.1 and 0.5 times that of the benchmark KH2PO4, respectively. The first-principles studies reveal that the non-π-conjugated [SO4]2–anions are the dominate NLO-active groups, and the large NLO gap between Iand Πcan be ascribed to the nonbonding O 2porbitals of different orientations in the crystallographically independent S1O4groups. This work provides an innovative non-π-conjugated source that is distinct from the traditional π-conjugated ones for deep-UV NLO materials.

The predictable topologies and designable structures of metal–organic frameworks (MOFs) are the most important advantages for this emerging crystalline material compared to traditional porous materials. However, pore-environment engineering in MOF materials is still a huge challenge when it comes to the growing requirements of expanded applications. A useful method for the regulation of pore-environments, linker installation, has been developed and applied to a series of microporous MOFs. Herein, employing PCN-700 and PCN-608 as platforms, ionic linker installation was successfully implemented in both microporous and mesoporous Zr-based MOFs to afford a series of ionic frameworks. Selective ionic dye capture results support the ionic nature of these MOFs. The mesopores in PCN-608 are able to survive after installation of the ionic linkers, which is useful for ion exchange and further catalysis. To illustrate this, Ru(bpy)32+, a commonly used photoactive cation, was encapsulated into the anionic mesoporous PCN-608-SBDC via ion exchange. Photocatalytic activity of Ru(bpy)3@PCN-608-SBDC was examined by aza-Henry reactions, which show good catalytic performance over three catalytic cycles.

Two-dimensional (2D) materials have been well developed for polarization-sensitive photodetection, while new 2D members used in shortwave region (>2.5 eV) still remain scarce. The family of 2D hybrid perovskite ferroelectrics, in which the coupling of spontaneous polarization (Ps) and light benefits dissociation of photoinduced carriers, has shown great potential in this portfolio. Here, we report a new 2D hybrid perovskite ferroelectric, [CH3(CH2)3NH3]2(CH3NH3)Pb2Br7(1), which exhibits a superior Psof 3.6 μC/cm2and a relatively wide bandgap (∼2.55 eV). The unique 2D perovskite motif results in an intrinsic anisotropy of optical absorption (the ratio αc/αa≈ 1.9 at 405 nm), involving its polarization-sensitive activity. As expected, the strongest photoresponses were observed along the c-axis (i.e., parallel to Ps), along with a large dichroism ratio (Iphc/Ipha≈ 2.0) and highly sensitive detectivity up to ∼109Jones. Further, crystal-device of 1 shows a fast responding rate (∼20 μs) and excellent antifatigued merits. As pioneering work, 1is the first polarization-sensitive ferroelectric in the new branch of 2D hybrid perovskites. Such intriguing behaviors make 1a potential candidate for the shortwave polarized-light detection, which also sheds light on new functionalities for future optoelectronic application of hybrid perovskites.

Two novel 3D metal-organic frameworks (MOFs) with cds network, {[MeNH3]7[Ln8(PgC2)2(H2O)y(HCOO)7]}n·x(Solvent) (FJIY4, FJI=Fujian Institute, Ln=Gd, y=12; FJI-Y5, Ln=Dy, y=11; PgC2=C-ethylpyrogallol[4]arene), based on unprecedented dimeric pyrogallol[4]arene-based Ln8metal-organic nanocapsule (MONC) supramolecular building blocks and formate linkers, have been prepared under solvothermal conditions. To our best of knowledge, they present not only the first two examples of 3D hierarchical structures constructed from MONCs in metal-pyrogallol[4]arene system, but also the first two examples of MOFs based on lanthanide MONCs. Remarkably, the inner cavity volume of the Ln8capsule in FJI-Y4and FJI-Y5is approximately 151 Å3, which is larger than those found in previous transition metal-seamed dimeric PgCn-based MONCs. Magnetic investigation on FJI-Y4suggests a significant magnetocaloric effect (23.97 J kg−1K−1, ΔH=7 T, 2.5 K), while FJI-Y5exhibits slow relaxation of the magnetization.

Considering rapidly rising Hg emission from industrial waste effluents, it is imperative to explore practical and effective adsorbents for Hg. Herein, a mild and facile method has been developed to confine ultrasmall In2S3nanoparticles (about 2.5 nm) in the cavities of a MOF for the first time. The resulting composite (In2S3@MIL-101) can remove 99.95% of the Hg2+from wastewater very efficiently in as short as 1 min with the highest distribution coefficient (2.2 × 107mL g–1) among all MOF-based mercury adsorbents. It also displays excellent selectivity for Hg even when other interferential metal ions are present, and it can be reused with almost retained adsorption capacity. All of these features make the composite a potential adsorbent for Hg removal from industrial wastewater.

Detection of harmful chemical reagents and pollutants is of great significance for protecting human health and environmental sustainability. In this work, a 3D metal–organic framework, named In-BTDI, has been synthesized, featuring a two-fold interpenetrated framework. In-BTDI shows intense luminescence with the emission peak at 502 nm and exhibits high structural and photo-stability in water and common organic solvents, which provides a good foundation to be unitized as a chemical sensor. In-BTDI can selectively and sensitively sense 4-nitroaniline (4-NA) and antibiotics by the fluorescence quenching effect not only in the organic solvent but also in water. It is noteworthy that the limits of detection (LOD) of 4-NA and antibiotics in water are 240 and 202 ppb, respectively, both reaching a ppb level, suggesting the good detection ability of trace analytes in water. The sensing mechanism was then discussed in detail.

Anisotropically conductive hydrogels have promising applications in artificial intelligence and wearable flexible electronics. However, for conductive hydrogels, the integration of comprehensive properties, such as high electrical conductivity, strong moisture retention, and high mechanical properties, is very important. In this article, sandwich-shaped anisotropically conductive hydrogels were constructed with a conductivity of up to 1.5 S/m. The difference in conductivity along the different directions is about a factor of 6. The formation of dynamic coordination bonding enhances the cross-linked network between poly(acrylic acid) and Nd3+, which causes the hydrogels to have excellent self-healing properties and fatigue resistance, with a self-healing efficiency of up to 90%. The middle layer of the hydrogels is compounded with nanographene, which cuases the hydrogels to have good mechanical properties, such as ultrastretchability (∼1930%) and high strength (∼0.7 MPa). The binary solvent consisting of glycerin and water gives the hydrogels an excellent moisturizing and antifreezing function. It maintains good flexibility and conductivity even at −18 °C. Based on the rapid response and high sensitivity, the sandwich-shaped hydrogel strain sensors can detect human motion (such as knuckle motion, wrist movement, etc.), showing great application potential in flexible sensors.