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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.