Recovery of sulfur hexafluoride (SF6) electronic specialty gas through SF6/N2 separation is economically and environmentally important. Herein, the prototypic metal-organic framework (MOF) of DMOF-1 and its stepwise chlorinated analogues (DMOF-2Cl and DMOF-4Cl) with varying pore sizes, pore volumes and pore chemistry are manipulated for evaluating SF6/N2 separation systematically. DMOF-4Cl shows the highest SF6 capacity and SF6/ N2 adsorption selectivity among the present MOFs, emphasizing the importance of chlorination. The high SF6 sorption capacity of 2.0 mmol g-1 and storage density of 4.71 mmol cm-3 at 10 kPa and 298 K and SF6/N2 selectivity endow DMOF-4Cl highly promising for separating SF6/N2 mixtures. Column dynamic experiments show that the high-purity SF6 (>99.1 %) with a high recovery of 27.4 L kg-1 can be harvested from SF6/N2 (10:90) mixtures through a singular adsorption-desorption cycle by DMOF-4Cl. Experiments and calculations revealed that the optimal pore sizes and matched surface electrostatic potential synergistically boost highefficient SF6/N2 separation for DMOF-4Cl. This work develops a novel strategy of programmed functionalization of organic linkers for fine-tuning pore structures and pore chemistry, thereby achieving high-performance MOFs for gas separation.

Separating perfluoropropane (C3F8) electronic specialty gas from C3F6/C3F8 mixtures is a challenging issue because of their similar physical properties and the stringent industrial purity standards for C3F8. We present a cage-based metal-organic framework (MOF) (JXNU-22) constructed from [Fe2Co(μ3-O)] clusters bridged by 4-(1H-tetrazol-5-yl)benzoic and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT) linkers, which features trigonal bipyramidal and cylindrical cages. Precise regulation of cylindrical cage geometry is achieved by replacing TPT with 1,3,5-trimethyl-2,4,6-tris (4-pyridyl)benzene (MTPB), yielding JXNU-22(Me). The isostructural JXNU-22 and JXNU-22(Me) have comparable C3F6 uptakes of 140.8 and 138.3 cm3 g−1 (298 K and 1 bar), exceeding any reported porous materials. The presence of methyl groups enables the rotation of the peripheral pyridyl rings of MTPB ligands to generate the contracted cylindrical cages, which exhibit size exclusion towards C3F8, resulting in markedly enhanced C3F6/C3F8 selectivity for JXNU-22(Me). Breakthrough experiments demonstrate high-purity C3F8 (99.999

Although adsorptive separation of hexafluoropropylene/octafluoropropane (C3F6/C3F8) mixture is of great significance for producing C3F8 electronic specialty gas, it remains an extremely challenging task. Here, a metal-organic framework (MOF) of Fe-phth-tpt with optimized pore cages enables selective capture of C3F6, achieving an impressive C3F6 uptake of 3.85 mmol g-1 at 0.1 bar and 298 K. Highly efficient C3F6/C3F8 separation is achieved by Fe-phth-tpt, affording the long breakthrough time of 57.1 min g-1 and high-purity C3F8 gas in one step with a record productivity of 564 cm3 g-1. The pore cages decorated with dense hydrogen atoms and aromatic rings offer multiple adsorption sites for binding C3F6. Additionally, the cylindrical pore cages show shape matching with C3F6 molecules that possess a nearly planar configuration. This work establishes an effective strategy for constructing MOFs with well-matched pores and multiple binding sites for C3F6 recognition, thereby enabling efficient purification of C3F8.

Birefringent crystals with the ability to precisely modulate polarized light are indispensable optical devices in modern optics and optoelectronics. However, achieving high birefringence in such crystals remains a challenge. Integration of the π-conjugated 2-amino-5-methylpyridine (AMPy), which has large polarizability anisotropy, with non-π-conjugated tetrahedral groups produces two birefringent crystals, AMPy·PO4 and AMPy·SO4. AMPy·PO4 has a three-dimensional hydrogen-bonding structure, whereas AMPy·SO4 exhibits a two-dimensional hydrogen-bonded layer. Remarkably, upon substituting phosphate with sulfate, the experimental birefringence increases 3.8-fold, yielding a giant birefringence of 0.506 at 550 nm coupled with broad optical transparency and establishing AMPy·SO4 as a new benchmark for metal-free sulfate crystals. Structural and computational investigations reveal that the outstanding birefringence of AMPy·SO4 mainly originates from two key factors: the formation of a layered structure where tetrahedral sulfate anions modulate the arrangement of optically anisotropic AMPy cations to achieve nearly parallel alignment via hydrogen bonding, and the dense stacking of planar π-conjugated AMPy moieties. This work not only offers a universal strategy for designing semiorganic birefringent crystals via synergistically combining π-conjugated groups and non-π-conjugated rigid tetrahedral moieties but also pushes the birefringence limit of metal-free sulfate crystals to a new level.

It is highly desirable to achieve both high Xe uptake and big Xe/Kr selectivity for Xe/Kr separation but it remains a long-term challenging issue due to an inherent trade-off between Xe uptake and Xe/Kr selectivity. We herein show a general and convenient digging-patching (DP) strategy in a covalent organic framework for simultaneously boosting Xe uptake and Xe/Kr selectivity. Notably, this DP method plays dual functions, creating dual micropores to match the kinetic diameter of Xe and increasing the porosity with surface areas from 573 m2/g to 1134 m2/g. As a result, we observed a large enhancement in both Xe uptake and selectivity from 1.37 to 2.29 mmol/g and from 14.6 to 22.0. It was found that structural design by the digging (D) operation in the DP strategy functions to create dual adsorption sites for Xe, which helps to improve Xe uptake, while the patching (P) operation functions to optimize the second adsorption site with its size close to the kinetic diameters of Xe, which helps to improve Xe/Kr selectivity, finally breaking the inherent trade-off between Xe uptake and Xe/Kr selectivity. The actual Xe-Kr separation capability was further confirmed by breakthrough experiments. This work highlights a fundamental structural design of two-dimensional COFs for size-based gas separation.

Aroylhydrazones have attracted considerable attention owing to their diverse biological properties and strong coordination ability toward metal ions. In the present study, two novel copper(II) complexes, [CuL(MeOH)]NO3·MeOH (1) and [CuBrL(MeOH)]·MeOH (2), derived from the aroylhydrazone ligand N’-(3-bromo-5-chloro-2-hydroxybenzylidene)-4-methylbenzohydrazide (HL), were successfully synthesized and comprehensively characterized using various physicochemical techniques. Single-crystal X-ray diffraction analyses revealed that the ligand coordinates to the copper(II) center in its deprotonated form (L⁻). Complex 1 exhibits a square planar geometry, and complex 2 exhibits a distorted square-pyramidal geometry around the Cu(II) ions. In complex 1, the coordination polyhedron is formed by the three donor atoms of the aroylhydrazone ligand and one methanol oxygen. In complex 2, the basal plane is defined by the three donor atoms of the aroylhydrazone ligand and one methanol oxygen, and the axial position is occupied by a bromide ligand. In addition, one methanol molecule is present as a solvent of crystallization in each complex. The supramolecular architectures of the complexes are further reinforced through intermolecular hydrogen-bonding interactions. Biological evaluation demonstrated that both copper(II) complexes possess remarkable inhibitory activity against Jack bean urease, with IC50 values of 0.5 and 1.1 μmol L⁻1 for complexes 1 and 2, respectively, indicating their potential as potent urease inhibitors.

Uric acid (UA) detection is critical for human health monitoring, necessitating the development of electrochemical sensing electrodes suitable for physiological environments. This study evaluated four 2D conductive metal-organic frameworks (2D c-MOFs), namely Cu-HHTP, Ni-HHTP, Cu-HAB, and Ni-HAB, which share identical graphene-like 2D sheet structures but differ in pi-conjugation extent and catalytic active centers [MX4] (M = Cu or Ni; X = O or NH) as electrosensing electrodes. Electrochemical sensing performance was compared by detecting UA in phosphate-buffered saline (PBS). Herein, the Ni-HHTP electrode demonstrated superior sensitivity (6.79 mu Amu M-1cm-2), the lowest oxidation potential (0.272 V), and the lowest detection limit (0.44 mu M). Langmuir adsorption isotherm analysis revealed that the Ni-HHTP electrode possesses the highest surface coverage (Gamma A) (5061.16 pmol cm-2) and the most favorable Gibbs adsorption free energy (Delta G degrees) (-18.775 kJ mol-1), indicating its strongest UA adsorption capacity and molecular interaction. This enhanced performance is attributed to the optimal synergy between [NiO4] catalytic centers and extended ligand pi-conjugation, facilitating greater analyte adsorption and electron transfer efficiency. This work establishes clear structure-performance relationships for 2D c-MOF electrodes in UA detection, providing key insights for designing advanced electrosensing materials.

Despite the widespread use of birefringence crystals in optical instruments, the birefringence of commercially available crystals is generally limited (Delta n < 0.3), making them less suitable for demanding optical requirements. In this work, three novel birefringent crystals, namely (C2N5H8)(H2C3N3O3)H2O (1), (C2N5H8)(3)(H2C3N3S3)(HC3N3S3)H2O (2), and (C2N5H8)(H2C3N3S3)H2O (3), were successfully synthesized via a two-step strategy. In their anionic structures, a displaced parallel arrangement is observed among three crystals, combined with a partially distinct arbitrary intersecting arrangement. Further research findings indicate that sulfur (S) substitution (from 1 to 2) and the optimized arrangement of functional groups (from 2 to 3) lead to a significant enhancement in the birefringence. The experimental birefringence values at 550 nm increased from 0.259 (1) to 0.347 (2), reaching 0.403 (3). Remarkably, the birefringence performance of compound 3 ranks third among all reported [C3N3S3]-based materials. Theoretical calculations reveal that its high birefringence is primarily attributed to S-substitution and the optimized arrangement of functional groups. This work provides critical guidance for further exploration of the impact of structure on birefringence performance and opens up new research directions for designing high-performance optical materials.

This work presents the synthesis of Zr/Fe bimetallic organic frameworks (Zr/Fe-UiO-66) with varying compositions via a straightforward solvothermal method, targeting fluoride ions (F-) removal from the aqueous phase. Adsorption experiments elucidated the effect of factors (i.e., adsorbent dosage, initial concentration (C0), temperature, contact time and pH) on fluoride adsorption, and the parameters were optimized. The results show that the Zr/Fe-UiO-66(C) achieved the maximal uptake capacity of 164.4 mg/g, with the conditions of pH = 5.0, T = 298 K, C0 = 190 mg/L. The adsorption behavior of fluoride on Zr/Fe-UiO-66 can be well followed with the pseudo-second-order (PSO) kinetic model and the Sips isotherm model, described as the spontaneous, chemical driven and endothermic process. The adsorption mechanism was comprehensively explained by characterizations and microscopic simulations, such as molecular dynamics methods (MD) and independent gradient model analysis (IGM), which involves the chemical bonding, hydrogen-bond interaction and electrostatic interactions. Furthermore, Zr/Fe-UiO-66(C) exhibited excellent fluoride ion selectivity and superior stability. After 5 cycles of adsorption, Zr/Fe-UiO-66(C) maintained the removal efficiency of 83.4 % for F-. This research provides significant insights into the development of bimetallic metal-organic framework materials and fluoride removal research.

Separation of Xe/Kr mixtures obtained from the by-products of air separation is a paramount industrial process but still a formidable challenge due to the inherent inertness and close physicochemical properties of Xe and Kr. Herein we present two isostructural metal -organic frameworks (MOF), MIL-88B-tpt and MIL-88B-tpt-F, which were found to have high Xe uptake capacities and efficient Xe/Kr separation resulted from the suitable pore caged structures and pore sizes. Remarkably, MIL-88B-tpt exhibits a record-high Xe sorption capacity of 210.2 cm 3 g -1 at 273 K and 1 bar. The highest Xe uptake and moderate Xe/Kr separation selectivity endow MIL-88B-tpt with high -performance Xe/Kr separation, ranking it among the best-performing MOF. The comparable Xe/Kr separation performance observed for the fluorinated version of MIL-88B-tpt-F and MIL-88B-tpt indicates the fluorine groups have a negligible effect on the Xe/Kr separation. Thus the efficient Xe/Kr separation for both MOF is mainly resulted from the optimal pore cages for Xe trapping and the well-matched pore sizes for Xe atom. The extensive Xe & sdot;& sdot;& sdot;framework interactions unveiled by computational simulations facilitate a strong binding affinity to Xe, thus leading to the highest Xe uptakes and efficient separation ability for both MOF.

Adsorption separation of the Xe/Kr mixture remains a tough issue since Xe and Kr have an inert nature and similar sizes. Here we present a chlorinated metal-organic framework (MOF) [JXNU-19(Cl)] and its nonchlorinated analogue (JXNU-19) for Xe/Kr separation. The two isostructural MOFs constructed from the heptanuclear cobalt-hydroxyl clusters bridged by organic ligands are three-dimensional structures. Detailed contrast of the Xe/Kr adsorption separation properties of the MOF shows that significantly enhanced Xe uptakes and Xe/Kr adsorption selectivity (17.1) are observed for JXNU-19 as compared to JXNU-19(Cl). The main binding sites for Xe in the MOF revealed by computational simulations are far away from the chlorine sites, suggesting that the introduction of the chlorine groups results in the unfavorable Xe adsorption for JXNU-19(Cl). The optimal pores, high surface area, and multiple strong Xe-framework interactions facilitate the effective Xe/Kr separation for JXNU-19.

The second harmonic generation effect and birefringence of (C 10 H 11 N 3 )BX 4 perovskites are considerably enhanced via structural evolution and halogen substitution strategies.

Birefringent crystals for modulating the polarization of light are of technological importance in optical communications. Herein we provide two novel two-dimensional hybrid halide perovskites, [(H2-dpys)(PbBr4)] (1) (dpys = di(pyridin-4-yl)sulfane) and [(H-cmpy)4(Pb3Br10)] (2) (cmpy = 4-chloro-3-methylpyridine), which can act as birefringent crystals. Remarkably, the crystal structures and the optoelectronic performance of the hybrid lead bromide perovskites are elaborately regulated by the organic cations of pyridine derivatives. Compound 2 constructed from the H-cmpy+ cations containing the single pyridyl moiety has a significantly enhanced birefringence (0.315@550 nm) compared to compound 1 (0.192@550 nm) with two pyridyl moieties of H2-dpys2+ cations, and it is larger than those of all commercial birefringent crystals and most of the hybrid metal halide perovskites. The results of the theoretical calculations showed that the highly distorted PbBr6 octahedra and the delocalized pi-conjugation of H-cmpy+ cations synergistically contribute to the enhanced birefringence of 2. This work provides a useful strategy for modulating the crystal structure and optoelectronic performance of the hybrid lead halide perovskites. Crystal structures and optoelectronic performance of hybrid two-dimensional lead bromide halide perovskites are elaborately regulated by pyridyl cations, which achieve a significantly enhanced birefringence of 0.315 (550 nm) for crystal 2.

Separation of C2H6/C2H4 mixtures is of significant importance in the chemical industry but remains a challenge due to the physicochemical similarities of C2H6 and C2H4. Herein, a metal-organic framework (MOF), [Zn-4(mu(4)-O)(PCTF)(3)](n) (Zn-PCTF) (PCTF2-= 5-trifluoromethyl-1H-pyrazole-4-carboxylic), is provided for the removal of C2H6 from C2H6/C2H4 mixtures. Zn-PCTF displays a three-dimensional framework featuring one-dimensional pore channels with periodic bottleneck segments. The well-balanced C2H6 adsorption capacity (79.0 cm(3) g(-1) at 298 K) and C2H6/C2H4 selectivity (1.8) for Zn-PCTF under ambient conditions boost Zn-PCTF with highly promising potentials for efficient purification of C2H4 from C2H6/C2H4 mixtures, which is verified by the dynamic column breakthrough experiments. The well-matched caged pores and suitable pore chemistry (particularly the presence of abundant Lewis base sites (N, O, and F) on the pore surfaces) for C2H6 account for the high-performance C2H6/C2H4 separation of Zn-PCTF unveiled by computational simulations.

Developing porous solids possessing efficient Xe/Kr separation remains a challenging issue owing to the similarities in the physicochemical properties of Xe and Kr. Herein, chlorinated metal-organic framework (MOF) JXNU-20(Cl) and its parent JXNU-20 were rationally developed for Xe/Kr separation. Remarkably, the Xe uptake (5 mmol cm(-3)) and Xe/Kr separation selectivity (9.4) for JXNU-20(Cl) (298 K and 1 bar) are 2.6 and 2.7 times higher than those for JXNU-20, empowering JXNU-20(Cl) with efficient Xe/Kr separation performance. The incorporation of chlorine groups into JXNU-20(Cl) generates a greatly polar pore environment and strong pore confinement effect resulting from the bottleneck segments of channels. The significant performance improvement of JXNU-20(Cl) can be rationalized as the enhanced pore surface polarity and strong pore confinement effect offered by the chlorine substituents. An elaborately effective approach for shaping pore channels and tuning pore polarity of a MOF is developed for the separation of targeted gases with polarizability differences.

Octafluoropropane (C3F8) electronic specialty gas is widely used in the process of etching and cleaning in the semiconductor manufacturing industry. Removal of hexafluoropropylene (C3F6) impurities from C3F6/C3F8 mixtures is therefore highly important but a formidable challenge since C3F6 and C3F8 possess similar physicochemical properties and molecular sizes. Herein, we present a cobalt metal-organic framework (MOF) (termed as JXNU-21) constructed using 3-chloroisonicotinic ligands, featuring dangling 3-chloroisonicotinic ligands in the one-dimensional channels. Due to the rotation flexibility of the aromatic rings of the dangling 3-chloroisonicotinate ligands with uncoordinated nitrogen sites, step-wise adsorption isotherms for the large-sized C3F8 were observed for JXNU-21. The high adsorption selectivity of 15.6 for the C3F6/C3F8 (10 : 90) mixture and high C3F6 storage density (5.8 mmol g-1) under ambient conditions endow JXNU-21 with high potential for C3F6/C3F8 separation. Results of breakthrough experiments show that high-purity (99.999%) C3F8 gas can be achieved from a C3F6/C3F8 (10 : 90) mixture in one step. Moreover, a benchmark C3F8 productivity of 173.8 cm3 g-1 was obtained from the breakthrough experiments under ambient conditions, outperforming all other reported porous materials.

Fluorinated dicopper(II) metal-organic framework JXNU-16F with 1,3,5-tri(3,5-bifluoro-4-carboxyphenyl)benzene ligands and nonfluorinated JXNU-16 exhibit high propyne uptakes of 443 and 496 cm3 g-1 under ambient conditions, respectively. Their remarkable propyne uptakes result from suitable pore spaces and strong propyne⋯propyne interactions amongst the adsorbed propyne molecules, as revealed by computational simulations.

Herein we present a fluorinated metal-organic framework of {(Me2NH2)[Ni3(μ3-OH)(CF3-BPDC-CF3)3(tpt)]}n (1) constructed from 2,2'-bis(trifluoromethyl)biphenyl-4,4'-dicarboxylic (CF3-BPDC-CF32‒) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) ligands, which is developed for separating propane (C3H8) and ethane (C2H6) from natural gas. Compound 1 preferentially adsorbs C3H8 and C2H6 over CH4 demonstrated by gas adsorption experiments. The presence of trifluoromethyl groups on the biphenyl-4,4'-dicarboxylic ligands facilitates the highly polarized micropore environments for compound 1, thus providing suitable micorpores for capturing the C3H8 and C2H6 molecules with larger polarizabilities and sizes compared to CH4 molecule. The dynamic mixture breakthrough experiments showed that compound 1 can separate C3H8 and C2H6 from the ternary CH4/C2H6/C3H8 mixtures efficiently, endowing compound 1 with excellent methane purification ability.

A pair of metal-organic frameworks (MOFs) of JXNU-15 (formulated as [Co6(μ3-OH)6(BTB)2(BPY)3]n, BTB3- = benzene-1,3,5-tribenzoate and BPY = 4,4'-bipyridine) and its fluorinated JXNU-15(F) ([Co6(μ3-OH)6(SFBTB)2(BPY)3]n) based on the fluorous 1,3,5-tri(3,5-bifluoro-4-carboxyphenyl)benzene (SFBTB3-) ligands were presented. The detailed comparisons of the acetylene/carbon dioxide (C2H2/CO2) separation abilities between the isostructural JXNU-15(F) and JXNU-15 were presented. In comparison with the parent JXNU-15, the higher C2H2 uptake, larger adsorption selectivity of the C2H2/CO2 (50/50) mixture, and enhanced C2H2/CO2 separation performance endow JXNU-15(F) with highly efficient C2H2/CO2 separation performance, which is demonstrated by singe-component gas adsorptions and dynamic gas mixture breakthrough experiments. The fluorine substituents exert the crucial effects on the enhanced C2H2/CO2 separation ability of JXNU-15(F) and play the dominant role in the C2H2-framework interactions, as uncovered by computational simulations. This work illustrates a powerful fluorine substitution strategy for boosting C2H2/CO2 separation ability for MOFs.

Herein, a metal-organic framework (MOF), {[(Me2NH2)4][Cd(H2O)6][Cd18(TrZ)12(TPD)15(DMF)6]}n (denoted as JXNU-18, TrZ = triazolate), constructed from the unique cucurbituril-shaped Cd18(TrZ)12 secondary building units bridged by 2,5-thiophenedicarboxylic (TPD2-) ligands, is presented. The formation of the cucurbituril-shaped Cd18(TrZ)12 unit is unprecedented, demonstrating the geometric compatibility of the organic linkers and the coordination configurations of the cadmium atoms. Each Cd18(TrZ)12 unit is connected to eight neighboring Cd18(TrZ)12 units through 30 TPD2- linkers, affording the three-dimensional structure of JXNU-18. More interesting is that JXNU-18 displays an efficient C2H2/CO2 separation ability, as revealed by the gas adsorption experiments and dynamic gas breakthrough experiments, which afford insights into the potential applications of JXNU-18 in gas separation. The tubular pores composed of two Cd18(TrZ)12 units bridged by six 2,5-thiophenedicarboxylic linkers provide the suitable pore space for C2H2 trapping, as unveiled by computational simulations.