Enhanced Catalytic Activity of Crystalline Phosphorus Nanosheets Fabricated via Solvothermal Phase Transformation.

The newly reported crystalline phosphorus nanosheets (cryst-P NSs) exhibit promising features for industrial applications, including outstanding air-water stability and facile large-scale production. However, their complex crystallization impedes a priori tailoring. Herein, the temporal evolution of cryst-P NSs was investigated with the optimized synthesis parameters. The occurrence of self-assembly and solid-state rearrangement unveiled the existence of an intermediate phase as the bulk crystalline precursor and the predominance of nonclassical crystallization pathway(s). With the upgraded synthesis protocol simultaneously strengthening the merits of cryst-P NSs, their catalytic performances were evaluated in various electro- and/or photocatalytic reactions spanning hydrogen and oxygen evolution, full water splitting, CO2 reduction, and organic pollutant decomposition. Superior catalytic activities and orders of magnitude longer lifetimes were consistently discerned compared with the widely employed black phosphorus nanosheets with similar size and thickness. The exciting discoveries in both fundamental crystallization and catalytic applications drastically thrust the comprehension of elemental phosphorus, shedding light on the encouraging capabilities of solvothermal synthesis strategies in the design and systematic tailoring of phosphorus materials.

Rare-Earth Metal-Organic Framework with Nonplanar Porphyrin Groups for High-Efficiency Photocatalysis.

Nonplanar porphyrins play crucial roles in many biological processes and chemical reactions as catalysts. However, the preparation of artificial nonplanar porphyrins suffers from complicated organic syntheses. Herein, we present a new rare-earth porphyrinic metal-organic framework (RE-PMOF), BUT-233, which is a three-dimensional (3D) framework structure with the flu topology consisting of 4-connected BBCPPP-Ph ligands H4BBCPPP-Ph = 5',5⁗-(10,20-diphenylporphyrin-5,15-diyl)bis([1,1':3',1″-terphenyl]-4,4'' dicarboxylic acid) and 8-connected Eu6 clusters. Noteworthily, the porphyrin cores of the BBCPPP-Ph ligands in BUT-233 are nonplanar with a ruffle-like conformation. In contrast, the porphyrin core in the free ligand H4BBCPPP-Ph is in a nearly ideally planar conformation, as confirmed by its single-crystal structure. BUT-233 is microporous with 6-8 Špores and a Brunauer-Emmett-Teller (BET) surface area of 649 m2/g, as well as high stability in common solvents. The MOF was used as a photocatalyst for the oxidation degradation of a chemical warfare agent model molecule CEES (CEES = 2-chloroethyl ethyl sulfide) under the light-emitting diode (LED) irradiation and an O2 atmosphere at room temperature. CEES was almost completely converted into its nontoxic light-oxidized product CEESO (CEESO = 2-chloroethyl ethyl sulfoxide) in only 5 min with t1/2 = 2 min (t1/2: half-life). Moreover, the toxic deep-oxidized product 2-chloroethyl ethyl sulfone (CEESO2) was not detected. The catalytic activity of BUT-233 was high in comparison with those of some previously reported MOF catalysts. The results of photo/electrochemical property studies suggested that the high catalytic activity of BUT-233 was benefited from the presence of nonplanar porphyrin rings on its pore surface.

Evaluation of Open-Source Large Language Models for Metal-Organic Frameworks Research.

Along with the development of machine learning, deep learning, and large language models (LLMs) such as GPT-4 (GPT: Generative Pre-Trained Transformer), artificial intelligence (AI) tools have been playing an increasingly important role in chemical and material research to facilitate the material screening and design. Despite the exciting progress of GPT-4 based AI research assistance, open-source LLMs have not gained much attention from the scientific community. This work primarily focused on metal-organic frameworks (MOFs) as a subdomain of chemistry and evaluated six top-rated open-source LLMs with a comprehensive set of tasks including MOFs knowledge, basic chemistry knowledge, in-depth chemistry knowledge, knowledge extraction, database reading, predicting material property, experiment design, computational scripts generation, guiding experiment, data analysis, and paper polishing, which covers the basic units of MOFs research. In general, these LLMs were capable of most of the tasks. Especially, Llama2-7B and ChatGLM2-6B were found to perform particularly well with moderate computational resources. Additionally, the performance of different parameter versions of the same model was compared, which revealed the superior performance of higher parameter versions.

Enhancing Ethane/Ethylene Separation Performance in Two Dynamic MOFs by Regulating Temperature-Controlled Structural Interpenetration.

The separation of ethane from ethylene is an important but challenging process in the chemical industry because of their similar physicochemical properties. Generally, the adsorbents for C2H6/C2H4 separation require an appropriate and relatively small aperture. Herein, we report two dynamic pillar-layered metal-organic frameworks (MOFs) BUT-111 and BUT-112 with isomorphic frameworks but different degrees of interpenetration for efficient C2H4 purification. The dynamic behavior makes both the activated MOFs exhibit ultramicropores and reversed order adsorption behavior for C2H6 and C2H4, which could obtain highly purified C2H4 in one step from the C2H6/C2H4 mixture. BUT-111 and BUT-112 could work in a wide temperature range, and with the decrease in temperature, the C2H6/C2H4 selectivity would increase. Moreover, the degree of interpenetration could be well controlled by the synthetic temperature, and the increase in the interpenetration degree of BUT-112 enhanced the C2H4 purification effectively.

Effective Removal of Clenbuterol and Ractopamine from Water with a Stable Al(III)-Based Metal-Organic Framework.

Clenbuterol (CLE) and ractopamine (RAC) are two kinds of typical ß2-adrenergic agonists which pose a serious threat to the health of human beings. In this work, 10 kinds of metal-organic frameworks (MOFs) with high stability and various pore features are screened to assess adsorption performance for CLE and RAC. An Al(III)-MOF (BUT-19) with abundant ethyl groups exhibits exceptional performance in removing CLE and RAC from water. The maximum adsorption capacity for CLE and RAC are up to 294.1 and 366.3 mg/g under the optimum adsorption conditions, respectively. Meanwhile, the adsorption mechanism effects of pH, temperature, and coexisted ions are investigated systematically. It is found that the MOF pore size and weak hydrogen-bond interactions between CLE/RAC molecules and the MOF are the main causes leading to the extraordinary adsorption. This study provides a new idea for the purposeful design and synthesis of MOFs for removing environmental pollutants and sheds light on the depuration of contaminated water.

A Base-Resistant Metalloporphyrin Metal-Organic Framework for C-H Bond Halogenation.

A base-resistant porphyrin metal-organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni8(OH)4(H2O)2Pz12] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F-, CO32-, and PO43- ions. Interestingly, the Mn3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C-H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOF was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.

Highly Stable Zr(IV)-Based Metal-Organic Frameworks for the Detection and Removal of Antibiotics and Organic Explosives in Water.

Antibiotics and organic explosives are among the main organic pollutants in wastewater; their detection and removal are quite important but challenging. As a new class of porous materials, metal-organic frameworks (MOFs) are considered as a promising platform for the sensing and adsorption applications. In this work, guided by a topological design approach, two stable isostructural Zr(IV)-based MOFs, Zr6O4(OH)8(H2O)4(CTTA)8/3 (BUT-12, H3CTTA = 5'-(4-carboxyphenyl)-2',4',6'-trimethyl-[1,1':3',1″-terphenyl]-4,4″-dicarboxylic acid) and Zr6O4(OH)8(H2O)4(TTNA)8/3 (BUT-13, H3TTNA = 6,6',6″-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(2-naphthoic acid)) with the the-a topological structure constructed by D4h 8-connected Zr6 clusters and D3h 3-connected linkers were designed and synthesized. The two MOFs are highly porous with the Brunauer-Emmett-Teller surface area of 3387 and 3948 m(2) g(-1), respectively. Particularly, BUT-13 features one of the most porous water-stable MOFs reported so far. Interestingly, these MOFs represent excellent fluorescent properties, which can be efficiently quenched by trace amounts of nitrofurazone (NZF) and nitrofurantoin (NFT) antibiotics as well as 2,4,6-trinitrophenol (TNP) and 4-nitrophenol (4-NP) organic explosives in water solution. They are responsive to NZF and TNP at parts per billion (ppb) levels, which are among the best performing luminescent MOF-based sensing materials. Simultaneously, both MOFs also display high adsorption abilities toward these organic molecules. It was demonstrated that the adsorption plays an important role in the preconcentration of analytes, which can further increase the fluorescent quenching efficiency. These results indicate that BUT-12 and -13 are favorable materials for the simultaneous selective detection and removal of specific antibiotics and organic explosives from water, being potentially useful in monitoring water quality and treating wastewater.

Pyrazolate-Based Porphyrinic Metal-Organic Framework with Extraordinary Base-Resistance.

Guided by a top-down topological analysis, a metal-organic framework (MOF) constructed by pyrazolate-based porphyrinic ligand, namely, PCN-601, has been rationally designed and synthesized, and it exhibits excellent stability in alkali solutions. It is, to the best of our knowledge, the first identified MOF that can retain its crystallinity and porosity in saturated sodium hydroxide solution (∼ 20 mol/L) at room temperature and 100 °C. This almost pushes base-resistance of porphyrinic MOFs (even if MOFs) to the limit in aqueous media and greatly extends the range of their potential applications. In this work, we also tried to interpret the stability of PCN-601 from both thermodynamic and kinetic perspectives.

Substitution reactions in metal-organic frameworks and metal-organic polyhedra.

Substitution reaction, as one of the most powerful and efficient chemical reactions, has been widely used in various syntheses, including those for the design and preparation of functional molecules or materials. In the past decade, a class of newly developed inorganic-organic hybrid materials, namely metal-organic materials (MOMs), has experienced a rapid development. MOMs are composed of metal-containing nodes connected by organic linkers through strong chemical bonds, and can be divided into metal-organic frameworks (MOFs) and metal-organic polygons/polyhedra (MOPs) with infinite and discrete structural features, respectively. Recent research has shown that the substitution reaction can be used as a new strategy in the synthesis and modification of MOFs and MOPs, particularly for pre-designed ones with desired structures and functions, which are usually difficult to access by a direct one-pot self-assembly synthetic approach. This review highlights the implementation of the substitution reaction in MOFs and MOPs. Examples of substitution reactions at metal ions, organic ligands, and free guest molecules of MOFs and MOPs are listed and analyzed. The changes or modifications in the structures and/or properties of these materials induced by the substitutions, as well as the nature of the associated reaction, are discussed, with the conclusion that the substitution reaction is really feasible and powerful in synthesizing and tailoring MOMs.

Tuning CO2 selective adsorption over N2 and CH4 in UiO-67 analogues through ligand functionalization.

Introducing functional groups into pores of metal-organic frameworks (MOFs) through ligand modification provides an efficacious approach for tuning gas adsorption and separation performances of this type of novel porous material. In this work, two UiO-67 analogues, [Zr6O4(OH)4(FDCA)6] (BUT-10) and [Zr6O4(OH)4(DTDAO)6] (BUT-11), with functionalized pore surfaces and high stability were synthesized from two functional ligands, 9-fluorenone-2,7-dicarboxylic acid (H2FDCA) and dibenzo[b,d]thiophene-3,7-dicarboxylic acid 5,5-dioxide (H2DTDAO), respectively, and structurally determined by single-crystal X-ray diffraction. Notwithstanding skeleton bend of the two ligands relative to the linear 4,4'-biphenyldicarboxylic acid in UiO-67, the two MOFs have structures similar to that of UiO-67, with only lowered symmetry in their frameworks. Attributed to these additional functional groups (carbonyl and sulfone, respectively) in the ligands, BUT-10 and -11 show enhanced CO2 adsorption and separation selectivities over N2 and CH4, in spite of decreased pore sizes and surface areas compared with UiO-67. At 298 K and 1 atm, the CO2 uptake is 22.9, 50.6, and 53.5 cm(3)/g, and the infinite dilution selectivities of CO2/CH4 are 2.7, 5.1, and 9.0 and those of CO2/N2 are 9.4, 18.6, and 31.5 for UiO-67, BUT-10, and BUT-11, respectively. The selectivities of CO2/CH4 and CO2/N2 are thus enhanced 1.9 and 2.0 times in BUT-10 and 3.3 and 3.4 times in BUT-11, respectively, on the basis of UiO-67. The adsorption mechanism of CO2 in BUT-11 has also been explored through computational simulations. The results show that CO2 molecules locate around the sulfone groups in pore surfaces of BUT-11, verifying at the molecular level that sulfone groups significantly increase the affinity toward CO2 molecules of the framework. This provides thus an efficient strategy for the design of CO2 capture materials.

catena-Poly[[di-chlorido-mercury(II)]-µ-1,4-bis-[2-(pyridin-4-yl)ethyn-yl]benzene-κ(2) N:N'].

In the polymeric title compound, [HgCl2(C20H12N2)] n , the Hg(II) atom is located on a twofold rotation axis and the benzene ring of the bidentate bridging 1,4-bis-[2-(pyridin-4-yl)ethyn-yl]benzene (L) ligand is located about a twofold rotation axis. The Hg(II) atom is coordinated by two N atoms of two different L ligands and by two chloride ions in a distorted tetra-hedral geometry. The dihedral angle between the coordinating pyridine and the benzene ring is 12.8 (2)°. The result of the bridging is the formation of a zigzag chain running parallel to [102]. The chains pack with no specific inter-molecular inter-actions between them.

Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils.

A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 µg kg(-1) range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.

Expanding the Structural Topologies of Rare-Earth Porphyrinic Metal-Organic Frameworks through Ligand Modulation.

Expanding the structural diversity of porphyrinic metal-organic frameworks (PMOFs) is essential to develop functional materials with novel properties or enhanced performance in different applications. Herein, we establish a strategy to construct rare-earth (RE) PMOFs with unprecedented topology via rational functionalization of porphyrinic ligands. By introducing phenyl/pyridyl groups to the meso-positions of the porphyrin core, the symmetries and connectivities of the ligands are tuned, and three RE-PMOFs (BUT-224/-225/-226) with new topologies are successfully obtained. In addition, BUT-225(Co), with both the Lewis basic and acidic sites, exhibits enhanced CO2 uptake and higher catalytic activity for the cycloaddition of CO2 and epoxides under mild conditions. This work reveals that the RE-PMOFs with novel topologies can be rationally designed and constructed through ligand functionalization, which provides insights into the construction of tailored PMOFs for various applications.

Tetra-aqua-{5-[(pyridin-2-yl-methyl-idene)amino]benzene-1,3-dicarboxyl-ato-κ(2)N,N'}nickel(II) tetra-hydrate.

The title structure, [Ni(C(14)H(8)N(2)O(4))(H(2)O)(4)]·4H(2)O, contains a mononuclear Ni(II) complex formed by a chelating bidentate Schiff base and by four Ni-bonded water mol-ecules. The Ni(II) atom is in a distorted octa-hedral coordination by two N atoms in a cis disposition [Ni-N = 2.0753 (16) and 2.1048 (16) Å] and by four water O atoms [Ni-O = 2.0500 (15)-2.0822 (15) Å]. The crystal structure is completed by four further non-coordinating water mol-ecules and all constituents are linked in a three-dimensional manner by an extensive system of 16 O-H⋯O hydrogen bonds.

[µ(2)-Bis(diphenyl-phosphanyl)methane][µ(3)-bis-(diphenyl-phosphanyl)meth-yl]trichlorido-tetra-gold(I) tetra-hydro-furan disolvate.

The title tetra-nuclear complex, [Au(4)(C(25)H(21)P(2))Cl(3)(C(25)H(22)P(2))]·2C(4)H(8)O, features two non-equivalent Ph(2)PCPPh(2) fragments, one of which represents the 'complete' mol-ecule (with two H atoms at the central C atom); each of the two P atoms of this mol-ecule is coordinated by an Au atom [Au-P = 2.2256 (13) and 2.2710 (13) Å], and these two Au atoms form an Au-Au bond [3.2945 (3) Å], thus closing the five-membered Au(2)P(2)C ring. The first of these Au atoms has a terminal chlorido ligand [Au-Cl = 2.2806 (12) Å], whereas the second Au atom forms a covalent bond with the central C atom of the bis-(diphenyl-phosphino)methyl group [Au-C = 2.114 (5) Å]; the latter group in turn coordinates with its P atoms the gold atoms of the Cl-Au-Au-Cl group [Au-P = 2.2356 (13) and 2.2338 (13), Au-Au = 3.3177 (3), Au-Cl = 2.3091 (12) and 2.2950 (13) Å], thus closing the second Au(2)P(2)C ring. The two such rings have different chemical functions, but both exhibit envelope conformations. However, the first (with different substituents at the Au atoms) is non-symmetrical with one of the P atoms in the flap position of the envelope; the other one has a conformation with mirror symmetry, and the gold-substituted C atom is displaced by 0.740 (5) Šfrom the almost exactly planar (r.m.s. deviation = 0.0038 Å) Au(2)P(2) group.

Diaqua-bis-(2-oxo-2H-chromene-3-carboxyl-ato-κO,O)manganese(II).

In the title compound, [Mn(C(10)H(5)O(4))(2)(H(2)O)(2)], the Mn(II) atom lies on a crystallographic inversion center and is six-coordinated by two O atoms from water mol-ecules in the axial positions and four O atoms from two deprotonated coumarin-3-carb-oxy-lic acid ligands in the equatorial plane. The overall coordination geometry is slightly distorted octa-hedral. The Mn-O bond distances vary between 2.0931 (12) and 2.2315 (13) Å. O-H⋯O hydrogen bonds between the H atoms of coordinated water mol-ecules and the O atoms of the carboxyl-ate groups link the complex mol-ecules into two-dimensional layers parallel to the ab plane.

Diaqua-bis-(2-oxo-2H-chromene-3-carboxyl-ato)copper(II).

In the title compound, [Cu(C(10)H(5)O(4))(2)(H(2)O)(2)], the Cu(II) atom lies on a crystallographic inversion center and exhibits an octa-hedral coordination defined by two O atoms from water mol-ecules in the axial positions and by four O atoms from two deprotonated coumarin-3-carb-oxy-lic acid ligands in the equatorial positions. The angles around the Cu(II) atom vary between 85.32 (6) and 94.68 (6)°. The Cu-O bond distances between the Cu(II) atom and the O atoms vary between 1.9424 (14) and 2.3229 (15) Å. The layers inter-digitate via face-to-face aromatic inter-actions [3.6490 (8) Å] between coumarin moieties such that the inter-layer separation is 10.460 (2) Å, i.e. the length of the c axis. O-H⋯O hydrogen bonds between the H atoms of coordinated water mol-ecules and the O atoms of carboxyl-ate groups link the complex mol-ecules into layers parallel to the ab plane.

UiO-66 Selective Enrichment Integrated with Thermal Desorption GC-MS for Detection of Benzene Homologues in Ambient Air.

In this study, UiO-66 was selected as sorbent media packed in the tube to selectively enrich trace levels of benzene homologues such as benzene, toluene, and xylene (BTX) in ambient air prior to thermal desorption (TD)-GC-MS determination. A series of experiments were conducted to obtain the optimal TD conditions. The results indicated that the optimal TD parameters were as follows: desorption temperature of 180°C, desorption flow rate of 50 mL min-1, and desorption time of 30 min. Furthermore, the method based on UiO-66 enrichment integrated with TD-GC-MS for trace levels of BTX was successfully developed. It exhibited a good linearity (R 2 > 0.99) in the range of 50-1000 ng, except for p, m-xylene in the range of 100-2000 ng, and achieved the recovery of 69.4-101.3%, and the relative standard deviation of 3.8-6.4%. The detection limits of BTX were 1.6-4.0 ng; according to 10 L of sampling volume, the method detection limits would be in the range of 0.16-0.40 µg m-3. Additionally, the method was successfully applied to determine BTX in indoor air and showed good selectivity and sensitivity. In summary, the findings in this work revealed that UiO-66 was an attractive adsorbent for selective enrichment trace levels of BTX compounds in ambient air, which was favorable for the subsequent detection by TD-GC-MS.

Diaqua-bis-(2-oxo-2H-chromene-3-carboxyl-ato-κO,O)cadmium.

In the title mononuclear cadmium complex, [Cd(C(10)H(5)O(4))(2)(H(2)O)(2)], the Cd(II) atom, located on a crystallographic inversion center, exhibits a slightly distorted octa-hedral geometry and is six-coordinated by two O atoms from water mol-ecules in the axial positions and four O atoms from two deprotonated coumarin-3-carb-oxy-lic acid ligands in the equatorial plane. Angles around the Cd(II) atom vary between 81.00 (5) and 99.00 (0)°. The Cd-O bond lengths vary between 2.1961 (13) and 2.3360 (13) Å. O-H⋯O hydrogen bonds between the H atoms of coordinated water mol-ecules and the O atoms of carboxyl-ate groups link the complex mol-ecules into layers parallel to the ab plane.

Diaqua-bis-(2-oxo-2H-chromene-3-carboxyl-ato)zinc(II).

In the title compound, [Zn(C(10)H(5)O(4))(2)(H(2)O)(2)], the Zn(II) atom lies on a crystallographic inversion center and is six-coordinated by two O atoms from water mol-ecules in the axial positions and four O atoms from two deprotonated coumarin-3-carb-oxy-late ligands in the equatorial plane, forming a slightly distorted octa-hedral coordination geometry. O-H⋯O hydrogen-bonding inter-actions involving the water mol-ecules form infinite chains parallel to [010].