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Photocatalytic reduction of CO 2 to value-added chemicals is known to be a promising approach for CO 2 conversion. The design and preparation of ideal photocatalysts for CO 2 conversion are of pivotal significance for the sustainable development of the whole society. In this work, we integrated two functional organic linkers to prepare a novel metal organic framework (MOF) photocatalyst {[Co(9,10-bis(4-pyridyl)anthracene) 0.5 (bpda)]·4DMF} (Co-MOF). The existence of anthryl and amino groups leads to a wide range of visible light absorption and efficient separation of photogenerated electrons. To extend the lifetime of photogenerated electrons in the photocatalytic system, we modified Co-MOF particles onto g-C 3 N 4 . As expected, Co-MOF/g-C 3 N 4 composites exhibited an ultrahigh selectivity (more than 97%) in the photocatalytic process, and the highest CO production rate (1824 μmol/g/h) was 7.1 and 27.2 times of Co-MOFs and g-C 3 N 4 , respectively. What's more, we also discussed the reaction mechanism of the Co-MOF/g-C 3 N 4 photocatalytic CO 2 reduction, and this work paves the pathway for designing photocatalysts with ideal CO 2 reduction performance.

Combining metal–organic frameworks (MOFs) with other functional materials can effectively improve the third‐order nonlinear optical (NLO) performances of MOFs. In this study, two distinct functional materials are selected and a PANI@MIL‐101(Cr)@CeO2 composite is successfully synthesized. The test results of third‐order NLO indicate that introducing PANI regulates the distribution of π electron clouds within the structure of the composite. Additionally, the core@shell structure formed by PANI@MIL‐101(Cr) and CeO2 promotes charge transfer and improves charge transfer efficiency under the weak heterojunction interaction, thereby enhancing nonlinear absorption and refractive signals. Under the double synergistic action of interior and exterior, a new charge transfer occurs between the components of the composite, resulting in excellent third‐order NLO performances. This study indicates that encapsulating polymer and loading metal oxides can effectively improve the NLO response of MOFs, which offers a new idea for more research on multiphase NLO materials. [ABSTRACT FROM AUTHOR]

The delocalization and rearrangement of π electron clouds in space is the crucial source of regulating nonlinear optical (NLO) performance. Herein, a core‐shell metal organic framework (MOF)‐heterojunction is constructed to achieve the effect of tuning NLO properties by promoting charge transfer through multiple interactions between heterogeneous interfaces. [Cd(L)(4,4′‐bpy)(H2O)]n (Cd‐MOF) is selected to coat on polyaniline (PANI) surface to form PANI@Cd‐MOF. The constructed heterojunction displays an enhanced reverse saturation absorption (RSA) signal compared with Cd‐MOF, and it should be noted that the third‐order NLO refractive behavior changes from the self‐defocusing of Cd‐MOF to the self‐focusing of PANI@Cd‐MOF. It is proposed that high‐speed electronic communication bridges established via the rich hydrogen bond network (O... H‐N) and π–π interactions between heterogeneous interfaces can effectively modify the π electron cloud density that finally regulates the NLO properties. This work is believed to provide new avenues and insights for the design of third‐order NLO materials. [ABSTRACT FROM AUTHOR]

New stable frictional materials based on metal–organic frameworks (MOFs) are greatly desired for applications in self-powered systems. This work reports an ionic MOF material with efficient charge separation mediated by charge induction. ZUT-iMOF-1(Cu) is chemically stable and its triboelectric output performance surpasses those of traditional MOF materials. The short-circuit current of the iMOF triboelectric nanogenerator is 73.79 μA at 5 Hz. The output performance remains stable over 50 000 cycles of continuous operation. The charge and power densities peak at 123.20 μC m−2 and 3133.23 mW m−2. Owing to its high output performance, ZUT-iMOF-1(Cu) effectively prevents metal corrosion in cathodic-protection systems. Theoretical calculations show that increasing the charge-separation effect promotes the frictional electricity generation behaviour. This study provides research suggestions for ionic MOF frictional materials and will promote their application in self-powered electrochemical cathodic-protection systems. [ABSTRACT FROM AUTHOR]

Metal‐organic framework (MOF) composites based on MOFs‐wrapped metals or metallic compounds (denoted as M/MC@MOFs) are an important class of materials that integrate M/MCs and MOFs. MOFs can fix and confine M/MCs to regulate their size, prevent uncontrollable aggregation, and enhance the exposure and ordered arrangement of active sites. In turn, M/MCs support the MOFs to enhance their stability and realize more targeted properties. In this review, the features and application scope of different M/MC@MOF synthesis methods are explored, considering the influential factors and regulation modes of the M/MC–MOFs integration. Additionally, the performances of the M/MC@MOF composites are comprehensively discussed, and the underlying mechanisms are clarified. The performance of M/MC@MOFs is dependent on the orderly synergy between the MOFs and M/MCs. MOFs can sieve and transfer specific molecules to the M/MC surface, whereas the robust interface provides new charge/energy‐transfer pathways, which enhance the activity and selectivity of the composites for diverse molecules. Furthermore, the challenges facing this field are analyzed, and the recommendations for advancing the development of M/MC@MOF composites are presented. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) based on contact electrification and electrostatic induction can effectively convert low-frequency mechanical energy into electrical energy and has attracted considerable attention. However, the low current output performance seriously hinders the wide application of TENGs. Herein, a 3D nanocrystalline metal–organic framework (Cd-MOF) with a specific structure and morphology was reasonably designed as a high-performance triboelectric positive electrode material. The triboelectric test results showed that the maximum instantaneous short-circuit current of Cd-MT was 55.32 μA and the stable output performance maintained a long-term continuous operation for 10 000 s. The peak values of the charge density and electric power density were 102.39 μC m−2 and 2451.04 mW m−2, respectively. In addition, the Cd-MT could quickly fully charge commercial capacitors and light a large number of LED lamps. This work provides a new idea for the development and design of functional MOF triboelectric materials. [ABSTRACT FROM AUTHOR]

Changing the chemical composition and generating heterogeneous structures have a synergistic effect on the third‐order nonlinear optical (NLO) properties of metal–organic frameworks (MOFs) materials. In this work, it is demonstrated that the transformations from a parent‐MOF [Zn4(dcpp)2(DMF)3(H2O)2]n (1, dcpp = 3,4‐bis(4‐carboxyphenyl)phthalate) into two child‐MOFs, [Cu4(dcpp)2(DMF)3(H2O)2]n (2) or [Zn2.5Co1.5(dcpp)2(DMF)3(H2O)2]n (3), via central metal exchange can regulate the third‐order NLO properties of the parent‐MOF, especially its third‐order NLO absorption signal can change from the reverse saturable absorption (RSA) to the saturable absorption (SA) when Cu2+ are introduced. Heterogeneous 1@CeO2 materials are further engineered by depositing CeO2 nanospheres onto the whole surface of 1, and are surprisingly still able to be exchanged into 2@CeO2 or 3@CeO2. Analyses on these MOFs@CeO2 indicate that the interfacial interaction between metal oxide particles and MOFs surface can effectively tune the charge transfer efficiency of the material which leads to their third‐order NLO refraction signals. The interface inducement of CeO2‐shell to the MOF‐core also significantly changes their third‐order NLO properties compared to pure MOFs. This work provides new insights and efficient strategies for the development of new third‐order NLO materials with potential practical usage. [ABSTRACT FROM AUTHOR]

The development of novel metal organic framework (MOF) friction power generation materials with high stability is important. This paper reports the first example of a double‐helix metal chain organic framework with a network structure (ZUT‐8). ZUT‐8 shows high chemical stability, functional adjustability, and excellent output performance of friction power generation, which is superior to traditional coordination polymer materials. The cathodic protection system with ZUT‐8 can prevent metal corrosion significantly. The output performance can be improved effectively by enhancing the conjugate effect of the linker. The theoretical calculation results showed that an increase in the degree of conjugation could significantly reduce the band gap, thereby affecting the friction power output signal. This study opens the door to constructing MOF materials with a double‐helix metal chain and will promote their potential applications in self‐powered electrochemical cathodic protection. [ABSTRACT FROM AUTHOR]

A 3D Co‐based metal–organic framework (Co‐MOF) with two kinds of large pores filled by free Co2+ ions and ligands was synthesized and characterized. To expand the MOF structure and conductivity, the free Co2+ ions and ligands were exchanged by conductive ionic liquid EtpyBr and photosensitive AgNO3 through single crystal‐to‐single crystal transformation, which produced structure‐changed 3D MOFs Co‐MOF‐Br and Co‐Ag‐MOF, which were characterized by single‐crystal X‐ray diffraction. Incorporating small quantities of doped polyaniline (PANI) with redox activity into the pores could further tune the stability and conductivity of the three MOFs. The PANI/MOFs all show outstanding electrical conductivity (≈10−2 S cm−1), and PANI/Co‐MOF‐Br has the largest p‐type Seebeck coefficient of 66.6 μV K−1. PANI/Co‐MOF‐Br and PANI/Co‐Ag‐MOF have 4 and 15 times higher photocurrent density compared with PANI/Co‐MOF, respectively. This work sheds light on the design of advanced electrically conductive 3D MOFs. [ABSTRACT FROM AUTHOR]

A ligand‐doped silver triazolate MOF{[Ag8(Ph2tz)5.6(tBu2tz)0.4](BF4)2(H2O)6} (AgTz‐1/2, Ph2tzH=3,5‐di‐phenyl‐1,2,4‐triazole; tBu2tzH=3,5‐di‐tert‐butyl‐1,2,4‐triazole), was successfully synthesized by the use of solid solution approach and characterized by different techniques. The obtained material featuring good thermal and chemical stability is isostrutural with an earlier reported MOF {[Ag8(Ph2tz)6](BF4)2(H2O)3} (AgTz‐1). The study on the diclofenac sodium (DCF) adsorption from water by AgTz‐1/2 at higher pH value (pH=10) shows better efficiency in comparison with the parent MOF AgTz‐1. Especially, using AgTz‐1/2 as the adsorbent, the adsorption capacity at low concentration as well as the reaction rate is remarkable among those reported traditional and MOF materials. Anion‐exchange between BF4− and anionic DCF play a vital role on the adsorption. More importantly, the used AgTz‐1/2 adsorbent can be well regenerated and reused for the next four cycles of DCF adsorption while maintaining the structural integrity and the removal efficiency. [ABSTRACT FROM AUTHOR]

In this paper, two energy-transfer photochromic metal–organic frameworks (MOFs) {[Zn(L)0.5(bpy)]·H2O·DMF}n (1) and {[Zn(L)0.5(bpe)]·2H2O·DMF}n (2) (H4L = 9,9′-(1,4-phenylenebis(methylene))bis(9H-carbazole-3,6-dicarboxylic acid), bpy = 4,4′-bipyridine, bpe = 4,4′-vinylenedipyridine) were designed and synthesized. Both 1 and 2 showed similar pillared-paddle wheel type frameworks with bpy and bpe as the chromophore, respectively, and L4− as the antenna-type light harvester, yielding strut-to-strut energy transfer (antenna behavior) within the well-ordered structures. Among them, 1 displayed excellent energy-transfer photochromic behavior under UV light accompanied by color transformation from colorless to purple. In addition, the photochromic behavior of 1 has obvious, fast, controllable and reversible characteristics. On the other hand, 2 showed a different energy-transfer photochromic behavior in the aspects of color changing, gamut, and sensitivity. The variation has been ascribed to the substitution of chromophore bpy in 1 with bpe in 2, which influences the efficiency of energy transfer within the MOFs. Therefore, with the structural diversity and tunability of MOFs, the sensitivity, color, and gamut of energy-transfer of the photochromic MOFs can be tuned by the appropriate choice of the constitutions of MOFs. This work will provide useful guidance for developing novel energy-transfer photochromic MOF materials. [ABSTRACT FROM AUTHOR]

Constructing well-organized metal–organic framework (MOF) membranes with a uniform and continuous nanoarchitecture is an effective strategy for the functionalization of MOF-based heterogeneous catalysts. In this work, by employing surfactant PVA (poly(vinyl alcohol)) as a soft-template, a moderate synthetic approach was adopted to obtain a Cu-MOF (1, [Cu(BBDC)(azobpy)(H2O)]n, H2BBDC = 4′-benzoyl-(1,1′-biphenyl)-3,5-dicarboxylic acid; azobpy = 4,4′-azopyridine) for building highly ordered Cu-MOF membranes (1a) with good control of the morphology and thickness on the surface of macroporous Cu foam, which could facilitate the growth of homogeneous and high-quality Cu-MOF membranes. Furthermore, the catalytic performance of Cu-MOF membranes 1a was superior to that of large sized 1 for tandem three-component C–H hydroxyalkynylation reactions, because the Cu-MOF membranes could afford a functionalized and tunable platform with the benefit of readily accessible active sites to promote tandem reactions by minimizing the diffusion distance but did little for their regioselectivity. [ABSTRACT FROM AUTHOR]

Two new three‐dimensional (3D) LnIII metal‐organic frameworks (MOFs) were designed and successfully obtained via a solvothermal reaction between lanthanide(III) nitrates and a semi‐flexible carbazole tetracarboxylate acid linker as a high‐performance chromophore. 1 and 2 possess porous 3D networks with channels along the a axis, and more importantly, they show a highly sensitive and selective fluorescence quenching response to Fe3+ and CrVI anions. The sensing mechanism investigation revealed that the weak interactions of Fe3+ with nitrogen atoms of carbazole and deprotonated carboxylic acids protruding into the pores of MOFs quenched the luminescence of 1 and 2 effectively. In addition, the competition absorption also played an important role in the luminescence quenching detection of Fe3+ based on 1, and CrVI anions based on 1 and 2. Therefore, 1 and 2 represent an alternative example of regenerable luminescence based sensors for the quantitative detection of Fe3+ and CrVI anions. [ABSTRACT FROM AUTHOR]

Proton coupled electron transfer has been successfully introduced to a host–guest collaborative metal–organic framework material, which exhibits new photochromic properties with reversible, controllable and efficient characteristics. [ABSTRACT FROM AUTHOR]

The synthesis of molecular‐level artificial switchable catalysts, of which activity in different chemical processes can be switched by controlling different stimuli, has provided a new paradigm to perform mechanical tasks and measurable work. In this work, to obtain highly effective and regioselective artificial switchable catalysts, a hierarchical anion‐pillared framework {(H3O)[Cu(CPCDC)(4,4′‐bpy)]}n (1; H3CPCDC=9‐(4‐carboxyphenyl)‐9H‐carbazole‐3,6‐dicarboxylic acid, 4,4′‐bpy=4,4′‐bipyridine), including free [H3O]+ ions as guest molecules, was constructed. Upon dissolve–exchange–crystallization behavior, fascinating reversible structural transformations proceeded between anion framework 1 and neutral 2D stair‐stepping framework {[Cu(CPCDC)(4,4′‐bpe)]}n (2; 4,4′‐bpe=4,4′‐vinylenedipyridine). Moreover, frameworks 1 and 2 can act as heterogeneous artificial switchable catalysts to selectively promote the direct cyanation reaction of terminal alkynes and azobisisobutyronitrile. The results indicated that 1 and 2 exhibited excellent selectivity to generate vinyl isobutyronitrile skeletons or propiolonitrile frameworks, respectively, as unique products. Furthermore, indicating paper, GC‐MS, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy analysis demonstrated that the reversible structural transformations endowed 1 and 2 with well‐defined platforms to stabilize the isobutyronitrile and CN sources through the different catalytic pathways. [ABSTRACT FROM AUTHOR]

Up to now, the direct conversion of the thiadiazole ring to other heterocyclic rings has been a very challenging task. Herein, a CdII‐mediated alcohol‐substitution strategy for direct conversion from benzothiadiazole to benzimidazole is reported. Experimental and molecular modeling studies on the role of the chelated metal ion in this in situ alcohol‐substitution reaction revealed that it serves as an all‐rounder that is involved in the insertion of alcohol, activation of the thiadiazole ring by coordinative interaction, and the sulfur‐extrusion process. Interestingly, the insertion of alcohol occurs much earlier than the sulfur‐extrusion process, supported by a water‐mediated proton‐transfer process. This strategy also is suitable for constructing new benzimidazole‐derived MOFs [Cd2(HMBIDC2−)2]⋅4 H2O (Cd‐BID‐MOF‐1, HMBIDC2−=2‐methyl‐1H‐benzimidazole‐4,7‐dicarboxylate) and [Cd2(HPBIDC2−)2]⋅1/3 H2O (Cd‐BID‐MOF‐2, HPBIDC2−=2‐(3‐hydroxypropyl)‐2H‐benzimidazole‐4,7‐dicarboxylate). Because the terminal hydroxyl group on the imidazole ring protrudes into the circular channel in rhombohedral Cd‐BID‐MOF‐2, the cavity is closer to hydrophilic than the honeycomb‐like cavity in Cd‐BID‐MOF‐1 with similar 3D structure. This rare observation will provide a new strategy to develop in situ ligand‐reaction synthesis of functional MOFs and useful chelation‐assisted catalytic reactions in heteroaromatic chemistry. Ring the changes: A cadmium(II)‐mediated alcohol‐substitution strategy for direct conversion of a thiadiazole ring to an imidazole ring, as well as the construction of benzimidazole‐derived metal–organic frameworks showing adjustable cavities is reported (see figure). [ABSTRACT FROM AUTHOR]

To explore metal–organic frameworks (MOFs) based on Co-clusters as heterogeneous catalysts to selectively catalyze the reaction of C–H bond oxidation of aromatic alkanes to their corresponding ketones, three MOFs {[Co5(pmbcd)2(μ3-OH)2(H2O)4(DMF)2]·4DMF}n (MOF 1), {[Co2(pmbcd)(bpea)2]·2H2O·2DMF}n (MOF 2), and {[Co2(pmbcd)(dpp)2]·3H2O·2DMF}n (MOF 3) (H4pmbcd = 9,9′-(1,4-phenylenebis(methylene))bis(9H-carbazole-3,6-dicarboxylic acid), bpea = 1,2-bis(4-pyridyl)ethane, dpp = 1,3-di(4-pyridyl)propane) were successfully synthesized and structurally characterized. MOF 1 was constructed from a pentanuclear Co(ii) cluster and exhibited a porous framework with channels of 8 × 10 Å2 along the b axis. MOF 2 was constructed from [Co2(CO2)4] units and presented a porous three-dimensional (3D) framework with channels of 11 × 13 Å2 along the b axis and of 10 × 12 Å2 along the c axis. MOF 3 was a flat two-dimensional (2D) layer based on binuclear Co(ii) units when dpp as an auxiliary ligand was introduced. The Co5-cluster-based MOF 1 exhibited excellent catalytic activity for the direct C–H bond activation of arylalkanes to ketones in H2O under room temperature because of its high density of Lewis acidic sites within the frameworks and suitable channel size to access the catalytic sites. It also presented the spatial confinement effect and catalyzed the reaction with high regioselectivity, forming mono-ketones as the sole products. Easy product separation, simple reaction procedures, and recyclability of these catalysts make the catalytic system attractive. Our work highlights the superiority of the MOF-based materials as heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

Converting light hydrocarbons such as methane, ethane, propane, and cyclohexane into value‐added chemicals and fuel products by means of direct C−H functionalization is an attractive method in the petrochemical industry. As they emerge as a relatively new class of porous solid materials, metal–organic frameworks (MOFs) are appealing as single‐site heterogeneous catalysts or catalytic supports for C−H bond activation. In contrast to the traditional microporous and mesoporous materials, MOFs feature high porosity, functional tunability, and molecular‐level characterization for the study of structure–property relationships. These virtues make MOFs ideal platforms to develop catalysts for C−H activation with high catalytic activity, selectivity, and recyclability under relatively mild reaction conditions. This review highlights the research aimed at the implementation of MOFs as single‐site heterogeneous catalysts for C−H bond activation. It provides insight into the rational design and synthesis of three types of stable MOF catalysts for C−H bond activation, that is, i) metal nodes as catalytic sites, ii) the incorporation of catalytic sites into organic struts, and iii) the incorporation of catalytically active guest species into pores of MOFs. Here, the rational design and synthesis of MOF catalysts that lead to the distinct catalytic property for C−H bond activation are discussed along with the post‐synthesis of MOFs, intriguing functions with MOF catalysts, and microenvironments that lead to the distinct catalytic properties of MOF catalysts. Form and functionalization: C−H bond activation can be catalyzed by metal–organic framework (MOF) catalysts (see figure). The rational design and synthesis of MOFs, the superior characteristics of MOF catalysts, and microenvironments that lead to the distinct catalytic properties of MOF catalysts are discussed. [ABSTRACT FROM AUTHOR]

Homogeneous host-guest (H-G) MOF composites without heterogeneous interfaces attracted wide attention in recent years. H-G interaction as a "bridge" plays an important role in the development and application of H-G MOF composites. The bridge dominates the connection of hosts and guests, and provides additional charge and energy transfer pathways to improve the performance of homogeneous H-G MOF composites. In this review, we focus on H-G interaction to discuss the combination of host MOFs and guests, and analyze the factors regulating the combination. The homogeneous H-G MOF composites with excellent catalytic performances reported in recent years as representative examples are summarized, and the regulatory factors of the catalytic performance are explored in detail. The synergistic mechanisms of H-G MOF composites during the catalytic process are analyzed deeply. Besides, some challenges and perspectives of developing H-G MOF composites are proposed to provide a reference for future development. [Display omitted] • The synthesis and catalysis of homogeneous H-G MOF composites are summarized. • The combination of host MOFs and guests driven by H-G interaction is discussed. • The influence factors on the catalysis of H-G MOF composites are analyzed. • We emphasized the interaction mechanisms of host MOFs and guest molecules. [ABSTRACT FROM AUTHOR]

Photo-induced free radical production was observed in tetraphenylethylene ligand-based metal–organic frameworks (MOFs). This feature endows the MOFs with reversible, fast, obvious, and controllable photo-induced color/emission transformation, excellent fatigue resistance ability and good light stability. [ABSTRACT FROM AUTHOR]

Abstract: One‐step selective benzene acylation–Nazarov cyclization is an attractive, yet challenging method for the synthesis of the benzocyclopentanone skeleton, which is key intermediate of many natural products. Herein, two metal‐cluster‐based metal–organic frameworks (MCOFs) {(H3O)2[Co4(pbcd)2(μ3‐OH)2]⋅CH3CH2OH⋅4 H2O}n (1; pbcd=9,9′‐(propan‐1,3‐diyl)bis(9H‐carbazole‐3,6‐dicarboxylic acid) and {[Co5.25(mcd)2(HCO2)(μ2‐O)0.5(μ3‐OH)0.5(H2O)4]⋅6 H2O⋅5 DMF}n (2; mcd=9,9′‐methylenebis(9H‐carbazole‐3,6‐dicarboxylic acid) were developed to catalyze a tandem Nazarov cyclization reaction of 1,3‐dimethoxybenzene with α,β‐unsaturated carboxylic acids for the synthesis of cyclopentenone[b]benzenes. MCOFs 1 and 2, which were constructed from tetranuclear CoII cluster [Co4(μ3‐OH)2] and hexanuclear CoII cluster [Co6(HCO2)(μ2‐O)(μ3‐OH)], respectively, exhibit high catalytic activity arising not only from their suitable channel size and accessible catalytic sites, but also because of their high density of Lewis acidic sites within the frameworks and the synergic activity among CoII ions. In contrast, {[Co2(pbcd)(bpe)]⋅2 H2O⋅2 DMF}n (3; bpe=1,2‐bis(pyridin‐4‐yl)ethane) containing binuclear CoII and having large pore windows is a highly selective catalyst for obtaining exclusively the acylation products. Easy product separation, simple reaction procedures, and catalyst recycling make the catalyst system attractive. This work highlights the synergistic effect among ions of MCOFs in interacting with substrates in a sequential or cooperative manner to achieve tandem catalysis. [ABSTRACT FROM AUTHOR]

Two novel Eu metal–organic frameworks (MOFs), namely {[Eu2(pdba)3(H2O)3]·2H2O}n (1) and {[Eu3(pdba)4(H2O)4]·5H2O}n (2), were prepared with 4′-(1H-pyrazol-3-yl)-[1,1′-biphenyl]-3,5-dicarboxylic acid (H2pdba) under hydrothermal conditions. MOF 1 exhibits a 3D supramolecular structure assembled from the π…π interactions between the benzene rings of the ligands, whereas 2 comprises a 3D structure through coordination connection between nitrogen atom and Eu3+. It is worth noting that the two MOFs showed good luminescence performance and high-sensitivity fluorescence quenching behavior toward Fe3+ (Cr3+) and nitrobenzene. Furthermore, the experimental results for stability in water and cycle test show that these two MOFs can be used as potential fluorescent probes. [ABSTRACT FROM AUTHOR]

The first example of micro-adjustments of a metal organic framework (MOF) structure was observed in a new Zn(ii) MOF (Zn-BTDC-M1) derived from a benzothiadiazole-4,7-dicarboxylic acid (H2BTDC) ligand using a light-driven decarboxylation process. Interestingly, such decarboxylation occurs at the non-chelated wing of the ligand, which induced a change in the capability of the MOF for physical N2 adsorption and chemical NH3 gas adsorption. [ABSTRACT FROM AUTHOR]

Several new isostructural lanthanide metal–organic frameworks {[Ln3(L)4(OH)(H2O)2]·DMAC}n (Ln = Tb (1), Gd (2), Eu (3), Gd0.81Tb0.10Eu0.09 (4) and Gd0.75Tb0.18Eu0.07 (5)) were designed and prepared. Excitingly, samples 1, 3, 4 and 5 showed reversible Al3+-induced chromaticity switching as well as reversible Fe3+-induced emission switching. [ABSTRACT FROM AUTHOR]

Upon single-crystal-to-single-crystal (SCSC) oxidation/reduction, reversible structural transformations take place between the anionic porous zeolite-like CuI framework and a topologically equivalent neutral CuICuII mixed-valent framework. The unique conversion behavior of the CuI framework endowed it as a redox-switchable catalyst for the direct arylation of heterocycle C–H bonds. [ABSTRACT FROM AUTHOR]

Two series of new lanthanide coordination polymers have been obtained by solvothermal reaction of Ln(NO3)3 and pamoic acid under different pH values. Both series of compounds show three-dimensional porous frameworks composed of dinuclear Ln(iii) subunits. Series B demonstrates fascinating solvent-induced dynamic behaviors in an SCSC (single crystal to single crystal) manner. The capability of activated series B to absorb liquid acetone was investigated by means of 1H NMR spectroscopy, demonstrating the potential of Ln-MOFs as highly efficient and reusable liquid acetone sorbents. In addition, photoluminescence properties of Nd (3), Eu (5) and Yb (10) were measured and discussed. Lanthanide contraction effect also played a crucial role in the formation of each series of complexes. Analysis of the relations between the ionic radius (Ln3+) and the number of f electrons in these complexes indicates that lanthanide contraction effect in both series can be well described by the Raymond model. [ABSTRACT FROM AUTHOR]

In our continuing quest to develop a metal-organic framework (MOF)-catalyzed tandem pyrrole acylation-Nazarov cyclization reaction with α,β-unsaturated carboxylic acids for the synthesis of cyclopentenone[ b]pyrroles, which are key intermediates in the synthesis of natural product (±)-roseophilin, a series of template-induced Zn-based ( 1-3) metal-organic frameworks (MOFs) have been solvothermally synthesized and characterized. Structural conversions from non-porous MOF 1 to porous MOF 2, and back to non-porous MOF 3 arising from the different concentrations of template guest have been observed. The anion-π interactions between the template guests and ligands could affect the configuration of ligands and further tailor the frameworks of 1-3. Futhermore, MOFs 1-3 have shown to be effective heterogeneous catalysts for the tandem acylation-Nazarov cyclization reaction. In particular, the unique structural features of 2, including accessible catalytic sites and suitable channel size and shape, endow 2 with all of the desired features for the MOF-catalyzed tandem acylation-Nazarov cyclization reaction, including heterogeneous catalyst, high catalytic activity, robustness, and excellent selectivity. A plausible mechanism for the catalytic reaction has been proposed and the structure-reactivity relationship has been further clarified. Making use of 2 as a heterogeneous catalyst for the reaction could greatly increase the yield of total synthesis of (±)-roseophilin. [ABSTRACT FROM AUTHOR]

Four complexes based on a benzimidazole-thioether derivative ligand 2-[(4-pyridine)sulfydryl]-ethyl-1H-benzimidazole (pteHb), namely, {[CdCl2(pteHb)2]2 ·2DMF} n ( 1), [CdI2(pteHb)]2 ( 2), {[CoCl2(pteHb)]2 ·DMF} ( 3), and {[ZnCl2(pteHb)]2 ·DMF} ( 4), were prepared under solvothermal and solvent evaporation conditions. X-ray diffraction analysis reveals that the Cl- ions of complex 1 act as μ2 bridge to connect the CdII ions resulting in a dinuclear unit. The units are bridged by the ligand pteHb to give a 1D double-looped chain. Complexes 2- 4 are dinuclear and further assembled into a 3D supramolecular architecture via π-π interactions, hydrogen bonding interactions, and intermolecular forces. Complexes 1- 4 were characterized by elemental analyses and IR spectroscopy. Furthermore, solid-state luminescent properties of complexes 1, 4, and ligand pteHb were also investigated. [ABSTRACT FROM AUTHOR]

Herein, a mechanism of stepwise metal-center exchange for a specific metal-organic framework, namely, [Zn4(dcpp)2(DMF)3(H2O)2] n (H4dcpp=4,5-bis(4′-carboxylphenyl)phthalic acid), is disclosed for the first time. The coordination stabilities between the central metal atoms and the ligands as well as the coordination geometry are considered to be dominant factors in this stepwise exchange mechanism. A new magnetic analytical method and a theoretical model confirmed that the exchange mechanism is reasonable. When the metathesis reaction occurs between CuII ions and framework ZnII ions, the magnetic exchange interaction of each pair of CuII centers gradually strengthens with increasing amount of framework CuII ions. By analyzing the changes of coupling constants in the Cu-exchanged products, it was deduced that Zn4 and Zn3 are initially replaced, and then Zn1 and Zn2 are replaced later. The theoretical calculation further verified that Zn4 is replaced first, Zn3 next, then Zn1 and Zn2 last, and the coordination stability dominates the Cu/Zn exchange process. For the Ni/Zn and Co/Zn exchange processes, besides the coordination stability, the preferred coordination geometry was also considered in the stepwise-exchange behavior. As NiII and CoII ions especially favor octahedral coordination geometry in oxygen-ligand fields, NiII ions and CoII ions could only selectively exchange with the octahedral ZnII ions, as was also confirmed by the experimental results. The stepwise metal-exchange process occurs in a single crystal-to-single crystal fashion. [ABSTRACT FROM AUTHOR]

Changing the chemical composition and generating heterogeneous structures have a synergistic effect on the third‐order nonlinear optical (NLO) properties of metal–organic frameworks (MOFs) materials. In this work, it is demonstrated that the transformations from a parent‐MOF [Zn4(dcpp)2(DMF)3(H2O)2]n (1, dcpp = 3,4‐bis(4‐carboxyphenyl)phthalate) into two child‐MOFs, [Cu4(dcpp)2(DMF)3(H2O)2]n (2) or [Zn2.5Co1.5(dcpp)2(DMF)3(H2O)2]n (3), via central metal exchange can regulate the third‐order NLO properties of the parent‐MOF, especially its third‐order NLO absorption signal can change from the reverse saturable absorption (RSA) to the saturable absorption (SA) when Cu2+ are introduced. Heterogeneous 1@CeO2 materials are further engineered by depositing CeO2 nanospheres onto the whole surface of 1, and are surprisingly still able to be exchanged into 2@CeO2 or 3@CeO2. Analyses on these MOFs@CeO2 indicate that the interfacial interaction between metal oxide particles and MOFs surface can effectively tune the charge transfer efficiency of the material which leads to their third‐order NLO refraction signals. The interface inducement of CeO2‐shell to the MOF‐core also significantly changes their third‐order NLO properties compared to pure MOFs. This work provides new insights and efficient strategies for the development of new third‐order NLO materials with potential practical usage. [ABSTRACT FROM AUTHOR]

Adsorption-based passive solar air water collection devices have great potential for delivering potable water to arid or desert regions of the world. Here, we synthesized the hygroscopic salt-modified UiO-66 composite adsorbents by impregnation method. In the open adsorption test, LiCl particles have high water adsorption and a large contact area with water vapor, which enhances the water adsorption performance of the composite adsorbents. Furthermore, in the regeneration temperature test, LiCl/UiO-66 showed the performance of low regeneration temperature. The hydrothermal stability of LiCl/UiO-66 was confirmed by cycle tests. The experimental results show that the solar air water collection device based on LiCl/UiO-66 composite adsorbents is a promising method to solve the problem of water shortage in arid areas. [Display omitted] • LiCl/UiO-66 CSPMs obtained by dipping method. • The adsorption performance of the composite adsorbents was higher than that of the monomer UiO-66, and the adsorption performance was better with the increase of salt content. • UiO-66 and LiCl/UiO-66 CSPMs can desorption more than 95% of the adsorbed water in the structure at 85 °C. • UiO-66 and LiCl/UiO-66 CSPMs show good cycle performance. [ABSTRACT FROM AUTHOR]

A novel (4,4,7)-connected 3D self-penetrating network with unprecedented 7-connectivity, has been constructed using 1,4-bis(2-methylbenzimidazol-1-ylmethyl) benzene and 3,3′,4,4′-Benzophenonetetracarboxylic acid as co-ligands. It represents an unusual self-penetrating pattern with the entanglements of nonequivalent 4- and 6-membered shortest rings. [ABSTRACT FROM AUTHOR]

The optimized MOF composite adsorbents by various synthetic strategies play significant roles in water treatment. [Display omitted] • The review focuses on the potential of MOF composites for water purification. • The latest trends in MOF composites for the adsorption of organic and inorganic pollutants. • The modified MOF composite adsorbents via various strategies can significantly improve removal capacity. • The challenges and prospects of MOF composite adsorbents are suggested. The applications of metal organic framework (MOF) composites in water purification field have attracted extensive attention. Researchers aim to design multi-component MOF composites that possess the superiority of single components, and mitigate the shortage of MOFs and functional materials via their integration. In this review, we focus on the discussion of the advanced multifunctional MOF composite adsorbents (2017 to present). The adsorption properties of various MOF composites are evaluated, and the interaction mechanisms between MOFs and functional components are also systematically analyzed. Finally, we present our personal views on the opportunities and challenges of future researches, hoping to inspire more researchers to participate in this fascinating area. [ABSTRACT FROM AUTHOR]

Recently, there has been considerable interest in the transformation of metal nodes in metal-organic frameworks (MOFs) because this transformation can yield favorable changes in their chemical or physical properties. In this review, we provided an overview of crystalline central-metal transformation in MOFs, including central-metal spin-state transformation, central-metal oxidation-state transformation, and central-metal exchange in a single-crystal-to-single-crystal manner. Investigations of this concept suggest that crystalline central-metal transformation will play an emerging role in the exploration of novel MOFs for use in further applications in the near future. [ABSTRACT FROM AUTHOR]

Abstract: In this article, a chiral azolate-based octanuclear metallamacrocycle three-dimensional (3D) complexes {[Co2(pbt)2(H2O)2]·4.5H2O}n (1) have been synthesized and characterized. Complex 1 crystallizes in the space group P43212 and displays a complicate homochiral three-dimensional (3D) framework containing octanuclear cobalt metallamacrocycles. The trizole-N1, N2 bridging cobalt trinuclear secondary building units (SBUs) in complex 1 provides a platform to investigate the magneto-structural correlations. The weak magnetic exchange of this complex is due to the asymmetric doubly 1,2,4-triazole-N1,N2 bridged SBUs which reduces the ineffective overlap between the orbits of paramagnetic central ions. [Copyright &y& Elsevier]

Abstract: The self-assembly of 1,3,4-thiadiazole-2,5-di-4-pyridyl (L 1), 4,4′-dipyridyl (L 2) with Zn(II), Cu(II) salts afforded one unusual coordination polymer with left-handed homo-chiral 3-D open MOFs in which supramolecular left-handed methanol helices were selectively formed, and one 2-D coordination polymer where two-fold interpenetrated 3-D supramolecular frameworks were constructed by hydrogen bonds. [Copyright &y& Elsevier]

• A novel cationic MOF material was elaborately constructed and applied in Cr(VI) removal. • This is the first example of coordination substitution for removal Cr(VI) confirmed by SC-XRD. • Efficient reversible SC-SC was demonstrated in the trapping-releasing process. • The MOF shows a fast response and high capture capability (190 mg/g) for Cr(VI). • DFT calculations studies indicate the mechanism of Cr(VI) removal. An unusual water-stable cationic metal-organic framework {[Cu(L) 0.5 (bpe)(H 2 O)](NO 3)•(H 2 O) 0.5 } n (1) (H 4 L = bis(3,5-dicarboxypyridinium)-p-xylylene) was synthesized, which was developed into an effective capture material for removal chromate from water. The results show that this material efficiently traps HCrO 4 − pollutant ions via single-crystal to single-crystal (SC SC) coordination substitution process. The HCrO 4 − uptake capacity of 1 is high to 190 mg/g. Meaningfully, the structure of 1- HCrO 4 ({[Cu(L) 0.5 (bpe)(HCrO 4)]} n) can be accurately obtained by single-crystal X-ray diffraction, where the chromate enter the framework to form stable coordination with central metal ions Cu2+. This is the first example of a stable coordination between chromate and the framework during the capture process. The captured HCrO 4 − are not dissociated easily into the solution due to the coordination bond. This interaction makes the enrichment of HCrO 4 − more stable and the capture capacity excellent. Furthermore, the HCrO 4 − releasing process displays good regeneration in a single crystal state, which further elaborates the reversible SC SC transformation. The mechanism of Cr(VI) removal was also confirmed by DFT calculation studies. This work provides a new way to design and develop efficient MOF capture materials. [ABSTRACT FROM AUTHOR]