A C3‐Symmetric Macrocycle‐Based,Hydrogen‐Bonded,Multiporous Hexagonal Network as a Motif of Porous Molecular Crystals

A C₃‐symmetric π‐conjugated macrocycle combined with an appropriate hydrogen bonding module (phenylene triangle) allowed the construction of crystalline supramolecular frameworks with a cavity volume of up to 58 %. The frameworks were obtained through non‐interpenetrated stacking of a hexagonal sheet possessing three kinds of pores with different sizes and shapes. The activated porous material absorbed CO₂ up to 96 cm³ g⁻¹ at 195 K under 1 atm.     

An Ultrastable and Easily Regenerated Hydrogen‐Bonded Organic Molecular Framework with Permanent Porosity

A robust hydrogen‐bonded organic framework HOF‐TCBP (H₄TCBP=3,3′,5,5′‐tetrakis‐(4‐carboxyphenyl)‐1,1′‐biphenyl) has been successfully constructed and structurally characterized. It possesses a permanent 3D porous structure with a 5‐fold interpenetrated dia topological network. This activated HOF‐TCBP has a high BET surface area of 2066 m² g⁻¹ and is capable of highly selective adsorption and separation of light hydrocarbons under ambient conditions. It shows excellent thermal stability, as demonstrated by PXRD experiments and N₂ adsorption tests. Practical use of HOF‐TCBP is facilitated by the ease of its preparation and renewal through rotary evaporation.     

Control of Interpenetration and Gas‐Sorption Properties of Metal–Organic Frameworks by a Simple Change in Ligand Design

In metal–organic framework (MOF) chemistry, interpenetration greatly affects the gas‐sorption properties. However, there is a lack of a systematic study on how to control the interpenetration and whether the interpenetration enhances gas uptake capacities or not. Herein, we report an example of interpenetration that is simply controlled by the presence of a carbon–carbon double or single bond in identical organic building blocks, and provide a comparison of gas‐sorption properties for these similar frameworks, which differ only in their degree of interpenetration. Noninterpenetrated ( SNU‐70 ) and doubly interpenetrated ( SNU‐71 ) cubic nets were prepared by a solvothermal reaction of [Zn(NO₃)₂] ? 6 H₂O in N,N‐diethylformamide (DEF) with 4‐(2‐carboxyvinyl)benzoic acid and 4‐(2‐carboxyethyl)benzoic acid, respectively. They have almost‐identical structures, but the noninterpenetrated framework has a much bigger pore size (ca. 9.0×9.0 Å) than the interpenetrated framework (ca. 2.5×2.5 Å). Activation of the MOFs by using supercritical CO₂ gave SNU‐70′ and SNU‐71′ . The simulation of the PXRD pattern of SNU‐71′ indicates the rearrangement of the interpenetrated networks on guest removal, which increases pore size. SNU‐70′ has a Brunauer–Emmett–Teller (BET) surface area of 5290 m² g^?1, which is the highest value reported to date for a MOF with a cubic‐net structure, whereas SNU‐71′ has a BET surface area of 1770 m² g^?1. In general, noninterpenetrated SNU‐70′ exhibits much higher gas‐adsorption capacities than interpenetrated SNU‐71′ at high pressures, regardless of the temperature. However, at P<1 atm, the gas‐adsorption capacities for N₂ at 77 K and CO₂ at 195 K are higher for noninterpenetrated SNU‐70′ than for interpenetrated SNU‐71′ , but the capacities for H₂ and CH₄ are the opposite; SNU‐71′ has higher uptake capacities than SNU‐70′ due to the higher isosteric heat of gas adsorption that results from the smaller pores. In particular, SNU‐70′ has exceptionally high H₂ and CO₂ uptake capacities. By using a post‐synthetic method, the C?C double bond in SNU‐70 was quantitatively brominated at room temperature, and the MOF still showed very high porosity (BET surface area of 2285 m² g^?1).     

3D Enantiomorphic Mg‐Based Metal–Organic Frameworks as Chemical Sensor of Nitrobenzene and Efficient Catalyst for CO2 Cycloaddition

Two enantiomorphic Mg^II‐based metal‐organic frameworks, {MgL(H₂O)₂}_n ( 1‐D and 1‐L ) (where H₂L=2,2′‐bipyridyl‐4,4′‐dicarboxylic acid) have been synthesized by solvothermal reaction without any chiral auxiliary. The single‐crystal X‐ray measurement and the structural analysis indicate that both 1‐D and 1‐L possess 2‐fold interpenetrated frameworks with different left‐ and right‐handed helical chains simultaneously, which serve as chiral source, thus transmitting chirality over the whole frameworks. The fluorescence measurements reveal that they exhibit a strong quenching response to nitrobenzene and could be potentially used as a chemical sensor. Owing to the accessible Lewis acidic sites in channels, they display high catalytic efficiency for cycloaddition reaction of CO₂ with epoxides and could be reused five times without losing activity.     

Docking Strategy To Construct Thermostable,Single‐Crystalline,Hydrogen‐Bonded Organic Framework with High Surface Area

Enhancing thermal and chemical durability and increasing surface area are two main directions for the construction and improvement of the performance of porous hydrogen‐bonded organic frameworks (HOFs). Herein, a hexaazatriphenylene (HAT) derivative that possesses six carboxyaryl groups serves as a suitable building block for the systematic construction of thermally and chemically durable HOFs with high surface area through shape‐fitted docking between the HAT cores and interpenetrated three‐dimensional network. A HAT derivative with carboxybiphenyl groups forms a stable single‐crystalline porous HOF that displays protic solvent durability, even in concentrated HCl, heat resistance up to 305 °C, and a high Brunauer–Emmett–Teller surface area [SA_(BET)] of 1288 m² g⁻¹. A single crystal of this HOF displays anisotropic fluorescence, which suggests that it would be applicable to polarized emitters based on robust functional porous materials.     

Distorted Fivefold‐Diamond Structure of 4,4‐Bis(2‐carboxyethyl)pimelic Acid (‘Methanetetrapropionic Acid’)

The molecules of 4,4‐bis(2‐carboxyethyl)pimelic acid (=4,4‐bis(2‐carboxyethyl)heptanedioic acid; 1 ) assemble to build up hollow, five‐fold interpenetrating diamond‐like networks in tetragonal crystals via standard pairwise H‐bonds between the carboxy groups. In keeping with the flat, extended molecular conformation of 1 of approximate D_2d symmetry, the supramolecular diamondoid networks are tetragonally compressed. Their mode of interpenetration is unusual and corresponds to that of adamantane‐1,3,5,7‐tetracarboxylic acid, which has an undistorted five‐fold diamond structure. Both the degree and the mode of interpenetration of 1 differ from those of the lower homologue 3,3‐bis(carboxymethyl)glutaric acid ( 2 ), which adopts a more‐common tetragonally elongated triple‐diamond architecture in the solid state.     

Water‐Stable Homochiral Cluster Organic Frameworks Built by Two Kinds of Large Tetrahedral Cluster Units

Compared with metal organic frameworks (MOFs), the proton conductivity of cluster organic frameworks has been less studied. Herein, two supertetrahedral cluster organic frameworks (SCOFs) have been made that show two‐fold interpenetrated networks built by trivalent lanthanide tetrahedral clusters and monovalent cuprous T₃‐supertetrahedral clusters. The structure analysis, second harmonic generation signals, and solid‐state circular dichroism spectroscopy consistently reveal the chirality of these SCOFs. Remarkably, the water‐stable SCOFs show a high proton conductivity value of 1.4×10^?3 S cm^?1 at 80 °C and 95 % RH (relative humidity).     

Giant Enhancement of Second Harmonic Generation Accompanied by the Structural Transformation of 7‐Fold to 8‐Fold Interpenetrated Metal–Organic Frameworks (MOFs)

Interpenetration in metal–organic frameworks (MOFs) is an intriguing phenomenon with significant impacts on their properties, and functional applications. Herein, we show that a 7‐fold interpenetrated MOF ( 1 ) is transformed into an 8‐fold interpenetrated MOF by the loss of DMF in a single‐crystal‐to‐single‐crystal manner. This is accompanied by a giant enhancement of the second harmonic generation (SHG ca. 125 times) and two‐photon photoluminescence (ca. 14 times). The strengthened π–π interaction between the individual diamondoid networks and intensified oscillator strength of the molecules aid the augment of dipole moments and boost the nonlinear optical conversion efficiency. Large positive and negative thermal expansions of 1 occur at 30–150 °C before the loss of DMF. These results offer an avenue to manipulate the NLO properties of MOFs using interpenetration and provide access to tunable single‐crystal NLO devices.     

Design,Synthesis, and X‐Ray Crystal Structure of a Fullerene‐Linked Metal–Organic Framework

Given the unique structural and electronic properties of C₆₀, metal–organic frameworks (MOFs) containing C₆₀ linkers are expected to exhibit interesting characteristics. A new hexakisfullerene derivative possessing two pairs of phenyl pyridine groups attached to two methano‐carbon atoms located at the trans‐1 positions was designed and synthesized. The four pyridyl nitrogen atoms define a perfectly planar rectangle. This new C₆₀ derivative was used to assemble the first fullerene‐linked two‐dimensional MOF by coordination with Cd²⁺.     

Borromean‐Entanglement‐Driven Assembly of Porous Molecular Architectures with Anion‐Modified Pore Space

A series of metal–organic frameworks based on a flexible, highly charged Bpybc ligand, namely 1? Mn?OH^?, 2? Mn?SO₄^2?, 3? Mn?bdc^2?, 4? Eu?SO₄^2? (H₂BpybcCl₂=1,1′‐bis(4‐carboxybenzyl)‐4,4′‐bipyridinium dichloride, H₂bdc=1,4‐benzenedicarboxylic acid) have been obtained by a self‐assembly process. Single‐crystal X‐ray‐diffraction analysis revealed that all of these compounds contained the same n‐fold 2D→3D Borromean‐entangled topology with irregular butterfly‐like pore channels that were parallel to the Borromean sheets. These structures were highly tolerant towards various metal ions (from divalent transition metals to trivalent lanthanide ions) and anion species (from small inorganic anions to bulky organic anions), which demonstrated the superstability of these Borromean linkages. This non‐interpenetrated entanglement represents a new way of increasing the stability of the porous frameworks. The introduction of bipyridinium molecules into the porous frameworks led to the formation of cationic surface, which showed high affinities to methanol and water vapor. The distinct adsorption and desorption isotherms of methanol vapor in four complexes revealed that the accommodated anion species (of different size, shape, and location) provided a unique platform to tune the environment of the pore space. Measurements of the adsorption of various organic vapors onto framework 1? Mn?OH^? further revealed that these pores have a high adsorption selectivity towards molecules with different sizes, polarities, or π‐conjugated structures.     

Synthesis,Characterization and Photoluminescence of Lanthanide Metal‐organic Frameworks,Constructed from Triangular 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate Ligands

Eight isomorphous metal‐organic frameworks: [Ln₂(TATAB)₂(H₂O)(DMA)₆]·5H₂O (Ln = Sm ( 1 ), Eu ( 2 ), Gd ( 3 ), Tb ( 4 ), Dy ( 5 ), Er ( 6 ), Tm ( 7 ), Yb ( 8 )); TATAB = 4,4′,4″‐s‐triazine‐1,3,5‐triyl‐p‐aminobenzoate, DMA = N,N‐dimethylacetamide), were synthesized by the self‐assembly of lanthanide ions, TATAB, DMA and H₂O. Single‐crystal X‐ray crystallography reveals they are three dimensional frameworks with 2‐fold interpenetration. Solid‐state photoluminescence studies indicate ligand‐to‐metal energy transfer is more efficient for compounds 2 and 4 which exhibit intense characteristic lanthanide emissions at room temperature.     

4,4’－二(磷酸二甲酯甲基)联苯连接的具有互穿结构的二维锰(II)配位聚合物的合成与结构研究

在常规条件下,合成了具有新颖结构的配位聚合物[Mn(bdpbp)2(NO3)2]n (1) [bdpbp =4,4’-二(磷酸二甲酯甲基)联苯]。配合物1由单晶x-射线衍射确定结构,并用元素分析、红外光谱、荧光光谱和热重进行了表征和性质研究。配合物1具有二维无限的网格状结构,形成双重互穿,并由弱的C-H···O氢键进一步连接成三维超分子网络。     

Activation‐Dependent Breathing in a Flexible Metal–Organic Framework and the Effects of Repeated Sorption/Desorption Cycling

A non‐interpenetrated metal–organic framework with a paddle‐wheel secondary building unit has been activated by direct thermal evacuation, guest exchange with a volatile solvent, and supercritical CO₂ drying. Conventional thermal activation yields a mixture of crystalline phases and some amorphous content. Exchange with a volatile solvent prior to vacuum activation produces a pure breathing phase with high sorption capacity, selectivity for CO₂ over N₂ and CH₄, and substantial hysteresis. Supercritical drying can be used to access a guest‐free open phase. Pressure‐resolved differential scanning calorimetry was used to confirm and investigate a systematic loss of sorption capacity by the breathing phase as a function of successive cycles of sorption and desorption. A corresponding loss of sample integrity was not detectable by powder X‐ray diffraction analysis. This may be an important factor to consider in cases where flexible MOFs are earmarked for industrial applications.     

Three‐Dimensional Anionic Cyclodextrin‐Based Covalent Organic Frameworks

Three‐dimensional covalent organic frameworks (3D COFs) are promising crystalline materials with well‐defined structures, high porosity, and low density; however, the limited choice of building blocks and synthetic difficulties have hampered their development. Herein, we used a flexible and aliphatic macrocycle, namely γ‐cyclodextrin (γ‐CD), as the soft struts for the construction of a polymeric and periodic 3D extended network, with the units joined via tetrakis(spiroborate) tetrahedra with various counterions. The inclusion of pliable moieties in the robust open framework endows these CD‐COFs with dynamic features, leading to a prominent Li ion conductivity of up to 2.7 mS cm⁻¹ at 30 °C and excellent long‐term Li ion stripping/plating stability. Exchanging the counterions within the pores can effectively modulate the interactions between the CD‐COF and CO₂ molecules.     

Cobalt(II)‐Terephthalate Frameworks Containing Bis(benz­imidazole) Derivative Co‐ligands: Syntheses,Crystal Structures,Catalytic and Fluorescence Properties

Two metal‐organic coordination polymers of Co^II with the molecular formulae [Co(L₁)(tp)(H₂O)₂]_n ( 1 ) and [Co(L₂)(tp) · H₂O]_n ( 2 ) [L₁ = 1, 4‐bis(benzimidazole‐1‐ylmethyl)‐ benzene; L₂ = 1, 1‐(1, 4‐butanediyl)bis(5, 6‐dimethylbenzimidazole); tp = terephthalate] were synthesized and characterized by single‐crystal X‐ray diffraction studies, infrared spectroscopy (IR), thermogravimetric analysis (TGA), X‐ray powder diffraction (XRPD), and elemental analysis. The structure determination of complex 1 reveals a 2D layer with (4, 4) topology, with Co^II ions at the nodes connected through tp and L₁ co‐ligands. Complex 2 is the first example of a four‐connected SrAl₂ structure type ( sra , 4²6³8 topology) with threefold interpenetration in Co^II coordination frameworks, forming by bridging L₂ and tp co‐ligands. In addition, the fluorescence and catalytic performances of the complexes for the degradation of methyl orange were investigated.     

Non‐Interpenetrated Single‐Crystal Covalent Organic Frameworks

Growth of covalent organic frameworks (COFs) as single crystals is extremely challenging. Inaccessibility of open‐structured single‐crystal COFs prevents the exploration of structure‐oriented applications. Herein we report for the first time a non‐interpenetrated single‐crystal COF, LZU‐306, which possesses the open structure constructed exclusively via covalent assembly. With a high void volume of 80 %, LZU‐306 was applied to investigate the intrinsic dynamics of reticulated tetraphenylethylene (TPE) as the individual aggregation‐induced‐emission moiety. Solid‐state ²H NMR investigation has determined that the rotation of benzene rings in TPE, being the freest among the reported cases, is as fast as 1.0×10⁴ Hz at 203 K to 1.5×10⁷ Hz at 293 K. This research not only explores a new paradigm for single‐crystal growth of open frameworks, but also provides a unique matrix‐isolation platform to reticulate functional moieties into a well‐defined and isolated state.     

Two Disparate 2‐fold Interpenetrating Frameworks Constructed from ZnII, 4,4′‐Dipyridyl Disulfide and Maleic/ Fumaric Acid

The reaction of Zn^II nitrate with maleic acid (H₂mal) / fumaric acid (H₂fum) and 4,4′‐dipyridyl disulfide (4‐pds) resulted under same conditions in two distinct interpenetrated compounds, namely [Zn(4‐dps)₂(H₂O)₂]·2Hmal ( 1 ) and [Zn(4‐dps)(fum)] ( 2 ). In 1 , Hmal anion adopts bridging mode based on hydrogen bonding, affording a 2‐fold parallel interpenetrated 3D→3D α‐Po net hydrogen‐bonded framework, in which 1D double‐stranded chains are formed, and then extended to a 3D supramolecular architecture combining second‐sphere hydrogen‐bonded interactions. For 2 , fum dianion takes on bis‐dentate bridging coordination fashion, furnishing a 2‐fold interpenetrated 2D→2D (4,4) layered coordination network, in which the tetrahedral Zn^II atoms are interlinked by 4‐dps and fum. Additionally, the compound 2 shows strong fluorescence in the solid state at room temperature.     

Vinylene‐Linked Covalent Organic Frameworks by Base‐Catalyzed Aldol Condensation

Two 2D covalent organic frameworks (COFs) linked by vinylene (?CH=CH?) groups (V‐COF‐1 and V‐COF‐2) are synthesized by exploiting the electron deficient nature of the aromatic s‐triazine unit of C₃‐symmetric 2,4,6‐trimethyl‐s‐triazine (TMT). The acidic terminal methyl hydrogens of TMT can easily be abstracted by a base, resulting in a stabilized carbanion, which further undergoes aldol condensation with multitopic aryl aldehydes to be reticulated into extended crystalline frameworks (V‐COFs). Both V‐COF‐1 (with terepthalaldehyde (TA)) and V‐COF‐2 (with 1,3,5‐tris(p‐formylphenyl)benzene (TFPB)) are polycrystalline and exhibit permanent porosity and BET surface areas of 1341 m² g^?1 and 627 m² g^?1, respectively. Owing to the close proximity (3.52 Å) of the pre‐organized vinylene linkages within adjacent 2D layers stacked in eclipsed fashion, [2+2] photo‐cycloadditon in V‐COF‐1 formed covalent crosslinks between the COF layers.     

Layer‐by‐Layer Assembled Conductive Metal–Organic Framework Nanofilms for Room‐Temperature Chemiresistive Sensing

The utility of electronically conductive metal–organic frameworks (EC‐MOFs) in high‐performance devices has been limited to date by a lack of high‐quality thin film. The controllable thin‐film fabrication of an EC‐MOF, Cu₃(HHTP)₂, (HHTP=2,3,6,7,10,11‐hexahydroxytriphenylene), by a spray layer‐by‐layer liquid‐phase epitaxial method is reported. The Cu₃(HHTP)₂ thin film can not only be precisely prepared with thickness increment of about 2 nm per growing cycle, but also shows a smooth surface, good crystallinity, and high orientation. The chemiresistor gas sensor based on this high‐quality thin film is one of the best room‐temperature sensors for NH₃ among all reported sensors based on various materials.     

A C3‐Symmetric Macrocycle‐Based,Hydrogen‐Bonded,Multiporous Hexagonal Network as a Motif of Porous Molecular Crystals

A C₃‐symmetric π‐conjugated macrocycle combined with an appropriate hydrogen bonding module (phenylene triangle) allowed the construction of crystalline supramolecular frameworks with a cavity volume of up to 58 %. The frameworks were obtained through non‐interpenetrated stacking of a hexagonal sheet possessing three kinds of pores with different sizes and shapes. The activated porous material absorbed CO₂ up to 96 cm³ g^?1 at 195 K under 1 atm.