Sponge‐Like Behaviour in Isoreticular Cu(Gly‐His‐X) Peptide‐Based Porous Materials

We report two isoreticular 3D peptide‐based porous frameworks formed by coordination of the tripeptides Gly‐L ‐His‐Gly and Gly‐L ‐His‐L ‐Lys to Cu^II which display sponge‐like behaviour. These porous materials undergo structural collapse upon evacuation that can be reversed by exposure to water vapour, which permits recovery of the original open channel structure. This is further confirmed by sorption studies that reveal that both solids exhibit selective sorption of H₂O while CO₂ adsorption does not result in recovery of the original structures. We also show how the pendant aliphatic amine chains, present in the framework from the introduction of the lysine amino acid in the peptidic backbone, can be post‐synthetically modified to produce urea‐functionalised networks by following methodologies typically used for metal–organic frameworks built from more rigid “classical” linkers.     

Construction of Two 3D Main Group Coordination Polymers Based on 2‐(2‐Pyridyl)‐4,5‐imidazole‐dicarboxylic Acid: Structures and Luminescent Properties

Two main group coordination polymers based on 2‐(2‐pyridyl)‐4,5‐imidazole‐dicarboxylic acid (H₃oPyIDC), namely [Ba(H₂oPyIDC)₂(H₂O)]_n ( 1 ) and [Pb₂(HoPyIDC)₂]_n ( 2 ) are obtained under hydrothermal conditions. In compound 1 , the Ba²⁺ cations and HoPyIDC^2– anions are connected to a 1D chain, and the 1D chains are further interconnected by Ba–O bonds, forming a 3D 3‐connected framework. In compound 2 , a 2D layer with (4,4) topology is formed by Pb^II ions and HoPyIDC^2– anions. The 2D layer are pillared by HoPyIDC^2–, yielding a 3D (3,4)‐connected framework. The thermogravimetric analyses and luminescence properties of compounds 1 and 2 are also investigated.     

A three‐dimensional zinc‐based coordination polymer built from 5‐carboxylato‐1‐carboxylatomethyl‐2‐oxidopyridinium with a 4‐connected sra topology

A novel three‐dimensional Zn^II complex, poly[aqua(μ₄‐5‐carboxylato‐1‐carboxylatomethyl‐2‐oxidopyridinium)zinc(II)], [Zn(C₈H₅NO₄)(H₂O)]_n, has been prepared by hydrothermal assembly of Zn(CH₃COO)₂·2H₂O and 5‐carboxy‐1‐(carboxymethyl)pyridin‐1‐ium‐2‐olate (H₂ccop). The ccop²⁻ anions bridge the Zn^II cations in a head‐to‐tail fashion via monodentate aromatic carboxylate and phenolate O atoms to form an extended zigzag chain which runs parallel to the [011] direction. One O atom of the aliphatic carboxylate group of the ccop²⁻ ligand coordinates to the Zn^II atom of a neighbouring chain thereby producing undulating layers which lie parallel to the (01) plane. A similar parallel undulating planar structure can be obtained if a path involving the other O atom of the aliphatic carboxylate group is considered. Thus, the aliphatic carboxylate group acts in a bridging bidentate mode to give extended –Zn–O–C–O–Zn– sequences running parallel to [001] which link the layers into an overall three‐dimensional framework. The three‐dimensional framework can be simplified as a 4‐connected sra topology with a Schläfli symbol of 4².6³.8 if all the Zn^II centres and ccop²⁻ anions are regarded as tetrahedral 4‐connected nodes. The three‐dimensional luminescence spectrum was measured at room temperature with excitation and emission wavelengths of 344–354 and 360–630 nm, respectively, at intervals of 0.15 and 2 nm, respectively.     

A novel one‐dimensional double‐chain‐like ZnII coordination polymer: poly[bis(1‐benzyl‐1H‐imidazole‐κN3)tris(μ‐cyanido‐κ2C:N)(cyanido‐κC)disilver(I)zinc(II)]

One of most interesting systems of coordination polymers constructed from the first‐row transition metals is the porous Zn^II coordination polymer system, but the numbers of such polymers containing N‐donor linkers are still limited. The title double‐chain‐like Zn^II coordination polymer, [Ag₂Zn(CN)₄(C₁₀H₁₀N₂)₂]_n, presents a one‐dimensional linear coordination polymer structure in which Zn^II ions are linked by bridging anionic dicyanidoargentate(I) units along the crystallographic b axis and each Zn^II ion is additionally coordinated by a terminal dicyanidoargentate(I) unit and two terminal 1‐benzyl‐1H‐imidazole (BZI) ligands, giving a five‐coordinated Zn^II ion. Interestingly, there are strong intermolecular Ag^I…Ag^I interactions between terminal and bridging dicyanidoargentate(I) units and C—H…π interactions between the phenyl rings of BZI ligands of adjacent one‐dimensional linear chains, providing a one‐dimensional linear double‐chain‐like structure. The supramolecular three‐dimensional framework is stabilized by C—H…π interactions between the phenyl rings of BZI ligands and by Ag^I…Ag^I interactions between adjacent double chains. The photoluminescence properties have been studied.     

A 3D Porous Metal Organic Framework Based on Infinite 1D Nickel(II) Chains with Rutile Topology Displaying Open Metal Sites

The reaction of Ni^II with a tetra‐benzoate pyrene ligand produces a 3D porous framework based on infinite 1D Ni^II chains. The Ni^II–O connectivity and the formation of a hydroxo‐bridge (μ₃‐OH) responsible for the connection of the central Ni^II atoms within the 1D Ni^II–(μ₃‐OH)₂–Ni^II chains can be straightforwardly compared with the Ti^IV–O–Ti^IV connectivity seen in TiO₂. The arrangement of the TBAPy ligand around the 1D rutile‐based chains leads in the generation of a porous framework with two distinct types of pores; based on the chemistries of these two types of pores, one can be labelled as hydrophobic and the other as hydrophilic. The use of different activation methods results in the generation of either a porous framework free of guest molecules or a completely solvent‐free material, in which the terminal H₂O molecules bound to Ni^II were removed, leading thus to a framework with open Ni^II sites. CO₂ isotherms collected on both frameworks at 195 K and one barshowed type I isotherms characteristic of microporous materials (BET surface areas for: guest‐free framework: 257(3) m² · g^–1; solvent‐free framework: 362(2) m² · g^–1). The affinity of both networks at zero coverage for both CO₂ and CH₄ was found to be greater when the unsaturated Ni^II sites are available within the void space.     

A Three‐dimensional DyIII‐based Metal‐organic Framework: Smart Drug Carrier and Anti‐lung Cancer Activity

A 3D lanthanide metal‐organic framework (MOF) with the formula [Dy₂(L)₂(H₂O)₂]_n ( 1 ) (H₃L = biphenyl‐3,4′,5‐tricarboxylic acid) was synthesized under solvothermal conditions and structurally characterized by elemental analysis, powder X‐ray diffraction analysis, infrared spectroscopy, and single‐crystal X‐ray diffraction analysis. Compound 1 features a 3D porous framework based on 1D rod‐shaped Dy^III‐carboxylate chains. The efficient encapsulation and controllable release of an anticancer drug (5‐Fu) make it a promising drug delivery host. Furthermore, the GCMC simulation was used to probe the drug‐framework interaction at the atomic lever. The in vitro anti‐lung cancer activity of 1 and 5‐Fu loaded 1a were also evaluated using MTT assay.     

Syntheses,Structures, and Photophysical Properties of Two Coordination Polymers Based on 2,3‐Dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic Acid

Two complexes based on the ligand 1,4‐dihydro‐2,3‐quinoxalinedione, namely [Mn(H₂L)₂(H₂O)₂]_n ( 1 ) and {[Zn₂(H₂L)₂(tz)₂] · 5H₂O}_n ( 2 ) (H₃L = 2,3‐dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic acid, Htz = 1,2,4‐triazole) were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, as well as single‐crystal and powder X‐ray diffraction. Complex 1 exhibited a 1D comb‐like chain formed by H₂L^– anions linking Mn^II ions, whereas complex 2 was a 2D layer‐like structure with square‐shaped windows and outstretched arms built by combination of H₂L^– and tz^– ligands with Zn^II ions. The adjacent chains or layers connected with each other by intermolecular hydrogen bonding and π–π stacking to further extend to a 3D supermolecular framework. In addition, the thermal stabilities, luminescence properties, and optical energy gap of 1 and 2 were investigated in detail.     

Non‐Porous Iron(II)‐Based Sensor: Crystallographic Insights into a Cycle of Colorful Guest‐Induced Topotactic Transformations

Materials capable of sensing volatile guests at room temperature by an easily monitored set of outputs are of great appeal for development as chemical sensors of small volatile organics and toxic gases. Herein the dinuclear iron(II) complex, [Fe^II₂( L )₂(CH₃CN)₄](BF₄)₄?2 CH₃CN ( 1 ) [ L =4‐(4‐methylphenyl)‐3‐(3‐pyridazinyl)‐5‐pyridyl‐4H‐1,2,4‐triazole], is shown to undergo reversible single‐crystal‐to‐single‐crystal (SCSC) transformations upon exposure to vapors of different guests: 1 (MeCN)? 2 (EtOH)→ 3 (H₂O)? 1 (MeCN). Whilst 1 and 2 remain dimetallic, SCSC to 3 involves conversion to a 1D polymeric chain (due to a change in L bridging mode), which, remarkably, can undergo SCSC de‐polymerization, reforming dimetallic 1 . Additionally, SC‐XRD studies of two ordered transient forms, 1TF3 and 2TF3 , confirm that guest exchange occurs by diffusion of the new guests into the non‐porous lattices as the old guests leave. These reversible SCSC events also induce color and magnetic responses. Indeed dark red 1 is spin crossover active (T_1/2↓ 356 K; T_1/2↑ 369 K), whilst orange 2 and yellow 3 remain high spin.     

Ab Initio and DFT Studies on CO2 Interacting with Znq+–Imidazole (q=0, 1, 2) Complexes: Prediction of Charge Transfer through σ‐ or π‐Type Models

Using first‐principles methodologies, the equilibrium structures and the relative stability of CO₂@[Zn^q+Im] (where q=0, 1, 2; Im=imidazole) complexes are studied to understand the nature of the interactions between the CO₂ and Zn^q+–imidazole entities. These complexes are considered as prototype models mimicking the interactions of CO₂ with these subunits of zeolitic imidazolate frameworks or Zn enzymes. These computations are performed using both ab initio calculations and density functional theory. Dispersion effects accounting for long‐range interactions are considered. Solvent (water) effects were also considered using a polarizable continuum model approach. Natural bond orbital, charge, frontier orbital and vibrational analyses clearly reveal the occurrence of charge transfer through covalent and noncovalent interactions. Moreover, it is found that CO₂ can adsorb through more favorable π‐type stacking as well as σ‐type hydrogen‐bonding interactions. The inter‐monomer interaction potentials show a significant anisotropy that might induce CO₂ orientation and site‐selectivity effects in porous materials and in active sites of Zn enzymes. Hence, this study provides valuable information about how CO₂ adsorption takes place at the microscopic level within zeolitic imidazolate frameworks and biomolecules. These findings might help in understanding the role of such complexes in chemistry, biology and material science for further development of new materials and industrial applications.     

A three‐dimensional supramolecular framework of silver(I), 2‐phenylquinoline‐4‐carboxylate and 4,4′‐bipyridine

A novel supramolecular framework, catena‐poly[[[aqua(2‐phenylquinoline‐4‐carboxylato‐κO)silver(I)]‐μ‐4,4′‐bipyridine‐κ²N:N′] dihydrate], {[Ag(C₁₆H₁₀NO₂)(C₁₀H₈N₂)(H₂O)]·2H₂O}_n, has been synthesized and structurally characterized. The Ag^I centres are four‐coordinated and bridged by 4,4′‐bipyridine (4,4′‐bipy) ligands to form a one‐dimensional Ag–bipy chain. The Ag–bipy chains are further linked together by intermolecular O—H...O and O—H...N hydrogen‐bonding interactions between adjacent chains, resulting in a three‐dimensional framework.     

Materials Discovery and Crystal Growth of Zeolite A Type Zeolitic–Imidazolate Frameworks Revealed by Atomic Force Microscopy

A new zeolitic–imidazolate framework (ZIF), [Zn(imidazolate)_2?x(benzimidazolate)_x], that has the zeolite A (LTA) framework topology and contains relatively inexpensive organic linkers has been revealed using in situ atomic force microscopy. The new material was grown on the structure‐directing surface of [Zn(imidazolate)_1.5(5‐chlorobenzimidazolate)_0.5] (ZIF‐76) crystals, a metal–organic framework (MOF) that also possesses the LTA framework topology. The crystal growth processes for both [Zn(imidazolate)_2?x(benzimidazolate)_x] and ZIF‐76 were observed using in situ atomic force microscopy; it is the first time the growth process of a nanoporous material with the complex zeolite A (LTA) framework topology has been monitored temporally at the nanoscale. The results reveal the crystal growth mechanisms and possible surface terminations on the {100} and {111} facets of the materials under low supersaturation conditions. Surface growth of these structurally complex materials was found to proceed through both “birth‐and‐spread” and spiral crystal‐growth mechanisms, with the former occurring through the nucleation and spreading of metastable and stable sub‐layers reliant on the presence of non‐framework species to bridge the framework during formation. These results support the notion that the latter process may be a general mechanism of surface crystal growth applicable to numerous crystalline nanoporous materials of differing complexity and demonstrate that the methodology of seeded crystal growth can be used to discover previously unobtainable ZIFs and MOFs with desirable framework compositions.     

β‐Peptidic Secondary Structures Fortified and Enforced by Zn2+ Complexation – On the Way to β‐Peptidic Zinc Fingers?

The correlation between β²‐, β³‐, and β^2,3‐amino acid‐residue configuration and stability of helix and hairpin‐turn secondary structures of peptides consisting of homologated proteinogenic amino acids is analyzed (Figs. 1–3). To test the power of Zn²⁺ ions in fortifying and/or enforcing secondary structures of β‐peptides, a β‐decapeptide, 1 , four β‐octapeptides, 2 – 5 , and a β‐hexadecapeptide, 10 , have been devised and synthesized. The design was such that the peptides would a) fold to a 14‐helix ( 1 and 3 ) or a hairpin turn ( 2 and 4 ), or form neither of these two secondary structures (i.e., 5 ), and b) carry the side chains of cysteine and histidine in positions, which will allow Zn²⁺ ions to use their extraordinary affinity for RS^? and the imidazole N‐atoms for stabilizing or destabilizing the intrinsic secondary structures of the peptides. The β‐hexadecapeptide 10 was designed to a) fold to a turn, to which a 14‐helical structure is attached through a β‐dipeptide spacer, and b) contain two cysteine and two histidine side chains for Zn complexation, in order to possibly mimic a Zn‐finger motif. While CD spectra (Figs. 6–8 and 17) and ESI mass spectra (Figs. 9 and 18) are compatible with the expected effects of Zn²⁺ ions in all cases, it was shown by detailed NMR analyses of three of the peptides, i.e., 2, 3, 5 , in the absence and presence of ZnCl₂, that i) β‐peptide 2 forms a hairpin turn in H₂O, even without Zn complexation to the terminal β³hHis and β³hCys side chains (Fig. 11), ii) β‐peptide 3 , which is present as a 14‐helix in MeOH, is forced to a hairpin‐turn structure by Zn complexation in H₂O (Fig. 12), and iii) β‐peptide 5 is poorly ordered in CD₃OH (Fig. 13) and in H₂O (Fig. 14), with far‐remote β³hCys and β³hHis residues, and has a distorted turn structure in the presence of Zn²⁺ ions in H₂O, with proximate terminal Cys and His side chains (Fig. 15).     

Well‐Arranged and Confined Incorporation of PdCo Nanoparticles within a Hollow and Porous Metal–Organic Framework for Superior Catalytic Activity

A convenient method for the confined incorporation of highly active bimetallic PdCo nanocatalysts within a hollow and porous metal–organic framework (MOF) support is presented. Several chemical conversions occur simultaneously during the one‐step low temperature pyrolysis of well‐designed polystyrene@ZIF‐67/Pd²⁺ core–shell microspheres, where ZIF (zeolitic imidazolate framework) is a subclass of MOF: the polystyrene core is removed, resulting in a beneficial hollow and porous ZIF support; the ZIF‐67 shell acts as a well‐defined porous support and as a felicitous Co²⁺ supplier for metal nanoparticle formation; and Pd²⁺ and Co²⁺ are reduced to form catalytically active bimetallic PdCo nanoparticles in the well‐defined micropores, inducing the confined growth of PdCo nanoparticles with excellent dispersity.     

A self‐penetrated three‐dimensional zinc(II) coordination framework based on 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid and 1,3‐bis[(imidazol‐1‐yl)methyl]benzene ligands: synthesis,structure and properties

With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H₃TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel Zn^II‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ₃‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn₃(C₂₄H₁₂N₃O₆)₂(C₁₄H₁₄N₄)₃]·2C₃H₇NO·3H₂O}_n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent Zn^II centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB^3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each Zn^II centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The Zn^II centres are connected by TATB^3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link Zn^II centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 6⁵·7·8¹³·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr⁴⁺ and Cu²⁺ ions.     

Polyoxometalate‐Based Entangled Coordination Networks Induced by an Extended Bis(triazole) Ligand

The introduction of an extended bridging bis(triazole) ligand, that is, 4,4′‐bis(1,2,4‐triazol‐1‐ ylmethyl)biphenyl (BBPTZ), into the hydrothermal reaction system containing transition metal ions and Keggin‐type polyoxometalates (POMs) led to the isolation of three new organic–inorganic hybrid entangled coordination networks, [Cu^I₂Cu^II(BBPTZ)₆][SiW₁₂O₄₀]?12 H₂O ( 1 ), [Ni(BBPTZ)₂(H₂O)][H₂SiW₁₂O₄₀]?11 H₂O ( 2 ), and [Ni₂(BBPTZ)₄(H₂O)₂][SiW₁₂O₄₀]?3 H₂O ( 3 ). All three compounds were characterized by elemental analysis, IR spectroscopy, TG analysis, powder X‐ray diffraction, and single‐crystal X‐ray diffraction. Compound 1 contains a 2‐D POM‐based metal–organic layer entangled with 1‐D ladder‐like metal–organic chains. The adjacent 2‐D networks are parallel to each other, further stacking into a 3‐D supramolecular framework with 1‐D channels. Compound 2 exhibits a 1‐D cantilever‐type loop‐containing chain. The Keggin‐type POMs act as the cantilever groups, leading to the adjacent catilever‐type chains interwaving together to form a 3‐D supramolecular open framework with two types of channels. Compound 3 possesses a 3‐D open framework based on 2‐D metal–organic undulated layer and Keggin‐type POM clusters. Three sets of such frameworks further interpenetrate with each other to form an interesting three‐fold interpenetrating framework. The photocatalytic activities of compounds 1–3 for the decomposition of methylene blue (MB) under UV light have been investigated.     

Porous Metal‐organic Framework based on Strip‐shaped Manganese(II) Chains: Synthesis,Structure, and Magnetic Properties

The Mn^II‐based porous metal‐organic framework, [Mn₃(btca)₂(HCOO)(μ₃‐OH)(H₂O)₂] · 2DMF ( 1 ) (H₂btca = benzotriazole‐5‐carboxylate acid), was prepared by the solvothermal reaction of Mn(CH₃COO)₂ · 4H₂O and H₂btca, which was characterized by infrared spectroscopy, thermogravimetric analyses, and X‐ray crystallographic study. 1 exhibits 3D framework with 1D rectangle channels constructed by the strip‐shaped chains containing [Mn₅(μ₃‐OH)₂(btca)₄]^– pentaclusters subunits. Furthermore, the magnetic measures show that 1 exhibits weak ferromagnetic behavior at low temperature.     

Metal‐Substituted Zeolitic Imidazolate Framework ZIF‐108: Gas‐Sorption and Membrane‐Separation Properties

A series of dual‐metal zeolitic imidazolate framework (ZIF) crystals with SOD and RHO topologies was synthesised by metal substitution from ZIF‐108 (Zn(2‐nitroimidazolate)₂, SOD topology) as the parent material. This was based on the concept that metal substitution of ZIF‐108 requires a much lower activation energy than homogenous nucleation owing to the metastability of ZIF‐108. In‐depth investigations of the formation processes of the daughter ZIFs indicated that the transformation of ZIF‐108 is a dissolution/heterogeneous nucleation process. Typical isostructural Co²⁺ substitution mainly occurs at the outer surface of ZIF‐108 and results in a core–shell structure. On the contrary, the Cu²⁺‐substituted ZIF has a RHO topology with a homogeneous distribution of Cu²⁺ ions in the structure. Substitution with Ni²⁺ resulted in a remarkable enhancement in adsorption selectivity toward CO₂ over N₂ by a factor of up to 227. With Co²⁺‐substituted nanoparticles as inorganic filler, a mixed matrix membrane based on polysulfone displayed greatly improved performance in the separation of H₂/CH₄, CO₂/N₂ and CO₂/CH₄.     

Syntheses and Crystal Structures of a Series of Coordination Polymers Constructed From C2‐Symmetric Ligand 1,3‐Adamantanedicarboxylic Acid

This article systematically investigates the influence of the properties of inhomogeneous N‐auxiliary ligands and pH value on the helical structures of complexes based on C₂‐symmetric ligand 1,3‐adamantanedicarboxylic acid (H₂ADC). Five kinds of neutral ligands (phen=1,10‐phenanthroline, bipy=4,4′‐bipyridine, bpa=1,2‐bis(4‐pyridyl)ethane, bpe=1,2‐bis(4‐pyridyl)ethane, and bpp=1,3‐bis(4‐pyridyl)propane) were selected, and a series of new Zn^II/Co^II dicarboxylates have been synthesized by slow diffusion, namely, [Zn(phen)(ADC)(H₂O)]₂ ? CH₃OH ( 1 ), {[Zn(ADC)(bpe)] ? H₂O}_n ( 2 ), {[Zn(ADC)(bipy)] ? 2 H₂O}_n ( 3 ), {[Zn(ADC)(bpa)]₂ ? 5 H₂O}_n ( 4 ), {[Zn(ADC)(bpp)]₂ ? CH₃OH}_n ( 5 ), {[Zn(ADC)(bpp)]}_n ( 6 ), {[Co(ADC)(bpp)(CH₃OH)(H₂O)] ? CH₃OH ? 2 H₂O}_n ( 7 ), and {[Co(ADC)(bpp)]}_n ( 8 ). Single‐crystal X‐ray structural analysis shows that complex 1 forms a 0D dinuclear with closed‐loop unit. The complex 2 is a 2D layer framework. Compounds 3 and 4 are isomorphous with a small discrepancy and present one‐dimensional chainlike structures. It is interesting that the 2D organic–inorganic hybrid frameworks containing meso‐helical chains have been observed. Compound 5 is a 2D interpenetrated network with (4,4) topology, in which homochiral left‐handed helical chains are arranged in an ABAB sequence parallel to the plane defined by (a,c), and right‐handed helical chains running along the a axis are also observed in the solid state, resulting in a meso‐helical structure. Compounds 6 , 7 , and 8 crystallize in a chiral space group P212121. Highly dimensional 6 and 8 are essentially isostructural and present a threefold interpenetrated 3D diamondoid network containing three helical chains, whereas 7 exhibits a 2D grid layer with a left‐handed helical chain. Furthermore, thermal stability, X‐ray powder diffraction, and the luminescent properties of 1 , 2 , 3 , 4 , 5 , 6 are also discussed.     

A Room‐Temperature Luminescent AgCF3COO Complex Consisting of Cationic Complex Chains and Anionic Guests

Reaction of p‐phenylenediacetonitrile (p‐phda) with AgCF₃COO afforded the coordination polymer, {[Ag₂(p‐phda)₂] [Ag₄(CF₃COO)₆]}_n ( 1 ), where the 1D cationic [Ag₂(p‐phda)₂]²⁺ chain acts as host and the anionic [Ag₄(CF₃COO)₆]^2– as guest molecules occupy the channel between neighboring host chains. This is a rare crystal example of AgCF₃COO complex consisting of cationic complex chains and anionic guests. In addition, complex 1 exhibits luminescence at room temperature in solid state.     

Two Robust Porous Metal–Organic Frameworks Sustained by Distinct Catenation: Selective Gas Sorption and Single‐Crystal‐to‐Single‐Crystal Guest Exchange

Assembly of copper(I) halide with a new tripodal ligand, benzene‐1,3,5‐triyl triisonicotinate (BTTP4), afforded two porous metal–organic frameworks, [Cu₂I₂(BTTP4)]?2 CH₃CN ( 1? 2 CH₃CN) and [CuBr(BTTP4)]?(CH₃CN ? CHCl₃ ? H₂O) ( 2? solvents), which have been characterized by IR spectroscopy, thermogravimetry (TG), single‐crystal, and powder X‐ray diffraction (PXRD) methods. Compound 1.CH3CN is a polycatenated 3D framework that consists of 2D (6,3) networks through inclined catenation, whereas 2 is a doubly interpenetrated 3D framework possessing the ThSi₂‐type ( ths ) (10,3)‐b topology. Both frameworks contain 1D channels of effective sizes 9×12 and 10×10 Ų, which amounts to 43 and 40 % space volume accessible for solvent molecules, respectively. The TG and variable‐temperature PXRD studies indicated that the frameworks can be completely evacuated while retaining the permanent porosity, which was further verified by measurement of the desolvated complex [Cu₂I₂(BTTP4)] ( 1′ ). The subsequent guest‐exchange study on the solvent‐free framework revealed that various solvent molecules can be adsorbed through a single‐crystal‐to‐single‐crystal manner, thus giving rise to the guest‐captured structures [Cu₂I₂(BTTP4)]?C₆H₆ ( 1.benzene ), [Cu₂I₂(BTTP4)]?2 C₇H₈ ( 1.2toluene ), and [Cu₂I₂(BTTP4)]?2 C₈H₁₀ ( 1.2ethyl benzene ). The gas‐adsorption investigation disclosed that two kinds of frameworks exhibited comparable CO₂ storage capacity (86–111 mL g^?1 at 1 atm) but nearly none for N₂ and H₂, thereby implying its separation ability of CO₂ over N₂ and H₂. The vapor‐adsorption study revealed the preferential inclusion of aromatic guests over nonaromatic solvents by the empty framework, which is indicative of selectivity toward benzene over cyclohexane.