Guo-Ping Yang

A series of Zn(II) coordination complexes derived from isomeric phenylenediacetic acid and dipyridyl ligands: syntheses, crystal structures, and characterizations

A series of new metal–organic frameworks (MOFs), [Zn(1,2-pda)(bipy)(H2O)2]n (1), [Zn(1,3-pda) (bipy)(H2O)]n·nH2O (2), [Zn(1,4-pda)(bipy)]n·nCH3OH (3), [Zn(1,2-pda)(dpe)]n·3nH2O (4), and [Zn(1,3-pda)(bpa)]n·2nH2O (5) [H2pda = phenylenediacetic acid, bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene, bpa = 1,2-bis(4-pyridyl)ethane] have been synthesized and structurally characterized. The structure determination reveals that complex 1 is a 2D layered network and exhibits a typical (4,4) topological net, which further assembles into a 3D two-fold interpenetrated pcu topology when hydrogen bonding interactions are considered. Complex 2 shows a 2D (5,2)-connected topological network via hydrogen bonding interactions based on the 1D double-chains. For complex 3, when the 1,4-pda ligands act as a three-connected node, the 2D double-layered structure displays a unique (5,3)-connected topology with a Schlafli symbol (42,67,8)(42,6). Complex 4 features a rare 3D three-fold interpenetrated diamondoid framework (dia, 66 topology) with (2.2.1) Hopf links and (6.3.3) Torus links, and the helical water chains are encased in the 1D neighboring channels. Complex 5 is a 2D corrugated net with a Schlafli symbol (44,62), and the puckered nature of the layers assembles them to interpenetrate in an unusual 2D → 3D parallel fashion. Particularly, a discrete tetramer water cluster, (H2O)4, is located in the crystal lattice of 5. The structural differences demonstrate that the backbones of the phenylenediacetic acids are a key point to form the final metal–ligand coordination polymers. Moreover, the fluorescent properties of complexes 1–5 were studied in the solid state at room temperature.

Investigation on the prime factors influencing the formation of entangled metal–organic frameworks

Metal–organic frameworks (MOFs) have become a rapidly expanding research topic in the fields of synthetic chemistry and materials science in recent years. Entanglement is often considered to be an important phenomenon in MOFs. Currently, a large number of entangled metal–organic frameworks (EMOFs) have been yielded and documented well in the literature. The structure–property relationships of an EMOF can be directed and fine-tuned not only by the starting materials, i.e. metal ions/clusters and organic ligands, but also by the various reaction conditions, including reaction temperature, pH value, and molar ratio of reactants etc. In this highlight, we carefully attempt to analyze and summarize the key factors which significantly influence the formation of EMOFs, and we hope this work may provide some primary guide information to the predesign and construction of desired EMOFs.

An unusual 1D ladder-like silver(I) coordination polymer involving novel 1D → 3D five-folded interpenetrated and [3 + 2] catenaned features generated by Ag⋯O interactions

An unusual 1D ladder-like silver(I) complex has been synthesized and characterized. The polymer exhibits interesting plywood-like stacking arrays and a novel five-folded interpenetrated supramolecular network with [3 + 2] catenations.

Dynamic Zn-based metal–organic framework: stepwise adsorption, hysteretic desorption and selective carbon dioxide uptake

A new porous metal–organic framework based on paddle-wheel Zn2 units and an unsymmetrical pyridyl dicarboxylate, contains a 3D intersecting pore system with uncommon stepwise adsorption and hysteretic desorption behavior for N2, CO2 and H2 gases at low temperature, and shows high selectivity for CO2 over N2 at ambient temperature.

Two isostructural amine-functionalized 3D self-penetrating microporous MOFs exhibiting high sorption selectivity for CO2

Two isostructural 3D microporous metal–organic frameworks, which show a 6-connected (48·66·8) self-penetrating net, contain two different narrow-sized channels functionalized by amino groups on the pore surface. In particular, both of them show exceptional stability and a high selectivity for CO2 over N2 at 298 K.

Unprecedented 1D alternate Co5 chain and discrete Co3 unit embedded in a 3D framework exhibiting slow magnetic relaxation behaviour

A new Co-based 3D framework has been constructed from an unprecedented 1D alternate Co5 chain and discrete linear Co3 unit as two distinct secondary building units, which exhibits slow magnetic relaxation behavior.

Highly selective luminescence sensing for the detection of nitrobenzene and Fe3+ by new Cd(II)-based MOFs

Herein, three new luminescent metal–organic frameworks (MOFs), namely {[Cd4(H3L)4(H2O)12]·2.5H2O}n (1), {[Cd(L)]·2.5H2O·3[H2N(Me)2]}n (2), and {[Cd2(L)(DMA)]·[H2N(Me)2]}n (3), were designed and successfully prepared via a solvothermal reaction using V-shaped rigid multicarboxylate 2,4-di(3′,5′-dicarboxylphenyl)benzoic acid (H5L) and Cd(II) salts in various solvent systems. The structural analyses indicated that the H3L2−/L5− ligands took three different coordination fashions in 1–3; this resulted in a diversity of targeted MOFs. The solid-state luminescence properties of three MOFs were studied under ultraviolet light irradiation at ambient temperature, and 3 showed a high selectivity and sensitivity for nitrobenzene and Fe3+ because of the quenching effect. Thus, it could be a potential crystalline material for detecting these substances. The mechanisms of the quenching effect and sensing properties of 3 have been discussed in detail.

Peculiar phenomena of structural transformations triggered from a nickel coordination polymer

Structural transformation has aroused wide interest and has emerged as a promising approach for the design and synthesis of novel coordination polymers. In this work, we found interesting structural transformation phenomena triggered from a nickel coordination polymer (CP). Two temperature-dependent two-dimensional (2D) CPs, 1 and 2 were synthesized from hydrothermal reactions, while the other two CPs, 2D 3 and 3D 4 were the products of the in situ thermal decomposition of 1. Interestingly, 1 could undergo methanol-mediated transformation to afford 2 and 2 might convert to 1 under the condition of adding bipy in water. The multi-step conversions from 1 to 3 and 3 to 4 triggered by heat treatment in the solid state accompany the very rare dynamic response of a sequential release of coordinated water and partial organic ligands. More importantly, the mechanism of the transformation has also been studied in detail. Moreover, 3 could revert back to 1 quickly upon exposure to air, and this reversible process of dehydration–rehydration could be repeated at least ten times, which could highlight the application for their use in moisture sensors.

Reaction-controlled assemblies and structural diversities of seven Co(II)/Cu(II) complexes based on a bipyridine-dicarboxylate N-oxide ligand

Seven complexes, namely, {[Co2[(R,S)-bpdado]2(CH3CN)2(H2O)2]·2H2O}n1, {Cu[(R,S)-bpdado](H2O)}n2, {[Cu2[(R,S)-bpdado]2(H2O)2]·H2O}n2′, {[Cu(R,S)-bpdado]·EtOH}n2′′, {Cu[(R,S)-bpdado](phen)}2 (phen = 1,10-phenanthroline) 3, {Cu[(R,S)-bpdado](phen)(H2O)}2·8H2O 4 and {Cu[(R,S)-bpdado](dpy)(H2O)}2·4H2O (dpy = 2,2′-pyridine) 5, have been obtained via solvothermal or layered diffusional reaction based on an axially chiral ligand, (R,S)-2,2′-bipyridyl-3,3′-dicarboxylic acid-1,1′-dioxide ((R,S)-H2bpdado). These complexes tend to form under thermodynamic control in the crystallization process of complexes. Among them, 2′ and 2′′ were reported and obtained along with the preparation of 2. Five new complexes, 1–5, are characterized by single-crystal X-ray diffraction, elemental analyses, X-ray powder diffraction, and IR and thermogravimetric analyses. Four different structural complexes, 2D achiral layers 1, 2 and 2′′ and 1D nanotubular structure 2′, are constructed by the M3[(R,S)-bpdado] tecton (M = Co(II) or Cu(II)) in different arrangement modes. When various N-donor ligands are used, different binuclear complexes, 3–5, are assembled by the Cu2[(R,S)-bpdado] tecton in the same arrangement mode. Apart from the arrangement modes of the tecton, some other elements are also discussed, which influence the final structures, such as the coordination modes and conformations of (R,S)-bpdado, the different metal ions, the reaction temperature, the N-donor ligand and the solvent system.

Synthesis, structures, and properties of lead(II) and cobalt(II) metal-organic frameworks based on a flexible benzophenone-2,4′-dicarboxylic acid (H2bpdc)

Two new coordination polymers, [Pb(bpdc)] n (1) and [Co(bpdc)(phen)] n (2) [H2bpdc = benzophenone-2,4′-dicarboxylic acid, phen = 1,10-phenanthroline], have been synthesized and structurally characterized. Hydrogen bonding and π ··· π stacking extend 1 and 2 into 3-D supramolecular architectures, where 1 exhibits a 3-D framework with 1-D hairpin-like helicates based on Pb–O covalent bonds and 2 displays a 3-D network with 1-D zipper-like chains based on Co–O and Co–N covalent bonds. The FT-IR spectra, PXRD and TG analyses are discussed for 1 and 2. Fluorescence spectra and luminescent lifetime are studied for 1.