Jing-Yun Wu

Giant metal–organic frameworks with bulky scaffolds: from microporous to mesoporous functional materials

New concepts on the design and synthesis of crystalline metal-organic frameworks (MOFs) have made them a subject of considerable interest in the growing field of materials science. By creating larger cavity sizes by a nearly infinite combination of metal nodes and organic linkers, many innovative characteristics of microporous MOFs have been revealed. The primary goal of this perspective article is to highlight the frontiers in the development of giant MOFs that are deliberately constructed from metallated or metal-free bulky scaffolds. Incorporating these types of distinct bulky ligands into giant MOFs may lead to MOFs with a large cavity size, intriguing properties and new framework topology. Emerging applications of these materials in catalysis, adsorption, and sensors are also discussed.

Highly emissive cyclometalated rhenium metallacycles: structure-luminescence relationship.

We report on a series of new self-assembled cyclometalated dirhenium(I) metallacyclic complexes via an unprecedented rhenium-mediated C-H bond activation and the relationship between their structures and luminescence properties.

Time‐Evolving Self‐Organization and Autonomous Structural Adaptation of Cobalt(II)–Organic Framework Materials with scu and pts Nets

Self-organization is a process, in which an internal system spontaneously opens a new route to increase system complexity without being guided by an external source. The concept of self-organization is central to the understanding of living organisms, biominerals, and new supramolecular materials. For chemistry, self-organizing equilibrium conditions can be controlled by changing a few critical factors (concentration, template, pH, temperature, solvent system, etc.) to generate desirable compounds. However, these explorations seem not to be completely applied in a few particular supramolecular systems. Inspired by biology, to construct a high-order architecture from individual building components, various driving forces may competitively predominate at certain stages of the self-assembly process. A subtle thermodynamic/kinetic balance may control and tune the materials growth delicately. Namely, self-organization processes can be operative if the building components are sufficient and in close proximity, under suitable conditions. If the supply of building units is depleted or reduced, the original equilibrium conditions will change, and a new self-organization process will take place. These intriguing phenomena of self-organization are triggered by an internal stimulus and seem to be easily understood in biology, but the phenomena has not been addressed in the synthesis system of metal–organic framework (MOF) materials. As part of our ongoing efforts in the design and synthesis of functional crystalline materials, we report herein on an intriguing supramolecular system that involves a distinct self-organization process, in which the product structures adapt to autonomous dynamic changes in the ratio of build-

From 1D Helix to 0D Loop: Nitrite Anion Induced Structural Transformation Associated with Unexpected N-Nitrosation of Amine Ligand

An infinite Ag(I) coordination 41-helical chain, [Ag(Hdpma)](NO3)2·H2O (1), was synthesized by the self-assembly of AgNO3 and di(3-pyridylmethyl)amine (dpma). Helix 1 is 5-fold interweaved and has a topological diamondoid-like net that is extended by ligand-unsupported helix-to-helix argentophilic interactions. Two identical diamondoid-like nets with opposite chiralities interpenetrate to form the whole 3D framework as a meso compound. Typical anion-exchange reactions cause a remarkable single-crystal-to-single-crystal (SCSC) structural transformation from the 1D helix 1 to the 0D molecular loop [Ag(dpma-NO)(NO2)]2 (2) (induced by the nitrite anion, NO2(-)) and a 1D molecular ladder [Ag(dpma)(H2O)](NO3) (induced by the fluoride anion, F(-)). Molecular loop 2 is an N-nitroso compound. This work is the first to present observations of nitrite-dominated in situ N-nitrosation of an amine ligand which accompanies SCSC structural transformation via an anion-exchange reaction.

Homochiral transition-metal camphorate coordination architectures containing “piperazine–pyridine” ligands

A total of five homochiral metal–organic coordination polymers (MOCPs) showing high thermal stability have been assembled from the reaction of divalent transition-metal ions (Co2+, Zn2+, and Cd2+), rigid enantiopure D-camphoric acid (D-H2Cam), and achiral neutral N,N′-bis(pyrid-4-yl)piperazine (bpypip) ligand under hydro(solvo)thermal conditions. Compound [Co2(D-Cam)2(bpypip)] (1) features a chiral-layered cobalt–camphorate coordination (4,4)-net, which is pillared by auxiliary linear N-tethering bpypip linkers to yield a homochiral three-dimensional coordination framework with Schlafli symbol of 44·610·8. Compounds [M(D-HCam)2(bpypip)] (2, M = Cd; 3, M = Zn) have nearly identical one-dimensional M–bpypip zigzag coordination-chain structures, in which each metal ion further attaches to two partially deprotonated monoanionic D-HCam terminals, which exhibit two types of partially deprotonating manner in 2 but only one type in 3. Through chain-to-chain C(O)OH⋯O(carboxylate) hydrogen bonds, the zigzag coordination-chain becomes extended to a three-dimensional uninodal 6-connected supramolecular network, which can be considered as a result of a M–D-HCam-based 4-connected supramolecular 65·8-net intersected by M–bpypip-based zigzag coordination-chains. Of particular interest, the supramolecular assembly contains a couple of single-stranded right- (SRH) and left-handed (SLH) supramolecular helices and a couple of double-stranded right- (DRH) and left-handed (DLH) supramolecular helices, and therefore exists as a meso-net in topology, i.e., there is no spatial chirality. Compounds [M2(OH)(OAc)(D-Cam)(bpypip)] (4, M = Co; 5, M = Zn) have identically homochiral ladder-like chain structures having meso-M2 units and presenting three kinds of different anions, i.e., hydroxyl, acetate, and D-Cam. The obtained acetate anion may be generated from the hydrolyzation of dimethylacetamide (DMAc) under hydro(solvo)thermal conditions.

Dissolution/reorganization toward the destruction/construction of porous cobalt(II)- and nickel(II)-carboxylate coordination polymers.

The alkali-metal-cation-induced structural transformation of porous coordination polymers (CPs), {A(2)[M(3)(btec)(2)(H(2)O)(4)]}(n) (1, A = K, M = Co; 2, A = K, M = Ni; 3, A = Cs, M = Co; and 4, A = Cs, M = Ni; btec = benzene-1,2,4,5-tetracarboxylate), occurred via a unique dissolution/reorganization process in the presence of an alkali chloride (LiCl, NaCl) in water. Treatment of 1 or 2 in an aqueous solution of LiCl resulted in the formation of new metal-carboxylate species [Co(2)(btec)(H(2)O)(10)] x H(2)O (5 x H(2)O) and {Li(2)[Ni(3)(btec)(2)(H(2)O)(10)] x 3.5 H(2)O}(n) (6 x 3.5 H(2)O), respectively. When NaCl was used in place of LiCl under similar reaction conditions, similar dissolution/reorganization processes were observed. The cobalt species 1 and 3 were converted into the metal-carboxylate product [Na(2)Co(btec)(H(2)O)(8)](n) (7), whereas the nickel-carboxylate frameworks 2 and 4 were transformed into {[Na(4)Ni(2)(btec)(2)(H(2)O)(18)] x 3 H(2)O}(n) (8 x 3 H(2)O). Single-crystal X-ray diffraction analysis revealed that 5 x H(2)O is a discrete molecule, which extends to a hydrogen-bonded 3D porous supramolecular network including tetrameric water aggregates. Compound 6 x 3.5 H(2)O adopts a 3D polymeric structure with a novel (2,4,4)-connected net on the basis of a 4-connecting organic node of a btec ligand, a square-planar 4-connecting metallic trans-Ni(O(2)C)(4)(H(2)O)(2) node, and a 2-connecting octahedral metallic trans-Ni(O(2)C)(2)(H(2)O)(4) hinge. Compound 7 possesses a 3D polymeric structure comprised of two types of intercrossed (4,4)-layers, a [Co(II)(btec)]-based layer and a [Na(I)(btec)]-based layer, in a nearly perpendicular orientation (ca. 87 degrees). Compound 8 x 3 H(2)O adopted a 2D sheet network by utilizing heterometallic trinuclear clusters of Na(2)Ni(O(2)C)(5)(H(2)O)(9) as secondary building units. Each sheet is hydrogen-bonded to neighboring units, giving a 3D supramolecular network. It is noteworthy that the dissolution/reorganization process demonstrates the cleavage and reformation of metal-carboxylate bonds, leading to a destruction/construction structural transformation of CPs.

Positional isomerism of unsymmetrical semirigid ligands toward the construction of discrete and infinite coordination architectures of zinc(II) and cadmium(II) complexes

Three unsymmetrical semirigid ligands, HInMe-n-py (n = 2, 3, 4), showing positional isomerism have assembled with ZnCl2 and CdCl2 to yield supramolecular coordination assemblies. Compound [Zn(InMe-2-py)2]·1/2THF·1/2CH3OH·1/4H2O (1) has a two-dimensional rhombus gridlike (4,4) layer structure constructed from the dinuclear paddlewheel [Zn2(O2C)4N2] units with two pendant side-arms. Compound [Zn2Cl2(InMe-3-py)2(HInMe-3-py)2] (2) forms a discrete armed M2L2 macrocycle, which connects with others by intermolecular O–H⋯O and C–H⋯Cl hydrogen bonds to give rise to a decorated three-dimensional supramolecular pcu net. Compound [Zn(InMe-4-py)2]·1/2H2O (3) adopts a two-dimensional chiral wavy (4,4) square grid. Opposite-handedness chiral wavy grids are stacked in an ABAB type of sequence that has small voids accommodating lattice water molecules. Compound [CdCl(InMe-3-py)] (4) displays a two-dimensional achiral meso layer in which the opposite-handedness Cd–L helical chains are interconnected by the Cd–O bridging bonds and stitched by zigzag Cd–Cl chains. Compound [Cd(InMe-4-py)2(H2O)2] (5) features a two-dimensional rhombus gridlike (4,4)-net. Through the connections of net-to-net O–H⋯O hydrogen bonds, the grids are offset-stacked to be a hydrogen-bonded three-dimensional oblique pcu net. The structural diversity and complexity in these supramolecular coordination architectures are most likely attributed to the various coordination modes adopted by these N- and O-donor ligands of different substituent position and the coordination preference exhibited by the metal ions. Thermogravimetric (TG) analyses showed that all the frameworks of compounds 1–5 exhibit a thermal stability higher than 300 °C. In addition, the solid-state photoluminescent properties of compounds 1–5 were investigated.

Host–guest key–lock hydrogen-bonding interactions: a rare case in the design of a V-shaped polycarboxylate Ni(II)-based chiral coordination polymer

A rare case in the design of a V-shaped polycarboxylate Ni(II)-based chiral coordination polymer from achiral ligands is described. Four metal–organic coordination networks, namely [Ni2(hfdpa)(bpypip)2(H2O)2](bpypip)·2.5H2O (1), [Ni3(Hodpa)2(bpypip)3(H2O)9] (2), [Ni2(odpa)(bpypip)2(H2O)2] (3), and [Cd2(bptc)(bpypip)2(H2O)2]·H2O (4), where H4hfdpa = 4,4′-(hexafluoroisopropylidene)diphthalic acid, H4odpa = 4,4′-oxydiphthalic acid, H4bptc = benzophenone-3,3′,4,4′-tetracarboxylic acid, and bpypip = N,N′-bis(pyrid-4-yl)piperazine, were prepared via a hydrothermal process. The structure of 1 exhibits a chiral three-dimensional porous framework, featuring left-handed Ni–O2C 21-screw helical chains along the crystallographic b axis and rectangular-shaped tubular open channels occupied by the uncoordinated bpypip and water molecules. Compound 2 possesses a 2-fold 2D + 2D → 2D interwoven sheet structure that is arranged interdigitally along the crystallographic a axis, forming an extensive three-dimensional supramolecular network through hydrogen-bonding. The structure of 3 shows a complicated 1D + 1D → 3D polyrotaxane coordination polymer entanglement, which suits a four-connected {6482}-net resembling the topology of a cds-net. Compound 4 has a complicated 2D + 2D → 3D coordination framework, which is simplified into a six-connected {496482}-net. In comparison with the crystal structures of the products, the uncoordinated bpypip ligands in 1, along with the guest water molecules, acts as a key for interacting with the coordinated V-shaped polycarboxylate hfdpa and coordinated bpypip ligands through simultaneous C–H⋯F, C–H⋯O, and C–H⋯N hydrogen-bonding, thereby assisting the generation of the chiral NiII coordination polymer. This type of host–guest key–lock interaction is unique and is observed for the first time by controlling the formation of a chiral coordination polymer.

Hydrogen bond-organized two-fold interpenetrating homochiral pcu net

Integrating enantiopure D-H2Cam ligands into a meso (4,4)-layer of Cu–4-ptz showing alternating orderly arranged right- and left-handed single-stranded 21 helices of achiral components leads to a hydrogen bond-organized three-dimensional two-fold interpenetrating homochiral pcu net.

Ag4L2 Nanocage as a Building Unit toward the Construction of Silver Metal Strings

Self-assembly of AgNO 3 with the semirigid tetratopic ligands 1,2,4,5-tetrakis(benzoimidazol-1-ylmethyl)benzene (TBim) and 1,2,4,5-tetrakis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene (TDMBim) afforded compounds [Ag 4(mu 4-TBim) 2(mu 2-eta (2)-NO 3) 2](NO 3) 2. (1)/ 2CH 2Cl 2.2CH 3OH ( 1mu (1)/ 2CH 2Cl 2.2CH 3OH) and [(NO 3 (-)) subset{Ag 4(mu 4-TDMBim) 2}][Ag(NO 3) 2](NO 3) 2.CH 2Cl 2.CH 3OH.4H 2O ( 2.CH 2Cl 2.CH 3OH.4H 2O), respectively. The structures of 1 and 2 were characterized by single-crystal X-ray diffraction analysis. Both compounds adopt a M 4L 2-type tetragonal metalloprismatic cage structure, [Ag 4(mu 4-L) 2] (4+), with strong intramolecular silver-silver contacts. Compound 1 is a discrete species, while compound 2 is a novel infinite chainlike supramolecular array involving silver metal strings assembled from a [Ag 4(mu 4-L) 2] (4+) nanocage and silver linkages. Thermogravimetric analyses of 1. (1)/ 2CH 2Cl 2.2CH 3OH and 2.CH 3OH.4H 2O indicate that the Ag 4L 2-cage structures of 1 and 2 both are thermally stable up to 330 degrees C. Results from an in situ (1)H NMR study of AgNO 3 and TDMBim in different molar ratios unambiguously revealed the successive self-organization process, in which self-organization of the molecular cage takes place initially followed by crystallization of the corresponding supramolecular arrays with silver metal strings.