Dong-Rong Xiao

A series of novel entangled coordination frameworks with inherent features of self-threading, polyrotaxane and polycatenane

Self-assembly of transition metal salts with long aromatic dicarboxylate ligands and N-containing ligands affords a series of entangled coordination frameworks based on different metal cores, namely [Mn4(μ2-OH2)2(sdba)4(bpp)4] (1), [Mn2(sdba)2(btb)0.5(H2O)] (2), [Mn4(sdba)4(bim)(H2O)4]·2H2O (3), [Ni(sdba)(bim)(H2O)2]·2H2O (4), [Co3(sdba)2(Hsdba)2(2,2′-bpy)2] (5) and [Ni2(bpda)2(bim)2]·H2O (6) (H2sdba = 4,4′-sulfonyldibenzoic acid, H2bpda = 4,4′-carbonyldibenzoic acid, bpp = 1,3-bis(4-pyridyl)propane, btb = 1,4-bis(1,2,4-triazol-1-yl)butane, bim = 1,4-bis(imidazol-1-yl)butane, 2,2′-bpy = 2,2′-bipyridine). Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, IR spectra and TG analyses. Compound 1 is a peculiar 2D self-threading network containing unusual triflexural helical motifs, which can be rationalized as a 6-connected 2D 36-hxl (hexagonal lattice) net with double edges. Compound 2 represents the first example of a 2D polycatenated framework formed by 1D quadruple chains, which could be considered as formed by interconnected 1D polyrotaxane columns involving the unusual [3]rotaxane components. Compound 3 consists of two interlocked 2D cage-containing frameworks and exhibits an unusual (2D → 2D) parallel interpenetrating array with coexistence of polyrotaxane and polycatenane. Compound 4 is composed of two interpenetrating 2D loop-containing frameworks with 4-connected (2.65) topology, and it can also be considered as being constructed by interconnected parallel 1D polyrotaxane chains. Compound 5 is comprised of two identical 2D hydrogen-bonded layers with 6-connected (22.48.65) topology that are interpenetrated in a parallel fashion, resulting in a twofold interpenetrating net having both polyrotaxane and polycatenane characters. Compound 6 represents an unusual mode of interpenetration of two distinct 3D frames both with CdSO4 topology, which is still very rare in entangled systems. In addition, the magnetic properties of compounds 1, 3, 4, 5 and 6 are discussed.

An unprecedented (5,12)-connected 3D self-penetrating metal–organic framework based on dinuclear barium clusters as building blocks

An unprecedented binodal (5,12)-connected 3D self-penetrating metal–organic framework was first assembled from dinuclear barium clusters as 12-connected nodes and flexible ligands 4,4′-sulfonyldibenzoate as 5-connected nodes, and it represents the highest connected self-penetrating topology presently known for metal–organic frameworks.

Unusual self-threading and interdigitated architectures self-assembled from long flexible ligands and d10 metal salts

Four new entangled metal–organic polymers, namely [Cd2(sdba)2(Htpim)2(H2O)2]·5H2O (1), [Zn(sdba)(Htpim)] (2), [Cd(sdba)(bim)] (3), [Cd(sdba)(bimp)] (4) (sdba = 4,4′-sulfonyldibenzoate, Htpim = 2,4,5-tri(4-pyridyl)-imidazole, bim = 1,4-bis(imidazol-1-yl)butane, bimp = 1,4-bis(imidazol-1-yl)propane), have been hydrothermally synthesized and further characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectra and TG analyses. Compound 1 consists of two identical 3D self-threading frameworks with CdSO4 topology, which exhibits a twofold interpenetrating architecture and represents the first entangled coordination polymer containing both interpenetration and self-threading features. Compound 2 exhibits a novel (1D → 3D) interdigitated architecture that is obtained from the self-assembly of 1D tubelike structures, in which each 1D tube is interdigitated by dangling arms from four adjacent tubes belonging to four different spatial orientations. Compounds 3 and 4 are close to being isostructural, and both exhibit a novel (2D → 3D) interdigitated architecture, which is assembled from hydrogen-bonded bilayer motifs that are formed by two kinds of chiral layers (one left-handed and the other right-handed) showing a deep mutual interdigitation. In addition, photoluminescent properties for 1–3 are investigated in detail.

Guest-induced expanding and shrinking porous modulation based on interdigitated metal–organic frameworks constructed by 4,4′-sulfonyldibenzoate and barium ions

A series of barium-4,4′-sulfonyldibenzoate (sdba) coordination polymers, namely, [Ba(μ2-OH2)(sdba)(H2O)3]·0.5H2O (1), [Ba(μ2-OH2)(sdba)(H2O)3]·0.5ben·H2O (2), [Ba(μ2-OH2)(sdba)(H2O)3]·0.5tolu·H2O (3), [Ba(μ2-OH2)(sdba)(H2O)3]·0.5bpy·H2O (4), [Ba(μ2-OH2)(sdba)(H2O)3]·0.25bim·H2O (5), [Ba(μ2-OH2)(sdba)(H2O)3]·0.5dfb·0.25H2O (6) and [Ba(μ2-OH2)(sdba)(H2O)3]·3.5H2O (7) (ben = benzene, tolu = toluene, bpy = 2,2′-bipyridine, bim = 1,4-bis(imidazol-1-yl)butane, dfb = 1,3-difluoro-benzene (a fragment of fluconazole)), have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, powder X-ray diffraction, elemental analysis, IR spectra, and TG analyses. Compounds 1–7 are built upon similar sidearm-containing 2D bilayer motifs, and the adjacent layers are stacked in a mutual interdigitation, such that channels are created. The channels form a hydrogen-bonded interior for guest molecules. In practice, compounds 1 and 7 contain different quantities of free water molecules as guests in the channels, whereas compounds 2–6 contain ben, tolu, bpy, bim and dfb molecules as well as free water molecules in their channels, respectively. The different interlayer distances and free void spaces of 1–7 indicate the effect of guest-induced expanding and shrinking porous modulation, and give a clue to the dynamic arrangement in this system. This indicates the obtained compounds (1–7) are categorized as a member of a new generation of compounds tending towards functional porous coordination polymers. In addition, the photoluminescent properties for all the compounds (1–7) were investigated in detail.

Helicity controlled by the chirality of amino acid: two novel enantiopure chiral 3D architectures containing fivefold interwoven helices

Two novel three-dimensional (3D) chiral coordination polymers, namely [Zn4(btc)2(Hbtc)(L-His)2(H2O)4]·1.5H2O (L-1) and [Zn4(btc)2(Hbtc)(D-His)2(H2O)4]·1.5H2O (D-1), have been assembled from zinc salt with mixed ligands 1,3,5-benzenetricarboxylic acid (H3btc) and chiral histidine (His). Their structures were determined by single-crystal X-ray diffraction analyses, elemental analyses, infrared (IR) spectra, X-ray powder diffraction, circular dichroism (CD) spectra, and thermogravimetric (TG) analysis. Compounds L-1 and D-1 are enantiomers and exhibit unique 3D chiral frameworks containing fivefold interwoven helices, which represent the first examples of chiral metal–amino acid complexes containing n-fold interwoven helices. Furthermore, the helices in L-1 are left-handed, while those in D-1 are right-handed, which indicate that the handedness of helices can be controlled by the chirality of His bound to the metal. More wonderfully, the 3D framework can be simplified to a (3,4)-connected chiral net with an unprecedented (4·92)(4·94·11) topology. Moreover, the luminescent properties of compound L-1 are discussed.

An unprecedented 3-fold interpenetrated double-edged pseudo-diamondoid network containing exceptional 5-fold interlocking tri-flexure helices and 15-fold interwoven helices

The first entangled metal-ppa complex, containing unique 5-fold interlocking tri-flexure helices and 15-fold interwoven helices, defines an unprecedented 3-fold interpenetrated double-edged pseudo-diamondoid (pseudo-dia) network, which, not only represents the first and only example of interpenetrating metal-quinolone complex, but also represents the highest degree of interpenetration presently known for double-edged nets.

An unusual 3D 8-connected entangled coordination network with coexistence of self-threading, polythreading and interpenetration

An 8-connected entangled metal–organic framework has been synthesized and characterized, which not only represents the first entangled framework with coexistence of self-threading, polythreading and interpenetration, but also represents the highest connected topology presently known for self-threading and polythreading systems.

Syntheses, structures and properties of five entangled coordination polymers constructed with trigonal N-donor ligands

Based on the mixed-ligand system, five new entangled coordination polymers have been synthesized, namely, [Co1.5(1,3-bdc)1.5(tib)(H2O)] (1), [Ni(1,3-bdc)(tib)(H2O)2]·0.5H2O (2), [Cu(Hbtc)(Htpim)] (3), [Co(bpndc)(pytpy)(H2O)]·0.5H2O (4), and [Ni(bpndc)(pytpy)(H2O)]·0.5H2O (5), (1,3-bdc = 1,3-benzenedicarboxylate, btc = 1,3,5-benzenetricarboxylate, bpndc = 4,4′-benzophenone dicarboxylate, tib = 1,3,5-tris(1-imidazolyl)benzene, Htpim = 2,4,5-tri(4-pyridyl)-imidazole, pytpy = 2,4,6-tris(4-pyridyl)pyridine). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy and TG analyses. Compound 1 exhibits a new trinodal (3,4,4)-connected 3D self-penetrating framework with (83)2(63.82.9)2(84.9.10) topology. Compound 2 displays an interesting 2D → 3D polythreading framework constructed from sidearm-containing 2D 63-hcb nets. Compound 3 exhibits an unusual (2D → 3D) entangled array with the coexistence of polythreading and interdigitation self-assembled from sidearm-containing 2D double-edged nets. Compounds 4 and 5 both show an intriguing 3-fold interpenetrated PtS-type (4,4)-connected 3D framework containing meso-helices. In addition, the magnetic properties of compounds 1–5 have been investigated in the temperature range 2–300 K.

Highly Stable Mesoporous Luminescence-Functionalized MOF with Excellent Electrochemiluminescence Property for Ultrasensitive Immunosensor Construction

In this work, a novel mesoporous luminescence-functionalized metal-organic framework (Ru-PCN-777) with high stability and excellent electrochemiluminescence (ECL) performance was synthesized by immobilizing Ru(bpy)2(mcpbpy)2+ on the Zr6 cluster of PCN-777 via a strong coordination bond between Zr4+ and -COO-. Consequently, the Ru(bpy)2(mcpbpy)2+ could not only cover the surface of PCN-777 but also graft into the interior of PCN-777, which greatly increased the loading amount of Ru(bpy)2(mcpbpy)2+ and effectively prevented the leaching of the Ru(bpy)2(mcpbpy)2+ resulting in a stable and high ECL response. Considering the above merits, we utilized the mesoporous Ru-PCN-777 to construct an ECL immunosensor to detect mucin 1 (MUC1) based on proximity-induced intramolecular DNA strand displacement (PiDSD). The ECL signal was further enhanced by the enzyme-assisted DNA recycling amplification strategy. As expected, the immunosensor had excellent sensitivity, specificity, and responded wide linearly to the concentration of MUC1 from 100 fg/mL to 100 ng/mL with a low detection limit of 33.3 fg/mL (S/N = 3). It is the first time that mesoporous Zr-MOF was introduced into ECL system to assay biomolecules, which might expand the application of mesoporous metal-organic frameworks (MOFs) in bioanalysis. This work indicates that the use of highly stable mesoporous luminescence-functionalized MOFs to enhance the ECL intensity and stability is a feasible strategy for designing and constructing high-performance ECL materials, and therefore may shed light on new ways to develop highly sensitive and selective ECL sensors.

Diaqua­(5-carb­oxy­benzene-1,3-dicarboxyl­ato-κO1)[8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydro­pyrido[2,3-d]pyrimidine-6-carboxyl­ato-κ2O5,O6]zinc monohydrate

In the title compound, [Zn(C14H17N5O3)(C9H4O6)(H2O)2]·H2O, the complex molecule exists in a zwitterionic form. The ZnII ion exhibits a distorted tetragonal-pyramidal geometry, being coordinated by two O atoms from the zwitterionic 8-ethyl-5-oxo-2-(piperazin-4-ium-1-yl)-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate (L) ligand, one O atom from the 5-carboxybenzene-1,3-dicarboxylate dianion, [Hbtc]2−, and two O atoms from two aqua ligands. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the components into a three-dimensional structure. The crystal packing exhibits π–π interactions between the aromatic rings, with centroid–centroid distances in the range 3.466 (3)–3.667 (3) Å.