Mingli Deng

Synthesis of Isoreticular Zinc(II)‐Phosphonocarboxylate Frameworks and Their Application in the Friedel–Crafts Benzylation Reaction

Three isoreticular zinc(II)-phosphonocarboxylate frameworks, namely {[Zn(3)(pbdc)(2)]·2H(3)O}(n) (ZnPC-2), {[Zn(3)(pbdc)(2)]·Hpd·H(3)O·4H(2)O}(n) (Hpd@ZnPC-2) and {[Co(1.5)Zn(1.5)(pbdc)(2)]·2H(3)O}(n) (CoZnPC-2) (H(4)pbdc=5-phosphonobenzene-1,3-dicarboxylic acid, pd=pyrrolidine), were solvothermally synthesized. ZnPC-2 has a 3D structure based on trinuclear Zn(II) clusters (Zn(3)-SBU) showing 3D interconnected channels. Hpd@ZnPC-2 contains an isoreticular framework of ZnPC-2 with small channels blocked by Hpd molecules. In CoZnPC-2, Zn(II) ions in ZnPC-2 are partially substituted by Co(II) ions. The Friedel-Crafts benzylation reactions were carried out over these isoreticular porous materials. The catalytic results reveal that ZnPC-2 is an excellent heterogeneous Lewis acid catalyst with a high selectivity (>90%) towards less bulky para-oriented products. The catalytic reaction has been proved to occur inside the pore of ZnPC-2, and the immobilized Zn(3)-SBUs are the active sites.

Novel Iso-Reticular Zn(II) Metal–Organic Frameworks constructed by Trinuclear-Triangular and Paddle-Wheel Units: Synthesis, Structure and Gas Adsorption

Two novel Zn(II) metal-organic frameworks (MOFs) constructed by trinuclear-triangular and paddle-wheel units, namely {[Zn(5)(dmtrz)(3)(IPA)(3)(OH)]·DMF·H(2)O}(n) (MAC-4, Hdmtrz = 3,5-dimethyl-1H-1,2,4-triazole, H(2)IPA = isophthalic acid, DMF = dimethyl formamide) and {[Zn(5)(dmtrz)(3)(OH-IPA)(3)(OH)]·DMF·5H(2)O}(n) (MAC-4-OH, OH-H(2)IPA = 5-hydroxyisophthalic acid), were solvothermally synthesized. Single-crystal analyses reveal that MAC-4-OH is an iso-reticular framework of MAC-4 with channels functionalized by hydroxyl groups. Gas adsorption reveals that MAC-4-OH shows a significant enhancement for CO(2) uptake compared with that of MAC-4 due to the existence of electrostatic attractive interactions, though its surface area is lower than that of MAC-4.

A flexible porous metal–azolate framework constructed by [Cu3(μ3-OH)(μ2-O)(triazolate)2]+ building blocks: synthesis, reversible structural transformation and related magnetic properties

A three-dimensional (3D) porous structure of [Cu3(μ3-OH)(μ2-O)(dmtrz)2(HCOO)(μ2-H2O)(H2O)3]·H2O (1) has been in situ solvothermally synthesized. In 1, the trinuclear triangular [Cu3(μ3-OH)(μ2-O)(dmtrz)2] cluster connects itself infinitely, resulting in the type-II channel structure, which is different from that of the rigid type-I channel structure reported previously. Reversible dehydration and rehydration induced crystal-to-amorphous-like phase transformation for structure 1 has been observed and confirmed by PXRD patterns and gas adsorption. Furthermore, as a response to the structural transformation, the stimuli-induced modulation of magnetic properties have been observed.

Solvothermal in situ synthesis of cyanide-containing ternary silver(I) coordination polymers and their phosphorescent properties

Cyanide group is a robust electron-mediate ligand, widely used in functional coordination polymers. Synthesis of cyanide-containing functional coordination polymersvia solvothermal in situ reaction is a new efficient approach. In this paper, four novel ternary coordination polymers, namely [Ag3(trz)2(CN)]n (1), [Ag3(detrz)2(CN)]n (2), [Ag4(dptrz)2(CN)2]n (3), [Ag3(dptrz)2(CN)]n (4) (Htrz = 1H-1,2,4-triazole, Hdetrz = 3,5-diethyl-1H-1,2,4-triazole, Hdptrz = 3,5-dipropyl-1H-1,2,4-triazole), were solvothermally synthesized and characterized. The cyanide groups are all in situ generated from C–C cleavage reaction of acetonitrile. The cyanide group acts as terminal group in 1, while as linker in 2, 3, 4. Phosphorescent properties of these in situ products are studied and compared with binary silver-triazole coordination polymers. The results show that phosphorescent emissions of 2, 3, and 4 are red-shifted compared to that of 1.

Controllable preparation and structures of two zinc phosphonocarboxylate frameworks with MER and RHO zeolitic topologies

3-Phosphonobenzoic acid (3-H3pbc) was designed as an extended 4-connected ligand to build zeolite-like metal–organic frameworks (ZMOFs). Controlled assembly of Zn2+ with ligand 3-H3pbc results in two distinct structures with zeolitic topologies of MER and RHO, namely [Zn(3-pbc)]·H3O·0.5H2O (1) and Zn2.5(3-pbc)2(H2O)·nS (S represents the disordered solvent molecules) (2), respectively. The framework of 1 consists of double crankshaft chains formed by alternating ZnO4 and O3PC tetrahedra that are cross-linked by 3-pbc to generate a three-dimensional zeolitic open-framework. It is worth noting that structure 2 builds a zeolitic framework in a novel way, which has not been found in other metal phosphonocarboxylates. The organic part of 3-pbc does not participate in the construction of zeolitic topology and only plays a decorative role inside the cages.

Acid-induced Zn(II)-based metal–organic frameworks for encapsulation and sensitization of lanthanide cations

Two Zn(II)-based metal–organic frameworks, namely, [Zn3(Hbptc)2(DMF)2]·2DMF(1) and [Zn5(bptc)3(H2O)]((CH3)2NH2)2(2), (H4bptc = 3,3′,5,5′-biphenyltetracarboxylic acid, DMF = N,N′-dimethylformamide), have been synthesized using different amounts of nitric acid under mixed-solvothermal conditions. 1 and 2 display different coordination geometries and donor ligands for the Zn2+ ions. In 1, only three carboxylic acid groups of H4bptc take part in the construction of the three-dimensional (3-D) framework with Zn2+, and one remains uncoordinated that can bind to other metal ions. Postsynthetic exchange of 1 with Ln3+ cations demonstrates that 1 can effectively capture metal cations and sensitize the visible-emitting Ln3+.

A self-catenated rob-type porous coordination polymer constructed from triazolate and carboxylate ligands: fluorescence response to the reversible phase transformation

A flexible structure of {[Zn2(dmtrz)2(L1)]·6H2O}n (MAC-11) (Hdmtrz = 3,5-dimethyl-1H,1,2,4-triazole, H2L1 = (E)-4,4′-stilbenedicarboxylic acid), which is a self-catenated rob-type net built of two-dimensional [Zn(dmtrz)] layers pillared by L1 ligands, has been solvothermally synthesized. It shows an interesting thermo/water-induced reversible phase transformation accompanied by a photoluminescence response from 418 nm to 453 nm. Based on an iso-framework of {[Zn2(dmtrz)2(L2)]·4H2O}n (MAC-13, H2L2 = (E)-azobenzene-4,4′-dicarboxylic acid), a pcu-type framework of {[Zn2(trz)2(L1)]·4H2O}n (MAC-14, Htrz = 1H, 1,2,4-triazole), and a layered structure of [Zn(dmtrz)(HCOO)], a possible mechanism for the photoluminescence response to the reversible phase transformation for MAC-11 was also proposed.

Four organic–inorganic compounds based on polyoxometalates: crystal structures and catalytic epoxidation of styrene

Four compounds based on polyoxometalates, [Cu(4-bpo)(H2O)][Cu2(μ2-Cl)(4-bpo)2(H2O)][SiW12O40][N(CH3)4]2·H2O (1), [Cu(4-bpo)]4[P2W18O62][N(CH3)4]2·6H2O (2), [Cu2(μ2-OH)(4-bpo)2(Hina)(H2O)2]2[P2W18O62]·4H2O (3), and [Cu2(Hina)4(H2O)2][H2P2W18O62](Hina)·11H2O (4) (4-bpo=2,5-bis(4-pyridyl)-1,3,4-oxadiazole, ina=isonicotinic acid), have been hydrothermally synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The 3-D framework of 1 is composed by Keggin-type polyoxoanions {SiW12} and two types of infinite chains, {Cu(4-bpo)(H2O)}n and {Cu2(μ2-Cl)(4-bpo)2(H2O)}n, through hydrogen bonds. Compound 2 has a 3-D rigid framework which is fabricated by Wells–Dawson type polyoxoanions {P2W18} and Cu-(4-bpo) chains through covalent bonds. Compound 3 contains an infinite {Cu2(μ2-OH)(4-bpo)2(Hina)(H2O)2}n double-chain and {P2W18} polyoxoanions immobilized in the voids between the chains. Compound 4 exhibits a 3-D supramolecular network directed by hydrogen bonds between {P2W18} polyoxoanions and the double paddle-wheel {Cu2(Hina)4(H2O)2}. Compounds 1–4 were tested as heterogeneous catalysts for the epoxidation of styrene using tert-butyl hydroperoxide (TBHP) as oxidant. The compounds show catalytic activity with 2 giving the highest yield of styrene oxide. Four organic–inorganic hybrid compounds were hydrothermally synthesized based on polyoxometalates, copper salts, and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole or isonicotinic acid ligands. Among those four compounds, compound 2, [Cu(4-bpo)]4[P2W18O62][N(CH3)4]2·6H2O, showed the best catalytic activity for heterogeneous epoxidation of styrene to styrene oxide using tert-butyl hydroperoxide as oxidant.

Predicting and creating 7-connected Zn4O vertices for the construction of an exceptional metal–organic framework with nanoscale cages

A 7-connected Zn4O unit has been theoretically predicted based on the model of basic zinc acetate [Zn4O(CH3COO)6], which was then experimentally extended into a three-dimensional structure featuring three kinds of nanocage in a unit cell.

Integrating Zeolite-Type Chalcogenide with Titanium Dioxide Nanowires for Enhanced Photoelectrochemical Activity

Developing photoanodes with efficient visible-light harvesting and excellent charge separation still remains a key challenge in photoelectrochemical water splitting. Here zeolite-type chalcogenide CPM-121 is integrated with TiO2 nanowires to form a heterostructured photoanode, in which crystalline CPM-121 particles serve as a visible light absorber and TiO2 nanowires serve as an electron conductor. Owing to the small band gap of chalcogenides, the hybrid electrode demonstrates obvious absorption in visible-light range. Electrochemical impedance spectroscopy (EIS) shows that electron transport in the hybrid electrode has been significantly facilitated due to the heterojunction formation. A >3-fold increase in photocurrent is observed on the hybrid electrode under visible-light illumination when it is used as a photoanode in a neutral electrolyte without sacrificial agents. This study opens up a new avenue to explore the potential applications of crystalline porous chalcogenide materials for solar-energy conversion in photoelectrochemistry.