Ying-Ying Liu

Four-, and six-connected entangled frameworks based on flexible bis(imidazole) ligands and long dicarboxylate anions

A series of four- and six-connected entangled structures, namely [Cd(oba)(bbi)]·0.5H2O (1), [Ni(oba)(bbi)]2·H2O (2), [Co(bpea)(bbi)]·H2O (3), [Co2(bpea)2(bbi)2]·1.5H2O (4), [Cd(oba)(1,4-bix)] (5), and [Ni2(oba)2(1,4-bix)(H2O)2] (6), where oba = 4,4′-oxybis(benzoate), bpea = biphenylethene-4,4′-dicarboxylate, 1,4-bix = 1,4-bis(imidazol-1-ylmethyl)benzene, and bbi = 1,1′-(1,4-butanediyl)bis(imidazole), have been successfully synthesized through a hydrothermal process. The structures of 1 and 2 both consist of two interpenetrating CdSO4 nets. In 1, the two nets are related by symmetry. By comparison, the individual nets are, unusually, crystallographically distinct in 2. The structures of 3 and 4 both contain interpenetrating diamond networks. In 3, there are 6 interpenetrating nets, and they show the usual mode of interpenetration. For 4, however, there are 7 nets, and a rare ‘abnormal’ [4 + 3] interpenetration mode is observed. In 5, the oba and 1,4-bix ligands linked the Cd(II) atoms into a deeply corrugated 2D sheet. The corrugated 2D sheets polycatenate each other in a parallel manner with DOC (degree of catenation) = 2, yielding a rare 2D → 3D parallel polycatenation net. In 6, the dinuclear Ni(II) units are bridged by the oba ligands to generate a 2D (4,4) square-grid with a rhombic window. It is interesting that the two identical (4,4) square-grids show 2D → 2D parallel interpenetration but are then further crosslinked by the 1,4-bix ligands to yield an unusual 3D self-penetrating net with an unique 6-connected 44.611 topology. The importance of bbi conformations and metal sources in the framework formation of complexes 1–6 was unraveled. Their infrared spectra, powder X-ray diffraction (XRD) and photoluminescent properties were also investigated in detail.

Controllable Syntheses of Porous Metal–Organic Frameworks: Encapsulation of LnIII Cations for Tunable Luminescence and Small Drug Molecules for Efficient Delivery

Two porous metal-organic frameworks (MOFs), [Zn3 (L)(H2 O)2 ]⋅3 DMF⋅7 H2 O (MOF-1) and [(CH3 )2 NH2 ]6 [Ni3 (L)2 (H2 O)6 ]⋅3 DMF⋅15 H2 O (MOF-2), were synthesized solvothermally (H6 L=1,2,3,4,5,6-hexakis(3-carboxyphenyloxymethylene)benzene). In MOF-1, neighboring Zn(II) trimers are linked by the backbones of L ligands to form a fascinating 3D six-connected framework with the point symbol (4(12) .6(3) ) (4(12) .6(3) ). In MOF-2, eight L ligands bridge six Ni(II) atoms to generate a rhombic-dodecahedral [Ni6 L8 ] cage. Each cage is surrounded by eight adjacent ones through sharing of carboxylate groups to yield an unusual 3D porous framework. Encapsulation of Ln(III) cations for tunable luminescence and small drug molecules for efficient delivery were investigated in detail for MOF-1.

An unusual ten-connected self-penetrating metal–organic framework based on tetranuclear cobalt clusters

The unusual ten-connected self-penetrating metal-organic framework based on tetranuclear cobalt clusters has been synthesized and characterized, which represents the highest-connected uninodal network topology presently known for self-penetrating systems.

Room-temperature ferromagnetism in (Mn, N)-codoped ZnO thin films prepared by reactive magnetron cosputtering

(Mn, N)-codoped ZnO films were grown on fused silica substrates by reactive magnetron cosputtering. X-ray diffraction measurements reveal that the films have the single-phase wurtzite structure with c-axis preferred orientation. X-ray photoelectron spectroscopy studies indicate the incorporation of both divalent Mn2+ and trivalent N3− ions into ZnO lattice. Acceptor doping with nitrogen partly compensates the “native donors,” which results in a low electron concentration of 3.16×1016cm−3 though p-type conductivity is not achieved. (Mn, N)-codoped ZnO films show significant ferromagnetism with Curie temperature above 300K. The mechanism of ferromagnetic coupling in codoped ZnO is discussed based on a bound magnetic polaron model.

A series of coordination polymers based on reduced Schiff base multidentate anions and bis(imidazole) ligands: syntheses, structures and photoluminescence

Eleven new coordination polymers, namely, [Zn(L1)(bbi)]·0.5H2O (1), [Co(L1)(bbi)]·0.5H2O (2), [Cd(L1)(bbi)]·0.5H2O (3), [Zn(L2)(bbi)]·H2O (4), [Co(L2)(bbi)]·1.25H2O (5), [Cd(L2)(bbi)0.5(H2O)] (6), [Zn(L3)(bbi)]·H2O (7), [Co(L3)(bbi)]·H2O (8), [Cd(L3)(bbi)0.5(H2O)]·2H2O (9), [Zn(HL4)(bbi)] (10) and [Cd(HL4)(bbi)(H2O)]·1.5H2O (11), where H2L1 = 4-carboxy-phenylene-methyleneamino-2-benzyl acid, H2L2 = 4-carboxy-phenylene-methyleneamino-3-benzyl acid, H2L3 = 4-carboxy-phenylene-methyleneamino-4-benzyl acid, H3L4 = 4-carboxy-phenylene-methyleneimino-3,5-dibenzyl acid and bbi = 1,4-bis(1H-imidazol-1-yl)butane, have been synthesized under hydrothermal conditions. Compounds 1–3 are isomorphous, and show 2D two-fold interpenetrating 63-hcb networks. Compound 5 is isomorphous with 4. Compound 4 displays a 2D undulated layer structure. Adjacent layers are connected through hydrogen bonds to generate a 3D supramolecular architecture. The structure of compound 6 is an unusual 2D 2-fold parallel interpenetrating network with both polyrotaxane and polycatenane characters. 7 and 8 show 2D undulated sheet structures. The sheets are penetrated by each other to give rise to 3D polycatenations. The structure of compound 9 is an intriguing 2D self-penetrating network. Further, the π–π interactions among the L3 anions link the 2D networks into a 3D supramolecular assembly. Compound 10 displays a corrugated 2D (4,4) sheet with dangling arms. Each sheet is threaded by the dangling arms of two others, leading to an unusual 3D polythreading framework. The structure of compound 11 is a 3D (3,4)-connected framework with (42·6)(42·6·123) topology. The thermogravimetric and luminescent properties have also been studied for the compounds.

A series of 1D, 2D and 3D coordination polymers based on a 5-(benzonic-4-ylmethoxy)isophthalic acid: syntheses, structures and photoluminescence

Seven new coordination polymers, namely, [Zn(HL)(H2O)] (1), [Zn(HL)(phen)]·1.5H2O (2), [Zn(HL)(L1)] (3), [Zn2(HL)2(L2)2]·2H2O (4), [Zn(HL)(L3)0.5] (5), [Zn(HL)(L4)] (6) and [Cu2(L)(OH)(H2O)]·0.5H2O (7) (H3L = 5-(benzonic-4-ylmethoxy) isophthalic acid, phen = 1,10-phenathroline, L1 = 1,2-bis(1,2,4-triazole-1-yl)ethane, L2 = 1,3-bis(1,2,4-triazole-1-yl)propane, L3 = 1,6-bis(1,2,4-triazole-1-yl)hexane and L4 = 4,4′-bis(1,2,4-triazole-1-ylmethyl)biphenyl), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. In compounds 1–6, the H3L ligand is partially deprotonated to form HL2−, while it is completely deprotonated in 7. Compound 1 shows a 3D framework with 4-connected (42·7·83)2 topology. Compound 2 displays a 1D ribbon structure. The neighboring ribbons are further linked by hydrogen-bonding interactions to form a 3D supramolecular architecture. Compound 3 exhibits a 2D undulated sheet. The sheets are further penetrated into each other to give rise to a 3D polycatenation structure. Compound 4 displays a 2D supramolecular layer structure. Compound 5 shows a 3D (3,6)-connected (4·8)(4·82·103) net. Compound 6 reveals a 3D four-fold interpenetrating diamondoid architecture. Compound 7 displays a (3,8)-connected (4·62)(44·68·812·104) topology. These compounds have been characterized by powder X-ray diffractions (PXRD) and thermal gravimetric analyses (TGA). In addition, the photoluminescent behaviours of 1–6 have been investigated in detail.

A new microporous anionic metal–organic framework as a platform for highly selective adsorption and separation of organic dyes

We report a new microporous negatively charged metal–organic framework (MOF), [(C2H5)2NH2]2[Mn6(L)(OH)2(H2O)6]·4DEF (1) (H12L = 5,5′,5′′,5′′′,5′′′′,5′′′′′-[1,2,3,4,5,6-phenylhexamethoxyl]hexaisophthalic acid and DEF = N,N′-diethylformamide), and its utilization as a platform for the highly selective adsorption and separation of organic dyes through an ion-exchange process. The dynamics of selective adsorption, separation and release of a series of organic dyes demonstrated that this exchange-based separation process is highly related to the sizes or charges of organic dyes, and this relationship can be controlled by the structural characteristics of MOF 1.

Two novel 3D metal–organic frameworks based on two tetrahedral ligands: syntheses, structures, photoluminescence and photocatalytic properties

Two novel metal–organic frameworks (MOFs), namely [Co2(L1)(L2)]·4.25H2O (1) and [Cd4(L1)2(L2)2]·4H2O·DMF (2) (H4L1 = tetrakis[4-(carboxyphenyl)-oxamethyl]methane acid and L2 = tetrakis(imidazol-1-ylmethyl)methane), have been hydrothermally synthesized. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses, UV-vis absorption spectra, optical energy gap and emission spectra. In 1, tetrahedral L1 and L2 ligands link neighboring Co(II) atoms to generate a unique 3D self-penetrating framework with a tetranodal 4-connected (6·85)2(63·83)(86) topology. However, in 2, Cd(II) atoms are bridged by L1 and L2 ligands to furnish a 3D framework with a highly rare (4,8)-connected (46)(44·62)(410·614·74) topology. In addition, compound 1 exhibits photocatalytic activity for dye degradation under UV light or visible-light and shows good stability toward photocatalysis.

Flexible Resistive Switching Memory Device Based on Amorphous InGaZnO Film With Excellent Mechanical Endurance

Semitransparent flexible resistive-switching memory devices, using amorphous InGaZnO as the switching layer, are fabricated on plastic substrates at room temperature. The device shows high performance, excellent flexibility, and mechanical endurance in bending tests. No performance degradation occurs, and the stored information is not lost after bending the device to different angles and up to 105 times. Studies on the temperature-dependent electrical properties reveal that the conducting channels of the low-resistance state are composed of oxygen-deficient defects, and partial oxidation of these defects switches the device to the high-resistance state. The unique electronic structure and flexible mechanical properties of amorphous InGaZnO ensure stable device performance in flexible applications.

Syntheses, structures and photoluminescent properties of a series of metal–organic frameworks based on a flexible tetracarboxylic acid and different bis(imidazole) ligands

A series of new metal–organic frameworks (MOFs), namely, [Co2(L)(H2O)3]·5H2O (1), [Co(L)0.5(biim-4)]·H2O (2), [Co(L)0.5(biim-5)]·H2O (3), [Co(L)0.5(biim-6)]·1.5H2O (4), [Co2(L)(BIE)1.5]·H2O (5), [Co2(L)(bbip)2]·3H2O (6), [Ni(L)0.5(biim-4)1.5] (7), [Ni2(L)(biim-6)2]·2H2O (8), [Zn(L)0.5(biim-4)]·H2O (9), [Zn(L)0.5(biim-5)]·H2O (10), [Zn(L)0.5(biim-6)]·H2O (11), [Zn2(L)(BIE)] (12), and [Zn(L)0.5(bbip)0.5]·0.5H2O (13), where biim-4 = 1,1′-(1,4-butanediyl)bis(imidazole), biim-5 = 1,1′-(1,5-pentanedidyl)bis(imidazole), biim-6 = 1,1′-(1,6-hexanedidyl)bis(imidazole), BIE = 1,1′-(2,2′-oxybis(ethane-2,1-diyl))bis(1H-imidazole), bbip = 1,1′-(1,4-butanediyl)bis(imidazole-2-phenyl), and H4L = 5,5′-(ethane-1,2-diyl)-bis(oxy)diisophthalic acid, have been synthesized under hydrothermal conditions. Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD) and thermogravimetric (TG) analyses. Compound 1 features a 3D 2-fold interpenetrating diamond framework. Compounds 2–4 and 9–11 are isostructural and display 3D 3-fold interpenetrating frameworks with (64·82)(66) topologies. Compound 5 exhibits a 3D (4,6)-connected (64·72)(4·65)(42·64·75·84) topology. Compounds 6 and 7 are 3D 2-fold interpenetrating frameworks with (66)2(64·82) and (42·64)(43·67) topologies, respectively. Compound 8 shows a 2D double-layer structure. Compound 12 possesses a 3D framework with (4,6)-connected (3·42·52·6)(32·42·52·64·74·8)2 topology. Compound 13 has a 3D 2-fold interpenetrating framework with (44·62)(44·610·8) topology. The luminescent properties of 9–13 have also been investigated in detail.