Jie-Ping Liu

Four metal–organic frameworks based on the 5-(1H-tetrazol-5-yl)isophthalic acid ligand: luminescence and magnetic properties

Four transition metal coordination polymers with 5-(1H-tetrazol-5-yl)isophthalic acid ligand (H3TZI) were synthesized and structurally characterized. They are formulated as [Zn(TZI)]·(CH3)2NH2+·H2O (1), [Cd2(OH)(TZI)(H2O)2]·DMF·0.5H2O (2), [MnNa(TZI)]·2H2O (3), and [Mn3(TZI)2(12H2O)]·4H2O (4). Compound 1 displays a 3D (4,4)-connected framework with a Schlafli symbol of 426282. 2 exhibits 3D frameworks in which strip-shaped chains with Cd3(μ3-OH) triangles are linked by TZI ligands, presenting a rare (3,4,5,6)-connected 4-nodal net topology with the point symbol (43)(4462)(4664)(4768). 3 features 2D 2p–3d heterometallic layers in which 1D chains with mixed bridges linking alternating Mn(II) ions and Na(I) ions are interlinked by TZI spacers. The layers are further stabilized and associated into 3D architectures through intra- and interchain hydrogen bonds and/or π–π stacking. 4 consists of 1D double chains, and the 1D chains are assembled through hydrogen bonds to give a 3D supramolecular architecture. Intriguingly, Mn(II) ions from different double chains are linked through hydrogen bonding bridges to give unprecedented hydrogen bonded chains with alternating single O–H⋯O bridges and double (O–H⋯O)2 bridges. Compounds 1 and 2 display intense photoluminescence properties in the solid state at room temperature, while 4 exhibits an antiferromagnetic interaction between Mn(II) ions.

Four coordination polymers based on dinuclear and trinuclear units with a new multifunctional pyridyl-dicarboxylate ligand: luminescence and magnetic properties

Four coordination polymers of different transition metal ions with a new pyridyl-dicarboxylate ligand, 4-(3,5-dicarboxylphenyl)-2-methylpyridine (H2L), were synthesized under solvothermal conditions and their structures and properties were characterized. They are formulated as [Zn(L)(H2O)]·H2O (1), [Mn3(L)2Cl2(H2O)2]·2H2O (2), [Co3(L)2(NO3)2(H2O)2] (3) and [Ni3(L)2(NO3)2(H2O)2]] (4). Compound 1 exhibits a 2D network with a (3,6)-connected kgd topology based on the dinuclear [Zn2O2] units. In compound 2, the linear trinuclear [Mn3(μ-Ocarboxylate)2(COO)2Cl2] units with mixed carboxylate and μ-Cl triple bridges are cross-linked by the L ligands into a 3D framework with a (3,6)-connected rtl topology. Compounds 3 and 4 are isostructural and both show 2D networks in which the linear trinuclear [M3(μ-Ocarboxylate)2(COO)2(μ-ONO3)2] units (M = Co (3) and Ni (4)) are cross-linked by the L ligands. Compound 1 shows strong blue emissions in the solid state at room temperature. Magnetic studies indicate that the mixed triple [(μ-Ocarboxylate)(COO)Cl] bridges transmit antiferromagnetic interactions between Mn(II) ions in 2, while the mixed triple (μ-Ocarboxylate)(COO)(μ-ONO3) bridges in 3 and 4 transmit ferromagnetic interactions. Further magnetic studies demonstrated that the Co(II) compound shows no long-range magnetic ordering at 2 K.

Six novel coordination polymers based on the 5-(1H-tetrazol-5-yl)isophthalic acid ligand: structures, luminescence, and magnetic properties

Six new coordination polymers (CPs), namely, [Mn2(OH)(TZI)(DMA)] (1), [Cu2(OH)(TZI)(DMA)]·3.5H2O (2), [Co2(OH)(TZI)(H2O)2] (3), [Zn2(OH)(TZI)(2,2′-bpy)]·H2O (4), [Zn2(OH)(TZI)(phen)]·2H2O (5) and [Zn2(OH)(TZI)(4,4′-bpy)0.5] (6), (H3TZI = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine, and DMA = N,N-dimethylacetamide), have been synthesized under solvo-/hydrothermal conditions. Both 1 and 2 exhibit 3D structures containing butterfly-shaped tetranuclear M4(μ3-OH)2 clusters as secondary building units (SBUs). In 1, the SBUs are connected into 1D chains by the tetrazolate groups of the TZI ligands and the chains are further interlinked into a (4,8)-connected 3D net by the TZI spacers. In 2, the SBUs are directly connected by TZI to give a (3,6)-connected 3D framework. CP 3 features a double-layered structure based on corner-sharing Co3(μ3-OH) triangle Δ-chains in which Co(II) ions are bridged by mixed (μ4-tetrazolate)(μ3-OH)(μ2-COO) bridges. CPs 4–6 were synthesized by the reactions of the H3TZI ligands, Zn(NO3)2 and three different N-donor auxiliary ligands. The auxiliary ligands change from chelating ligands (2,2′-bpy, phen) to 4,4′-bpy, which leads to remarkable structural changes from 2D to 3D. CPs 4 and 5 display 2D structures with dinuclear motifs as SBUs. In 4, the dinuclear motifs with mixed double (μ2-tetrazolate)(μ2-OH) bridges are connected by the TZI spacers to produce a 2D framework. Differently, in 5, the dinuclear motifs with mixed double (μ2-COO)(μ2-OH) bridges are interlinked into a 2D framework with a (4,4)-connected net topology. In 6, the square Zn4O4 clusters are interlinked by the organic ligands into a 3D framework with a (4,10)-connected (44·62)(412·58·616·76·83) topology. Magnetic studies indicate that CPs 1–3 exhibit antiferromagnetic coupling. Further magnetic measurement demonstrates that CPs 1 and 3 show no magnetic ordering above 2 K. CPs 4–6 exhibit strong luminescence with different energies in the solid state at room temperature.

Spin-canting magnetization in 3D metal organic frameworks based on strip-shaped Δ-chains

Three isostructural coordination polymers, M2(TZI)(OH)(H2O)2·xH2O (x = 3, M = Cu(II) 1, x = 4, M = Co(II) 2 and Ni(II) 3) (H3TZI = 5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. The compounds consist of 3D frameworks, in which the magnetic Δ-chain motifs based on corner-sharing M3(μ3-OH) isosceles triangle are linked by the TZI ligands, and they represent the rare (3,4,5,6)-connected 4-nodal net topology with the point symbol (43)(4462)(4664)(4768). Magnetic analyses indicate that compound 1 shows the coexistence of spin canting, metamagnetism and antiferromagnetic ordering, whereas compounds 2 and 3 exhibit canted antiferromagnetic coupling without magnetic ordering down to 2 K. Such magnetic behaviors above 2 K are still rare in Cu(II), Co(II) and Ni(II) compounds with similar chains.

Vapor-assisted room temperature nanoimprinting-induced molecular alignment in patterned poly(3-hexylthiophene) nanogratings and its stability during thermal annealing

Vapor-assisted imprinting technology has been well explored to have good potential for practical application to fabricate topographical nanostructures of polymer film. Herein, we demonstrated that the poly(3-hexylthiophene) (P3HT) nanograting topography can be excellently fabricated via the vapor-assisted room-temperature nanoimprinting lithography (VART-NIL) technique based on a poly(dimethylsiloxane) (PDMS) template and carbon disulfide (CS2) vapor atmosphere. Grazing incidence wide angle X-ray diffraction (GIWAXD) was employed to illustrate that the VART-NIL procedure could not only be used to fabricate the topographical pattern, but also to induce the molecular alignment transition from an edge-on to a face-on alignment, including both form II and form I crystals. Furthermore, according to GIWAXD and atomic force microscopy (AFM) investigations in situ, the stability of the nanopattern surface morphology and molecular alignment of P3HT nanograting film are dependent on the thermal annealing treatment differently. The patterned P3HT nanograting morphology largely disappears into a planar surface at elevated temperatures and the crystallographic structure of the P3HT crystal transfers from form II to form I during the elevated temperature process; however, the nanoimprint-induced face-on molecule alignment of form I conformation surprisingly remains eternal within the distorted nanograting film after the cooling step. Furthermore, the face-on molecular alignment of the form I conformation remained developed and steadily and successively enhanced during the cooling step.

Four 3D coordination polymers based on layers with single syn–anti carboxylate bridges: synthesis, structures, and magnetic properties

Four novel coordination polymers (CPs) based on a new 4-(3,5-dicarboxylphenyl) picolinic acid ligands (H3L), [M3(L)2(H2O)6]·4H2O (M3 = Mn3, 1; Co3, 2; Ni3, 3, Co1.01Ni1.99, 4), have been hydrothermally synthesized, and structurally and magnetically characterized. In these isomorphous CPs, octahedrally coordinated metal ions are linked by the single syn–anti carboxylate bridge (μ-COO) to give linear trinuclear motifs. The motifs are connected through the other single syn–anti carboxylate bridge (μ-COO) to give a 2D (4,4) layer, and the layers are interlinked by the L ligands into 3D frameworks. Magnetic measurement indicates that antiferromagnetic interactions between metal ions are mediated through the single syn–anti carboxylate bridges in 1 and 2, while the same carboxylate bridges in 3 transmit ferromagnetic couplings. The bimetallic CP 4 shows interesting complicated magnetic behaviors due to the competition effect of Co(II) and Ni(II) ions.

Maintaining nanoimprinting-induced face-on alignment in poly(3-hexylthiophene) nanopillars after thermal annealing

A key detail for conjugated polymers is to focus on the stability of the patterned nanostructure profile and the molecular alignment within the topography structure. We demonstrate here that the fabrication of a patterned poly(3-hexylthiophene) (P3HT) nanopillar film can be achieved by a simple and cost-effective solvent-assisted room-temperature nanoimprinting lithography (SART-NIL) method. This indicates that a face-on molecular alignment is induced in the nanostructure of the arrays of the nanopillars. In order to investigate the thermal stability of the P3HT nanopillar film, the effect of thermal annealing treatment on the nanostructure morphology and molecular alignment of the nanopillar film is performed here. This confirms that the thermal annealing plays a different role in the stability of the nanostructure morphology and molecular alignment for the P3HT nanopillar film. The stability of the patterned nanopillar profile significantly depends on the annealing temperature, however, the stability of the nanoimprint-induced face-on molecule alignment is immune to heating during annealing. The nanoimprint-induced face-on molecule alignment is maintained after the thermal annealing. In addition, the evolution of the surface topography and the molecule alignment during the thermal annealing is also investigated in detail.