Lumei Liu

The novel open-framework uranium silicates Na2(UO2)(Si4O10).2.1H2O (USH-1) and RbNa(UO2)(Si2O6).H2O (USH-3)

The new open-framework uranium silicates Na2(UO2)(Si4O10)·2.1H2O (USH-1) and RbNa(UO2)(Si2O6)·H2O (USH-3) have been synthesized by hydrothermal reactions at 230 °C. USH-1 has a framework structure formed from silicate single layers cross-linked by interlayer UO6 tetragonal bipyramids. The silicate layers consist of interconnected tetrahedral 4-rings and 8-ring voids. The 8-ring voids are lined up to form 1-dimensional channel systems in the framework. In contrast to the silicate layers of USH-1, individual 4-rings of silicate tetrahedra are found in USH-3 which are cross-linked by UO6 tetragonal bipyramids to form an open framework.

Breathing and twisting: an investigation of framework deformation and guest packing in single crystals of a microporous vanadium benzenedicarboxylate.

The structural details of the compounds vanadium benzenedicarboxylate VO(bdc)·Guest, where the Guests are the absorbed six-ring molecules: benzene, 1,4-cyclohexadiene, 1,3-cyclohexadiene, cyclohexene and cyclohexane, have been determined from single crystal X-ray data. All of the six-ring guest molecules show a high degree of ordering inside the channels of VO(bdc). The interactions between the guests and the host framework are dominated by van der Waals bonding. The six-ring molecules are all packed in two columns in the channels, either in herringbone or close to parallel patterns. The packing changes the space group symmetry of VO(bdc) from Pnma to the noncentrosymmetric space group P2(1)2(1)2(1). The VO(bdc) framework deforms to closely adapt to the shape and thickness changes of the double columns of the guest molecules. In addition to the well studied breathing deformation, a twisting deformation mechanism that involves a cooperative rotation of the octahedral chains accompanied by bending of the bdc ligand is apparent in the detailed structural data. More quantitative information on the remarkable flexibility of the VO(bdc) framework was obtained from ab initio calculations.

Synthesis and crystal structures of [H3N(CH2)2NH3]NbMOF(PO4)2(H2O)2, M = Fe,Co and [H3N(CH2)2NH3]Ti(Fe0.9Cr0.1)(F1.3O0.7)(H0.3PO4)2(H2O)2

The new niobium phosphates [H3N(CH2)2NH3]NbFeOF(PO4)2(H2O)2 and [H3N(CH2)2NH3]NbCoOF(PO4)2(H2O)2 have been synthesized in single crystal form by hydrothermal reactions at 165 °C. The new phase [H3N(CH2)2NH3]Ti(Fe0.9Cr0.1)(F1.3O0.7)(H0.3PO4)2(H2O)2 has been obtained by hydrothermal electrocrystallization at 170 °C. The crystal structures have been refined from X-ray diffraction data. They are structurally similar to the known layered iron phosphate [H3N(CH2)2NH2][Fe2F2(HPO4)2(H2O)2] designated as ULM-10 and the mineral curetonite.

Influence of reaction conditions on the electrochemical-hydrothermal synthesis of two ammonium vanadium phosphates: (NH4)2VO(HPO4)2·H2O and (NH4)2VO(V0.88P1.12O7)

The new phase (NH 4 ) 2 VO(HPO 4 ) 2 ·H 2 O, 1, has been synthesized by hydrothermal electrocrystallization at 100°C. 1 is triclinic, space group P1 with Z=2, a=7.2499(8), b=8.1244(9), c=8.6529(9) A, α=73.472(2), β=80.085(2), γ=85.077(2)° and V=480.94(9) A 3 . When the reaction temperature is increased to 110°C, 1 is completely transformed into the known compound (NH 4 ) 2 VO(V 0.88 P 1.12 O 7 ), 2. The layered compound NH 4 VOPO 4 ·xH 2 O, 3, a new example of the well-known M x VOPO 4 ·xH 2 O phase has also been prepared by the same technique.

Hydrothermal synthesis and structures of Ba3(NbO)2(PO4)4and Co3(NbO)2(PO4)4(H2O)10

The new niobium phosphates Ba3(NbO)2(PO4)4 (1) and Co3(NbO)2(PO4)4(H2O)10 (2) have been synthesized in single crystal form by hydrothermal reactions at 250 °C and 170 °C respectively. The crystal structures have been determined from X-ray diffraction data. Both compounds contain NbP2O9 complex chains as a fundamental structural unit. The chains are similar to those of the known compound K3NbP2O9 and structurally may be considered similar to a slice of the Zr(HPO4)2 layer in α-zirconium phosphate. In compound 1 the chains are separated and are held together by Ba–O bonds while in 2 the chains are linked by CoO6 octahedra to form a framework structure.

Synthesis and crystal structures of yttrium sulfates Y(OH)(SO4), Y(SO4)F, YNi(OH)3(SO4)-II and Y2Cu(OH)3(SO4)2F.H2O

Abstract Y(OH)(SO 4 ), Y(SO 4 )F, YNi(OH) 3 (SO 4 )-II and Y 2 Cu(OH) 3 (SO 4 ) 2 F·H 2 O are obtained from hydrothermal reactions at 380°C under a pressure of 210 MPa. Their crystal structures were refined from single-crystal X-ray diffraction data. The four compounds have the following space groups and unit cells: Y(OH)(SO 4 ), P 2 1 / n , a =7.9498(6), b =10.9530(9), c =8.1447(6) A, β =93.764(1)°; Y(SO 4 )F, Pnma , a =8.3128(9), b =6.9255(7), c =6.3905(7) A; YNi(OH) 3 (SO 4 )-II, Pnma , a =6.9695(8), b =7.2615(8), c =10.292(1) A; Y 2 Cu(OH) 3 (SO 4 ) 2 F·H 2 O, P 2 1 / n , a =11.6889(7), b =6.8660(4), c =12.5280(8) A, β =97.092(1)°. The coordination environments of the yttrium atoms in the four structures vary from highly irregular 6+2, 6+3, 7+1 coordination polyhedra to relatively regular dodecahedra.

Hydrothermal synthesis and structures of the novel niobium phosphates Ba2[NbOF(PO4)2] and Ba3[Nb3O3F(PO4)4(HPO4)](H2O)7

The new niobium phosphates Ba2[NbOF(PO4)2] (1) and Ba3[Nb3O3F(PO4)4(HPO4)](H2O)7 (2) have been synthesized in single crystal form by hydrothermal reactions at mild temperatures. Their crystal structures determined from X-ray diffraction data are based on defected derivatives of the NbO(H2O)PO4 layers found in hydrated niobium phosphate. The niobium phosphate layers in 1 or 2 can be derived by removing one half or one quarter of the NbO6 octahedra from the NbO(H2O)PO4 layer, respectively. In compound 1 the layers are separated and are held together by interlayer Ba-O and Ba-F bonds while in 2 the layers are linked by interlayer PO4 tetrahedra to form a framework structure.

Electrochemical-hydrothermal synthesis and structure of [N(CH3)4]2[Co(H2O)4V12O28]

Electrochemical oxidation of a vanadium electrode under hydrothermal conditions in the presence of tetramethylammonium and cobalt ions gives the novel compound [N(CH 3 ) 4 ] 2 [Co(H 2 O) 4 V 12 O 28 ].

Two Distinct Redox Intercalation Reactions of Hydroquinone with Porous Vanadium Benzenedicarboxylate MIL-47

One of the enticing features of metal-organic frameworks (MOFs) is the potential to control the chemical and physical nature of the pores through postsynthetic modification. The incorporation of redox active guest molecules inside the pores of the framework represents one strategy toward improving the charge transport properties of MOFs. Herein, we report the vapor-phase redox intercalation of an electroactive organic compound, hydroquinone (H2Q) or benzene-1,4-diol, into the channels of the host [V(IV)O(bdc)], (bdc =1,4-benzenedicarboxylate) conventionally denoted as MIL-47. The temperatures and especially the atmosphere in which the reactions took place were found to determine the products. In ambient atmosphere, quinhydrone charge-transfer complexes are formed inside the channels. Under anhydrous conditions, the framework itself was functionalized by a radical anion species derived from the pyrolysis of hydroquinone. Both cases are accompanied by the reduction of V(4+) to V(3+) via single-crystal-to-single-crystal transformations. The products were characterized by single crystal X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and electron paramagnetic resonance spectroscopy.

Open-Framework Copper Titanosilicates

Four open-framework copper titanosilicates have been synthesized by hydrothermal techniques. The crystal structure of Phase 1 determined from single crystal X-ray data is closely similar to that reported for the titanosilicate ETS-4 with ca. one third TiO5 pyramids randomly replaced by CuO4 squares. Phase 2 also has the ETS-4 structure but all the TiO5 pyramids are replaced by CuO4 squares which are not randomly disordered. Phase 3 with the composition Na8CuTi3Si16O43 has the same structure as the mineral narsarsukite, a titanosilicate closely related to the microporous titanosilicate ETS-10. Narsarsukite and ETS-10 have the same straight single chains of TiO6 octahedra which are partially substituted by CuO4 squares in 3. Phase 4 with the composition K4CuTiSi8O21 contains CuO4 squares and TiO5 tetragonal pyramids that crosslink a new type of silicate double layer to form an open framework.