Robert C. Finn

Molecular manipulation of solid state structure: Influences of organic components on vanadium oxide architectures

Abstract Among the inorganic materials enjoying widespread contemporary interest, the metal oxide based solid phases occupy a prominent position by virtue of their applications to catalysis, sorption, molecular electronics, energy storage, optical materials and ceramics. The diversity of properties associated with these materials reflects the chemical composition, which allows variations in covalency, geometry and oxidation states, and the crystalline architecture, which may provide different pore structures, coordination sites, or juxtapositions of functional groups. Despite such fundamental and practical significance, the design of the structure of such materials remains a challenge in solid state chemistry. While organic materials have been synthesized which self-assemble into ordered arrays at low temperature and which exhibit molecular recognition and biomimetic activity, the ability to synthesize inorganic materials by rational design remains elusive. Small, soluble molecular building blocks with well-defined reaction chemistries which allow their low-temperature assembly into crystalline solid state inorganic materials are not well known. However, the existence of naturally occurring, structurally complex minerals establishes that hydrothermal synthesis can provide a low temperature pathway to produce open-framework and layered metastable structures utilizing inorganic starting materials. Thus, hydrothermal conditions have been used to prepare microporous tetrahedral framework solids that are capable of shape-selective absorption, like zeolites and aluminophosphates, and more recently in the preparation of complex solid arrays of the M/O/PO3−4 and M/O/RPO2−3 systems (M=V and Mo). The hydrothermal technique may be combined with the introduction of organic components which may act as charge compensating groups, space-filling units, structure directing agents, templates, tethers between functional groups, or conventional ligands in the preparation of inorganic/organic composites. In the past decade, this general strategy has been exploited in the evolution of a family of vanadium oxides incorporating structure-directing organic or secondary-metal organic subunits, which are the topic of this review. The synthetic approach to novel vanadium oxide solids occupies the interface between materials science and coordination chemistry. The emerging theme focuses on the association of an organic component, acting as a ligand, tether, or structure directing moiety, with the inorganic framework of the solid to provide unique composites. While some organic components may limit the size of inorganic cluster subunits of a solid by passivating the surface of an aggregate through capping, such ligands may also serve to link inorganic subunits into complex networks. In other cases, the organic subunit, rather than participating as a covalently bound unit of the framework, acts in a structure directing role, producing amphiphilic materials whose structures are determined by hydrophobic–hydrophilic interactions. This latter feature is reminiscent of the factors influencing biomineralization, a field which may prove relevant to the development of new strategies for the controlled synthesis of organized inorganic and organic/inorganic composite materials. These various approaches to the “design” of inorganic solids are discussed and assessed in terms of the new structural types recently observed in the vanadium oxide chemistry.

A three dimensional organic-inorganic composite material constructed from cobalt-3,3'-bipyridyl networks linked through tetravanadate clusters: [{Co(3,3'-bpy)2}2V4O12]

Abstract The hydrothermal reaction of CoCl2·6H2O, 3,3′-bipyridine and NaVO3 in water at 160°C for 48 h yields the three-dimensional bimetallic oxide [{Co(3,3′-bpy)2}2V4O12] (1). The structure of 1 consists of two-dimensional {Co(3,3′-bpy)2}n2n+ networks, linked through cyclic tetranuclear {V4O12}4− clusters into a three-dimensional covalently linked assembly. Crystal data for C20H16CoN4O6V2 (1): monoclinic, P21/n, a=9.9794(6), b=16.129(1), c=13.4190(8) A, β=93.039(1)o, V=2156.9(2) A3, Z=4, Dcalc=1.753 g/cm3.

The synthesis and characterization of two new copper phosphonates: the one-dimensional [Cu(terpy)(HO3PCH2CH2PO3H)].4H2O and the molecular [{Cu(phen)(H2O)}2(O3PCH2CH2PO3)].9H2O (terpy = 2,2':6', 2 -terpyridine, phen = 1,10-phenanthroline)

The reaction of copper with 1,2-ethylene diphosphonic acid and 2,2′:6′,2″-terpyridine and o -phenanthroline under hydrothermal conditions resulted in the one-dimensional [Cu(terpy)(HO 3 PCH 2 CH 2 PO 3 H)]·4H 2 O ( 1 ·4H 2 O) and the molecular species [{Cu(phen)(H 2 O)} 2 (O 3 PCH 2 CH 2 PO 3 )]·9H 2 O ( 2 ·9H 2 O), which were isolated by slow evaporation. Crystal data: ( 1 ·4H 2 O) C 17 H 21 CuN 3 O 8 P 2 , triclinic, P 1; a =10.6468(6) A, b =14.2195(7) A, c =14.2906(7) A, α =73.466(1)°, β =89.020(1)°, γ =71.597(1)°, V =1961.7(2) A 3 , Z =4; ( 2 ·9H 2 O) C 26 H 42 Cu 2 N 4 O 17 P 2 , orthorhombic, Pna 2 1 ; a =14.4018(6) A, b =11.9020(5) A, c =20.6049(8) A, V =3531.9(2) A 3 , Z =4.

Surface complexation of [Nb6O19]8− with NiII: solvothermal synthesis and X-ray structural characterization of two novel heterometallic NiNb-polyoxometalates ☆

Abstract Solvothermal reaction of NiCl2, Nb(OEt)5 and 1,3,5-triamino-1,3,5-trideoxy-cis-inositol (taci) in a 1:1:1 ratio under alkaline conditions (NaOH) resulted in the formation of two new NbNi heteropolyoxometalate complexes. [Ni(taci)2]2{trans-[Nb6O19][Ni(taci)]2}·26H2O (1) and [Na(H2O)6]2{cis-[H2Nb6O19][Ni(taci)]2}·18H2O (2), were characterized by single crystal X-ray analysis. In both compounds, two [Ni(taci)]2+ entities are each bonded to three NbONb bridges of a central Nb6O19 unit, resulting in the formation of an approximately C3v symmetric NiN3O3 coordination geometry. The mononuclear analogue [Ni(taci)(H2O)3]2+ was crystallized as the sulfate and structurally characterized for comparison. The two isolated anions {trans-[Nb6O19][Ni(taci)]2}4− and {cis-[H2Nb6O19][Ni(taci)]2}2− have approximate D3d and C2v symmetry, respectively. Compound 2 crystallized, however, in the cubic space group Pn 3 m (No. 224) with the two Ni centers equally distributed over four symmetry equivalent sites. In this structure, the [Na(H2O)6]+ cations and the {cis-[H2Nb6O19][Ni(taci)]2}2− anions represent linearly and tetrahedrally connecting building blocks in a hydrogen bonded supramolecular architecture which can be described in terms of two independent but interpenetrating diamond-type nets.

Solvatothermal Syntheses and Structural Characterizations of Polyoxoalkoxometalates: The Heptanuclear [{Fe(OH)(CH3CN)2} Fe6OCl6{(OCH2)3CCH2OH}4], the Decanuclear [Fe10O2Cl8{(OCH2)3CCH2CH3}6], and the Bimetallic [(VO)2Fe8O2Cl6{(OCH2)3CCH2CH3}6]

Solvatothermal syntheses have been exploited to effect the isolation of three novel polyoxoalkoxometalate clusters, [{Fe(OH)(CH3CN)2} Fe6OCl6{(OCH2)3CCH2OH}4] (1), [Fe10O2Cl8{(OCH2)3CCH2CH3}6] (2), and [(VO)2Fe8O2Cl6{(OCH2)3CCH2CH3}6] (3). The structure of 1 may be described as a hexametalate core {Fe6OCl6}10+, consisting of a octahedral arrangement of chloride ligands encasing an octahedron of six Fe(III) sites, with a central oxo group. The remaining four coordination sites at each octahedral iron center are occupied by doubly bridging oxygen donors from the trisalkoxo ligands. One triangular face of this substructure, defined by three oxygen atoms, from three adjacent trisalkoxo ligands, is capped by the {Fe(OH)(CH3CN)2}2+ subunit. The structure of 2 is based on the decametalate core of edge-sharing octahedra. The eight peripheral Fe(III) sites of the cluster bond to four oxygen donors from the trisalkoxo ligands, a terminal Cl− ligand, and one of the μ6-oxo groups. The two central iron sites are linked to four oxygen donors from the trisalkoxo ligands and to both of the μ6-oxo groups. Cluster 3 is structurally related to 2 with two {FeCl}2+ units replaced by {VO}2+ groups.

Structural isomerism among octanuclear oxomolybdenum(V) coordination compounds with pyridines. Two isomers of [Mo8O16(OCH3)8(RPy)4]

Abstract The condensation of dinuclear {Mo2O4}2+ leads, under conditions of the solvothermal synthesis, to two distinct architectures: (i) the cluster species of [Mo8O16(OCH3)8Py4]·2CH3OH (Py=pyridine, C5H5N) (1·2CH3OH) whose four building blocks, {Mo2O4}2+ units, are linked through doubly or triply bridging oxo and methoxo groups into a compact array; and (ii) [Mo8O16(OCH3)8(4-MePy)4] (4-MePy=4-methylpyridine, C6H7N) (2) which displays an open, bent cyclic structure made of four building blocks linked to each other by pairs of methoxo bridges. The MoMo distances within dinuclear units, 2.5638(12) and 2.6012(13) A in 1, and 2.5661(3) A in 2, are characteristic for single metal–metal bonds. All metal atoms of 1 are in a distorted octahedral coordination; each octahedron shares several edges (two, three or four) with its neighbors. Compound 2 displays two types of coordination polyhedra, square pyramids and octahedra (four of each) that are connected through common edges. Each polyhedron shares two edges with the adjacent polyhedra.

Hydrothermal synthesis and structural characterization of an organically templated copper-vanadium phosphate: [{(bpy-dicarb)Cu}2{V3O3(OH)2(H2O)}(O3PCH2PO3)2]·2H2O (bpy-dicarb=2,2′-bipyridyl-4,4′-dicarboxylic acid)

Abstract The hydrothermal reaction of Cu2O, Na3VO4, H2O3PCH2PO3H2, 2,2′-bipyridine-4,4′-dicarboxylic acid, and H2O in the mole ratio 2.5:1.7:10:1.0:2700 at 200°C for 42 h yields [{(bpy-dicarb)Cu}2{V3O3(OH)2(H2O)}(O3PCH2PO3)2]·2H2O (1·2H2O). The structure of 1 is a two-dimensional sheet constructed from pentanuclear {V3Cu2O3(OH)2(H2O)}8+ units linked by (O3PCH2PO3)4− ligands into a network. Crystal data: C13H14N2O14P2V1.5Cu, triclinic, P 1 : a=7.8993(7) A, b=11.0417(9) A, c=11.857(1) A, α=100.845(1)°, β=98.400(2)°, γ=105.290(2)°, V=958.7(1) A3.

Structural properties of a series of photochromic fluorinated indolylfulgides

Fluorinated indolylfulgides are a class of photochromic organic compounds that meet many of the requirements for use as optical memory media and optical switches. The X-ray crystal structures of a series of five photochromic fluorinated indolylfulgides have been determined, namely (3Z)-3-[1-(1,2-dimethyl-1H-indol-3-yl)-2,2,2-trifluoroethylidene]-4-(1-methylethylidene)dihydrofuran-2,5-dione (trifluoromethylisopropylideneindolylfulgide), C(19)H(16)F(3)NO(3), (I), (3Z)-3-[1-(1,2-dimethyl-1H-indol-3-yl)-2,2,3,3,3-pentafluoropropylidene]-4-(1-methylethylidene)dihydrofuran-2,5-dione (pentafluoroethylisopropylideneindolylfulgide), C(20)H(16)F(5)NO(3), (II), (3Z)-3-[1-(1,2-dimethyl-1H-indol-3-yl)-2,2,3,3,4,4,4-heptafluorobutylidene]-4-(1-methylethylidene)dihydrofuran-2,5-dione (heptafluoropropylisopropylideneindolylfulgide), C(21)H(16)F(7)NO(3), (III), (3Z)-3-[1-(1,2-dimethyl-1H-indol-3-yl)-2,2,2-trifluoroethylidene]-4-(tricyclo[3.3.1.1(3,7)]decylidene)dihydrofuran-2,5-dione (trifluoromethyladamantylideneindolylfulgide), C(26)H(24)F(3)NO(3), (IV), and (3Z)-3-[1-(1,2-dimethyl-1H-indol-3-yl)-2,2,3,3,4,4,4-heptafluorobutylidene]-4-(tricyclo[3.3.1.1(3,7)]decylidene)dihydrofuran-2,5-dione (heptafluoropropyladamantylideneindolylfulgide), C(28)H(24)F(7)NO(3), (V). The photochromic property of fulgides is based on the photochemically allowed electrocyclic ring closure of a hexatriene system to form a cyclohexadiene. For each fulgide examined, the bond lengths within the hexatriene system alternate between short and long, as expected. Comparing the structures of the five fulgides with each other demonstrates no significant difference in bond lengths, bond angles or dihedral angles within the hexatriene systems. The distance between the bond-forming C atoms at each end of the hexatriene system does vary. Correlations of structural properties with optical properties are addressed.

The hydrothermal syntheses and characterization of one- and two-dimensional structures constructed from metal–organic derivatives of polyoxometalates: [{Cu(bpy)2}{Cu(bpy)(H2O)}(Mo5O15){O3P(CH2)4PO3}]·H2O and [{Cu2(tpypyz)(H2O)2}(Mo5O15)(O3PCH2CH2PO3)]·5.5H2O [bpy = 2,2′-bipyridine, tpypyz = tetra(2-pyridyl)pyrazine]

The hydrothermal reaction of CuSO4·5H2O, Na2MoO4·2H2O and 2,2′-bipyridine with the bridging diphosphonate ligand H2O3P(CH2)4PO3H 2 yields the one-dimensional chain [{Cu(bpy)2}{Cu(bpy)(H2O)2 }(Mo5O15){O3P(CH2) 4PO3}]·H2O; the introduction of a second bridging component in the reaction of Cu(MeCO2)2·H2O, MoO3, H2O3PCH2CH2PO3H 2 and tetra(2-pyridyl)pyrazine yields the network solid [{Cu2(tpypyz)(H2O)2}(Mo5 O15)(O3PCH2CH2PO3 )]·5.5H2O.

Hydrothermal synthesis and structural characterization of prototypical organic–inorganic hybrid materials: [{Cu(2,2′-bpy)(H2O)}(VO)(O3PCH2PO3)], [Cu(2,2′-bpy)(VO)(O3PCH2CH2PO3)], and [Cu(2,2′-bpy)(VO)(O3PCH2CH2CH2PO3)]·H2O. Bimetallic phosphonate networks with surface-modifying organic subunits

Hydrothermal reactions of Cu2O or CuCl2 with Na3VO4, 2,2′-bipyridine and the appropriate organodiphosphonate yielded the bimetallic, two-dimensional phosphonate phases, [{Cu(2,2′-bpy)(H2O)}(VO)(O3PCH2PO3)], [Cu(2,2′-bpy)(VO)(O3PCH2CH2PO3)] and [Cu(2,2′-bpy)(VO)(O3PCH2CH2CH2PO3)]·H2O.