Substituents effects on two related families of dyes for dye sensitized solar cells: [Ru(4,4'-R,R-2,2'-bpy)(3)]2+ and [Ru(4,4'-COOH-2,2'-bpy)(4,4'-R,R-2,2'-bpy)(2)]2+

We studied the influence of the substituents over the composition of the molecular orbitals, electronic transitions, and reactivity of several ruthenium derivatives. We found a good agreement with the previously reported experimental data. In these theoretical calculations including spin-orbit coupling, we study several ruthenium-tris-(2,2'-bipyridine) substituted dyes, which do or do not have an anchoring group to get attached to the semiconductor surface. It was observed that the complexes that have electron-donor substituents might be more efficient to donate electrons if they are anchored to a semiconductor than those complexes that have electron-acceptor substituents. Therefore, the results suggest that these dyes with electron-donor substituents will give better yields in photocurrent generation. Also, the localization of the lowest unoccupied molecular orbital over the ligand that has the anchoring will help to improve electron injections into the TiO(2) nanoparticles. We propose here several not yet synthetized dyes, which could be used in this kind of device, due to their interesting molecular properties.     

Inorganic-organic hybrids derived from oxovanadium sulfate motifs: synthesis and characterization of [VIVO(mu 3-SO4)(2,2'-bpy)]infinity

The hydrothermal reaction of V2O5, V2O3, 2,2'-bpy and Na2SO4 in dilute sulfuric acid yields a novel hybrid, [VIVO(mu 3-SO4)(2,2'-bpy)]infinity, which demonstrates the potential of constructing a new class of robust composite solids composed of a (V/O/SO4)-based framework decorated with organic functionalities by combining appropriate vanadyl sulfate motifs with a variety of organic ligands.     

Syntheses, Characterization and Crystal Structures of Two-dimensional 4,4＇-Bipyridyl Lead Halides, PbI2 （4,4＇-bpy） and PbBr2 （4,4＇-bpy）

Two-dimensional 4,4-bipyridyllead halides, Pbl2 (4,4‘-bpy) (1) and PbBr2 ( 4,4‘-bpy ) (2), were synthesized. The structures were determined by means of X-ray single crystal diffraction. The structure shows a distorted octahedral configuration with six-coordinated central lead atoms. In crystals 1 and 2, the molecules are packed in a two-dimensional network structure through bridging halide atoms and 4,4‘-bipyridine ligands between the adjacent lead atoms.     

Cuprophilicity-induced cocrystallization of [Cu2(4,4'-bpy)(CN)2]n sheets and [Cu(SCN)]n chains into a 3-D pseudopolyrotaxane

The cocrystallization of [Cu(SCN)]n chains and [Cu2(4,4'-bpy)(CN)2]n (4,4'-bpy = 4,4'-bipyridine) layers generated a 3-D pseudopolyrotaxane compound, [Cu2(4,4'-bpy)(CN)2].[Cu(SCN)] (1), which can also be viewed as a 3-D network constructed by linkages of 2-D sheets and 1-D chains via unsupported CuI-CuI interactions. The CuI-CuI contact of 2.651(4) A in 1 is the shortest unsupported CuI-CuI distance documented to date, indicating cuprophilic attractions.     

Infinite Three-Dimensional Coordination Polymers: Synthesis and Structures of [Cd (4,4'-bpy)2 (H2O)2]n (pic)2n, [Zn (4,4'-bpy)2 (H2O)2 ]n-(pic)2n (H2O)2n, and [Zn (4,4'-bpy)2 (H2O)2]n (4,4'-bpy)n (H2O)n (pic)2n

Recently, a new research realm in crystal engineering of supramolecular architecturesassembled by means of coordinate covalent bonding', hydrogen bonding', or other weakintermolecular interactions= has been rapidly expanding in order to rationally developnew classes of functional materials with cavities or pores. These types of compoundsmay exhibit interesting topological structures and the clathrations of the cavity structuresmay have many potential properties such as catalysis', electrical co…     

Syntheses,crystal structures and magnetic properties of two cyano-bridged two-dimensional assemblies [Fe(salpn)]2 [Fe(CN)5NO] and [Fe(salpn)]2[Ni(CN)4]

Two cyano-bridged assemblies, [Fe^III(salpn)]₂[Fe^II(CN)₅NO] (1) and [Fe^III (salpn)]₂[Ni^II(CN)₄] (2) [salpn = N, N-1,2-propylenebis(salicylideneiminato)dianion], have been prepared and structurally and magnetically characterized. In each complex, [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– coordinates with four [Fe(salpn)]⁺ cations using four co-planar CN^– ligands, whereas each [Fe(salpn)]⁺ links two [Fe(CN)₅NO]^2– or [Ni(CN)₄]^2– ions in the trans form, which results in a two-dimensional (2D) network consisting of pillow-like octanuclear [—M^II—CN—Fe^III—NC—]₄ units (M = Fe or Ni). In complex (1), the NO group of [Fe(CN)₅NO]^2– remains monodentate and the bond angle of Fe^II—N—O is 180.0°. The variable temperature magnetic susceptibilities, measured in the 5–300 K range, show weak intralayer antiferromagnetic interactions in both complexes with the intramolecular iron(III)iron(III) exchange integrals of –0.017 cm^–1 for (1) and –0.020 cm^–1 for (2), respectively.     

Neutral coordination polymers based on a metal-mono(dithiolene) complex: synthesis, crystal structure and supramolecular chemistry of [Zn(dmit)(4,4'-bpy)]n, [Zn(dmit)(4,4'-bpe)]n and [Zn(dmit)(bix)]n (4,4'-bpy = 4,4'-bipyridine, 4,4'-bpe = trans-1,2-bis(4-pyridyl)ethene, bix = 1,4-bis(imidazole-1-ylmethyl)-benzene

This article describes a unique synthetic route that enables a neutral mono(dithiolene)metal unit, {Zn(dmit)}, to link with three different organic molecules, resulting in the isolation of a new class of neutral coordination polymers. The species {Zn(dmit)} coordinates with 4,4'-bipyridine (4,4'-bpy), trans-1,2-bis(4-pyridyl)ethene (4,4'-bpe) and 1,4-bis(imidazole-1-ylmethyl)-benzene (bix) as linkers giving rise to the formation of coordination polymers [Zn(dmit)(4,4'-bpy)](n) (1), [Zn(dmit)(4,4'-bpe)](n) (2) and [Zn(dmit)(bix)](n) (3) respectively. Compounds 1-3 were characterized by elemental analyses, IR, diffuse reflectance and single crystal X-ray diffraction studies. Compounds 1 and 3 crystallize in the monoclinic space group P2(1)/n, whereby compound 2 crystallizes in triclinic space group P1[combining macron]. In the present study, we chose three linkers 4,4'-bpy, 4,4'-bpe and bix (see , respectively, for their structural drawings), that differ in terms of their molecular dimensions. The crystal structures of compounds 1-3 are described here in terms of their supramolecular diversities that include π-π interactions, not only among aromatic stacking (compounds 1 and 3), but also between an aromatic ring and an ethylenic double bond (compound 2). The electronic absorption spectroscopy of compounds 1-3 support these intermolecular π-π interactions.     

Ligand influences on copper molybdate networks: the structures and magnetism of [Cu(3,4'-bpy)MoO(4)], [Cu(3,3'-bpy)(0.5)MoO(4)], and [Cu(4,4'-bpy)(0.5)MoO(4)].1.5H(2)O

The reactions of a Cu(II) salt, MoO(3), and the appropriate bipyridine ligand yield a series of bimetallic oxides, [Cu(3,4'-bpy)MoO(4)] (1), [Cu(3,3'-bpy)(0.5)MoO(4)] (2), and [Cu(4,4'-bpy)(0.5)MoO(4)].1.5H(2)O (3.1.5H(2)O). The structures of 1-3 exhibit three-dimensional covalent frameworks, constructed from bimetallic oxide layers tethered by the dipodal organoimine ligands. However, the [CuMoO(4)] networks are quite distinct. For structure 1, the layer consists of corner-sharing [MoO(4)] tetrehedra and [CuN(2)O(3)] square pyramids, while the layer of 2 is constructed from [MoO(4)] tetrehedra and binuclear [Cu(2)O(6)N(2)] units of edge-sharing copper square pyramids. The oxide substructure of 3 consists of [MoO(4)] tetrahedra corner-sharing with tetranuclear clusters of edge-sharing [CuO(5)N] octahedra. Crystal data: C(10)H(8)N(2)O(4)CuMo (1), orthorhombic Pbca, a = 12.4823(6) A, b = 9.1699(4) A, c = 19.5647(9) A, V = 2239.4(1) A(3), Z = 8; C(5)H(4)NO(4)CuMo (2), triclinic P, a = 5.439(1) A, b = 6.814(1) A, c = 10.727(2) A, alpha = 73.909(4)(o), beta = 78.839(4)(o); gamma = 70.389(4)(o); V = 357.6(1) A(3), Z = 2; C(10)H(8)N(2)O(8)Cu(2)Mo(2).3H(2)O 3.1.5H(2)O, triclinic P, a = 7.4273(7) A, b = 9.2314(8) A, c = 13.880(1) A, alpha = 71.411(2)(o), beta = 88.528(2)(o), gamma = 73.650(2)(o), V = 863.4(1) A(3), Z = 2. The magnetic properties of 1-3 arise solely from the presence of the Cu(II) sites, but reflect the structural differences within the bimetallic oxide layers. Compound 1 exhibits magnetic behavior consistent with ferromagnetic chains which couple antiferromagnetically at low temperature. Compound 2 exhibits strong antiferromagnetic dimeric interactions, with the magnetic susceptibility data consistent with the Bleaney-Bowers equation. Similarly, the magnetic susceptibility of 3 is dominated by antiferromagnetic interactions, which may be modeled as a linear S = 1/2 Heisenberg tetramer.     

Synthesis,crystal structure and magnetic properties of a two-dimensional mixed-valence assembly [Fe(salen)]2[Fe(CN)5NO]

A cyanide-bridged Fe^III–Fe^II mixed-valence assembly, [Fe^III(salen)]₂[Fe^II(CN)₅NO] [salen = N,N-ethylenebis(salicylideneiminato)dianion], prepared by slow diffusion of an aqueous solution of Na₂[Fe(CN)₅NO] · 2H₂O and a MeOH solution of [Fe(salen)NO₃] in an H tube, has been characterized by X-ray structure analysis, i.r. spectra and magnetic measurements. The product assumes a two-dimensional network structure consisting of pillow-like octanuclear [—Fe^II—CN—Fe^III—NC—]₄ units with dimensions: Fe^II—C = 1.942(7) Å, C—N = 1.139(9) Å, Fe^III—N = 2.173(6) Å, Fe^II—C—N = 178.0(6)°, Fe^III—N—C = 163.4(6)°. The Fe^II—N—O bond angle is linear (180.0°). The variable temperature magnetic susceptibility, measured in the 4.8–300 K range, indicates the presence of a weak intralayer antiferromagnetic interaction and gives an Fe^III–Fe^III exchange integral of –0.033 cm^–1.     

Hydrothermal synthesis and characterization of [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), a mixed-metal uranyl aquofluoride with a pillared layer structure

A mixed-metal uranyl aquofluoride, [(UO2)2F8(H2O)2Zn2(4,4'-bpy)2].(4,4'-bpy), has been synthesized under hydrothermal conditions and has been structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, thermogravimetric analysis, emission spectroscopy, and solid-state NMR spectroscopy. It is one of the few uranium fluoride-organic framework solids in which an organic molecule is directly incorporated into the extended structure of the metal fluoride and is the first example of mixed-metal uranium oxyfluoride incorporating an organic ligand. The structure consists of neutral layers of edge- and corner-sharing uranium-centered pentagonal bipyramids and zinc-centered octahedra, which are linked through 4,4'-bpy ligands into a 3-D framework. The 1H MAS NMR spectrum is in support of the conclusion that the occluded 4,4'-bpy molecules in the structural channels are not protonated. Crystal data: monoclinic, space group P2(1)/c, a = 9.4630(5) A, b = 22.384(1) A, c = 16.7534(8) A, beta = 91.899(2) degrees , V = 3546.7(4) A(3) and Z = 4.     

A three-dimensional zeolite-like organic-inorganic hybrid material constructed from (CuMo2O8N)n double helical chains linked via [Cu(4,4'-bpy)]n fragments

The three-dimensional microporous [Cu2Mo2O8(4,4'-bpy)]n.3nH2O 1 contains (CuMo2O8N) double helical chains, which are built up from (CuIIO4N) square pyramids linked by (MoVIO4) tetrahedra and further connected to each other by 4,4'-bpy coordinated (CuIIO5N); the study of the physical properties of 1 demonstrates it is a paramagnetic semiconductor and a zeolite material; the specific channeling cavities in 1 have potential adsorption activities, indicating that 1 might be an attractive functional microporous solid material.     

Formate--the analogue of azide: structural and magnetic properties of M(HCOO)2(4,4'-bpy).nH2O (M = Mn, Co, Ni; n = 0, 5)

Reaction of transition metal formate M(HCOO)(2).2H2O (M = Mn, Co, Ni) with 4,4'-bpy (4,4-bipyridine) has led to four new compounds with the formula M(HCOO)2(4,4'-bpy).nH2O (M = Mn, Co (1.Mn, 2.Co), n = 0; M = Co, Ni (3.Co, 4.Ni), n = 5). Compounds 1.Mn and 2.Co are isomorphous and crystallized in the tetragonal crystal system with the chiral space group P4(1)2(1)2. They are of three-dimensional diamondoid structure connected by anti-anti formate with 4,4'-bpy in the cavities of the framework reinforcing the intermetallic connections; the diamond-like net was observed also in their azide analogue (Mn(N3)2(4,4'-bpy)). Compounds 3.Co and 4.Ni are isomorphous also but crystallized in the monoclinic crystal system with the space group Cc. Both structures are uninterpenetrated 3D "CdSO4" type with big channels, constructed by anti-anti formate and 4,4'-bpy. This type of net was not observed in their azide analogue. Residing in the channels, water molecules form a new type of 1D tape constructed by vertex-sharing cyclic pentamers. Magnetic measurements were performed on all of these four compounds. 1.Mn and 2.Co are weak ferromagnets with the critical temperature Tc = 5.3 and 7.4 K, respectively. 3.Co is an antiferromagnet with Neel temperature TN = 3.0 K, and 4.Ni is a weak ferromagnet below 20 K. Hysteresis loop can be observed for 2.Co and 4.Ni at 1.8 K. As an analogue of azide, formate can be used to construct molecular architectures, which structurally and magnetically have great similarities to and also differences from those of azide. This offers a promising method for the design of new molecular architectures with formate.     

Synthesis, structure, and magnetic properties of a novel pillared layered iron(III) arsenate, [4,4'-bpyH2]3[Fe9(H2O)6F3(HAsO4)12(AsO4)2].2H2O

A three-dimensional iron arsenate [4,4'-bpyH2]3[Fe9(H2O)6F3(HAsO4)12(AsO4)2].2H2O, 1, has been synthesized using 4,4'-bipyridine as the templating agent under hydrothermal conditions. The structure is formed by FeO6, FeO3F3 octahedral units connected with HAsO4 and AsO4 units, forming one- and two-dimensional units in which the one-dimensional units act as a pillar. The presence of face-shared Fe-dimer units in the one-dimensional unit is noteworthy. Detailed magnetic studies indicate two possible magnetic interactions: antiferromagnetic interactions within the layer and a weak ferromagnetic polarization between the layers at very low temperatures through the Fe-dimer units.     

A cyclic tetra-nuclear dinitrosyl iron complex [Fe(NO)2(imidazolate)]4: synthesis, structure and stability

A novel cyclic tetra-nuclear dinitrosyl iron complex [Fe(NO)2(Im-H)]4 was isolated and characterized by X-ray crystallography, and in donor solvents this fragments into 17 e- monomeric units that give EPR spectra analogous to the g= 2.03 species seen in mammalian biology.