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.     

新型二维层状配合物[Cd_4(2,2-′dipha)_2(nicotinate)_4]_n的合成及晶体结构

利用水热法合成了一种新型的二维金属有机配合物[Cd4(dpa)2(HL)4]n[dpa=2,2'-联苯二甲酸,HL=烟酸],并通过X-射线单晶衍射、元素分析、红外光谱等手段对其结构进行了表征.结果表明:[Cd4(dpa)2(HL)4]n属于三斜晶系,空间群Pi,晶胞参数α=0.822 2(2)nm,6=1.497 6(3)nni,c=1.981 7(5)nm,α=80.245(4)°,β=83.885(4)°γ=89.972(4)°,V=2.390 9(10)nm3,Z=2.R1=0.071 6.ωR2=0.157 3,Mr=1 415.39.Dc=1.966 g/cm3.配合物中Cd(Ⅱ)均为六配位,CA与5个O原子和1个烟酸中的H原子配位形成扭曲八面体构型.金属离子Cd(Ⅱ)由联苯酸连成一条无限一维链,相邻的两条链由烟酸连接构成二维层状结构.     

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…     

Efficient intermolecular [2 + 2 + 2] alkyne cyclotrimerization in aqueous medium using a ruthenium(IV) precatalyst

The dimeric bis(allyl)-ruthenium(IV) complex [{Ru(eta3:eta3-C10H16)(mu-Cl)Cl}2] (C10H16 = 2,7-dimethylocta-2,6-diene-1,8-diyl) was found to catalyze efficiently the [2 + 2 + 2] cyclization of terminal and internal alkynes in aqueous medium.     

Structural study on highly oxidized states of a water oxidation complex [RuIII(bpy)2(H2O)]2(mu-O)4+ by ruthenium K-edge X-ray absorption fine structure spectroscopy

The oxidation-induced structural change of a water-oxidizing diruthenium complex, [(bpy)(2)(H(2)O)Ru(III)(micro-O)Ru(III)(OH(2))(bpy)(2)](4+) (bpy = 2,2'-bipyridine), was investigated by means of X-ray absorption spectroscopy. Ru K-edge XANES (X-ray absorption near-edge structure) spectra from the acidic solution and solid precipitates obtained by oxidation showed that the absorption edge shifts toward higher energy with a preedge feature slightly more enhanced than those of the lower oxidation states. This indicates that the higher oxidation state has a lower symmetry due to shortening of the Ru-O bonds that originated from the water ligands. The EXAFS (extended X-ray absorption fine structure) spectra were similar to those of the lower oxidation states, whose analysis revealed the existence of short Ru-O double bonds and an almost linear Ru-O-Ru angle (169 +/- 2 degrees ). Ab initio EXAFS simulations for several possible structural models suggest that the dimeric structure is maintained during the water oxidation reaction.     

Total enantioselectivity in the DNA binding of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [bpm = 2,2'-bipyrimidine; Me2bpy = 4,4'-dimethyl-2,2'-bipyridine

The binding of the three stereoisomers (DeltaDelta-, LambdaLambda- and DeltaLambda-) of the dinuclear ruthenium(II) complex [[Ru(Me2bpy)2]2(mu-bpm)]4+ [Me2bpy = 4,4'-dimethyl-2,2'-bipyridine; bpm = 2,2'-bipyrimidine] to a tridecanucleotide containing a single adenine bulge has been studied by 1H NMR spectroscopy. The addition of the DeltaDelta-isomer to d(CCGAGAATTCCGG)2 induced significant chemical shift changes for the base and sugar resonances of the residues at the bulge site (G3A4G5/C11C10), whereas small shifts were observed upon addition of the enantiomeric LambdaLambda-form. NOESY spectra of the tridecanucleotide bound with the DeltaDelta-isomer revealed intermolecular NOE's between the metal complex and the nucleotide residues at the bulge site, while only weak NOE's were observed to terminal residues to the LambdaLambda-form. Competitive binding studies were performed where both enantiomers were simultaneously added to the tridecanucleotide, and for all ratios of the two stereoisomers the DeltaDelta-isomer remained selectively bound at the bulge site with the LambdaLambda-enantiomer localised at the terminal regions of the tridecanucleotide. The meso-diastereoisomer (DeltaLambda) was found to bind to the tridecanucleotide with characteristics intermediate between the DeltaDelta- and LambdaLambda-enantiomers of the rac form. Two distinct sets of metal complex resonances were observed, with one set having essentially the same shift as the free metal complex, whilst the other set of resonances exhibited significant shifts. The NOE data indicated that the meso-diastereoisomer does not bind as selectively as the DeltaDelta-isomer, with NOE's observed to a greater number of nucleotide residues compared to the DeltaDelta-form. This study provides a rare example of total enantioselectivity in the binding of an inert transition metal complex to DNA, produced by the shape recognition of both ruthenium(II) centres.     

Salt and solvent effects on the kinetics and thermodynamics of the inclusion of the ruthenium complex [Ru(NH3)5(4,4'-bpy)]2+ in beta-cyclodextrin

The influences of solvents (in water-cosolvent mixtures) and salts on the kinetics and thermodynamics of the inclusion of [Ru(NH3)5(4,4'-bpy)]2+ in beta-cyclodextrin (beta-CD) have been studied. Solvent effects on the kinetics can be described as a consequence of the competition of the cosolvent for the beta-CD cavity. The salt effects on the kinetics depend on the ion pairing of the anions with the [Ru(NH3)5(4,4'-bpy)]2+ complex. On the other hand, the solvent effects on the equilibrium constant depend on the stabilization of the 4,4'-bipyridine ligand in the water-cosolvent mixture relative to water. Finally, salt effects on the equilibrium constant are interpreted as a consequence of ion pairing between the anion of the salt and the inclusion complex.     

Absorption spectrum and solvatochromism of the [Ru(4,4'-COOH-2,2'-bpy)2(NCS)2] molecular dye by time dependent density functional theory

We present a combined Density Functional/Time Dependent Density Functional study of the molecular structure, electronic states, and optical absorption spectrum of [Ru(4,4'-COOH-2,2'-bpy)(2)(NCS)(2)], a widely used charge-transfer sensitizer in nanocrystalline TiO(2) solar cells. Calculations have been performed both for the complex in vacuo and in ethanol and water solvents, using a continuum model to account for solute-solvent interactions. Inclusion of the solvent leads to important changes of the energies and composition of the molecular orbitals of the complex; as a consequence, whereas the computed spectrum for the Ru-complex in vacuo deviates from the experimental one in both energy and shape, the spectra calculated in the presence of the solvent are in good agreement with the experiment. The first two absorption bands are found to originate from mixed ruthenium-NCS to bipyridine-pi* transitions rather than to pure metal-to-ligand-charge-transfer (MLCT) transitions, whereas the third band arises from intraligand pi --> pi* transitions. The experimentally observed blue-shift of the spectrum in water with respect to ethanol is well reproduced by our calculations and appears to be related to a decreased dipole moment in the excited state.     

一维链状[Mn(9-AC)2(4,4'-bpy)(H2O)2]n配位聚合物的合成及晶体结构

在水热条件下(120 ℃),将醋酸锰、4,4'-联吡啶(4,4'-bpy)与9-蒽酸(9-HAC)反应,得到了配位聚合物[Mn(9-AC)2(4,4'-bpy)(H2O)2]n,通过元素分析、红外光谱、X射线单晶衍射对其进行了表征,并用TGA研究了该配位聚合物的热稳定性.结构解析结果表明,该晶体属于正交晶系,Fdd2空间群,a=1.66772(12) nm,b=3.36471(16) nm,c=1.1687(4) nm,V=6.558(2) nm3,Z=8,M -r=689.60,Dc=1.397 Mg/m3,R=0.0356,wR2 = 0.0604.在该配位聚合物中,中心锰原子采取略微变形的八面体构型,与两种配体共同构筑了一维直线形链结构,链与链之间通过氢键相互作用构筑成三维超分子网络.     

Photoinitiated DNA Binding by cis-[Ru(bpy)2(NH3)2]2+

The ligand-loss photochemistry of cis-[Ru(bpy)(2)(NH(3))(2)](2+) (bpy = 2,2'-bipyridine) was investigated in water and in the presence of added ligands such as bipyridine and chloride. Irradiation of the complex results in the covalent binding to 9-methyl- and 9-ethylguanine, as well as to single-stranded and double-stranded DNA. This photoinduced DNA binding is not observed for the control complex [Ru(bpy)(2)(en)](2+) (en = ethylenediamine) under similar irradiation conditions. The results presented here show that octahedral Ru(II) complexes with photolabile ligands may prove useful as photoactivated cisplatin analogs.     

Electron delocalization in a ruthenium(II) Bis(2,2':6',2' '-terpyridyl) complex

Photophysical properties have been recorded for a ruthenium(II) bis(2,2':6',2' '-terpyridine) complex bearing a single ethynylene substituent. The target compound is weakly emissive in fluid solution at room temperature, but both the emission yield and lifetime increase dramatically as the temperature is lowered. As found for the unsubstituted parent complex, the full temperature dependence indicates that the lowest-energy triplet state couples to two higher-energy triplets and to the ground state. Luminescence occurs only from the lowest-energy triplet state, but the radiative and nonradiative decay rates indicate that electron delocalization occurs at the triplet level. Comparison of the target compound with the parent complex indicates that the ethynylene group reduces the size of the electron-vibrational coupling element for nonradiative decay of the lowest-energy triplet state. Although other factors are affected by substitution, this is by far the most important feature with regard to stabilization of the triplet state.     

Synthesis, crystal structure and properties of a new organic-inorganic hybrid Dawson-like polyoxotungstate [Co(2,2''-bpy)3]2[Co(2,2''-bpy)2Cl][Co(2,2''-bpy)2]H2-[SbW18O60]·4H2O

A new organic-inorganic hybrid polyoxometalate based on Dawson-like polyoxotungstate anion [SbW18O60]9-, formulated [Co(2,2'-bpy)3]2[Co(2,2'-bpy)2Cl][Co(2,2'-bpy)2]H2[SbW18O60]·4H2O (2,2'-bpy= 2,2(-bipyridine) has been synthesized from Sb2O3, Na2WO4, CoCl2, and 2,2'-bipyridine materials by hydrothermal method, and which was characterized by elemental analyses, IR, XPS, EPR, TG, and X-ray single crystal diffraction. Structure analysis shows that the polyoxoanion self-assembled under hydrothermal conditions consists of a Dawson-like polyoxotungstate cluster anion [SbW18O60]9- encapsulating a pyramidal {SbO3} group within the {W18} cluster cage. EPR spectra show that the high-spin octahedral CoⅡ and low-spin CoⅡ ions coexist in the title compound. Magnetic properties indicate that the compound is antiferromagnetic.     

Fullerene-acene chemistry: single-crystal X-ray structures for a [60]fullerene-pentacene monoadduct and a cis-bis[60]fullerene adduct of 6,13-diphenylpentacene

[structure: see text]. Crystal structures of the cis-bis[60]fullerene adduct of 6,13-diphenylpentacene (with the closest carbon atoms on adjacent fullerenes only 3.065(8) angstroms apart) and the [60]fullerene-pentacene monoadduct are in remarkably close agreement with the MM2 calculated structures.     

一维链状[Mn(9-AC)2(4,4'-bpy)(H2O)2]n配位聚合物的合成及晶体结构

在水热条件下(120 ℃), 将醋酸锰、4,4'-联吡啶(4,4'-bpy)与9-蒽酸(9-HAC)反应, 得到了配位聚合物[Mn(9-AC)2(4,4'-bpy)(H2O)2]n, 通过元素分析、红外光谱、X射线单晶衍射对其进行了表征, 并用TGA研究了该配位聚合物的热稳定性. 结构解析结果表明, 该晶体属于正交晶系, Fdd2空间群, a=1.66772(12) nm, b=3.36471(16) nm, c=1.1687(4) nm, V=6.558(2) nm3, Z=8, Mr=689.60, Dc=1.397 Mg/m3, R=0.0356, wR2 = 0.0604. 在该配位聚合物中, 中心锰原子采取略微变形的八面体构型, 与两种配体共同构筑了一维直线形链结构, 链与链之间通过氢键相互作用构筑成三维超分子网络.