Search

A nanocrystalline TiO2 dye-sensitized solar cell device consisting of dye 2 and fabricated with commercially available materials reaches a conversion efficiency of η = 1.20%. Dye 2 is a low-cost and easily prepared copper(i) molecular sensitizer.

The synthesis, isolation and structural characterization of the novel heteroleptic copper(I) complexes [Cu(RDABdipp)(LCOOMe)](PF6) (R = H (3), R = Me (4)) incorporating the sterically demanding 1,4-diaza-1,3-butadienes RDABdipp (R = H, Me; dipp = 2,6-diisopropylphenyl) is reported. 3 and 4 were isolated in high yields and spectroscopically characterized. The synthetic strategy includes the in situ reaction of the bis-acetonitrile intermediates [Cu(RDABdipp)(NCMe)2](PF6), (R = H (1), R = Me (2)) with the required amounts of the methyl-2-(pyridin-2-yl)-quinoline-4-carboxylate (LCOOMe) that was used as the ancillary ligand. 3 and 4 are rare examples of heteroleptic copper(I) complexes comprising RDABdipp and an ancillary α-diimine ligand, while 3 is the first crystallographically characterized example of this class of compounds. As a side product during the formation of 3 and 4, the homoleptic complex [Cu(LCOOMe)2](PF6) (5) is detected, that has been independently synthesized, for comparison. All the products were characterized by elemental analysis, FT–IR, UV–Vis and NMR spectroscopy. The molecular structures of 2·CH2Cl2, 3 and 5·CHCl3 were elucidated by single-crystal X-ray diffraction.

Novel V2O5 bifunctional photocatalysts were prepared following a wet chemical process with the addition of anionic or non-ionic surfactants into the precursor solution and further heating under reflux. Detailed characterization and investigation of the relevant light-matter interactions proved that surfactants addition had a strong impact on the morphology, while also affecting the crystallinity, the optoelectronic properties, and the surface chemistry of the novel photocatalysts. The most efficient photocatalyst (T80) was based on tween 80, a surface-active agent employed for the first time in the synthesis of vanadium oxide materials. T80 presented crystalline nature without structural defects, which are usually centers of e&minus, &minus, h+ recombination. This material also exhibited small crystal size, high porosity, and short migration paths for the charge carriers, enabling their effective separation during photocatalysis. Under UV light illumination, T80 was capable to reduce hexavalent chromium to trivalent up to 70% and showed high yields in degrading methylene blue azo-dye and tetracycline antibiotic water pollutants. This remarkably high bifunctional performance defines T80 as a promising and capable photocatalytic material for both advanced oxidation and reduction processes (AOPs-ARPs).

In this study we describe the one-pot and high yield synthesis of the ruthenium(II) complex cis-dichloride [RuCl2(PPh3)2(L1)] (L1 = 4-methyl-2-(2′-pyridyl)quinoline) (1). The solid state structure of L1 is described. The catalytic activity of 1 in the transfer hydrogenation of various ketones by 2-propanol at 82 °C, has been studied and compared with the activity of the known catalyst precursors cis-[RuCl2(PPh3)2(L2)] (L2 = 2-(2'-pyridyl)quinoline) (2), cis-[RuCl2(PPh3)2(L3)] (L3 = 2-(2′-pyridyl)quinoxaline) (3) and cis-[RuCl2(PPh3)2(bipy)] (bipy = 2,2′-bipyridine) (4). The ruthenium monohydride complex [RuHCl(PPh3)2(L3)] 3-H (Cl cis to H) was prepared from the reaction of 3 with 2.5 equivalents of a KOiPr solution. Reaction of 3 with 10 equivalents of KOiPr yields the cis-[RuH2(PPh3)2(L3)] (3-H2). Treatment of 1, 2 and 4 with KOiPr (in excess) affords the ruthenium cis-dihydride complexes [RuH2(PPh3)2(L1)] (1-H2), [RuH2(PPh3)2(L2)] (2-H2) and [RuH2(PPh3)2(bipy)] (4-H2). The formation of 1-H2, 2-H2, 3-H2 and 4-H2 is supported by NMR spectroscopic data. The cis-dihydrides 1-H2 to 4-H2 catalyze successfully the transfer hydrogenation of benzophenone to benzhydrol in the absence of a base, suggesting that presumably the active catalyst is a ruthenium dihydride complex (RuH2). Catalyst 1 has been potentially recovered and reused at least four times.

The ruthenium(II) complex cis-[RuCl2(PPh3)2(L1)] (1) where L1 = 2-(2’-pyridyl)quinoline was obtained in high yield from the reaction of [RuCl2(PPh3)3] with L1. The new compound was characterized by different spectroscopic methods including FT-IR, UV-Vis, NMR (1H, 31P) spectroscopy along with a mass spectrometric analysis (ESI-MS) and conductivity measurements. 31P NMR spectroscopy provided evidence that the two PPh3 ligands are orientated trans to each other in an octahedral environment. Complex (1) was tested in the transfer hydrogenation of various ketones in 2-propanol at 82 oC. The catalytic activity of (1) displayed quantitative conversions for benzophenone and 4-chloroacetophenone.

The Friedlander condensation reaction was employed to synthesize the new bidentate ligands namely 6-bromo-4-phenyl-2-pyridin-2-yl-quinoline (1) and 4-(4-phenyl-2-(pyridin-2-yl)quinolin-6-yl)phenol (2). These compounds were fully characterized including the X-ray structures of 1 and the protonated form of 2, i.e. 2·HCl·H2O. We also report the synthesis and spectroscopic characterization of two rhodium(III) complexes of the general formula [Rh(1)Cl3(CH3OH)] (3) and [Rh(2)Cl3(CH3OH)] (4). The molecular structures of 3·2CH3OH and 4 were determined by single-crystal X-ray diffraction studies, revealing that these complexes adopt the mer-configuration. The solution stability of 3, 4 was studied by a combination of UV–Vis and 1H NMR spectroscopic techniques. All compounds were biologically evaluated for their anti- platelet activity using their potency to inhibit the action of PAF (Platelet-Activating Factor), which is an approach of continuous interest in the field. Complexes 3 and 4 were found to be potent PAF inhibitors with IC50 values in the micromolar range (1.0 μM and 3.9 μM respectively). Since PAF is the most potent inflammatory lipid mediator, the PAF-inhibitors and consequently the title compounds may be considered as potent examples in the search for novel anti-inflammatory drugs.

In this minireview, we refer to recent results as far as the Platelet Activating Factor (PAF) inhibitors are concerned. At first, results of organic compounds (natural and synthetic ones and specific and nonspecific) as inhibitors of PAF are reported. Emphasis is given on recent results about a new class of the so-called metal-based inhibitors of PAF. A small library of 30 metal complexes has been thus created; their anti-inflammatory activity has been further evaluated owing to their inhibitory effect against PAF in washed rabbit platelets (WRPs). In addition, emphasis has also been placed on the identification of preliminarystructure-activityrelationships for the different classes of metal-based inhibitors.

Starting from cis-[Ru(dcbpyH2)2Cl2] (1), two new heteroleptic ruthenium(II) complexes, [Ru(dcbpyH2)2(L1)](NO3)2 (L1 = 2-(2′-pyridyl)quinoxaline (2), and [Ru(dcbpyH2)2(L2)](NO3)2 (L2 = 4-carboxy-2-(2′-pyridyl)quinoline (4); dcbpyH2 = 2,2′-bipyridine-4,4′-dicarboxylic acid), were synthesized and spectroscopically characterized. During the preparation of 2 and 4, the homoleptic [Ru(dcbpyH2)3]Cl2 complex (3) was isolated as a side product. Characterization includes IR and Raman spectroscopy, UV-Vis, multinuclear NMR spectroscopy, elemental, and ESI-mass spectrometric analyses.

The present review article traces the discoveries that were instrumental to the evolution of DSSCs, taking a critical look at the principles of the operation mechanism and insisting on the most important recent developments in the field. We draw our attention mainly to the dye (photosensitizer); the primary processes that take place inside a solar cell, and which are affected by the dye, are also reviewed along with some of the most significant recent information found in literature that one should keep in mind before designing a novel ruthenium sensitizer. Specific emphasis is given in trying to answer vital questions like defining the optimum number of –COOH anchoring groups and protons that an efficient dye should carry, the correct choice of preparing either a homoleptic or a heteroleptic complex, as well as which counterions are the most suitable. Phenomena such as the role of the adsorption geometry, electrical fields at the double layer, dye-redox couple interaction and recombination effects are also analyzed, in order to show how these factors influence the photoelectrochemical characteristics of the cell. Next, the contributions from our group in the direction of designing, synthesizing, characterizing and evaluating novel ruthenium(II)-based complexes, utilized as photosensitizers in DSSCs, are thoroughly discussed. Two types of Ru(II) complexes are examined: one family mimicking the standard N719 dye, bearing bidentate ligands, and another, carrying tridendate ligands, resembling the “black dye”.

Electrochemical studies of the newly synthesized bis(triphenyl phosphine) ruthenium(II) complex, cis-[RuCl2(L)(PPh3)2] (1, with L = 2-(2′-pyridyl)quinoxaline, C13N3H9), were performed in acetonitrile (ACN). For this purpose, cyclic voltammograms (CVs) as well as electrochemical impedance spectra (EIS) were recorded on either glassy carbon (GC), platinum (Pt), gold (Au), or multi-walled carbon nanotube (MWCNT) electrodes. Qualitative examination of solutions of 1 in ACN was performed on the basis of conductivity measurements and electrospray ionization mass spectrometry (ESI–MS). The conductivity data suggest that 1 is a 1 : 1 type electrolyte in ACN. The ESI spectra further demonstrate that upon dissolution of 1 in ACN progressive replacement of chloro- and PPh3-ligands by ACN occurs, leading to formation of [RuCl(L)(PPh3)(CH3CN)2]+Cl−, [2 + Cl − ]. The CVs recorded for [2 + Cl − ] on various working electrodes demonstrate that the reversibility of the redox couple 22 +/+ enhances with the order: Au < Pt ...

The molar conductivities (Λ) of solutions of bis(2,2′-bipyridine)bis(thiocyanate)chromium(III) triiodide [CrIII(bipy)2(SCN)2]I3 (where bipy denotes 2,2′-bipyridine, C10H8N2), [ $\mathrm{A}^{+}\mathrm{I}_{3}^{-}$ ], were measured in acetonitrile (ACN) at the temperatures 294.15, 299.15, and 305.15 K. In addition, cyclic voltammograms (CVs) of [ $\mathrm{A}^{+}\mathrm{I}_{3}^{-}$ ] were recorded on platinum, gold, and glassy carbon working electrodes in ACN, using n-tetrabutylammonium hexafluorophosphate (NBu4PF6) as the supporting electrolyte, at scan rates (v) ranging from 0.05 to 0.12 V⋅s−1. Furthermore, electrochemical impedance spectroscopic (EIS) measurements were carried out in the frequency range 50 Hz0$ ). As a result, the Gibbs energy $\Delta G_{\mathrm{A}}^{\mathrm{o}}$ is negative ( $\Delta G_{\mathrm{A}}^{\mathrm{o}}

The reaction of RhCl3·3H2O with the ligand L = 2-(2′-pyridyl)quinoxaline (pqo) in a 1:2 molar ratio formed the mononuclear complex cis-[RhL2Cl2]Cl (1), which has been characterized by elemental analysis, FT-IR, FT-Raman, 1H, 13C NMR, electronic absorption spectroscopy and by electrospray mass spectrometry. The molecular structure of 1 (needle like and prismatic polymorphs) in the crystal has been elucidated by single-crystal X-ray diffraction, revealing a bidentate behavior of L, while the geometry around the Rh(III) atom is that of a distorted octahedron.. Preliminary biological tests revealed that this compound inhibited PAF-induced rabbit platelet aggregation.

Conductometric investigation on the bis(triphenyl phosphine) ruthenium(II) complex, cis-[RuCl2(L)(PPh3)2] (A) (where PPh3: triphenyl phosphine and L: 2-(2′-pyridyl)quinoxaline, C13N3H9), in dimethylsulfoxide (DMSO) was performed at temperatures ranging from 25 to 50 °C. In addition, cyclic voltammograms of A were recorded on platinum working electrode in dichloromethane (DCM) and dimethylsulfoxide (DMSO) using n-tetrabutylammonium hexafluorophosphate (NBu4PF6) as supporting electrolyte at 25 °C. The molar conductivities (Λ) demonstrate that A behaves as uni-univalent electrolyte in DMSO over the whole temperature range. This behavior can be explained in terms of the replacement upon dissolution of chlorine and PPh3 ligands by DMSO molecules, and consequently, the formation of the ion-pair [RuCl(L)(PPh3)(DMSO)2]Cl [B+Cl−] which is dissociated in some extent. The Λ values were analyzed by means of the Lee–Wheaton conductivity equation in order to estimate the limiting molar conductivities (Λo) and the ion-pair association constants (KA) of [B+Cl−]. The limiting ion conductivities ( λ + o ) for the B+ ion were evaluated using n-tetrabutylammonium chloride (NBu4Cl) as “reference electrolyte”. The thermodynamic functions related with the ion association, such as Gibbs free energy ( Δ G A o ) , enthalpy ( Δ H A o ) , and entropy ( Δ S A o ) , were evaluated as well. The mobility of B+ was found to increase linearly with rising temperature and the consequent decrease of the viscosity (η) of DMSO. The KA and Δ G A o values indicate that the association of [B+Cl−] increases to some extent with the rise of the temperature followed by the decrease of the dielectric constant (e) of DMSO. The voltammetric experiments indicated that the couple Ru3+/2+ is reversible and diffusion controlled in DCM and completely irreversible in DMSO.

cis-[Ru(bpy)(2)(L(n))]Cl(2) (n = 1, L(1) = 4-carboxy-2-(2'-pyridyl)quinoline (); n = 2, L(2) = 2,2'-pyridine-4,4'-dicarboxylic acid ()); and cis-[Ru(bpy)(2)(L')(2))]Cl(2) (L' = 4-pyridinecarboxylic acid ()) complexes, with surface anchoring groups, are prepared from the reaction of cis-[Ru(bpy)(2)Cl(2)] () with the appropriate ligand (L(1), L(2), L'). Ion exchange in aqueous solution with NH(4)PF(6) gives the corresponding bis(hexafluorophosphate) derivatives cis-[Ru(bpy)(2)(L(1))](PF(6))(2) (), cis-[Ru(bpy)(2)(L(2))](PF(6))(2) () and cis-[Ru(bpy)(2)(L')(2)](PF(6))(2) (), respectively. The photo-electrochemical properties of the dyes () are investigated and the efficiency of the corresponding dye sensitized solar cells is compared to a N719 sensitized device, under similar fabrication and testing conditions.

Conductometric investigation of n-tetrabutylammonium hexafluorophosphate (NBu4PF6) was performed in methanol (MeOH), ethanol (EtOH), 2-propanol (2-PrOH), acetone (ACE), 3-pentanone (PEN), tetrahydrofurane (THF), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), dichloromethane (DCM), acetonitrile (ACN) and N-methylformamide (NMF) at 298.15 K. The limiting molar conductivities (Λo) and the association constants (KA) were derived from the Lee–Wheaton conductivity equation. The limiting ion conductivities ( λ ± o ) were evaluated using n-tetrabutylammonium tetraphenylborate (NBu4BPh4) as a “reference” electrolyte according to the method of Krumgalz. The Stokes’ radii (rSt) of PF6− anion were estimated and used for the calculation of its solvation numbers (Sn) in investigated solvent media. The mobility of ions was found to be completely controlled by the bulk viscosity (η) and consequently the Walden product (W = ηΛo) was found to be almost constant. Slight ionic association was found for NBu4PF6 in solvent media with dielectric constant ɛ > 16 while the association becomes more significant in THF which has the lowest dielectric constant (ɛ = 7.5). The Sn values indicate weak interactions between PF6− and solvent molecules. The only exception was found in the case of MeOH, in which the great Sn value can be attributed to a hydrogen bond formation between the fluor atoms of PF6− and hydrogen of MeOH molecules.

Starting from the Ru(bpp)Cl3 precursor (1), a family of novel heteroleptic RuII complexes of the general formulae [Ru(bpp)(dcbpyH)(X)] [X = Cl– (2a), NCS–, (3)] and Na[Ru(bpp)(dcbpy)(CN)] (4) with the ligands 2,6-bis(1-pyrazolyl)pyridine (bpp) and 2,2′-bipyridine-4,4′-dicarboxylic acid (dcbpyH2) has been synthesized, spectroscopically characterized, and attached to nanocrystalline TiO2 electrodes to be tested as solar cell sensitizers. Addition of HCl to (2a) led to the corresponding cationic derivative [Ru(bpp)(dcbpyH2)Cl]Cl (2b). All complexes were characterized by FT-IR, FT-Raman, UV/Vis, 1H NMR spectroscopy, elemental analysis, and mass spectrometry. Complex 4 and the previously reported [Ru(bdmpp)(dcbpyH2)Cl](PF6) (5) [bdmpp is 2,6-bis(3,5-dimethyl-1-pyrazolyl)pyridine] were characterized by single-crystal X-ray diffraction. The photo-electochemical properties of the dyes 2–4 were investigated and the efficiency of the corresponding dye-sensitized solar cells was compared to the sensitizing performance of the cis-[Ru(dcbpyH)2(NCS)2](NBu4)2 (N719) dye.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Two novel heteroleptic ruthenium complexes of the type cis-[Ru(dppz-COOH)2(NCS)2] (1) and cis-[Ru(dppz-COOH)(phen)(NCS)2] (2), where dppz-COOH = 11-carboxyl-dipyrido[3,2-α:2′,3′-c]phenazine and phen = 1,10-phenanthroline, were synthesized and fully characterized by analytical and spectroscopic techniques. The complexes showed a broad and intense metal-to-ligand charge transfer (MLCT) transition band in the visible region, which is emissive both in MeOH at room temperature and in a MeOH–EtOH glass (77 K). Both complexes 1 and 2 were anchored to nanocrystalline TiO2 film electrodes and the resulting photoelectrodes were successfully incorporated in dye-sensitized solar cells (DSSCs) using a solid state redox electrolyte [PEO/TiO2/I−/I3− (PEO = polyethyleneoxide, MW = 2 × 106)]. The photovoltaic performance of the DSSCs was evaluated and compared with the cell prepared with cis-(NBu4)2[Ru(Hdcbpy)2(NCS)2], so-called N719 dye (dcbpyH2 = 4,4′-dicarboxy-2,2′-bipyridine). Although the efficiency of the 2-sensitized solar cell was 10% higher than the 1-sensitized solar cell, neither was as efficient as the N719-sensitized solar cell. The results obtained in the present article are consistent with the photochemical properties of the corresponding Ru(II) dyes.

The new tridentate ligand 4-(3,4-methylenedioxyphenyl)-2,6-dipyrazinylpyridine (2) was prepared in good yield in a one-pot reaction. The RuII complexes [Ru(2)2](PF6)2 and [Ru(1)(2)](PF6)2 [1 is 2,6-dipyrazinyl-4-(4-tolyl)pyridine] were prepared in good yields and tested as photosensitizers against [Ru(1)2](PF6)2 and [Ru(ttpy)2](PF6)2 [ttpy is 4′-(4-tolyl)-2,2′:6′,2″-terpyridine]. The photosensitization ability follows the order [Ru(1)2](PF6)2 > [Ru(1)(2)](PF6)2 > [Ru(2)2](PF6)2 >> [Ru(ttpy)2](PF6)2, which is explainable in terms of mechanism and driving force. Hydrolysis of the methylene acetal function affords the catechol-appended complexes [Ru(3)2](PF6)2 and [Ru(1)(3)](PF6)2 [3 is 4-(3,4-dihydroxyphenyl)-2,6-dipyrazinylpyridine] in excellent yields. These insoluble, paramagnetic precipitates when tested as photosensitizers in homogeneous solution and in one case adsorbed on titania are able to generate photocurrents in a photovoltaic cell, albeit more weakly compared to the so-called N719 dye. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

A supramolecular complex [Ru(dcb)2(α-CD-5-bpy)]Cl2 (1-α-CD) (dcb = 4,4′-dicarboxyl-2,2′-bipyridine, α-CD-5-bpy = 6-mono[5-methyl(5′-methyl-2,2′-bipyridyl)]-permethylated α-CD) (CD: cyclodextrin) based on a ruthenium tris-bipyridyl core with an appended α-CD cavity is designed and synthesised, in order to facilitate dye/redox couple interaction and dye regeneration in nanocrystalline TiO2 solar cells. The luminescent complex is fully characterized and anchored on mesoporous titania electrodes showing increased power-conversion efficiency in solid-state dye-sensitized solar cells using a composite polymer electrolyte. Direct comparison of the properties of the CD complex with an analogous ruthenium complex [Ru(dcb)2(5,5′-dmbpy)]Cl2 (2) (5,5′-dmbpy = 5,5′-dimethylbipyridine) without the CD cavity reveals that the photovoltaic performance of 1-α-CD is enhanced by about 40 % compared to 2. Independent studies have shown complexation of the iodide redox couple to the CD in 1-α-CD. These results indicate that the CD moiety is able to act as a mediator and fine tune the photoelectrode/electrolyte interface.

Ruthenium polypyridine and polypyridined-derivative complexes are used in dye-sensitized solar cell as a light to current conversion sensitizers, study on the electronic absorption spectroscopy of which are very important for the understanding of their photovoltaic character. A theoretical research of UV–Vis spectrum on the Ru(II)L2[L = bis(5′-methyl-2,2′-bipyridine-6-carboxylato)], a polypyridined-derivative mononuclear ruthenium complex, is presented here. Transition excited states of Ru(II)L2 in the gas phase have been studied by the time-dependent density functional theory (TD-DFT) using a hybrid functional, B3LYP, as well as the 3-21G∗ basis set. Two maximum absorptions are dominated by the metal-to-ligand-charge-transfer (MLCT) transitions, from Ru 4d orbitals to the bipyridine rings π∗. Taking account of solvent effect, the electronic absorption spectrum of Ru(II)L2 in N,N′-dimethyl formamide (DMF) solution has also been investigated on the basis of Polarized Continuum Model (PCM) in connection with TD-DFT. Calculation results indicate that the two maximum MLCT absorption peaks are blue-shifted in DMF solution with respect to those in the gas phase, which is in agreement with the observed phenomenon of other ruthenium polypyridine-type complexes.

A homoleptic ruthenium(II) complex with the ligand (5′-methyl-2,2′-bipyridine-6-carboxylate) has been prepared and characterized by elemental analysis, FT-IR, 1H, 13C NMR 1D and 2D and electronic absorption spectroscopy. The X-ray crystal structure of the complex has also been determined. It crystallizes in the triclinic crystal system space group P 1 ¯ , exhibiting a distorted octahedral geometry around the ruthenium atom.

The first reactions of the germylidyne complexes trans-[X(dppe)2W⋮Ge(η1-Cp*)]·[toluene] (1-Cl·C7H8, X = Cl; 1-I·C7H8, X = I) with nucleophiles and electrophiles are reported. Treatment of 1-I·C7H8 with KBH4 in refluxing THF affords selectively the hydrido−germylidyne complex trans-[H(dppe)2W⋮Ge(η1-Cp*)] (2). Similarly, metathetical exchange of 1-I·C7H8 with an excess of MY (M = Na, K; Y = NCO, N3, NCS, CN) gives the pseudohalide complexes trans-[Y(dppe)2W⋮Ge(η1-Cp*)]·x(toluene) (3a, Y = NCO, x = 0; 3b, Y = N3, x = 0; 3c·C7H8, Y = NCS, x = 1; 3d·0.5C7H8, Y = CN, x = 0.5). Chloride abstraction from 1-Cl·C7H8 with Li[B(C6F5)4]·2.5Et2O yields in the presence of acetonitrile the first cationic germylidyne complex, trans-[(MeCN)(dppe)2W⋮Ge(η1-Cp*)][B(C6F5)4] (4). All new complexes were well characterized. The molecular structures of 2·1.5C6D6, 3a·THF, 3d·0.5C7H8, and 4 were determined by single-crystal X-ray diffraction studies. The germylidyne complexes reveal very short W−Ge distances (dW-Ge = 229.91(9)−231.8...

The halogermylenes (Cp*GeX)n (1a, X = Cl, n = 1; 1b, X = Br, n = 2; Cp* = pentamethylcyclopentadienyl) were prepared in high yield by a redistribution reaction of GeCp*2 with GeX2(1,4-dioxane). The ionic compounds [Cp*Ge][GeX3] (2a, X = Cl; 2b, X = Br) were also formed to a small extent in this reaction. Treatment of trans-[Mo(dppe)2(N2)2] (3) (dppe = Ph2PCH2CH2PPh2) with 1 equiv of 1a,b affords in refluxing toluene the germylyne complexes trans-[X(dppe)2Mo⋮Ge−(η1-Cp*)] (4a, X = Cl; 4b, X = Br). Concomitant formation of GeCp*2 and the dihalo complexes trans-[Mo(dppe)2(X)2] (5a, X = Cl; 5b, X = Br) is observed in this reaction. In comparison, the reactions of trans-[W(dppe)2(N2)2] (6) with 1a,b and (Cp*GeI)∞ (1c) afford selectively the germylyne complexes trans-[X(dppe)2W⋮Ge−(η1-Cp*)] (7a−c). The molecular structures of 4a·0.5pentane and 4b·0.5pentane reveal very short Mo−Ge bonds, almost linear Mo−Ge−C(Cp*) sequences, and an η1-bonded Cp* substituent indicating the presence of a molybdenum−germanium tripl...

The preparation of Rh(I) and Rh(III) complexes with [2-(dimethylamino)ethyl]cyclopentadiene is described. Starting with C5H5(CH2)2NMe2 (1) or Na[C5H4(CH2)2NMe2] (2) and using [η5:η4-C5H4(CH2)2N(H)Me2Rh(I)(cod)]+(BF4)− (8) and [Rh(CO)2Cl]2, the complexes [η5:η1-C5H4(CH2)2NMe2Rh(I)(CO)2] (3), [η5:η1-C5H4(CH2)2N(H)Me2Rh(I)(CO)2]+(Cl)− (4a), [η5:η1-C5H4(CH2)2N(H)Me2Rh(I)(CO)2]+(BF4)−·Et2O (4b (4b·Et2O), [η5:η1-C5H4(CH2)2N(H)Me2Rh(III)(CO)I2]+(Cl)− (5), [η5:η1-C5H4(CH2)2NMe2Rh(III)I2] (6), [η5:η1-C5H4(CH2)2NMe2Rh(III)I2](PPh3)] (7), [η5:μ-C5H4(CH2)2NMe2Rh(III)I]22+· (BF4)2− (9), and [η5:μ:η1-C5H4(CH2)2N(H)Me2Rh(III)I2]22+·(BF4)2− (10) were synthesized and characterized by elemental analysis, IR, 1H and 13C NMR and mass spectroscopy. The results show that the dimethylamino side chain can play the role of the auxiliary base required to deprotonate cyclopentadiene and that this group may or not coordinate to the metal, depending on its protonation state and the oxidation state of the metal.

The synthesis of monometallic rhodium(III) and rhodium(I) derivatives of dialkylamino-functionalized cyclopentadienyl using the corresponding cyclopentadiene as starting material is facilitated by the presence of the basic amino group. This procedure affords the chloro salts of the substituted rhodicinium cation [(eta(5)-C(5)H(4)(CH(2))(2)NMe(2)H)(2)Rh(III)](3+) ([1][Cl](3)) from the reaction of the [2-(dimethylamino)ethyl]cyclopentadiene with Na(3)Rh(III)Cl(6). 12H(2)O. Similarly the cationic half-sandwich complexes [(eta(5)-C(5)H(4)(CH(2))(n)()NMe(2)H)Rh(I)(cod)](+) (n = 2, [2][Cl], n = 3, [5][Cl]) are obtained from the reaction of the corresponding dialkylamino cyclopentadiene with [RhCl(cod)](2). These types of cationic complexes, 1, 2, and 5, bear pendant ammonium groups. The most classical procedure, starting from the lithium or more efficiently from the sodium cyclopentadienide salt, was used to synthesize neutral complexes [(eta(5)-C(5)H(4)(CH(2))(n)()NMe(2))Rh(I)(cod)] (n = 2, 3; n = 3, 4). The structure of the chloride bis(hexafluorophosphate) salt, [(eta(5)-C(5)H(4)(CH(2))(2)NMe(2)H)(2)Rh(III)](3+)(Cl(-))(PF(6)(-))(2), ([1][Cl][PF(6)](2)) was solved in the triclinic space group Ponemacr; with one molecule in the unit cell, the dimensions of which are a = 6.617(2) Å, b= 7.436(2) Å, c = 13.965(3) Å, alpha = 76.39(2) degrees, beta = 82.31(3) degrees, gamma = 87.26(2) degrees, and V = 661.8(3) Å(3). The noncentrosymmetric character of this solid is attributed to the chloride ion. The tetrafluoroborate salt [(eta(5)-C(5)H(4)(CH(2))(2)NMe(2)H)Rh(I)(cod)](+)(BF(4)(-)) ([2][BF(4)]) crystallizes in the tetragonal space group P4(2)/n with eight molecules in the unit cell, the dimensions of which are a= 21.183(2) Å, b = 21.179(3) Å, c= 8.324(2) Å, and V = 3734(1) Å(3). Least squares refinement leads to values for the conventional R index of [1][Cl][PF(6)](2) (0.0484 for 2191 reflections used) and of [2][BF(4)] (0.0525 for 1083 reflections used); in both cases I3sigma(I). As expected, compounds like [2][Cl](3,) [1][Cl][PF(6)](2), [2][Cl], [2][BF(4)], [5][Cl], and [5][BF(4)] are soluble in water.

The genotoxic evaluation (in vitro analysis) of a series of eight inorganic tin(II) and tin(IV) compounds [tin(II) acetate, tin(II) chloride, tin(II) ethylhexanoate, tin(II) oxalate, tin(II) oxide, tin(IV) acetate, tin(IV) chloride and tin(IV) oxide], for the detection of micronuclei in human blood lymphocytes, was performed in the absence of metabolic activation by the cytokinesis-block micronucleus assay. Human lymphocytes were treated for over one cell cycle (31 hours), with concentrations ranging from 1 to 75 μM (1, 5, 10, 20, 50 and 75 μM), of tin(II) and tin(IV) salts dissolved in dimethyl sulfoxide. The above-listed concentrations cover the values that have been detected in humans with no occupational exposure to tin compounds. The experimental results show the absence of genotoxicity for all inorganic compounds tested in the specific concentrations and experimental conditions. Cytotoxic effects of tin(II) and tin(IV) compounds were evaluated by the determination of cytokinesis block proliferation index and cytotoxicity percentage. Our observations on the cytotoxicity pattern of the tested tin(II) and tin(IV) compounds indicate that they are cytotoxic in several tested concentrations to human lymphocytes treated in vitro. The observed differences in cytotoxicity of each tested compound might reflect differences in their chemical structure.

The reaction of trans-[W(dppe)2(N2)2] (1) with the m-terphenyl tin(II) chloride {Sn(Cl)(C6H3-2,6-Mes2)}2 (2) affords by elimination of dinitrogen the 18-electron stannylyne complex trans-[Cl(dppe)2...

Two square planar Rh(I) organometallic complexes namely [Rh(L(1))(cod)]Cl (cod = cycloocta-1,5-diene, L(1)=2,2'-pyridylquinoxaline (1-Cl), [Rh(L1)(cod)](NO3) (1-NO(3)) and a series of novel octahedral rhodium(III) complexes of the general formulae mer-[Rh(L(1))Cl(3)(MeOH)] (2) and cis-[Rh(L(2))(2)Cl(2)]Cl (L(2)=4 carboxy 2 (2' pyridyl)quinoline (3), L(3)=2,2' bipyridine 4,4' dicarboxylic acid (4) were synthesized and characterized spectroscopically. All the synthesized compounds including the previously prepared cis-[Rh(L(1))(2)Cl(2)]Cl complex (5) were biologically evaluated as potential inhibitors of the Platelet Activation Factor (PAF) and thrombin induced aggregation. In particular compounds 1-Cl and 1-NO(3) were found to be strong inhibitors of PAF with IC(50) values in the range of 16 nM and 15 nM rendering them good candidates for further investigation. Their potency is comparable to that of the widely used PAF receptor antagonists WEB2170, BN52021, and Rupatadine (IC(50) of 20, 30 and 260 nM respectively). Molecular docking calculations suggest that 1-Cl, 1-NO3 and 2 can be accommodated within the ligand-binding site of PAF receptor and block the activity of PAF. On the other hand, the octahedral rhodium(III) complexes 3-5 that cannot fit the ligand-binding domain, could potentially exhibit their activity at the extracellular domain of the receptor.

The present review article traces the discoveries that were instrumental to the evolution of DSSCs, taking a critical look at the principles of the operation mechanism and insisting on the most important recent developments in the field. We draw our attention mainly to the dye (photosensitizer); the primary processes that take place inside a solar cell, and which are affected by the dye, are also reviewed along with some of the most significant recent information found in literature that one should keep in mind before designing a novel ruthenium sensitizer. Specific emphasis is given in trying to answer vital questions like defining the optimum number of -COOH anchoring groups and protons that an efficient dye should carry, the correct choice of preparing either a homoleptic or a heteroleptic complex, as well as which counterions are the most suitable. Phenomena such as the role of the adsorption geometry, electrical fields at the double layer, dye-redox couple interaction and recombination effects are also analyzed, in order to show how these factors influence the photoelectrochemical characteristics of the cell. Next, the contributions from our group in the direction of designing, synthesizing, characterizing and evaluating novel ruthenium(II)-based complexes, utilized as photosensitizers in DSSCs, are thoroughly discussed. Two types of Ru(II) complexes are examined: one family mimicking the standard N719 dye, bearing bidentate ligands, and another, carrying tridendate ligands, resembling the " black dye" © 2010 Elsevier B.V.

The title compound, cis-[W(CO)2(dppe)2] [dppe is 1,2-ethane­diyl­bis­(di­phenyl­phosphine), C26H24P2], was obtained as a by-product during the preparation of the di­nitro­gen complex trans-[W(CO)(N2)(dppe)2]. The crystal structure of the benzene sesquisolvate, i.e. cis-[W(C26H24P2)2(CO)2]·1.5C6H6, has been determined.

The complex trans-[Mo(NCS)2(dppe)2] [dppe is ethane-1,2-diyl­bis­(di­phenyl­phosphane), C26H24P2] was obtained upon air oxidation of [N(n-Bu)4][Mo(NCS)(dppe)2(N2)] and the crystal structure of its toluene solvate, [Mo(NCS)2(C26H24P2)2]·C7H8, has been determined. The complex mol­ecule reveals a distorted octahedral coordination geometry, with two trans-oriented N-bonded thio­cyanate ligands. The Mo atom resides on a crystallographic center of symmetry.

trans-[MoCl2(dppe)2] [dppe is 1,2-ethane­diyl­bis­(di­phenyl­phos­phine), C26H24P2] was obtained as a side product from the reaction of trans-[Mo(dppe)2(N2)2] with Cp*GeCl to give the germyl­yne complex trans-[Cl(dppe)2Mo≡Ge(η1-Cp*)]. The crystal structures of the hemi­pentane (0.5C5H12) and di­tetra­hydro­furan (2C4H8O) solvates of trans-[MoCl2(dppe)2], (IIIa) and (IIIb), respectively, have been determined.