The impact of biomolecule interactions on the cytotoxic effects of rhenium(I) tricarbonyl complexes.

Rhenium complexes show great promise as anticancer drug candidates. Specifically, compounds with a Re(CO)(NN)(py) core in their architecture have shown cytotoxicity equal to or greater than that of well-established anticancer drugs based on platinum or organic molecules. This study aimed to evaluate how the strength of the interaction between rhenium(I) tricarbonyl complexes fac-[Re(CO)(NN)(py)], NN = 1,10-phenanthroline (phen), dipyrido[3,2-f:2',3'-h]quinoxaline (dpq) or dipyrido[3,2-a:2'3'-c]phenazine (dppz) and biomolecules (protein, lipid and DNA) impacted the corresponding cytotoxic effect in cells.

Gold(I) and Silver(I) Complexes Containing Hybrid Sulfonamide/Thiourea Ligands as Potential Leishmanicidal Agents.

Leishmaniasis is a group of parasitic diseases with the potential to infect more than 1 billion people; however, its treatment is still old and inadequate. In order to contribute to changing this view, this work consisted of the development of complexes derived from M metal ions with thioureas, aiming to obtain potential leishmanicidal agents. The thiourea ligands (HL) were obtained by reactions of -toluenesulfohydrazide with R-isothiocyanates and were used in complexation reactions with Ag and Au, leading to the formation of complexes of composition [M(HL)]X (M = Ag or Au; X = NO or Cl).

Visible light-driven CO2 photoreduction by a Re(I) complex immobilized onto CuO/Nb2O5 heterojunctions.

The immobilization of Re(I) complexes onto metal oxide surfaces presents an elegant strategy to enhance their stability and reusability toward photocatalytic CO2 reduction. In this study, the photocatalytic performance of fac-[ClRe(CO)3(dcbH2)], where dcbH2 = 4,4'-dicarboxylic acid-2,2'-bipyridine, anchored onto the surface of 1%m/m CuO/Nb2O5 was investigated. Following adsorption, the turnover number for CO production (TONCO) in DMF/TEOA increased significantly, from ten in solution to 370 under visible light irradiation, surpassing the TONCO observed for the complex onto pristine Nb2O5 or CuO surfaces.

Well-dispersed titanium dioxide and silver nanoparticles on external and internal surfaces of asymmetric alumina hollow fibers for enhanced chromium (VI) photoreductions.

Heterogenous photocatalysis is a suitable alternative for wastewater treatment. The supporting of the solid catalyst in a porous material is suggested to facilitate catalyst recovery and reuse. Here we propose for the first time the evaluation of supporting silver (Ag)-decorated titanium dioxide (TiO) catalysts on internal and external surfaces of alumina hollow fibers with asymmetric pore size distribution.

Electrocatalytic properties of a novel ruthenium(II) terpyridine-based complex towards CO reduction.

The electrocatalytic properties of Ru complexes are of great technological interest given their potential application in reactions such water splitting and CO reduction. In this work, a novel terpyridine-based Ru(II) complex, [RuCl(trpy)(acpy)], trpy = 2,2':6',2''-terpyridine, acpy = 2-pyridylacetate was synthesized and its spectroscopic, electrochemical and catalytic properties were explored in detail. In dry acetonitrile, the complex exhibits two reduction peaks at -1.

On the influence of hydrothermal treatment pH on the performance of BiWO as photocatalyst in the glycerol photoreforming.

Solar driven semiconductor-based photoreforming of biomass derivatives, such as glycerol is a sustainable alternative towards green hydrogen evolution concerted with production of chemical feedstocks. In this work, we have investigated the influence of the pH of the hydrothermal treatment on the efficiency of BiWO as photocatalyst in the glycerol photoreforming. BiWO is pointed as a promising material for this application due its adequate band gap and the ability to promote hole transfer directly to glycerol without formation of non-selective OH radicals.

Mechanistic investigation of the aerobic oxidation of 2-pyridylacetate coordinated to a Ru(II) polypyridyl complex.

A new ruthenium polypyridyl complex, [Ru(bpy)(acpy)] (acpy = 2-pyridylacetate, bpy = 2,2'-bipyridine), was synthesized and fully characterized. Distinct from the previously reported analog, [Ru(bpy)(pic)] (pic = 2-pyridylcarboxylate), the new complex is unstable under aerobic conditions and undergoes oxidation to yield the corresponding α-keto-2-pyridyl-acetate (acpyoxi) coordinated to the Ru center. The reaction is one of the few examples of C-H activation at mild conditions using O as the primary oxidant and can provide mechanistic insights with important implications for catalysis.

Electrocatalytic water oxidation reaction promoted by cobalt-Prussian blue and its thermal decomposition product under mild conditions.

Cobalt-Prussian blue analogues are remarkable catalysts for the oxygen evolution reaction (water oxidation) under mild conditions such as neutral pH. Although there are extensive reports in the literature about the application of these catalysts in water oxidation (the limiting step for hydrogen evolution), some limitations must be overcome in terms of improving the turnover frequency, oxygen production, long term stability, and elucidation of the mechanism. Another important feature to consider is the industrial processability of electrolytic cells for water splitting.

Aluminum oxides as alternative building blocks for efficientblocking layers in dye-sensitized solar cells.

All inorganic layer-by-layer (LbL) thin films composed by TiOnanoparticles and [Al(OH)]anions () as well as AlOand NbOnanoparticles () have been deposited to fluorine-doped tin-oxide coated glass (FTO) surfaces and applied as blocking layers in dye-sensitized solar cells (DSCs). Structural and morphological characterization of the LbL films by different techniques reveal that inassembly, aluminate anions undergo condensation reactions on the TiOsurface leading to the formation of highly homogeneous films with unique optical properties. After 25 depositions transmittance losses below 10% in relation to the bare FTO substrate are observed.

Innovative multifunctional hybrid photoelectrode design based on a ternary heterojunction with super-enhanced efficiency for artificial photosynthesis.

Electrochemical cells for direct conversion of solar energy to electricity (or hydrogen) are one of the most sustainable solutions to meet the increasing worldwide energy demands. In this report, a novel and highly-efficient ternary heterojunction-structured BiO/Bi(VO)O/BiVO photoelectrode is presented. It is demonstrated that the combination of an inversion layer, induced by holes (or electrons) at the interface of the semiconducting Bi(VO)O and BiVO components, and the rectifying contact between the BiO and Bi(VO)O phases acting afterward as a conventional p-n junction, creates an adjustable virtual p-n-p or n-p-n junction due to self-polarization in the ion-conducting BiVO constituent.

Intramolecular C(sp)-C (sp) bond formation between phenanthroline and β-diketone thiosemicarbazones in Pt complexes: crystal structures and computational studies.

[PtCl(phen)] reacts with thiosemicarbazones derived from β-diketones (HL) leading to an intramolecular C-C coupling between phen and the ketone upon formation of tetradentate N,N,N,S chelates [Pt(Lphen)]. The reactions proceed via bidentate coordination of the doubly deprotonated (L) followed by an intra-nucleophilic attack and consecutive C-C bond formation.

Spectroscopic characterization of a new Re(I) tricarbonyl complex with a thiosemicarbazone derivative: towards sensing and electrocatalytic applications.

This work describes the preparation of a new thiosemicarbazone derivative, (Z)-N-ethyl-2-(6-oxo-1,10-phenanthrolin-5(6H)-ylidene)hydrazinecarbothioamide (phet) and its respective Re(i) tricarbonyl chloro complex, fac-[ReCl(CO)3(phet)]. The spectroscopic, photophysical and electrochemical properties of the new complex were fully investigated through steady state and time-resolved techniques along with computational calculations. In fac-[ReCl(CO)3(phet)], the new ligand is coordinated to the metal center through the pyridyl rings of the phenanthroline moiety.

Unraveling the photocatalytic properties of TiO/WO mixed oxides.

TiO2/WO3 heterojunctions are one of the most investigated systems for photocatalytic applications. However, distinct behavior can be found in the literature depending on the pollutant to be degraded and the photocatalyst preparation conditions. Some authors reported improved photocatalytic activities in relation to TiO2, while others a deleterious effect.

Influence of the preparation conditions on the morphology and photocatalytic performance Pt-modified hexaniobate composites.

The preparation of lamellar nanostructures through exfoliation of stacked niobates is an interesting approach to the development of photocatalysts for energy conversion and environmental remediation. These materials exhibit a rich surface chemistry and several nanocomposites can be produced through intercalation or impregnation of suitable precursors. In this work, the influence of the physico-chemical preparation conditions on the photocatalytic activity of Pt-hexaniobate nanocomposites was investigated aiming at the establishment of the main factors that control their photoreactivities.

Quenching Effects of Graphene Oxides on the Fluorescence Emission and Reactive Oxygen Species Generation of Chloroaluminum Phthalocyanine.

The photophysical behavior and reactive oxygen species (ROS) generation by chloroaluminum phthalocyanine (AlClPc) are evaluated by steady state absorption/emission, transient emission, and electron paramagnetic resonance spectroscopies in the presence of graphene oxide (GO), reduced graphene oxide (RGO), and carboxylated nanographene oxide (NGO). AlClPc and graphene oxides form a supramolecular structure stabilized by π-π interactions, which quantitatively quenches fluorescence emission and suppresses ROS generation. These effects occur even when graphenes are previously functionalized with Pluronic F-127.

Photochemistry of fac-[Re(CO)(dcbH)( trans-stpy)]: New Insights on the Isomerization Mechanism of Coordinated Stilbene-like Ligands.

In this work, a novel complex fac-[Re(CO)(dcbH)( trans-stpy)], (dcbH = 4,4'-dicarboxylic acid-2,2'-bipyridine; trans-stpy = trans-4-styrylpyridine) was synthesized and characterized toward its spectroscopic, photochemical, and photophysical properties. The experimental data provide new insights on the mechanism of photochemical trans-to- cis isomerization of the stilbene-like ligand coordinated to Re(I) polypyridyl complexes. The new complex exhibits an unusual and strong dependence of the isomerization quantum yield (Φ) on the irradiation wavelength.

A hole inversion layer at the BiVO4/Bi4V2O11 interface produces a high tunable photovoltage for water splitting.

The conversion of solar energy into hydrogen fuel by splitting water into photoelectrochemical cells (PEC) is an appealing strategy to store energy and minimize the extensive use of fossil fuels. The key requirement for efficient water splitting is producing a large band bending (photovoltage) at the semiconductor to improve the separation of the photogenerated charge carriers. Therefore, an attractive method consists in creating internal electrical fields inside the PEC to render more favorable band bending for water splitting.

Layer-by-layer TiO(2)/WO(3) thin films as efficient photocatalytic self-cleaning surfaces.

New TiO2/WO3 films were produced by the layer-by-layer (LbL) technique and successfully applied as self-cleaning photocatalytic surfaces. The films were deposited on fluorine doped tin oxide (FTO) glass substrates from the respective metal oxide nanoparticles obtained by the sol-gel method. Thirty alternative immersions in pH = 2 TiO2 and pH = 10 WO3 sols resulted in ca.

fac-[1,2-Bis(pyridin-4-yl)ethane-κN]tricarbon-yl(1,10-phenanthroline-κ(2) N,N')rhenium(I) hexa-fluorido-phosphate aceto-nitrile monosolvate.

The asymmetric unit of the title compound, [Re(C12H8N2)(C12H12N2)(CO)3]PF6.·CH3CN, contains one cation, one hexa-fluorido-phosphate anion and one aceto-nitrile solvent mol-ecule. The Re(I) ion is coordinated by two N atoms from the 1,10-phenanthroline ligand and one N atom from the 1,2-bis-(pyridin-4-yl)ethane ligand [mean Re-N = 2.

Solid state molecular device based on a rhenium(I) polypyridyl complex immobilized on TiO2 films.

The photochemical and photophysical behaviors of fac-[Re(CO)3(phen)(trans-stpyCOOH)](+) (phen = 1,10-phenanthroline, trans-stpyCOOH = 4-[trans-(pyridin-4-yl-vinyl)]benzoic acid) in acetonitrile solution and adsorbed on a TiO2 film have been investigated. The trans-to-cis photoisomerization at 404 nm irradiation of coordinated stpyCOOH occurs efficiently in fluid solution as shown by quantum yield determined spectrophotometrically (Φ(UV-vis) = 0.37 ± 0.

Interfacial electron transfer dynamics following laser flash photolysis of [Ru(bpy)2((4,4'-PO3H2)2bpy)]2+ in TiO2 nanoparticle films in aqueous environments.

Nanosecond laser flash photolysis has been used to investigate injection and back electron transfer from the complex [(Ru(bpy)(2)(4,4'-(PO(3)H(2))(2)bpy)](2+) surface-bound to TiO(2) (TiO(2)-Ru(II)). The measurements were conducted under conditions appropriate for water oxidation catalysis by known single-site water oxidation catalysts. Systematic variations in average lifetimes for back electron transfer, <τ(bet)>, were observed with changes in pH, surface coverage, incident excitation intensity, and applied bias.

Excited-state dynamics in fac-[Re(CO)3(Me4phen)(L)]+.

Excited-state dynamics in fac-[Re(CO)(3)(Me(4)phen)(cis-L)](+) (Me(4)phen = 3,4,7,8-tetramethyl-1,10-phenanthroline, L = 4-styrylpyridine (stpy) or 1,2-bis(4-pyridyl)ethylene (bpe)) were investigated by steady-state and time-resolved techniques. A complex equilibrium among three closely lying excited states, (3)IL(cis-L), (3)MLCT(Re→Me(4)phen), and (3)IL(Me(4)phen), has been established. Under UV irradiation, cis-to-trans isomerization of coordinated cis-L is observed with a quantum yield of 0.

Making oxygen with ruthenium complexes.

Mastering the production of solar fuels by artificial photosynthesis would be a considerable feat, either by water splitting into hydrogen and oxygen or reduction of CO(2) to methanol or hydrocarbons: 2H(2)O + 4hnu --> O(2) + 2H(2); 2H(2)O + CO(2) + 8hnu --> 2O(2) + CH(4). It is notable that water oxidation to dioxygen is a key half-reaction in both. In principle, these solar fuel reactions can be coupled to light absorption in molecular assemblies, nanostructured arrays, or photoelectrochemical cells (PECs) by a modular approach.

Photoswitches and luminescent rigidity sensors based on fac-[Re(CO)3(Me4phen)(L)]+.

The fac-[Re(CO)3(Me4phen)(trans-L)]+ complexes, Me4phen = 3,4,7,8-tetramethyl-1,10-phenanthroline and L = 4-styrylpyridine, stpy, or 1,2-bis(4-pyridyl)ethylene, bpe, were synthesized and characterized by their spectroscopic,photochemical, and photophysical properties. The complexes exhibit trans-to-cis isomerization upon 313, 334, 365,and 404 nm irradiation, and the true quantum yields can be efficiently determined by absorption changes combined with 1H NMR data. For fac-[Re(CO)3(Me4phen)(trans-bpe)]+ similar quantum yields were determined at all wavelengths investigated.