Literatura científica selecionada sobre o tema "[Pt]-Oligomers"

AbstractThis review covers almost 100 organoplatinum complexes: trimers (40 examples), tetramers (40 examples), pentamers (4 examples), hexamers (5 examples), nona- and oligomers (8 examples). Platinum is predominantly found in the oxidation states +2 and +4. A number of coordination geometries are observed, the most common being essentially square planar, especially with Pt(II), and distorted octahedral, especially with Pt(IV). The most common ligands are methyl, carbonyl, PX3 and bis(diphenylphosphine)methane. Relationships between the Pt-Pt distances, Pt-X-Pt bridge angles, Pt-L bond distances and covalent radii of coordinated atoms are discussed. The mean Pt-Pt bond distance elongates in the order of nuclearity: 269.0 pm (trimers)<270.5 pm (tetramers)<271.5 pm (dimers)<278.0 pm (oligomers). A comprehensive brief discussion on over 1600 organoplatinum complexes and over 2500 platinum coordination complexes is given. These complexes prefer to crystallize in monoclinic (53%) and triclinic (27%) crystal classes. About l0% of these 4100 plus complexes exist as isomers. It is observed that these isomers are more often stereoisomers than structural isomers and that distortion isomerism is surprisingly more common than the better known cis-trans isomerism, especially in the chemistry of Pt(II) complexes.

Platinum(II) compounds of the type cis-[Pt(L)2X2] where L = tetramethylenesulfoxide (TMSO), ethylmethylsulfoxide (EMSO), di-n-propylsulfoxide (DPSO), benzylmethylsulfoxide (BMSO), and dibenzylsulfoxide (DBSO) and X = Cl− and I− have been synthesized. The reactions of these compounds with a silver salt were studied in aqueous solution. Monomers of the type cis-[Pt(L)2(ClO4)2] (L = TMSO, EMSO, and DBSO), cis-[Pt(EMSO)2(SO4)] and hydroxy-bridged oligomers were isolated. Dimers, cis-[Pt(L)2(OH)]2(NO3)2 (L = TMSO, DPSO), and cis-[Pt(EMSO)2(OH)]2SO4 and possibly a trimer (cis-[Pt(EMSO)2(OH)]3)2(SO4)3 were characterized. The compounds were studied by infrared spectroscopy and by 1H nmr.

Several mono- or bis-alkynyl derivatives of the [Pt₆(μ-PBu^t₂)₄(CO)₄]²⁺ core, pivotal intermediates in the synthesis of new cluster-containing oligomers, were prepared and fully characterized.

A study of the reaction between trans-[Pt(15NH3)2(H2O)2](NO3)2 and N-acetyl-L-cysteine (H3accys) was undertaken to confirm the identity of the products formed. In alkaline solution, the platinum products observed were mononuclear species, while in acidic solution, the oligomeric products were obtained. The mass spectrometry of the reaction in alkaline solution showed a sulfur-bridged dinuclear platinum(II) species, trans-[{Pt(H2accys-S)2(15NH3)2}2((-H2accys-S)]+ giving m/z 948 and the lost of two ammines was observed. Keywords: thiolate, oligomers, 2D NMR, mass spectrometry

This study aims to develop specific-molecular-weight hyaluronic acid oligosaccharides-coated paclitaxel-loaded casein nanoparticles (HA-PT-Cas NPs) via chemical conjugation to increase the stability and antitumor effects. Optimized HA-PT-Cas NPs (HA/casein of 3:1) were obtained with a mean size of 235.3 nm and entrapment efficiency of 93.1%. HA-PT-Cas exhibited satisfactory stability at 4 °C for 12 days and 37 °C for 3 h; paclitaxel was retained at rates of 81.4% and 64.7%, respectively, significantly higher than those of PT-Cas (only 27.8% at 4 °C after 16 h and 20.3% at 37 °C after 3 h). HA-PT-Cas exhibited high efficiency (61.3%) in inhibiting A375 tumor owing to the enhanced stability of HA oligosaccharides barrier, which was comparable with that of 10 μg/mL cis-platinum (64.9%). Mice experiments showed the 74.6% tumor inhibition of HA-PT-Cas by intravenously administration, significantly higher than that of PT-casein (39.8%). Therefore, this work provides an effective carrier for drug delivery via HA oligomers-coated modification.

Lignin is a natural biopolymer present in lignocellulosic biomass. During paper pulp production with the Kraft process, it is solubilized and degraded in Kraft lignin and then burned to recover energy. In this paper, the solvolysis of Kraft lignin was studied in water and in water/alcohol mixtures to produce oligomers and monomers of interest, at mild temperatures (200–275 °C) under inert atmosphere. It was found that the presence of alcohol and the type of alcohol (methanol, ethanol, isopropanol) greatly influenced the amount of oligomers and monomers formed from lignin, reaching a maximum of 48 mg·glignin−1 of monomers with isopropanol as a co-solvent. The impact of the addition of various solid catalysts composed of a metal phase (Pd, Pt or Ru) supported on an oxide (Al2O3, TiO2, ZrO2) was investigated. In water, the yield in monomers was enhanced by the presence of a catalyst and particularly by Pd/ZrO2. However, with an alcoholic co-solvent, the catalyst only enhanced the formation of oligomers. Detailed characterizations of the products with FTIR, 31P-NMR, 1H-NMR and HSQC NMR were performed to elucidate the chemical transformations occurring during solvolysis. The nature of the active catalytic specie was also investigated by testing homogeneous palladium catalysts.

Ce manuscrit se consacre au développement d'oligomères à base de platine en tant que nouveaux donneurs pour des cellules solaires organiques à hétérojonction en vrac, dans le but d'améliorer leurs performances par le biais de modifications structurelles. Le travail est divisé en trois parties principales. La première partie examine comment réduire la bande interdite des [Pt]-oligomères en modifiant la structure du ligand. Cette adaptation vise à accroître la longueur de conjugaison, la planéité, la stabilisation des quinones et à renforcer l'effet "push-pull", notamment grâce à l'ajout de 3,4éthylènedioxythiophène (EDOT). Cette approche a conduit à la création de nouveaux matériaux donneurs qui ont atteint une efficacité de conversion de puissance (ECP) moyenne de 14,81% avec des accepteurs non-fullérènes dans des cellules solaires à hétérojonction en vrac binaires, et de 15.97% dans des cellules ternaires à hétérojonction en vrac. La deuxième partie se concentre sur l'amélioration de l'organisation moléculaire des [Pt]-oligomères en intégrant un groupe mésogène discotique de triphénylène dans la structure conjuguée au moyen d'un espaceur. Il a été démontré que remplacer un espaceur triazole rigide par un espaceur aliphatique linéaire plus flexible améliorait les propriétés des [Pt]-oligomères, entraînant une augmentation de l'efficacité de conversion photovoltaïque, passant de 13 % à 15 %. Enfin, la troisième partie explore des pistes d'amélioration supplémentaires en synthétisant des [Pt]-oligomères dotés de longueurs de conjugaison étendues, associés à un groupe organisateur discotique relié par un espaceur aliphatique. Les ligands qui combinent l'EDOT et le groupe triphénylène, reliés par un espaceur aliphatique, ont affiché des propriétés prometteuses, soulignant ainsi l'importance de poursuivre ces travaux de synthèse pour tester et valider pleinement ces [Pt]-oligomères améliorés
This manuscript focuses on developing [Pt]-oligomers as novel donors for bulk heterojunction organic solar cells, aiming to enhance their performance through structural modifications. The work is divided into three main parts. The first part addresses the reduction of the band gap in [Pt]-oligomers by modifying the ligand structure to improve conjugation length, planarity, quinone stabilization, and the "push-pull" effect, specifically through the inclusion of 3,4ethylenedioxythiophene (EDOT). This approach led to new donor materials that achieved an average power conversion efficiency (PCE) of 14.81% with non-fullerene acceptors in binary bulk heterojunction solar cells and 15.97% in ternary bulk heterojunction cells. The second part focuses on enhancing the molecular organization of [Pt]-oligomers by integrating a triphenylene discotic mesogenic group into the conjugated backbone via a spacer. It was found that replacing a rigid triazole spacer with a more flexible linear aliphatic spacer improved the properties of the [Pt]-oligomers, resulting in an increase in the average PCE from 13.36% to 15.93%. The third part explores further improvements by synthesizing [Pt]oligomers with extended conjugated lengths and a discotic organizing group connected through an aliphatic spacer. Ligands that incorporate both EDOT and the triphenylene group, connected by an aliphatic spacer, demonstrated promising properties, suggesting the need for further synthesis to fully test and validate these improvements on [Pt]-oligomers

Type IIE von Willebrand disease has previously been identified in a single family with two affected members. We have identified a second family with five affected individuals. The pattern of inheritance is autosomal dominant and the clinical picture is characterized by mild mucocutaneous bleeding. Laboratory results for affected patients: VIII:C ranged from .62 u/ml to 1.0 u/ml, VWD antigen 2.0 u/ml to 4.75 u/ml, and ristocetin cofactor activity 0.04 u/ml to .32 u/ml. Bleeding times, PT and APTT results were within normal ranges.Multimeric analysis of both citrated plasma and platelet lysates utilizing sodium dodecyl sulfate-polyacrylamide electrophoresis was characterized by a decrease of the largest oligomers and the individual multimers were abnormal with a single identifiable band. Plasma samples collected in the presence of a variety of inhibitors had no effect on the multi-meric pattern. Intravenous infusion of DDAVP (.3 ug/kg of body weight) resulted in a slight increase in the highest molecular weight oligomers but no change in the ristocetin cofactor activity or individual multimeric patterns.