Photocatalytic Water-Soluble Cationic Platinum(II) Complexes Bearing Quinolinate and Phosphine Ligands.

Cationic Pt(II) complexes ([Pt(QO/S)(P∧P)]X), having 8-oxy or 8-thioquinolinate (QO/S) and seven different mono- or bidentate phosphines as ligands, have been synthesized and characterized. The photophysical, stability, and photocatalytic properties of those complexes were studied and compared to that of the parent [Pt(QO/S)(dmso)(Cl)]. The coordination of phosphines induced a red-shift in the absorption energy of the MLCT band, whereas the emission wavelength of the complexes only depended on the nature of the quinolinate ligand. Moreover, the photocatalytic activity of the Pt(II) complexes was evaluated in the oxidation of sulfides using atmospheric oxygen as an oxidant. All the complexes were active photocatalysts for that transformation, with [Pt(QO)(BINAP)]Cl and [Pt(QO)(SEGPHOS)]Cl (BINAP: 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl, SEGPHOS: (4,4'-bibenzodioxole)-5,5'-diyldiphosphine) exhibiting high catalytic performance and stability. In addition, the enhanced water solubility of the complexes allowed performance of the photooxidation reaction under environmentally friendly conditions. In particular, the catalyst [Pt(QS)(dppe)]Cl, bearing 8-thioquinolinate and diphenylphosphinoethate (dppe) as ligands, successfully catalyzed the oxidation of a variety of sulfides using water as a solvent.

Visible light photocatalytic asymmetric synthesis of pyrrolo[1,2-a]indoles via intermolecular [3+2] cycloaddition.

The intermolecular diastereoselective and enantioselective synthesis of pyrrolo[1,2-a]indoles is developed through a [3+2] cycloaddition between silyl-indole derivatives and α,ß-unsaturated N-acyl oxazolidinones by merging photocatalysis and Lewis acid catalysis.

8-Mercaptoquinoline as a Ligand for Enhancing the Photocatalytic Activity of Pt(II) Coordination Complexes: Reactions and Mechanistic Insights.

A family of quinoline-platinum(II) complexes as efficient photocatalysts is presented. Their key characteristic is their easy preparation by coordination of the readily available 8-hydroxy- or 8-thio-quinoline ligands, which are well known for their strong chelating ability to different metal ions. In the different photochemical transformations investigated, such as cross-dehydrogenative coupling, oxidation of arylboronic acids, and asymmetric alkylation of aldehydes, 8-mercaptoquinoline-Pt(II) complex proved to be the most general catalyst. Moreover, quenching experiments showed that, contrary to related methods reported in the literature, these complexes followed an oxidative quenching mechanism in all transformations studied. Besides, simulations performed with high-level ab initio methods of the complexes have helped to understand their photocatalytic activity.

Effect of electronic and steric properties of 8-substituted quinolines in gold(III) complexes: Synthesis, electrochemistry, stability, interactions and antiproliferative studies.

In this work the synthesis and characterization of new gold(III) complexes with quinoline ligands are described. These complexes contain different steric and electronic properties of the donor atom at 8-position of the quinoline in order to modulate their stability and their biological activity. Their redox potential, stability in organic and aqueous solvents, and their biological activity in a panel of six different human tumor cell lines are also presented. In addition, interaction studies of the complexes with model biological molecules (pBR322 and L-acetyl-N-cysteine) were carried out, suggesting that their main target are proteins. From these studies, we have found that the gold(III) complex with an N-tosyl-8-aminoquinoline ligand is the most active complex in all the tumor cell lines, including the cisplatin resistant T-47D and WiDr cell lines. Moreover, this complex showed to be the most stable compound in DMSO and saline solution, even after several hours.

Pt(ii) coordination complexes as visible light photocatalysts for the oxidation of sulfides using batch and flow processes.

A new catalytic system for the photooxidation of sulfides based on Pt(ii) complexes is presented. The catalyst is capable of oxidizing a large number of sulfides containing aryl, alkyl, allyl, benzyl, as well as more complex structures such as heterocycles and methionine amino acid, with complete chemoselectivity. In addition, the first sulfur oxidation in a continuous flow process has been developed.