The Antimicrobial Properties of PdII - and RuII -pyta Complexes.

Infections associated with antimicrobial resistance (AMR) are poised to become the leading cause of death in the next few decades, a scenario that can be ascribed to two phenomena: antibiotic over-prescription and a lack of antibiotic drug development. The crowd-sourced initiative Community for Open Antimicrobial Drug Discovery (CO-ADD) has been testing research compounds contributed by researchers around the world to find new antimicrobials to combat AMR, and during this campaign has found that metallodrugs might be a promising, yet untapped source. To this end, we submitted 18 PdII - and RuII -pyridyl-1,2,3-triazolyl complexes that were developed as catalysts to assess their antimicrobial properties. It was found that the Pd complexes, especially Pd1, possessed potent antifungal activity with MICs between 0.06 and 0.125 µg mL-1 against Candida glabrata. The in-vitro studies were extended to in-vivo studies in Galleria mellonella larvae, where it was established that the compounds were nontoxic. Here, we effectively demonstrate the potential of PdII -pyta complexes as antifungal agents.

Phenylacetylene polymerisation mediated by cationic cyclometallated palladium(ii) complexes bearing benzylidene 2,6-diisopropylphenylamine and its derivatives as ligands.

A series of novel cationic palladacycle complexes bearing benzylidene-2,6-diisopropylphenylamine derivatives as ligands and with the general formula [Pd(MeCN)(L)(R-C6H3)CH[double bond, length as m-dash]N{2,6-iPr2-C6H3}][B(3,5-(CF3)2-C6H3)] (R = H, Cl, Br, F, OMe and L = 1,3,5-triaza-7-phosphaadamantane (PTA), tricyclohexylphosphine (PCy3) and triphenylphosphine (PPh3)) were prepared and characterized by a range of analytical techniques. These cationic palladacycle complexes were found to be active precatalysts for the polymerisation of phenylacetylene. The meta-substituent on the cyclometallated ring was found to have a marked effect on the catalyst performance in that complexes, which contained electron-withdrawing substituents, were found to be the most active in the polymerisation process. Furthermore, increasing the steric bulk of the phosphine ligand led to the production of higher molecular weight polyphenylacetylenes (PPA). Polymerisation reactions performed at 25 °C gave a mixture of both cis-transoidal and trans-cisoidal PPA while trans-cisoidal PPA was selectively produced at elevated temperatures (60 °C). Preliminary mechanistic studies demonstrated that polymerisation proceeds via dissociation of the C,N-chelating ligand, and involves the formation of an iminium cationic fragment.