Water-soluble SNS cationic palladium(II) complexes and their Suzuki-Miyaura cross-coupling reactions in aqueous medium

Molecular docking-assisted investigation of Pd(II) complexes carrying "SNS" pincer-type pyridine-thioether ligand as potential drug candidates against COVID-19

The coronavirus disease 2019 (COVID-19) pandemic has posed a threat to public health throughout the world since the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was discovered in late 2019. Since the beginning of the pandemic, scientists have done a tremendous amount of work in this area. However, among these studies, the investigation of the effect of newly synthesized compounds against coronavirus is rather weak. Examining the newly synthesized compounds with a computer-assisted molecular docking study provides quite an advantage in terms of the estimation and analysis of the biochemical activity and binding affinity of existing synthesized compounds against a biological target in a labor, time, and cost-saving way. In this study, the SNS pincer type 2,6-bis[[(4-methylphenyl)thio]methyl]pyridine ligand(L) (1) and its novel Pd(II) complexes ([Pd(κ2-L)(OAc)2]·3H2O (2) and [Pd(κ2-L)Cl2]·3H2O (3)) were synthesized and characterized by using FT-IR, UV-Vis, NMR, mass and elemental analysis techniques. The synthesized Pd complexes exhibited a square planar structure. The compounds were found to have non-electrolytic behavior. In the meantime, in silico investigations have defined and justified interaction processes between these molecules and Pd(II) at the atomic level. Furthermore, using molecular docking against target proteins of SARS-CoV-2, the efficiency of the SNS pincer type ligand and its Pd (II) complexes produced was studied and discussed for the first time. The experimental data has been supported and illuminated using computational visual methods and molecular docking, and the findings produced indicate compatibility. The binding energy values of the relevant compounds on the four protein model structures of SARS-CoV-2 (Main Protease, Papain-like protease, RdRp without RNA, and RdRp with RNA) are represented. Compound 2 ([Pd(κ2-L)(OAc)2]·3H2O) is the structure that exhibits the highest biochemical activity. According to all of the docking studies, Papain-like protease is the SARS-CoV-2 protein with which the three compounds exhibit mutual interaction. The compound 2 structure, in particular, is the most effective in terms of structural and interaction with the targets, as well as binding orientations.

Effect of chalcogen bonding interactions on molecular structures; theoretical and crystallographic studies on two palladium(ii) acetate complexes

New palladium complexes, [Pd(L)(OAc))], have been synthesized. The complexes and their ligand have been characterized by X-ray crystal structure analysis. Interestingly, the molecular structures of the two complexes are stabilized by S⋯O chalcogen bonds.

Experimental and theoretical insights into the trans influence of organo-sulfur and -selenium ligands in 5,6-membered palladium(ii) cationic pincer complexes based on iminophosphoranes

The trans influence of organochalcogen ancillary ligands was assessed by experimental and DFT studies in 5,6-membered SNS and SNSe Pd(ii) pincers.

A robust polyfunctional Pd(II)-based magnetic amphiphilic nanocatalyst for the Suzuki-Miyaura coupling reaction

Herein, a robust Pd(II)-based polyfunctional magnetic amphiphilic artificial metalloenzyme was prepared by anchoring a Pd(2,2'-dipyridylamine)Cl2 bearing hydrophilic monomethyl ether poly(ethylene glycol) (mPEG) chains on the surface of amino-functionalized silica-coated magnetic nanoparticles. The 2,2'-dipyridylamine (dpa) has shown excellent complexation properties for Pd(II) and it could be easily anchored onto functionalized magnetic support by the bridging nitrogen atom. Moreover, the bridging nitrogen atom at the proximity of Pd(II) catalytic center could play an important role in dynamic suppramolecular interactions with substrates. The leaching, air and moisture resistant [Pd(dpa)Cl2] complex endow the dynamic and robust structure to the designed artificial enzyme. Moreover, the water dispersibility of designed artificial metalloenzyme raised from mPEG chains and the magnetic nanoparticles core which could function as protein mimics endow it other necessary characters of artificial enzymes. The prepared artificial metalloenzyme displayed remarkable activity in Suzuki-Miyaura cross-coupling reaction employing low-palladium loading under mild conditions, with the exceptionally high turnover frequency, clean reaction profile, easy work-up procedure, good to excellent products yields and short reaction times. The designed air- and moisture-stable artificial metalloenzyme could recycle more than fifteen times with easy separation procedure in aqueous solution under aerobic conditions without any noticeable loss in activity.