Formation, electrochemical and radical scavenging properties of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic chelators

Herein, we communicate the formation of novel ruthenium compounds with N, X-donor (X = O, N) heterocyclic- derived ligands. A paramagnetic ruthenium(IV) complex, [RuCl(pho)(bzca)(PPh3)](1) (pho = 2- aminophenolate; bzca = 2-carboxylate-1H-benzimidazole) was isolated from the reaction of the ruthenium(II) precursor, trans-[RuCl2(PPh3)3] and 2-((1H-benzimidazole)methylamino)phenol (Hbzap). The 1:1 molar reaction between the same metal precursor and N-(benzoxazole)-2-hydroxybenzamide (H2bhb) led to the formation of cis-Cl, trans-P-[RuIII(Hbhb)Cl2(PPh3)2](2). The dinuclear ruthenium compounds, (l-Htba,Cl)2[RuIICl(PPh3)]2(3) (Htba = N-(thiophene)methyl-benzoxazole-2-amine) and (l-Cl)2[RuIIICl(Hchpr)(PPh3)]2(4) (H2chpr = 2-amino-3-((tetrahydro-2H-pyran-4-ylimino)methyl)-4Hchromen- 4-one) were formed from the equimolar ratio coordination reactions between trans- [RuCl2(PPh3)3] and the respective free-ligands, Htba and H2chpr. These metal complexes were characterized via IR-, NMR- and UV–Vis spectroscopy, molar conductivity measurements and structural elucidations were confirmed by single crystal X-ray analysis. The X-ray studies revealed that all the metallic compounds exhibited octahedral geometries and that the Hbzap free ligand has undergone a unique molecular transformation to afford the pho and bzca bidentate chelators in 1. The electrochemical properties of the respective metal complexes were investigated by voltammetric analysis. The cyclic voltammograms (CVs) of 1–3 showed one redox couple while within the CV of the dinuclear compound 4, two redox couples were observed. The ligands and their metal complexes were also subjected to DPPH radical scavenging studies. The IC50 values showed that all the metallic compounds have higher radical scavenging activities than their corresponding free-ligands and the natural antioxidant, Vitamin C

Ruthenium complexes with lumazine derivatives: structural, electrochemical, computational and radical scavenging studies

In this research study, the formation and characterization of new ruthenium(II) and (III) complexes encompassing multidentate ligands derived from 6-acetyl-1,3, 7-trimethyllumazine (almz) are reported. The 1:1 molar coordination reactions of trans-[RuCl2(PPh3)3] with N-1-[1,3, 7-trimethyllumazine]benzohydride (bzlmz) and 6-(N-methyloxime)- 1,3,7-trimethyllumazine (ohlmz) formed a diamagnetic ruthenium(II) complex, cis-[RuCl2(bzlmz)(PPh3)] (1), and paramagnetic complex, cis-[RuIIICl2(olmz)(PPh3)] (2) [Holmz = 6-(N-hydroxy-N0-methylamino)-1,3,7-trimethyllumazine], respectively. These ruthenium complexes were characterized via physico-chemical and spectroscopic methods. Structural elucidations of the metal complexes were confirmed using single crystal X-ray analysis. The redox properties of the metal complexes were investigated via cyclic voltammetry. Electron spin resonance spectroscopy confirmed the presence of a paramagnetic metal centre in 2. The radical scavenging activities of the metal complexes were explored towards the DPPH and NO radicals. Quantum calculations at the density functional theory level provided insight into the interpretation of the IR and UV–Vis experimental spectra of 1

Coordination of di- and triimine ligands at ruthenium(II) and ruthenium(III) centers: structural, electrochemical and radical scavenging studies

Herein, we explore the coordination of di- and triimine chelators at ruthenium(II) and ruthenium(III) centers. The reactions of 2,6-bis-((4- tetrahydropyranimino)methyl)pyridine (thppy), N1,N2-bis((3-chromone) methylene)benzene-1,2-diamine (chb), and tris-((1H-pyrrol-2-ylmethylene) ethane)amine (H3pym) with trans-[RuIICl2(PPh3)3] afforded the diamagnetic ruthenium(II) complex cis-[RuCl2(thppy)(PPh3)] (1) and the paramagnetic complexes [mer-Ru2(μ-chb)Cl6(PPh3)2] (2), and [Ru(pym)] (3), respectively. The complexes were characterized by IR, NMR, and UV–vis spectroscopy and molar conductivity measurements. The structures were confirmed by single crystal X-ray diffraction studies. The redox properties of the metal complexes were probed via cyclic- and squarewave voltammetry. Finally, the radical scavenging capabilities of the metal complexes towards the NO and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radicals were investigate

Synthesis, characterization and electrocatalytic behavior of cobalt and iron phthalocyanines bearing chromone or coumarin substituents

<div><p>Cobalt and iron phthalocyanines (Pcs) bearing peripherally tetra-substituted chromone (chr) or coumarin (cou) moieties were formulated and characterized by UV–Vis and FTIR spectroscopy, ESI-TOF mass spectrometry, and elemental analysis. The structural elucidations of the ligands, 4-(chromone-7-oxy)phthalonitrile (<b>1</b>) and 4-(4-(trifluoromethyl)-coumarin-7-oxy)phthalonitrile (<b>2</b>) were complemented by NMR spectroscopy and single crystal X-ray analysis (for <b>1</b>). The redox properties of the complexes were investigated via voltammetry and the subsequent voltammetric assignments were corroborated by UV–Vis spectroelectrochemistry. Each metal complex displayed four redox processes of which their Pc ring oxidations are irreversible and the remaining redox couples are quasi-reversible. Utilizing the respective metallophthalocyanines, modified working electrodes were prepared by electropolymerization and their electrocatalytic activities toward nitrite oxidation were explored. All the metal complexes showed an increase in nitrite oxidation currents and a minor decrease in oxidation potentials which is indicative of electrocatalysis. The trend of electrocatalytic activity was found to be as follows: CoPc–chr (<b>3</b>) > FePc–cou (<b>4</b>) > CoPc–cou (<b>5</b>).</p></div

Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries

This was an investigator initiated study funded by Nestle Health Sciences through an unrestricted research grant, and by a National Institute for Health Research (UK) Professorship held by RP. The study was sponsored by Queen Mary University of London

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally