Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid: Synthesis, X-ray crystal structures, spectral properties and antimicrobial studies

Chloro-diorganotin(IV) complexes of 4-methyl-1-piperidine carbodithioic acid (4-MePCDTA) have been synthesized by the reaction with diorganotin dichloride in 1:1 molar ratio in anhydrous toluene. These newly synthesized complexes have been characterized by elemental, IR, multinuclear NMR (¹H and ¹³C) and mass spectrometric studies. The crystal structures of complex 1 [Me₂SnCl(4-MePCDT)] and 3 [Ph₂SnCl(4-MePCDT)] have been determined by X-ray single crystal analysis, which show trigonal bipyramid geometry. These complexes were tested for their antimicrobial activity against six different plant and human pathogens. The screening results show that the complexes exhibit higher antibacterial and antifungal activity than the free ligand.     

Neutral Particle Motion around a Schwarzschild Black Hole in Modified Gravity

We investigate circular motion of neutral test particles on equatorial plane near a black hole in scalar-tensor-vector gravity. We consider three cases (i) α < G/G_N (ii) α = G/G_N and (iii) α > G/G_N to find the regions where motion can exist. The corresponding effective potential, energy, angular momentum and center of mass energy are evaluated. Further, we define four different cases for α > G/G_N and identify stable and unstable regions of circular orbits. It is found that circular orbits having zero angular momentum exist at r = αGNM due to repulsive gravity effects. We conclude that the structure of stable regions for α < G/G_N as well as α = G/G_N case is completely different from that of α > G/G_N.     

Fluorescent Immunoassays for Detection and Quantification of Cardiac Troponin I: A Short Review

Cardiovascular diseases are considered one of the major causes of human death globally. Myocardial infarction (MI), characterized by a diminished flow of blood to the heart, presents the highest rate of morbidity and mortality among all other cardiovascular diseases. These fatal effects have triggered the need for early diagnosis of appropriate biomarkers so that countermeasures can be taken. Cardiac troponin, the central key element of muscle regulation and contraction, is the most specific biomarker for cardiac injury and is considered the “gold standard”. Due to its high specificity, the measurement of cardiac troponin levels has become the predominant indicator of MI. Various forms of diagnostic methods have been developed so far, including chemiluminescence, fluorescence immunoassay, enzyme-linked immunosorbent assay, surface plasmon resonance, electrical detection, and colorimetric protein assays. However, fluorescence-based immunoassays are considered fast, accurate and most sensitive of all in the determination of cardiac troponins post-MI. This review represents the strategies, methods and levels of detection involved in the reported fluorescence-based immunoassays for the detection of cardiac troponin I.     

Synthesis and spectral characterization of chloro-organotin(IV) complexes of S-donor ligand: Crystal structure of chloro-t-dibutyltin[4-methyl-1-piperidine]thiocarboxylate

New chloromono- and diorganotin(IV) complexes of 4-methyl-1-piperidine dithiocarboxylic acid have been synthesized in anhydrous chloroform. The complexes were characterized by microanalysis, IR, ¹H and ¹³C NMR, mass spectrometry and XRD. The FTIR spectra clearly demonstrate that organotin(IV) moieties react with [S,S] atoms of the ligand. Compound (1) and (3) exhibits the 5-coordinated while the compound (2) exhibit 6-coordinated geometry in solid state. Compound (3) shows distorted trigonal bipyramidal geometry which is confirmed by X-ray single-crystal diffraction.     

Biological and Cheminformatics Studies of Newly Designed Triazole Based Derivatives as Potent Inhibitors against Mushroom Tyrosinase

A series of nine novel 1,2,4-triazole based compounds were synthesized through a multistep reaction pathway and their structures were scrutinized by using spectral methods such as FTIR, LC-MS, 1H NMR, and 13C NMR. The synthesized derivatives were screened for inhibitory activity against the mushroom tyrosinase and we found that all the synthesized compounds demonstrated decent inhibitory activity against tyrosinase. However, among the series of compounds, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide exhibited more prominent activity when accompanied with the standard drug kojic acid. Furthermore, the molecular docking studies identified the interaction profile of all synthesized derivatives at the active site of tyrosinase. Based on these results, N-(4-fluorophenyl)-2-(5-(2-fluorophenyl)-4-(4-fluorophenyl)-4H-1,2,4-triazol-3-ylthio) acetamide could be used as a novel scaffold to design some new drugs against melanogenesis.     

Five‐coordinate dinuclar cobalt (II), copper (II), zinc (II) and cadmium (II) complexes with 4‐bromo‐N‐(2‐pyridinylmethylene)benzenamine: Synthesis,characterisation and methyl methacrylate polymerization

A series of late transition metal complexes, [(bpma)Co(μ – Cl)Cl] ₂ , [(bpma)Cu(μ – Cl)Cl] ₂ , [(bpma)Zn(μ – Cl)Cl] ₂ and [(bpma)Cd(μ – Br)Br] ₂ (where bpma is 4‐bromo‐N‐((pyridin‐2‐yl)methylene)benzenamine) have been synthesized and structurally characterized. The X‐ray structures of dimeric complexes [(bpma)M(μ – X)X] ₂ (M = Co, Cu and Zn, X = Cl; M = Cd, X = Br) showed a distorted 5‐coordinate trigonal bipyramidal geometry involving two nitrogen atoms of N,N‐bidentate ligand, two bridged and one terminal halogen atoms. The complex [(bpma)Cu(μ – Cl)Cl] ₂ revealed the highest catalytic activity for the polymerisation of methyl methacrylate in the presence of modified methylaluminoxane with an activity of 9.14 × 10⁴ g PMMA/mol·Cu·h at 60 °C and afforded syndiotactic poly (methylmethacrylate) (rr = 0.69).     

Kinetic study of thermal degradation of di-, chlorodi- and triorganotin(IV) complexes of 2-[(2,6-dichlorodiphenyl)amino]benzene acetate

The organotin complexes of the general formulae R₂SnL₂, R₂SnLCl and R₃SnL where R = C₄H₉, C₆H₅, and C₇H₇ and L = 2-[(2,6-dichlorodiphenyl)amino]benzene acetate, were subjected to thermal decomposition by thermogravimetric analysis (TGA). The decomposition of these compounds occurs mostly in two steps. Kinetic parameters such as order of reaction (n), activation energy (Ea), enthalpy (ΔH^?) and entropy (ΔS^?) of activation were calculated by using the Coats and Horowitz methods. The calculated values are in good agreement with observed TG values that confirm the structural integrity of the complexes.     

Synthesis,characterisation, and X-ray structures of zinc(II) complexes bearing camphor-based ethyleneamineimines as pre-catalysts for heterotactic-enriched polylactide from rac-lactide

Transition Metal Chemistry - A series of Zn(II) complexes bearing camphor-based ethyleneamine derivatives, [LnZnCl2]...     

Novel Flurbiprofen‐iminothiazoline Hybrid Compounds: Synthesis and Characterization

A series of novel flurbiprofen‐iminothiazoline hybrid compounds of biological interest were synthesized by base‐catalyzed heterocyclization of the flurbiprofen thioureas with 4‐chloro‐α‐bromoacetophenone in dry dichloromethane.     

Oxovanadium(IV) complexes with cephradine: Synthesis, Semi-Empirical study, spectroscopy, potentiometric study and antimicrobial activity

The reactions between cephradine and VOSO₄.3H₂O in 1:1, 1:2 and 1:3 molar ratios in methanol were investigated at room temperature, 0 °C and ?10 °C. In various pH conditions, the different complexes formulated as VO(H₂O)₃L^2?, VO(H₂O)L₂ ^2? and VL₃ ^? were formed by titration of VOSO₄.3H₂O and cephradine with NaOH. These complexes were characterized by elemental analysis and IR spectroscopy. IR spectra of all the complexes show the disappearance of ν(O-H) band of cephradine, which confirms complexation. Estimation of vanadium in the complexes was carried out by ICP-AES. The stability constants of each complex were calculated on the basis of which a general mechanism is hereby proposed with regard to the formation of these complexes. In complex (1) the cephradine ligand bind in bidentate [O,O] fashion together with a terminal oxo ligand and water molecules complete the metal coordination sphere. In complex (2) the cephradine ligands bind in bis-bidentate [O,O] fashion and the axial positions are occupied by the oxo ligand and a trans-water molecule. Biological screening tests show significant antibacterial and anti-fungal activities against various bacterial and fungal strains.