Synthesis,structural identification,DNA interaction and biological studies of divalent Mn,Co and Ni chelates of 3-amino-5-mercapto-1,2,4-triazole azo ligand

New Mn (II), Co (II) and Ni (II) azo chelates of 3-amino-5-mercapto-1,2,4-triazole have been designed and obtained. The structures of these newly isolated complexes were assigned according to elemental, thermal analyses, spectral measurements, conductivity and magnetic moment. The metal complexes were predicted to be not electrolytic from the measured molar conductance values. The magnetic moment and UV–Vis spectral data denoted the formation of octahedral geometries for Mn (II), Co (II) and Ni (II) complexes. Thermal properties and decomposition kinetics of the metal chelates are investigated using Coats-Redfern method. The kinetic parameters like activation energy (E^*), pre-exponential factor (A) and entropy of activation (ΔS^*) were quantified. The geometry of the metal complexes is optimized with the help of molecular modeling. The interaction of metal chelates with calf thymus DNA (CT-DNA) was evaluated via UV–Vis absorption and viscosity measurements. The obtained data elucidated that the Ni (II) chelate interact with DNA by groove binding while partial intercalative binding mode have been predicted for Mn (II) and Co (II) chelates. The estimated binding constants for the DNA-complexes are 3.85 ± 0.03 × 10⁴, 1.03 ± 0.2 × 10⁵ and 2.81 ± 0.02 × 10⁵ M⁻¹, for Mn (II), Co (II) and Ni (II) azo chelates, successively. Also, the synthesized complexes were tested for their in-vitro antimicrobial and anticancer efficacy.     

Controlled Growth of Ag Nanocrystals in a H-Bonded Open Framework

A procedure that enabled rational access to the first example of hybrid material made of NPs grown within a H-bonded framework is reported. To avoid competitive reactions with the framework units, the metal precursor was chemically trapped in the porous structure and subsequently photo-reduced to afford the hybrid material Ag@SPA-2 , which consists of Ag NPs of nanometric sizes (<15 nm) homogeneously distributed in the crystals of the host material. In a subsequent step, taking advantage of the porous matrix the silver NPs have been transformed in situ to Ag₂S NP by simple infiltration of H₂S. The supramolecular network is shown to play an important role in stabilizing the inorganic nanomaterials and thus in controlling their growth.     

Insights on the Quantitative Concurrent Fluorescence-Based Analysis of Anti-COVID-19 Drugs Remdesivir and Favipiravir

Journal of Fluorescence - We hereby introduce a sensitive fast straightforward spectrofluorometric method for the estimation of remdesivir and favipiravir. The two drugs are prescribed in some...     

DNA Binding and Antitumor Activity of a New Fluorescent Probe Eu(Ⅲ)-Complex Containing 4-Methyl-Coumarin Moiety

A new europium (Ⅲ) complex containing (4-Methyl-2-oxo-2H-chromen-7-yloxy)-acetic acid moiety (CMMC) was synthesized, characterized, and confirmed as antitumor agent and fluorescent probe. The spectroscopic measurements of Eu(Ⅲ) in the presence of CMMC were obtained in different solvents. The results show that the strongest Eu(Ⅲ) emission bands were monitored in iso-propyl alcohol while the weakest Eu(Ⅲ) emission band was observed in acetonitrile. The interaction of Eu(Ⅲ)-(CMMC)₂ complex with DNA was monitored using absorption and emission techniques. From fluorescence titration measurements, the binding constants of DNA with Eu(Ⅲ)-(CMMC)₂ complex were found to be 1.04×105 L·mol-1 in Tris-HCl and 1.17×107 L·mol-1 in DMSO-Tris-HCl buffer (9∶1 V/V). Hypochromism was observed from the absorption titration experiment which indicates the intercalation of Eu(Ⅲ)-complex between the base pair of DNA. This result further confirmed by fluorescent Ethidium bromide displacement assay. The fluorescence calibration curve was used for the determination of DNA with LOD of 1.2 ng in DMSO-Tris-HCl buffer (9∶1 V/V) and 5 ng in Tris-HCl buffer. The preliminary antitumor investigation shows promising cytotoxicity against MDA-MB-231, MCF-7 (mammary cancer), and PC-3 (prostate carcinoma) cell lines with IC₅₀ values of 40.63, 25.42 and 30.25 μmol·L-1, respectively.     

Impulsive effect on exponential synchronization of neural networks with leakage delay under sampled-data feedback control

We consider the impulsive effect on the exponential synchronization of neural networks with leakage delay under the sampled-data feedback control. We use an appropriate Lyapunov–Krasovskii functional combined with the input delay approach and some inequality techniques to derive sufficient conditions that ensure the exponential synchronization of the delayed neural network. The conditions are formulated in terms of the leakage delay, the sampling period, and the exponential convergence rate. Numerical examples are given to demonstrate the usefulness and the effectiveness of the results.