Potentiometric, spectroscopic and thermal studies on the metal chelates of 1-(2-thiazolylazo)-2-naphthalenol

Anti-cancer property and DNA binding interaction of first row transition metal complexes: A decade update

Metal ions carry out a wide variety of functions, including acid-base/redox catalysis, structural functions, signaling, and electron transport. Understanding the interactions of transition metal complexes with biomacromolecules is essential for biology, medicinal chemistry, and the production of synthetic metalloenzymes. After the coincidental discovery of cisplatin, importance of the metal complexes in biochemistry became a top priority for inquiry. In this review, a decade update on various synthetic strategies to first row transition metal complex and their interaction with DNA through non-covalent binding are explored. Moreover, this effort provides an excellent analysis on the efficacy of theoretical and practical approaches to the systematic generation of new non-platinum based metallodrugs for anti-cancer therapeutics.

Spectroscopic investigation, thermal behavior, catalytic reduction, biological and computational studies of novel four transition metal complexes based on 5-methylthiophene Schiff base type

Four new complexes prepared from 5-Methyl-2-carboxaldehyde-thiophene and 2,6-pyridinediamine with cobalt, nickel, copper and cadmium ions have been synthesized because of the significance of these complexes in pharmacological research and catalytic reduction. The prepared compounds were characterized using elemental analysis, mass, UV-visible, NMR and FTIR spectroscopy, as well as molar conductance, magnetic susceptibility measurements, fluorescence properties and TGA analysis. The stoichiometry mode was confirmed as 1:1 (metal: ligand) for Co, Ni and Cu complexes and 1:2 (metal: ligand) for Cd complex according to the results of the elemental and spectral studies. Furthermore, the thermal stability and luminescence properties of complexes have been studied. Thermal studies confirmed the presence of water molecules. The thermodynamic properties of the complexes were measured via the Coats-Redfern procedure. The geometric structures of the complexes were found to be octahedral around the metal ions. The optical energy gaps (Eopt) vary between 2.92 and 3.71 eV indicating that these compounds can be used as selective absorbing solar energy in photovoltaic applications. In the presence of NaBH₄, the greatest reduction efficiency for the conversion of 2-NP to 2-AP was discovered to be 73-91% within 15-25 min. In vitro, high antifungal and antibacterial activity was shown by complexes than the ligand alone. The Cd(II) complex was shown to have greater activity than all of the examined microorganisms when compared to the reference drug in addition it had 4.94 μg/ml minimal inhibitory concentration against "S. aureus", "B. subtilis", and "E. coli". The bond angles, bond lengths, and quantum chemical factors of the ligand and complexes were shown in the molecular modeling using the DFT approach. The studied compounds' binding modes were confirmed using the Gaussian 09 program.

Synthesis, structural characterization, thermal analysis, DFT, biocidal evaluation and molecular docking studies of amide-based Co(II) complexes

Abstract

Many distinct amino acid and aromatic amine-derived transition metal complexes are used as physiologically active compounds. A few Cobalt (II) complexes have been synthesized by reacting cobalt (II) chloride with 1, 8-diaminonapthalene-based tetraamide macrocyclic ligands in an ethanolic media. These synthesized ligands (TAML1-3) and associated Co(II) complexes were fully characterized with various spectroscopic techniques, such as IR, NMR, CHN analysis, EPR, molar conductance, and magnetic susceptibility measurements, TGA, UV-visible spectra, powder X-ray diffraction and DFT analysis. The IR spectra reveal interactions between the core metal atom and ligands through N of 1, 8-diaminonapthalene. The distorted octahedral geometry of synthesized Co(II) macrocyclic complexes were confirmed by ESR, UV-Vis and DFT studies. The synthesized ligands (TAML1-TAML3) and their Co(II) complexes were tested for antimicrobial activity against A. niger, C. albicans, and F. oxysporum in addition to bacteria like S. aureus, B. subtilis, and Gram-negative bacteria like E. coli. The ligand TAML1 and complex [Co(TAML1)Cl2] showed an excellent antibacterial activity. The minimum inhibitory concentration of TAML1 and [Co(TAML1)Cl2] against S. aureus were found to be 7 mm and 10 mm zone of inhibition at 500 ppm, respectively, compared to drug ampicillin (3 mm). Additionally, each molecule exhibited notable antioxidant activity. The biological significance of the synthesized compounds was then evaluated by molecular docking experiments with the active site of the receptor protein such as Sars-Cov-2, C. Albicans, X. campestris and E. coli. The molecular docking assisted data strongly correlated to the experimental approach of antimicrobial activity.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11696-023-02843-y.

Structural elucidation, theoretical investigation, biological screening and molecular docking studies of metal(II) complexes of NN donor ligand derived from 4-(2-aminopyridin-3-methylene)aminobenzoic acid

Complexes of 4-(((2-aminopyridin-3-yl)methylene)amino)benzoic acid ligand with cobalt(II) (1), nickel(II) (2), copper(II) (3), zinc(II) (4) and palladium(II) (5) are synthesized and characterized by using different spectroscopic methods like, UV-Visible, infrared, ¹H, ¹³C NMR, molar conductance, ESR and elemental analysis. Quantum chemical computations were made using DFT (density functional theory), B3LYP functional and 6-31+ +G(d,p)/SDD basis set in order to determine optimized structure parameters, frontier molecular orbital parameters and NLO properties. Based on DFT and experimental evidence, the complexes ensured that the octahedral geometry have been proposed for complexes 1, 2 and 4, square planar for complexes 3 and 5. All the complexes showed only residual molar conductance values and hence they were considered as non-electrolytes in DMF. In addition, the anti-proliferative activity of the compounds was evaluated against different human cancer cell lines (IMR-32, MCF-7, COLO205, A549, HeLa and HEK 293) and cisplatin is used as a reference drug. Compounds 1 and 4 showed remarkable cytotoxicity in five cancer cell lines tested except MCF-7. Also, the compounds were examined for their in vitro antimicrobial and scavenging activities. The molecular docking results are well corroborated with the experimental anticancer activity results.

Crystal structure of 3-meth-oxy-4-[2-(thia-zol-2-yl)diazen-1-yl]aniline monohydrate

In the title hydrated azo dye, C10H10N4OS·H2O, the benzene and thia-zole, are nearly coplanar, with a dihedral angle between their mean planes of 4.69 (17)°. The aromatic rings on the -N=N- moiety exhibit a trans configuration. The crystal structure features many types of inter-molecular inter-actions involving all the functional groups - strong hydrogen bonds (N⋯H and O⋯H), weak hydrogen bonds (C-H⋯O and C-H⋯N), C-H⋯π and π-π inter-actions - resulting in the formation of a three-dimensional framework.

Synthesis, biological evaluation and corrosion inhibition studies of transition metal complexes of Schiff base

Background

The transition metal complexes formed from Schiff base is regarded as leading molecules in medicinal chemistry. Because of the preparative availability and diversity in the structure of central group, the transition metals are important in coordination chemistry. In the present work, we have designed and prepared Schiff base and its metal complexes (MC₁–MC₄) and screened them for antimicrobial, anticancer and corrosion inhibitory properties.

Methodology

The synthesized metal complexes were characterized by physicochemical and spectral investigation (UV, IR, ¹H and ¹³C-NMR) and were further evaluated for their antimicrobial (tube dilution) and anticancer (SRB assay) activities. In addition, the corrosion inhibition potential was determined by electrochemical impedance spectroscopy (EIS) technique.

Results and discussion

Antimicrobial screening results found complexes (MC₁–MC₄) to exhibit less antibacterial activity against the tested bacterial species compared to ofloxacin while the complex MC₁ exhibited greater antifungal activity than the fluconazole. The anticancer activity results found the synthesized Schiff base and its metal complexes to elicit poor cytotoxic activity than the standard drug (5-fluorouracil) against HCT116 cancer cell line. Metal complex MC₂ showed more corrosion inhibition efficiency with high R_ct values and low C_dl values.

Conclusion

From the results, we can conclude that complexes MC₁ and MC₂ may be used as potent antimicrobial and anticorrosion agents, respectively.

Synthesis, characterization and biological evaluation of Pd(ii), Cu(ii), Re(i) and 99mTc(i) thiazole-based complexes

A new thiazole-containing multidentate ligand 2-((2-phenylthiazol-4-yl)methylthio)ethanamine, L, was synthesized and used to prepare new complexes of the formula Pd^IILCl₂ (Pd-L), Cu^IIL₂Cl₂ (Cu-L) and fac-[Re/^99mTc^I(CO)₃(L)]⁺ (Re/^99mTc-L). The ligand L and the metal complexes were characterized spectroscopically. Furthermore, the structures of Re-L and Cu-L were elucidated by X-ray crystallography. Ligand L acts as a bidentate (N_th, S) chelator in Pd-L, as a bidentate (N, S) chelator in Cu-L and as a tridentate (N_th, S, N) chelator in Re-L. The radiotracer ^99mTc-L was synthesized in high yield and characterised by HPLC comparison with the Re-L analog. The synthesized compounds were evaluated for their anti-inflammatory and cytotoxic properties. The compounds exhibited low anti-inflammatory activity with Pd-L showing the highest activity among them. The cytotoxic activity of the ligand and the complexes against several human cancer cell lines (cervical adenocarcinoma HeLa, colorectal adenocarcinoma LS-174T, lung adenocarcinoma A549, breast adenocarcinoma MDA-MB-231 and normal human lung fibroblast cell line MRC-5) was examined using the MTT assay. The complex Cu-L exhibited the highest cytotoxicity and the complex Pd-L showed the best tumor selectivity. The changes in the cell cycle phase distribution were determined by flow cytometry and it was found that ligand L shows the highest apoptotic activity. The biodistribution studies of ^99mTc-L in mice showed fast tissue clearance. Of all the thiazole-containing compounds, the palladium complex appears to be more promising for future efforts.

A simple and low cost dual-wavelength β-correction spectrophotometric determination and speciation of mercury(II) in water using chromogenic reagent 4-(2-thiazolylazo) resorcinol

The most common problems in spectrophotometric determination of various complex species originate from the background spectral interference. Thus, the present study aimed to overcome the spectral matrix interference for the precise analysis and speciation of mercury(II) in water by dual-wavelength β-correction spectrophotometry using 4-(2-thiazolylazo) resorcinol (TAR) as chromogenic reagent. The principle was based on measuring the correct absorbance for the formed complex of mercury(II) ions with TAR reagent at 547nm (lambda max). Under optimized conditions, a linear dynamic range of 0.1-2.0μgmL^-1 with correlation coefficient (R²) of 0.997 were obtained with lower limits of detection (LOD) of 0.024μgmL^-1 and limit of quantification (LOQ) of 0.081μgmL^-1. The values of RSD and relative error (RE) obtained for β-correction method and single wavelength spectrophotometry were 1.3, 1.32% and 4.7, 5.9%, respectively. The method was validated in tap and sea water in terms of the data obtained from inductively coupled plasma-optical emission spectrometry (ICP-OES) using student's t and F tests. The developed methodology satisfactorily overcomes the spectral interference in trace determination and speciation of mercury(II) ions in water.

Cellulose derivatives modified by sodium tellurate and a chromium(III) tellurate complex

A novel cellulose (Cell) derivative, sodium-tellurato (Cell-TeO(OH)4(ONa)/Cell-Cl), has been synthesized from the reaction of 6-chloro-6-deoxycellulose (Cell-Cl) with telluric acid in the presence of sodium hydroxide. The subsequent reaction of this polymeric material with chromium(III) in aqueous solution yields the [Cr(Cell-TeO3(OH)3/Cell-Cl)(Cell-TeO2(OH)4/Cell-Cl)(H2O)3] complex. The molecular structures and morphology of the new polymer and the Cr(III) complex have been examined using elemental analysis, solid-state (13)C NMR, UV-vis, XRD and FTIR spectroscopy, and SEM-EDX, TGA and magnetic measurements. The results are considered to be consistent with the formulations proposed. The deprotonation constants of the modified cellulose and the stability constant of the Cr(III) complex have been determined by pH-metric measurements.

Structure characterization of the non-crystalline complexes of copper salts with native cyclodextrins

The characterization of non-crystalline complexes is very difficult when techniques like X-ray diffraction or NMR are not available. We propose a simple procedure to characterize the physicochemical properties of amorphous new coordination compounds between cyclodextrins (CD) and Cu²⁺ salts, by several techniques as TGA, FT-IR, EPR.

Selective colorimetric sensing of Co2+ and Cu2+ using 1-(2-pyridylazo)-2-naphthol derivative immobilized polyvinyl alcohol microspheres

A novel optical sensor was proposed. The sensor can be used to monitor Co²⁺ and Cu²⁺ ions.

Bio-sensitive activities of coordination compounds containing 1,10-phenanthroline as co-ligand: synthesis, structural elucidation and dna binding properties of metal(II) complexes

Present work reports the DNA binding and cleavage characteristics of a series of mixed-ligand complexes having the composition [M(L)(phen)2]Cl2 (where M=Cu(II), Ni(II), Co(II) and Zn(II) and phen as co-ligand) in detail. Their structural features and other properties have been deduced from their elemental analyses, magnetic susceptibility and molar conductivity as well as from IR, UV-Vis, (1)H NMR and EPR spectral studies. The UV-Vis, magnetic susceptibility and EPR spectral data of metal complexes suggest an octahedral geometry. The binding properties of these complexes with calf thymus DNA (CT-DNA) have been explored using electronic absorption spectroscopy, viscosity measurement, cyclic voltammetry and differential pulse voltammetry. The DNA-binding constants for Cu(II), Ni(II), Co(II), and Zn(II) complexes are 6.14×10(5)M(-1), 1.8×10(5)M(-1), 6.7×10(4)M(-1) and 2.5×10(4)M(-1) respectively. Detailed analysis reveals that these complexes interact with DNA through intercalation binding. Nuclease activity has also been investigated by gel electrophoresis. Moreover, the synthesized Schiff base and its mixed-ligand complexes have been screened for antibacterial and antifungal activities. The data reveal that the complexes exhibit higher activity than the parent ligand.