Pyramidal Geometry Research Articles

Novel 5-(2-chloro-quinolin-3-yl)-[1,3,4]thiadiazol-2-ylamines and their copper(II) metallates: Preparation, spectroscopy, X-ray crystallography, nucleic acid/albumin binding, DNA cleavage and in vitro cytotoxicity

Copper(II) metallates of 2-chloroquinoline-3-carboxaldehyde-4(N)-substituted thiosemicarbazone (CuQ1, CuQ2, CuQ3, CuQ4) were synthesized, characterized by Fourier-Transform Infrared (FT-IR), Ultraviolet–Visible (UV–Vis), Electron Paramagnetic Resonance (EPR) and Mass spectrometry. The true nature of the ligands and a representative complex was confirmed by X-ray single crystal analysis. During the complexation, the ligands underwent cyclisation to form thiadiazole and two units of thiadiazole were coordinated to copper ion through N2-nitrogen atom. The remaining sites were occupied with two chloride ions and a water molecule which led to a square pyramidal geometry around copper ion. Absorption and emission titration methods confirmed the partial intercalative mode of binding interaction between CT-DNA and the metal complexes. The interaction between complexes and BSA led to the formation of ground state fluorophore-quencher complex by following static quenching mechanism. In vitro cytotoxic effect of the ligands and complexes were done by taking Human cervical cancer (HeLa) cells and toxicity of the test compounds were analyzed by using normal human kidney cell (HEK). The complexes CuQ2, CuQ3 and CuQ4 showed better cytotoxic activity against HeLa cells as compared with the standard cisplatin. Among the complexes, CuQ3 exhibited higher activity with least IC50 value (17 µM).

TEMPLATE-ENGINEERED TRIVALENT IRON AND CHROMIUM CONTAINING MACROCYCLIC COMPLEXES: CHARACTERIZATION AND IN VITRO STUDIES

A novel series of tetraaza macrocyclic complexes of biological importance was synthesized by “in situ” template reaction between triethylenetetramine and dibenzoylmethane in the presence of trivalent Fe and Cr metal salts in 1:1:1 molar ratio. These complexes are represented by molecular formula [M(C[Formula: see text]H[Formula: see text]N[Formula: see text]X]X2; [Formula: see text](III) and Cr(III); [Formula: see text], NO[Formula: see text], −OAc; C[Formula: see text]H[Formula: see text]N[Formula: see text] ligand. The reported complexes were characterized by using various physicochemical and spectroscopic techniques including elemental analyses, molar conductance, thermo-gravimetric analysis, FTIR, UV–Visible and mass spectral studies. The results obtained from analytical techniques and spectroscopic techniques together suggested the complexes have a square pyramidal geometry. Various computational studies were performed including molecular docking and modeling. Further, macrocyclic complexes were also screened for their “in vitro” antimicrobial activity against selected bacterial and fungal strains. The antioxidant activity of these complexes was also evaluated. Some of the complexes were found to possess remarkable antimicrobial activity and antioxidant activity. However, complex [Fe(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to be most potent against selected bacterial and fungal strains. On the other hand, complex [Cr(C[Formula: see text]H[Formula: see text]N[Formula: see text](NO[Formula: see text]](NO[Formula: see text] was found to show best antioxidant activity with lowest value of IC[Formula: see text].

Centrosymmetric homo- and heteroleptic core paddle-wheel copper(II) carboxylates; Syntheses, crystal structures, antioxidant, anticancer and enzyme inhibition activity

Synthesis and characterization of homo- (C5H7N2)2[Cu2(3,5-F2C6H3CH2COO)6] (1) and heteroleptic [Cu2(3,5-F2C6H3CH2COO)4(2-CH3Py)2] (2) core paddle-wheel copper(II) carboxylates is reported in the present work. The characterization was made by spectroscopic techniques, elemental and single crystal XRD analyses. The single crystal XRD analysis revealed a rare homoleptic anionic copper(II) carboxylate complex (1) consisting 2-aminopyridinium counter cations and a neutral heteroleptic copper(II) carboxylate complex (2) consisting 2-methyl pyridine as a co-ligand. The copper ions adopted a distorted square pyramidal geometry in both the paddle-wheel dimeric complexes. To evaluate the biological potency of the synthesized complexes, in vitro antioxidant, enzymes inhibition and anticancer activities were performed. The synthesized complexes have shown overall better biological activity compared to the ligand acid. Complex 2 was the most potent DPPH (IC50 =180.96 ± 9.04 µg/mL) and •OH (IC50 = 189.51 ± 9.33 µg/mL) radicals scavenger, α-amylase (IC50 = 441.86 µg/mL) and acetylcholinesterase (IC50 = 88.62 µg/mL) inhibitor. Furthermore, complex 2 activity against malignant glioma U-87 cell line (IC50 = 21.95 µg/mL) was also highest among the tested compounds. However, complex 1 with an IC50 value of 51.83 µg/mL has shown somewhat better inhibition of the butyrylcholinesterase enzyme compared to the complex 2 (IC50 = 56.36 µg/mL).

De novo design and preparation of Copper(II)–based chemotherapeutic anticancer drug candidates with Boc–glycine and N,N–donor ligands: DNA binding, cleavage profile, and cytotoxic therapeutic response against MCF–7, PC–3, and HCT–116 cells

Two new copper(II) complexes [Cu(Boc–glycine)(2,2–bipyridyl)2]NO31 and [Cu(Boc–glycine)(1,10–phenanthroline)2]NO32 were prepared, and thoroughly characterized by multiple spectroscopic methods. The SC X–ray diffraction studies revealed that the complexes crystallized in triclinic (P 1¯) system with distorted square pyramidal and octahedral geometry in 1 and 2, respectively. To predict the anticancer potential of the drug candidates 1 and 2, binding studies with the ct–DNA were performed by using various complimentary biophysical methods. The drug candidates 1 and 2 interact strongly with DNA exhibiting ‘hypochromic’ effect in the absorbance bands at 300 nm implicating non–covalent intercalation binding mode that could be induced by the presence of strong recognition domain ligand (phen) which is known to ‘wedge–in’ in-between the bases of DNA helix. The intrinsic binding constant, Kb values were quantified by employing Wolfe–Shimer equation, and were found to be 0.10(±0.14) × 105 M−1 and 1.53 × 106(±0.1) M−1, respectively, showing higher binding propensity of 2 as compared to 1. pBR322 plasmid DNA cleavage studies of the complexes 1 and 2 showed that the complexes induced single–strand cleavage of DNA at a low concentration of 20 µM and 15 µM which mediated via an oxidative mechanism. The cytotoxicity activity of complexes was evaluated against MCF–7, PC–3, and HCT–116 cancer cells and the complexes displayed exceptionally good cytotoxicity against the tested cell lines (1, HCT–116:IC50 = 0.6 ± 0.02 μM and 2, MCF–7:IC50 = 1.91 ± 0.1 μM).

Crystal structure and Hirshfeld surface of a pentaaminecopper(II) complex with urea and chloride

The reaction of copper(II) oxalate and hexamethylenetetramine in a deep eutectic solvent made of urea and choline chloride produced crystals of pentaaminecopper(II) dichloride–urea (1/1), [Cu(NH3)5]Cl2·CO(NH2)2, which was characterized by single-crystal X-ray diffraction. The complex contains discrete pentaaminecopper(II) units in a square-based pyramidal geometry. The overall structure of the multi-component crystal is dictated by hydrogen bonding between urea molecules and amine H atoms with chloride anions.

Morphological studies, photocatalytic degradation of organic dyes and anticancer potential of copper sulfide nanoparticles prepared from bis(diallyl dithiocarbamato)copper(II) complex

Bis(diallyl dithiocarbamato)copper(II) complex was synthesized and characterized by single crystal X-ray crystallography. The molecular structure revealed dimeric copper(II) complex consisting of two copper(II) ions that coordinate two molecules of diallydithiocarbamato anions in bidentate chelating modes and the centrosymmetrically related diallydithiocarbamato anions bridges the S-atom of the adjacent chelating ligand to formed square pyramidal geometry around the copper(II) ions. Copper sulfide nanoparticles were prepared at 160 °C by thermolysis of the copper(II) complex in dodecylamine (DDA), hexadecylamine (HDA), and octadecylamine (ODA) to study the effect of capping agents on the structural morphologies, photocatalytic properties, and anticancer potential of the as-prepared copper sulfides nanoparticles. Powder X-ray diffraction patterns confirmed Cu9S5 digenite crystalline phases for CuS-DDA and CuS-HDA while CuS-ODA is covellite crystalline phase. HRTEM images showed spherical particles with particle sizes in the range 2–25 nm. The copper sulfide nanophotocatalysts are efficient for the degradation of bromophenol blue with the highest photocatalytic efficiency of 95.14 % for CuS-DDA followed by CuS-HDA with 94.52 % and 93.95 % for CuS-ODA. The anticancer potentials of the compounds showed that CuS-HDA is the most potent with IC50 values of 1.22 µg/mL against HEK293 and 28.78 µg/mL against HeLa.

Assessing the antimicrobial and cytotoxic activities of VO(IV), Cr(III), Cu(II)-metformin-schiff-base's complexes enhanced by gold nanoparticles

A new series of VO(IV), Cr(III), and Cu(II) complexes have been synthesized by condensation of metformin with β-diketones (acetylacetone, benzoylacetone, dibenzoylmethane) in the presence of metal salts. The elemental analysis, magnetic susceptibility, conductivity assessments, Infra-Red, UV–visible spectroscopy measurements, SEM, XRD, ESR, GCMS–, DTA, and DTG were used to characterize the novel compounds. The results show that every complex has a metal: ligand ratio of 1:1. The complexes exhibit distorted tetrahedral structural geometry for Cu(II), square pyramidal and octahedral geometry for VO(IV), and octahedral geometry for Cr(III), according to their electronic absorption spectra and magnetic susceptibility studies. Using the computer program Expo2014, crystallographic parameters were estimated for the complexes. The outcomes show that every complex has triclinic crystal structures with the space group P-1, apart from complex [VOL1OSO3], which has a monoclinic structure with the P 1 2 1 space group. In contrast to the complex [VOL1OSO3], which includes monodentate sulfate, conductivity data, XRD, EDX, and GC–MS verified the purity and composition of the compounds being studied. IR data showed that the complexes Na.[VOL2O2SO2] and Na.[VOL3O2SO2] has bidentate chelating sulfate ion. TG, DTG, and DTA have all been used to investigate the complexes' thermal stabilities. Some Schiff-base metformin complexes under investigation had their biological activity evaluated both with and without the addition of AuNPs. Various bacteria and harmful fungi strains have been used to screen the antimicrobial activity. The findings indicate that only copper-loaded Schiff base complexes on AuNPs gave promising results versus Staphylococcus aureus, Escherichia coli, Salmonella, and Candida albicans. On human cell lines of breast cancer (MCF7) and cancer of the human liver (HEPG2), in vitro cytotoxic activity was tested. Results showed that vanadium benzoylacetone doped with gold nanoparticles, with an IC50 value of 7 µg/ml against the HEPG2 cell line and 9.8 against MCF7 has the most effective cytotoxic effect.

Synthesis, structural characterization of phenoxo-bridged zinc(II) complexes and their binding interaction with the spike protein of SARS-CoV-2

The research article reports the synthesis and structural study of the optimized geometry of selenium (Se) bearing 24- and 28- membered macrocyclic Schiff bases, LaH2 , LbH2 and their reactions with zinc metal ion. The reactions of the macrocyclic Schiff bases with ZnCl2 in 1:2 molar ratios result in the formation of bimetallic Zn(II) complexes having molecular composition [Se{(CH2)2N = CPh(4-CH3-C6H2O) PhC = O}2 · Zn2Cl2], (1) and [Se{(CH2)3N = CPh(4-CH3-C6H2O)PhC = O}2 · Zn2Cl2], (2). Moreover, as confirmed by various physico-chemical techniques such as elemental analysis, UV–Vis, FTIR,1H NMR, and mass spectrometry, the proligands underwent partial hydrolytic cleavage at one of the C = N positions and behave like hexadentate (N2O4) ligands binding to two Zn(II) ions via bridging through the Ophenolic atoms, which results in a square pyramidal geometry around Zn(II) with the chlorine atom occupying axial positions. Further, following density functional study, the stable optimized configuration of the Schiff bases LaH2 and LbH2 is found to adopt bowl shape geometry. Conversely, in molecular docking studies, the synthesized complex 1 exhibits a significantly stronger binding affinity (−8.7 kcal/mol) to the spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as compared to the common coronavirus disease 2019 (COVID-19) treatment drugs such as chloroquine, hydroxychloroquine, and remdesivir with activity percentage showing more than 20% overall effectiveness than remdesivir and thus indicating its potential for COVID-19 therapeutics.

A theoretical study on a new drug combines between vanadyl sulfate and vitamin E in a single component: A novel antioxidant medication in female reproductive health

This study explores the theoretical properties of a novel complex formed by combining vitamin E (VitE) and vanadyl(II) sulfate. The complex, [VO(VitE)2(H2O)2]2H2O (Vcom), was synthesized in solid form through a reaction between VitE and VOSO4.xH2O in a specific solvent mixture and pH. VitE binds to the vanadyl ion as a single ligand via its deprotonated phenolic oxygen. To characterize the complex, various analytical techniques were employed, including elemental analysis, spectral analysis, conductivity measurements, thermal analysis, X-ray diffraction, and microscopy. Electronic and magnetic properties were also investigated. Theoretical calculations - molecular docking simulations were used to assess the binding affinity of Vcom with two receptors known to interact with vitamin E: α-tocopherol transfer protein (α-TTP) and p105 subunit of nuclear factor NF-kappa-B p105 subunit (NF-κB). The findings revealed a square pyramidal geometry for the Vcom complex. Additionally, Density Functional Theory (DFT) were performed on both VitE and Vcom, focusing on their optimized structures, electrostatic properties, and HOMO-LUMO energy gaps. In summary, this research delves into the theoretical aspects of a newly formed VitE-vanadyl complex, providing insights into its structure, properties, and potential interactions with relevant receptors. KEY WORDS: New drug, Vanadyl sulfate, Vitamin E, Antioxidant, Female, Reproductive health, DFT Bull. Chem. Soc. Ethiop. 2024, 38(4), 989-1001. DOI: https://dx.doi.org/10.4314/bcse.v38i4.14

Nanostructure and dynamics of N-truncated copper amyloid-β peptides from advanced X-ray absorption fine structure.

An X-ray absorption spectroscopy (XAS) electrochemical cell was used to collect high-quality XAS measurements of N-truncated Cu:amyloid-β (Cu:Aβ) samples under near-physiological conditions. N-truncated Cu:Aβ peptide complexes contribute to oxidative stress and neurotoxicity in Alzheimer's patients' brains. However, the redox properties of copper in different Aβ peptide sequences are inconsistent. Therefore, the geometry of binding sites for the copper binding in Aβ4-8/12/16 was determined using novel advanced extended X-ray absorption fine structure (EXAFS) analysis. This enables these peptides to perform redox cycles in a manner that might produce toxicity in human brains. Fluorescence XAS measurements were corrected for systematic errors including defective-pixel data, monochromator glitches and dispersion of pixel spectra. Experimental uncertainties at each data point were measured explicitly from the point-wise variance of corrected pixel measurements. The copper-binding environments of Aβ4-8/12/16 were precisely determined by fitting XAS measurements with propagated experimental uncertainties, advanced analysis and hypothesis testing, providing a mechanism to pursue many similarly complex questions in bioscience. The low-temperature XAS measurements here determine that CuII is bound to the first amino acids in the high-affinity amino-terminal copper and nickel (ATCUN) binding motif with an oxygen in a tetragonal pyramid geometry in the Aβ4-8/12/16 peptides. Room-temperature XAS electrochemical-cell measurements observe metal reduction in the Aβ4-16 peptide. Robust investigations of XAS provide structural details of CuII binding with a very different bis-His motif and a water oxygen in a quasi-tetrahedral geometry. Oxidized XAS measurements of Aβ4-12/16 imply that both CuII and CuIII are accommodated in an ATCUN-like binding site. Hypotheses for these CuI, CuII and CuIII geometries were proven and disproven using the novel data and statistical analysis including F tests. Structural parameters were determined with an accuracy some tenfold better than literature claims of past work. A new protocol was also developed using EXAFS data analysis for monitoring radiation damage. This gives a template for advanced analysis of complex biosystems.

Zn(II), Mn(III), and Co(III) complexes of Schiff base derived from 2‐hydroxy‐1‐naphthaldehyde: Synthesis, spectral surveys, single crystal structure studies, Hirshfeld surface analysis, density functional theory calculation, molecular electrostatic potential, and molecular docking evaluations

A new series of transition metal complexes of bidentate Schiff base compound derived from 2‐hydroxy‐1‐(2‐methoxyethylimino)‐naphthalene (HL) were synthesized and characterized using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR), and UV–vis spectroscopies. X‐ray single crystal structures of Zn(II), Mn(III), and Co(III) complexes (1–4) have also been determined, and it was indicated that these Zn(II) and Co(III) complexes (1, 4) are in an octahedral geometry. Whereas, it was found that the Zn complex (2) is in quite a regular tetrahedral environment. Also, the Mn center in complex (3) is ligated by two azomethine nitrogen atoms, two ligand oxygen atoms, and one Cl atom of metal salt forming five coordinated tetragonal pyramid geometry around the Mn atoms. The cyclic voltammetry of the complexes specifies an irreversible redox behavior for all complexes (1–4). Next, DFT/B3LYP theoretical method was used to determine the optimal geometrical configurations and comparison between experimental and theoretical data, as well as for calculations of molecular electrostatic potential, highest‐occupied molecular orbital (HOMO)‐lowest‐unoccupied molecular orbital (LUMO) energy values of selected compounds. The study of non‐covalent interactions was done by Hirshfeld surface analysis using CrystalExplorer program. Furthermore, molecular docking inspection was carried out to study the binding affinity of the tested complexes towards protein B‐cell lymphorna (PDB ID: 4LXD). Using the results obtained from the molecular docking and the summarized interaction of the binding processes, these structures show the validity of effective inhibition against liver cancer.

3D-printed pyramid nickel-based electrode enabling directional bubble traffic and electrolyte flow for efficient hydrogen evolution

For efficient and stable large-scale water electrolysis, practical industrial electrodes should meet the following characteristics: high activity, structural stability, and fast bubble removal. Here we report a structured electrode (NiS–Co–NiP) prepared via 3D printing of nickel-based substrate and subsequent electrodeposition for the hydrogen evolution reaction (HER). With unique 3D nanosheets, the NiS–Co–NiP electrode exhibits large electrochemical surface area (ECSA), strong hydrophilicity, high mechanical strength and electrical conductivity, delivering outstanding HER activity. It requires low overpotentials of 134 mV and 169 mV to achieve the current densities of 100 mA cm−2 and 300 mA cm−2, respectively. Moreover, rational design of the NiS–Co–NiP electrode in pyramidal geometry facilitates directional bubble transport and electrolyte flow, resulting in superior stability of 350 h at a current density of 150 mA cm−2. This work demonstrates a new approach for manufacturing binder-free structured electrode of excellent HER performance at high current densities.

Interaction with CT-DNA and in vitro cytotoxicity of two new copper(II)-based potential drugs derived from octanoic hydrazide ligands

Two copper(II) complexes [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(peoh)(N3)]2 (2) were designed and synthesized by reaction of Cu(NO3)2·3H2O with hydrazone Schiff base ligands,abbreviated with Hpmoh and Hpeoh. Hpmoh and Hpeoh were prepared by condensation reaction of octanoic hydrazide with pyridine-2-carboxyaldehyde and 2-acetylpyridine, respectively. Complexes 1 and 2 were characterized using different analytical techniques such as FT-IR, UV–Vis, IR, EPR and single X-ray diffraction (XRD) analyses as well as computational methods (DFT). The XRD of 1 and 2 shows a mononuclear or a dinuclear structure with the copper(II) centre adopting a slightly distorted square pyramidal geometry. In water-containing solution and in DMSO, 1 and 2 undergo a partial transformation with formation of [Cu(Hpmoh)(NO3)(NCS)] (1) and [Cu(Hpmoh)(NO3)(H2O/DMSO)] (1a) in one system and [Cu(peoh)(N3)] (2a) in the other one, as supported by DFT calculations. Docking simulations confirmed that the intercalation is the preferred binding mode with DNA for 1, 1a and 2a, but suggested that the minor groove binding is also possible. A significant fluorescence quenching of the DNA–ethidium bromide conjugate was observed upon the addition of complexes 1 and 2 with a quenching constant around 104 M−1 s−1. Finally, both 1 and 2 were examined for anti-cancer activity using MDA-MB-231 (human breast adenocarcinoma) and A375 (malignant melanoma) cell lines through in vitro MTT assay which suggest comparable cancer cell killing efficacy, with the higher effectiveness of 2 due to the dissociation into two [Cu(peoh)(N3)] units.

Synthesis, characterization, thermal, anticancer studies, and density functional theory for potentially active pyrimidine‐based complexes

This work aimed to create and characterize some new bioactive chelates of bis azodye ligand, 5‐((2‐hydroxy‐4,6‐dioxo‐1,4,5,6‐tetrahydropyrimidin‐5‐yl)diazenyl)naphthalen‐1‐yl)diazenyl) pyrimidine 2,4,6 (1H,3H,5H)‐trione. Except for the Sm(III) chelate, which exhibited a (3M:1L) molar ratio, all chelates had a (2M:1L) stoichiometry. According to Fourier transform infrared spectroscopy (FT‐IR), azo groups were not included in chelating with all ions except Sm(III), where just one azo group was coordinated. With the Ni(II) and Zn(II) ions, the ligand behaved as OON‐tridentate moiety; with the Co(II) and Cu(II) ions, it behaved as ON‐bidentate moiety. Co(II) and Cu(II) chelates had square planar structure, and Ni(II) and Zn(II) chelates had square pyramidal geometry. The chelates had greater thermal stability than the uncoordinated ligand due to the chelate's structure. [Sm3(H4L)(OH)7(NO3)2.H2O].4.5EtOH exhibited the maximum thermal stability, which may be due to the large number of solvent molecules and the high number of chelate rings. With the exception of the Sm(III) chelate, all of the examined chelates were more cytotoxic against MCF‐7 and Hep‐G2 cells than their parent ligand. With the exception of the Zn(II) chelate, which demonstrated activity on Hep‐G2 rather than MCF‐7, the effects of each metal chelate on the two cells were nearly equivalent. All of the studied chelates, especially Zn(II) and Co(II), were potent as antioxidants more than the native ligand. To support experimental findings, density functional theory (DFT) studies were performed via the CAM‐B3LYP/LanL2DZ method, and the geometry of the ligand and its chelates had been validated.

Contact mechanics of open-cell foams with macroscopic asperities

Poroelastic materials mounted against rigid surfaces often result in partial contact between the two, affecting their mechanical interaction. The surface roughness of cellular materials introduces complexity in predicting their behavior due to the interface with partial contact. This interface exhibits a stiffness distinct from the bulk material, which is driven by the surface asperities and the preload. This study conducts compression experiments on an open-cell poroelastic melamine foam, and compares them to finite elements simulations and analytic predictions. The material’s intrinsic stress–strain nonlinearity is accounted for, and an original hyperelastic aging model is proposed to achieve accurate predictions of its compression stiffness across multiple time scales. Predicting the compression stiffness of a macroscopic pyramidal asperity demonstrates a good agreement with the simple analytic solution for an elastic pyramidal geometry. Using a Greenwood–Williamson-like model based on the distribution of asperities of different heights, we propose a method to predict the contact stiffness of a rough surface. Our findings have important implications for understanding and optimizing efficient vibration barriers, resulting from the simple stacking of layers and screens of raw poroelastic materials, a configuration widely adopted in the transportation and civil engineering industries.

Catecholase and phenoxazinone synthase activities of two structurally characterized mononuclear complexes [Cu(L)(NCS)(ClO4)] and [Zn(L)(NCS)2] [L = N,N-diethyl-2-((phenyl(pyridin-2-yl)methylene)-amino)ethan-1-amine

Synthesis and X-ray structural characterization of a Cu(II) and a Zn(II) mononuclear complexes [Cu(L)(NCS)(ClO4)] (1) [Zn(L)(NCS)2] (2) [L = N,N-diethyl-2-((phenyl(pyridin-2-yl)methylene)-amino)ethan-1-amine] were done. 1 and 2 were crystalized in Pbca and P121/c1 space groups. Metal centres at both the complexes adopted distorted square pyramidal geometries. Both 1 and 2 responded to catecholase and phenoxazinone synthase activities in different solvents. The biomimicking activities were monitored by repetitive UV–Vis scan. Several kinetic parameters for both 1 and 2 were measured. The turn over numbers of 1 were 25.20 (MeOH) and 50.00 (ethylacetate), and for 2, 582.00 (MeOH) for the catecholase activity. For the phenoxazinone synthase activity the turn over numbers were 78.28 (MeOH), 21.17 (MeCN) and 43.06 (ethylacetate) for 1, and 40.00 (MeOH), 11.00 (MeCN) and 4.00 (ethylacetate) for 2.

Rational Design of Metallylenes for Hydrogenation Reactions

AbstractThe hydrogenation of alkenes, alkynes, carbonyls, and imines by H2‐activated metallylenes (H3C−EH2−L, CELH2; E=Si, Ge, Sn and L=NMe2, PMe2) was studied using relativistic density functional theory at ZORA‐BP86/TZ2P. By means of activation strain and Kohn–Sham molecular orbital analyses, the physical factors underlying the trends in reactivity were identified and quantified. Firstly, the hydrogenation reactivity increases on descending Group 14, that is from silylenes (E=Si) to stannylenes (E=Sn). This reactivity trend originates primarily from a reduced energy required to break the bonds between the Group 14 atom and the hydrogen atoms because the strength of these bonds decreases from Si−H to Ge−H to Sn−H. Secondly, the reactivity decreases as the Group 15 ligand changes from nitrogen to phosphorus (L=NMe2, PMe2) which stems from the trigonal pyramidal PMe2 geometry compared to the trigonal planar NMe2 geometry. The latter can, therefore, effectively engage in stronger orbital interactions with the substrate than the former, due to a more efficient HOMO–LUMO orbital overlap. By combining our insights, we rationally designed an optimally tuned catalyst (Group 14 atom and ligand) considering the overall catalytic cycle involving H2 activation of the metallylene and subsequent hydrogenation.

Synthesis of Novel [{(2-Amino-5-Nitro-N-[(E)-Thiophen-2-yl-Methylidene]Aniline-κ3N1:N4:S)(Sulphato-κ2O1:O3)}Zinc(II)] Complex with Physico-Chemical and Biological Perspective Exploration: A Combined Experimental and Computational Studies.

A novel metal complex was synthesized using freshly prepared 2-Amino-5-nitro-N-[(E)-thiophen-2-yl-methylidene]aniline ligand with Zn (II) sulphate heptahydrate in a 1:1 molar ratio. The ligand and the complex were characterized using different spectroscopic techniques, and the complex was assigned a distorted square pyramidal geometry. Additionally, DNA binding assays and antibacterial activity were used to assess the biological perspectives for the synthesized complex, including the ligand and complex which was further confirmed by molecular docking. Fluorescence Spectroscopy, viscosity measurement, and adsorption measurement were used to investigate the interaction of the Zn (II) complex with CT-DNA. A comparativein vitroantibacterial activity study againstEscherichia coli, Klebsiella pneumoniae,Bacillus subtilis,andStaphylococcus aureusstrains were studied with free ligand and Zn (II) metal complex. The stable geometry of the complex was additionally established through computational simulation utilizing density functional theory, which was followed by the calculation of several electronic properties. The ADMET characteristics of the complex and ligand were also assessed using ADMET analysis. The in-silico ADMET properties pointed to a significant drug-likeness feature in the synthesized compounds, based on the Lipinski criteria.

Structure elucidation {single X-ray crystal diffraction studies, Hirshfeld surface analysis, DFT} and antibacterial studies of 1,2-benzothiazine metal complexes

The 2-benzyl-4‑hydroxy-1,1-dioxo-1,2-benzothiazine-3-carboxylic acid methyl ester i.e., ligand 1 was utilized to synthesize Mn(II) 2, Co(II) 3, Ni(II) 4, Cu(II) 5 and Zn(II) 6 derived metal complexes in mild basic conditions. The structural investigation was carried out by UV–vis, FT-IR, NMR spectroscopy, CHN analysis, conductivity measurement, ESI-MS analysis and magnetic susceptibility techniques. The X-ray diffraction analysis confirmed the octahedral and distorted square pyramidal geometries of the cobalt and copper complexes. The ligand 1 coordinated with metal centres through enolic oxygen atoms of the thiazine ring and ester group while methanol coordinated with metal center via oxygen atom. The Hirshfeld surface analysis (HSA) was utilized to determine the intermolecular interactions. In support of the experimental data, DFT studies were also performed for the cobalt and copper complexes. The NBO analysis resulted in the large stabilization values 11.91 and 12.35 kcal/mol for the cobalt and copper complexes. The global reactivity indicated the higher values of hardness and the large values of FMO analysis which support the higher stability of the metal complexes. The synthesized compounds were also evaluated against six bacterial strains to check their antibacterial potential. It was observed from results that highest activity was depicted by copper complex 5 against B. subtilis and the zone of inhibition is 23.4 ± 0.6 mm which is comparable to ampicillin (standard drug).

The Crystal Structure and Physicochemical Properties of New Complexes Containing a CuII-LnIII-CuII Core

Three new cationic complexes, [Cu4Tb2(H2L)4(NO3)4(H2O)3](NO3)2·5.5H2O·2MeOH (1), [Cu4Ho2(H2L)4(NO3)4(H2O)3](NO3)2·7.5H2O (2), and [Cu4Er2(H2 L)4(NO3)4(H2O)3](NO3)2·7H2O·3MeOH (3), were synthesized and studied using elemental and TG/DTG/DSC analyses, single-crystal X-ray diffraction, and magnetic measurements. The structure analysis showed that 1–3 crystallize as (NO3)-bridged compounds and that the lanthanide(III) ion acts as a joint connecting two [CuH2L] coordination units. In each heterotrinuclear unit, an asymmetry in the degree of planarity of the bridging CuO2Ln fragments is observed. The CuII ions are five- and six-coordinate, with distorted square pyramidal and octahedral geometry, respectively, whereas the LnIII ions are nine-coordinate. The solvates 1–3 are stable at room temperature, and their desolvation process is consistent with the loss of water and/or methanol molecules. The temperature dependence of the magnetic susceptibility and the field-dependent magnetization indicate the weak ferromagnetic interaction between the paramagnetic centers CuII and TbIII/HoIII 1 and 2.