Metal-ligand Complexes Research Articles

Open-Cage Fullerene as a Macrocyclic Ligand for Na, Pt, and Rh Metal Complexes.

An open-cage [60]fullerene derivative was prepared through Malaprade oxidation of a vicinal triol moiety as the key step. Above the 17-membered orifice, there is one carboxyl group. Three ketone carbonyl groups and one lactone carbonyl group are located on the rim of the orifice. The carboxylic and carbonyl oxygen atoms around the orifice act as strong polydentate ligands for a sodium ion. These oxygen atoms also react with [Rh(CO)2Cl]2 to form various isomeric rhodium complexes with comparable stability. The fullerene C═C bond on the rim of the orifice forms a stable platinum complex when treated with Pt(PPh3)4. Single crystal X-ray diffraction data reveal that one of the carboxylic oxygen atoms above the orifice forms a H-bond with the water molecule trapped in the cage.

Structural investigation, quantum chemical calculation, energy framework analysis and MIC studies of silver and cobalt complexes of 4-amino-N-(4, 6-dimethyl-2 pyrimidinyl) benzenesulfonamide in presence of secondary ligand

Silver and cobalt complexes of SMZ ligand (SMZ = 4-amino-N-(4, 6-dimethyl-2 pyrimidinyl) benzenesulfonamide) have been synthesized and characterized by elemental, FT-IR and 1H-NMR spectroscopy analysis. Due to the magnetic behaviour of the cobalt complex, it was characterized by EPR and magnetic susceptibility analysis. Single crystal X-ray diffraction (SC-XRD) study reveals the [Ag2(C12H14N4O2S)2(C6H7N), complex-1 crystallizes in orthorhombic space group Pbca, while [{Co(C12H13N4O2S)2(C5H5N)2}.(C5H5N)], complex-2 crystallizes in monoclinic space group C2/c. The SC-XRD analysis shows that silver in complex-1 is four-coordinate exhibiting distorted tetrahedral geometry, while cobalt in complex-2 is coordinated to six nitrogen’s leading to distorted octahedral geometry. Additionally, Hirshfeld surfaces and 2D fingerprint plots analysis shows that the H…H intermolecular contacts are the main contribution to the Hirshfeld surface area displaying values for complex-1 and complex-2 are 59.1% and 50% respectively (%H-H; complex 1 > Complex 2). In 3D energy frameworks analysis, complex-1, has shown the highest dispersion interaction energies than that of complex 2 [dispersion energy; -74.5 kJ mol-1 (complex-1) > -63.4 kJ mol-1 (complex-2)], Moreover, computational studies such as frontier molecular orbital (FMO), natural bond orbital (NBO) and Mulliken population analysis (MPA) were calculated using B3LYP method. Besides, The MIC data against panel of gram-positive and gram-negative organisms confirm that both the metal complexes of SMZ ligand possesses better inhibitory activities than that of SMZ ligand. The MIC data shows the silver complex exhibits comparatively better response towards the panel of the gram positive and gram negative bacteria. Furthermore, the molecular docking study agrees that the binding affinity of the complexes with 1BNA is higher than that of free SMZ ligand.

A Chemist's View on Electronic and Steric Effects of Surface Ligands on Plasmonic Metal Nanostructures.

ConspectusPlasmonic metal nanostructures have been extensively developed over the past few decades because of their ability to confine light within the surfaces and manipulate strong light-matter interactions. The light energy stored by plasmonic nanomaterials in the form of surface plasmons can be utilized to initiate chemical reactions, so-called plasmon-induced catalysis, which stresses the importance of understanding the surface chemistry of the plasmonic materials. Nevertheless, only physical interpretation of plasmonic behaviors has been a dominant theme, largely excluding chemical intuitions that facilitate understanding of plasmonic systems from molecular perspectives. To overcome and address the lack of this complementary understanding based on molecular viewpoints, in this Account we provide a new concept encompassing the well-developed physics of plasmonics and the corresponding surface chemistry while reviewing and discussing related references. Inspired by Roald Hoffmann's descriptions of solid-state surfaces based on the molecular orbital picture, we treat molecular interfaces of plasmonic metal nanostructures as a series of metal-ligand complexes. Accordingly, the effects of the surface ligands can be described by bisecting them into electronic and steric contributions to the systems. By exploration of the quality of orbital overlaps and the symmetry of the plasmonic systems, electronic effects of surface ligands on localized surface plasmon resonances (LSPRs), surface diffusion rates, and hot-carrier transfer mechanisms are investigated. Specifically, the propensity of ligands to donate electrons in a σ-bonding manner can change the LSPR by shifting the density of states near the Fermi level, whereas other types of ligands donating or accepting electrons in a π-bonding manner modulate surface diffusion rates by affecting the metal-metal bond strength. In addition, the formation of metal-ligand bonds facilitates direct hot-carrier transfer by forming a sort of molecular orbital between a plasmonic structure and ligands. Furthermore, effects of steric environments are discussed in terms of ligand-ligand and ligand-surface nonbonding interactions. The steric hindrance allows for controlling the accessibility of the surrounding chemical species toward the metal surface by modulating the packing density of ligands and generating repulsive interactions with the surface atoms. This unconventional approach of considering the plasmonic system as a delocalized molecular entity could establish a basis for integrating chemical intuition with physical phenomena. Our chemist's outlook on a molecular interface of the plasmonic surface can provide insights and avenues for the design and development of more exquisite plasmonic catalysts with regio- and enantioselectivities as well as advanced sensors with unprecedented chemical controllability and specificity.

Naphthalimide-benzimidazole conjugate towards “Turn-on” recoginition of Hg2+ in pure aqueous medium

A chemosensor, 6-(1-cyclohexyl-1H-benzo[d]imidazol-5-yl)-2-(2-(diethylamino)ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (9), containing 1H,3H-benzo[de]isochromene-1,3-dione and 1-cyclohexyl-1H-benzo[d]imidazole moieties has been designed and found to be selective towards Hg2+ ions over-tested wide-range of metal ions. Compound 9 shows the absorption and emission peaks at 370 nm and 540 nm, respectively. The addition of Hg2+ ions to compound 9 (20 μM; H2O, pH = 7.4) prompted the formation of a 2:1 ligand–metal complex, 9-Hg2+, which shows a significant blue-shifted emission enhancement to 495 nm, due to the mechanism of ligand to metal charge transfer. The formation of compound 9 and Hg2+ ions complex has also been confirmed through mass spectrometry and 1H NMR titrations. The photophysical properties of the compound and its complex corroborated with Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TDDFT) calculations.

Synthesis and X-ray crystal structures of mononuclear and multinuclear metal complexes of 3-substituted 4-cyanopyrazole ligands

Complexes of pyrazole ligands with a cyano substituent in the 4-position and alkyl or aryl substituents in the 3-position are reported, including mononuclear {M(HpzR,4CN)4X2 (X = Cl, M = Ni, R = t-Bu, c-Pr, Cy, Et; X = Cl, M = Co, R = Et, Cy, t-Bu; X = Br, M = Ni, R = i-Pr), [Pt(Hpzt-Bu,4CN)2Cl4], [Cu(HpzEt,4CN)2(H2O)2(NO3)2], M(HpzR,4CN)2Cl2 (M = Pt, Pd; R = t-Bu), [Pd(HpztBu,4CN)2Br2], [Pd(HpzPh2)2Cl2]}, dinuclear {(NEt4)2{Ni(pztBu,4CN)2(μ-pztBu,4CN)}2, {Pd(HpzPh2)(μ-pzPh2)Br}2}, and trinuclear {Ni3(pzPh)6, Pd3(pzPh,4CN)6} complexes, as well as a novel octanuclear complex {(NEt4)2[Ni8(pzPh,4CN)8Cl4(OH)6]}. Computational analysis is utilized to address the observation of only one isomer of tetrakis(pyrazole)dihalometal complexes. X-ray crystal structures are reported for two new pyrazoles and 18 metal complexes.

Synthesis, characterization of polymeric ligand-metal complexes and their biological activity properties

New members are joining to the Schiff bases family every day. In our study, firstly a new Schiff base was abbreviated as ligand (L) that was synthesized via condensation reaction between 3-aminonaphtalen-2-ol and 2,3-dihydroxybenzaldaheyde. Then, poly-ligand (PL) was obtained in basic medium in the presence of ammonium persulfate (NH4)2S2O8 via poly-condensation reaction by using L. Metal complexes were synthesized from the interaction of PL with various metal species such as Zn2+, Hg2+, Ni2+, Pb2+and Cu2+. The structures of compounds were confirmed by FT-IR, UV–Vis, 1HNMR and elemental analysis. Their SEM images were recorded at different sizes. Looking at the SEM images, it can be seen that the [Hg(PL)2] metal complex is similar to the red blood cells. Thermal analyses of PL and its metal complexes [M(PL)2] were performed. The biological properties such as DNA binding-cleavage, antioxidant and antibacterial activities of all synthesized compounds were investigated. According to the results, it was determined that such properties of its metal complexes were better than PL. For example, when the oxidative cleavage activity was examined, it was determined that [Cu(PL)2] complex completely cleaved the DNA and also it denatured all DNA at higher concentrations (≥100 ppm). DNA binding for the poly-ligand and its metal complexes bounded to CT-DNA in electrostatic mode. The antioxidant activity results showed that [Hg(PL)2] complex had a high inhibition value of 78.70±0.55% at 100 ppm. The [Hg(PL)2] complex was much more effective against all bacterial strains. The antibacterial activity of [Cu(PL)2] and [Zn(PL)2] complexes showed the highest activity against B. subtilis strain at the concentration of 62.5 µg/mL. DNA binding was determined from the UV–Vis spectra of the interaction of the PL and its metal complexes with CT-DNA. According to these UV–Vis results, it can be said that the poly-ligand and its metal complexes bounds to CT-DNA in electrostatic mode.

Synthesis, spectroscopic, and lead(II) binding behavior of three novel dibenzo-18-crown-6 hydrazones

Three novel hydrazonic derivatives of dibenzo-18-crown-6 were synthesized and their vibrational and electronic absorption spectroscopic properties thoroughly investigated. Their lead binding behaviors were also characterized and the observations rationalized by density functional theoretical modeling. All three cis-dihydrazonic compounds are of low overall molecular symmetry with their ether cavity adopting an open configuration at the global energy minima where the hydrazonic side-arms are electronically and vibrationally nonequivalent. Their optical absorption features are dominated by π → π * transitions where one side of the molecule exhibits Lewis acid behavior whereas the other behaves like a Lewis base. In addition to their sensitivity to pH, all three derivatives form stable 2:1 metal-ligand complexes with lead, due to coordination at the ether cavity, in addition to the hydrazone “backbone” and possibly the heterocyclic ring. The most stable lead complex is formed with the thiophene carboxylic acid hydrazide derivative due to favorable soft-soft interactions between lead and the ring-based sulfur atom.

Synthesis, structure of luminescence complexes and metalopolymers of Dy(III) and influence of the nature of substitutes on their emission

The new complexes of Dy (III) other β-diketones containing unsaturated, alkyl- and aryl- substituents were obtainted. Their heteroligand complexes with phenanthroline were synthesized. Quantum-chemical calculations of ligand molecules and metal complexes were performed. The main energy characteristics of ligand molecules were calculated: enthalpy of formation, total energy of the molecule and bond lengths, electronic population parameters of ligands. Metal polymers based on synthesized complexes were obtained by the method of radical polymerization. The composition and structure of synthesized complexes and metal polymers are established. It is shown that during polymerization the coordination environment of the central ion remains unchanged. The spectral-luminescent characteristics of the synthesized compounds were studied. The peculiarities of the influence of substituents in the diketonate fragment on the luminescent properties of metal complexes have been established. It is shown that the emission intensity of powdered samples depends on their morphology and dispersion.

Preparation and Properties of Three Plasticiser-Free Novel Di-benzo-18-Crown-6 Aldimine-Derived Lead(II) Ion-Selective Electrodes

Three novel dibenzo-18-crown-6 aldimines were successfully synthesised and structurally characterised via various spectroscopic methods (1H,13H NMR, FT-IR) and their solution phase lead binding behaviours probed via absorption spectroscopy, the results are supported by Density Functional Theoretical (DFT) modelling. These methods revealed that the asymmetric nature of these compounds is such that at equilibrium the ether cavity adopts an open configuration where the constituent oxygen atoms exhibit a highly negative electrostatic potential; hence, they spontaneously (ΔG~−58 kJ mol−1) interact/bind aqueous lead ions to form stable 2:1 metal–ligand complexes. As indicated by cyclic and square voltammetry studies, all compounds are redox active and polymerise relatively easily onto a platinum surface to form a multi-layered lead Ion-selective Membrane (ISM), the structure of which is confirmed by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). These novel Ion-selective Electrodes (ISEs), as characterised by Differential Pulse Anodic Stripping Voltammetry (D PASV), allow selective electrochemical detection and quantification of lead at concentrations as low as 10 ppm, over a range of 15–60 ppm, with only minimal interference from mercury(II) and aluminium(III) ions at a 1:1 analyte-interferent ratio.

Schiff base functionalized 1,2,3-triazole derivative for Fe(III) ion recognition, as N,O,O-Fe-O,O,N sandwich complex: DFT analysis

The present research aims to synthesize Schiff base tethered 1,2,3-triazole derivative using Cu(I) catalyzed click reaction as a highly sensitive and selective optical chemosensor for the recognition of ferric ions. The synthesized probe was characterized using Fourier transform infrared spectroscopy (FTIR), NMR (1H and 13C), mass spectrometry, CHN analysis, and Thermal gravimetric analysis (TGA). The UV–vis spectroscopy was employed in eco-friendly EtOH:H2O (9:1 v/v) solvent media to investigate the optical properties of the developed chemosensor SBT, the association constant and limit of detection of Fe3+ was determined to be 2.6 × 104 M- 1 and 1.3 × 10-7 M establishing the designed SBT as a potent probe for analytical and practical applications. Additionally, the time-dependent study and pH sensitivity of the developed probe SBT and metal–ligand complex were also studied via UV–visible spectroscopy. Besides, FTIR spectra and TGA curve of the synthesized (SBT-metal complex) confirmed the binding of the metal–ligand complex. Furthermore, the real sample application for detection of Fe3+ in spinach (food rich in Iron) was analysed, and the SBT-based sensing system yielded a recovery rate of greater than 99.07%. The synthesized probe was also explored for its computational-based DFT studies via Gaussian 09 programs using the DFT method with (B3LYP)/-311G (d,p) basis set of hybrid density functional theory.

Characterization, DFT calculations and antimicrobial assays of some novel nanoparticles mixed ligand complexes of 5-cyano-6-phenyl-2-thiouracil in presence of 1,10-phenanthroline

Some trivalent (Cr(III), Fe(III)) and divalent (Co(II), Ni(II), Cu(II) Zn(II)) combined with synthesized 5-cyano-6-phenyl-2-thiouracil (H2CPT) in presence 1,10-phenanthroline monohydrate (Phen) to produce crystalline and semi-crystalline nanoparticles mixed ligand metal complexes. The separated nanoparticles complexes were investigated by physicochemical, spectroscopic techniques (FT-IR, UV–Vis. and 1H NMR), X-ray powder diffraction (XRD) and thermal analyses (TG-DTG-DTA). The metal complexes were ionic with 1:2 electrolytes for divalent elements and 1:3 electrolytes for trivalent elements. The FT-IR spectra indicated that H2CPT and Phen functioning as bidentate ligand binding to the metal ions via oxygen and nitrogen of cyano group of H2CPT and through two nitrogen of Phen. According to the magnetic moment and UV–vis. spectra the complexes were identified as octahedral geometries. The XRD analysis of the prepared compounds revealed that H2CPT and the complexes of Cr(III), Fe(III), Co(II) and Ni(II) display semi-crystalline peaks while, Cu(II) and Zn(II) complexes were crystalline in nature. The mechanism of the thermal degradation was identified and the kinetic parameters of the disintegration stages were assessed using Coats-Redfern (CR) and Horowitz-Metzger (HM) methods. DFT computations were used to calculate equilibrium geometric parameters and the lowest energy model structures. H2CPT, Phen and their metal complexes were examined for effectiveness towards two G(+), two G(-) bacteria and two fungi. Co(II) complex was significant, highly significant and very highly significant against all tested bacterial and fungi strains compared with H2CPT, Phen, references standard control and all other complexes.

Critical roles of metal–ligand complexes in the controlled synthesis of various metal nanoclusters

Metal nanoclusters (NCs), an important class of nanoparticles (NPs), are extremely small in size and possess quasi-molecular properties. Due to accurate stoichiometry of constituent atoms and ligands, NCs have strong structure-property relationship. The synthesis of NCs is seemingly similar to that of NPs as both are formed by colloidal phase transitions. However, they are considerably different because of metal-ligand complexes in NC synthesis. Reactive ligands can convert metal salts to complexes, actual precursors to metal NCs. During the complex formation, various metal species occur, having different reactivity and fraction depending on synthetic conditions. It can alter their degree of participation in NC synthesis and the homogeneity of final products. Herein, we investigate the effects of complex formation on the entire NC synthesis. By controlling the fraction of various Au species showing different reactivity, we find that the extent of complex formation alters reduction kinetics and the uniformity of Au NCs. We demonstrate that this concept can be universally applied to synthesize Ag, Pt, Pd, and Rh NCs.

Corrosion prevention and control using in situ phase layers formation via application of the complexing‐type inhibitors

AbstractA set of organic ligands of different natures has been investigated as complexing‐type corrosion inhibitors for the protection of low carbon steel in an acidic medium. The inhibitive mechanism implying the formation of phase protective layers on the metal surface as a result of the complexation process of added organic ligands with the metal cations is being discussed. The results of the investigation of the influence of pH and temperature conditions on the phase layers formation dynamics have been presented. A range of practical aspects of the application of organic ligands as complexing‐type inhibitors for the formation of ultrathin coatings have been discussed. The stability constant of the metal–ligand complex and its solubility have been proposed as the basis of a predictive model for analytical assessment of their potential protective efficiency.

Quantifiable Regulation of Chemical Kinetics Barriers for Creation of Single-Atom Metal Sites on Photocatalytic Atomic Layers

Cation exchange (CE) under mild conditions promises a facile strategy to anchor single metal sites on colloidal chalcogenides toward catalytic applications, which however has seldom been demonstrated. The dilemma behind this is the rapid kinetics and high efficiency of the reaction disfavoring atomic dispersion of the metal species. Here we report that a fine-tuning of the affinity between the incoming metal cations and the deliberately introduced ligands can be exploited to manipulate the kinetics of the CE reaction, in a quantitative and systematic manner defined by the Tolman electronic parameter of the ligands used. Moreover, the steric effect of metal-ligand complexes offers thermodynamic preference for spatial isolation of the metal atoms. These thereby allow the rational construction of single atom catalysts (SACs) via simple one-step CE reactions, as exemplified by the CE-derived incorporation of single metal atoms (M = Cu, Ag, Au, Pd) on SnS2 two-unit-cell layers through M-S coordination.

Photoluminescent iridium(III) complexes with phenylvinylpyridine-base cyclometalating ligands: Synthesis, photophysical properties, and photocyclization

Photoresponsive materials have recently garnered significant research interest and have been designed using various molecules. A viable approach to develop photoresponsive materials is by integrating photoisomeric structures into the organic ligands of phosphorescent transition metal complexes. In this study, we designed two photoresponsive cyclometalating ligands, 2-phenyl-3-vinylpyridine (HL1) and trans-4-methyl-2-phenyl-3-styrylpyridine (HL2), via the replacement of a phenyl group with a pyridyl group in vinylbiphenyl. Upon photoirradiation under an argon atmosphere, both ligands underwent photocyclization and demonstrated hypochromism and bathochromic shifts in absorption. Notably, HL2 underwent additional oxidative dehydrogenation upon photoirradiation in the presence of oxygen, resulting in an elongated conjugation structure that exhibited significant fluorescence intensity increase at 363 nm. Additionally, three photoresponsive iridium(III) complexes cyclometalated with HL1 or HL2 were synthesized and characterized. The photocyclization process of the complexes was much faster than that of the free ligands because the phenylpyridine moiety became coplanar upon cyclometalation. Upon photoirradiation under an argon atmosphere, these complexes exhibited significant luminescence enhancement by about 10–20 folds because of photocyclization resulting in a rigid closed structure that limited nonradiative decay of the excited complexes. These molecules present a unique strategy to construct photocyclization complexes and provide important insights into the development of photoresponsive materials.

Aptamer-Modified Homogeneous Catalysts, Heterogenous Nanoparticle Catalysts, and Photocatalysts: Functional "Nucleoapzymes", "Aptananozymes", and "Photoaptazymes".

Conjugation of aptamers to homogeneous catalysts ("nucleoapzymes"), heterogeneous nanoparticle catalysts ("aptananozymes"), and photocatalysts ("photoaptazymes") yields superior catalytic/photocatalytic hybrid nanostructures emulating functions of native enzymes and photosystems. The concentration of the substrate in proximity to the catalytic sites ("molarity effect") or spatial concentration of electron-acceptor units in spatial proximity to the photosensitizers, by aptamer-ligand complexes, leads to enhanced catalytic/photocatalytic efficacies of the hybrid nanostructures. This is exemplified by sets of "nucleoapzymes" composed of aptamers conjugated to the hemin/G-quadruplex DNAzymes or metal-ligand complexes as catalysts, catalyzing the oxidation of dopamine to aminochrome, oxygen-insertion into the Ar─H moiety of tyrosinamide and the subsequent oxidation of the catechol product into aminochrome, or the hydrolysis of esters or ATP. Also, aptananozymes consisting of aptamers conjugated to Cu2+ - or Ce4+ -ion-modified C-dots or polyadenine-stabilized Au nanoparticles acting as catalysts oxidizingdopamine or operating bioreactor biocatalytic cascades, are demonstrated. In addition, aptamers conjugated to the Ru(II)-tris-bipyridine photosensitizer or the Zn(II) protoporphyrin IX photosensitizer provide supramolecular photoaptazyme assemblies emulating native photosynthetic reaction centers. Effective photoinduced electron transfer followed by the catalyzed synthesis of NADPH or the evolution of H2 is demonstrated by the photosystems. Structure-function relationships dictate the catalytic and photocatalytic efficacies of the systems.

Synthesis, Assembly, and Applications of Magic-Sized Semiconductor (CdSe)13 Cluster.

ConspectusAtomically precise metal chalcogenide clusters (MCCs) are model molecular compounds of scientifically and technologically important semiconductor nanocrystals, which are known as quantum dots (QDs). The significantly high ambient stability of MCCs of particular sizes, as compared to that of slightly smaller or larger sizes, made them be termed "magic-sized clusters" (MSCs). In other words, MSCs with specific sizes between sizes of precursors (typically, metal-ligand complexes) and nanocrystals (typically, QDs) appear sequentially during the colloidal synthesis of nanocrystals, while the other cluster species decompose to precursor monomers or are consumed during the growth of the nanocrystals. Unlike nanocrystals with an ambiguous atomic-level structure and a substantial size distribution, MSCs possess atomically monodisperse size, composition, and distinct atomic arrangement. Chemical synthesis and exploration of properties of MSCs are of great significance since they help systematically understand the evolution of fundamental properties as well as build structure-activity relationships at distinct molecular levels. Furthermore, MSCs are anticipated to offer atomic-level insights into the growth mechanism of the semiconductor nanocrystals, which is highly desirable in the design of advanced materials with new functions. In this Account, we cover our recent efforts in the advancement of one of the most important stoichiometric CdSe MSCs, (CdSe)13. In particular, we present its molecular structure derived from a single crystal X-ray crystallographic study of the closest MSC, Cd14Se13. The crystal structure of MSC enables not only the understanding of the electronic structure and prediction of the potential sites for heteroatom dopants (e.g., Mn2+ and Co2+) but also the identification of favorable synthetic conditions for the selective synthesis of desired MSCs. Next, we focus on enhancing the photoluminescence quantum yield and stability of Mn2+ doped (CdSe)13 MSCs through their self-assembly, which is facilitated by the rigid diamines. In addition, we show how atomic-level synergistic effects and functional groups of the assemblies of alloy MSCs can be utilized for a highly enhanced catalytic CO2 fixation with epoxides. Benefiting from the intermediate stability, the MSCs are explored as single-source precursors to low-dimensional nanostructures, such as nanoribbons and nanoplatelets, through the controlled transformation. Distinct differences in the outcome of the solid-state and colloidal-state conversion of MSCs suggest the need for careful consideration of the phase and reactivity of MSCs as well as the type of dopant to achieve novel structured multicomponent semiconductors. Finally, we summarize the Account and provide future perspectives on the fundamental and applied scientific research of MSCs.

Synthesis, structure, DNA/BSA binding, antibacterial and molecular docking studies of tetradentate ONNO schiff base metal complexes

A new Schiff base ligand 3-bis((E)-2 hydroxy-3-methoxybenzylidene)amino) malononitrile was synthesized by combining O-vanillin and 2, 3-diaminomaleonitrile. This ligand was subsequently complexed with Copper (II), Nickel (II) and Vanadyl (IV) metal ions. Using FT-IR, NMR and MS spectroscopic techniques, the synthesized malononitrile ligand and the Copper (II), Nickel (II) and Vanadyl (IV) metal complexes were investigated. The reliability of the geometrical parameters of the synthesized Copper (II), Nickel (II) and Vanadyl (IV) metal complexes was confirmed by electronic spectra, EPR analysis, and magnetic moment measurements. The calorimetric technic was employed to study the DNA binding to BSA. Concerning the Gram-positive and Gram-negative bacterial species Bacillus substilis, Staphylococcus aureus, Escherichia coli, Pseudomonas fluorescens, and Bacillus cereus, all of the metal complexes under investigation demonstrated antibacterial activity when compared to tetracycline. When Schiff base and its metal complexes were screened for in vitro antioxidant activity, the Ni(II) complex had better antioxidant activity than the ligand and other metal complexes, which was further substantiated by molecular docking.

Computational Drug Designing, Synthesis, Characterization and Anti-bacterial Activity Evaluation of Some Mixed Ligand–Metal Complexes of 2-hydroxybenzaldehydethiosemicarbazone as Primary Ligand

Computational Drug Designing, Synthesis, Characterization and Anti-bacterial Activity Evaluation of Some Mixed Ligand–Metal Complexes of 2-hydroxybenzaldehydethiosemicarbazone as Primary Ligand

‘Turn-ON’ furfurylamine-based fluorescent sensor for Cd2+ ion detection and its application in real water samples

The ability of the new furfurylamine-derived Schiff base ligand (E)-4-chloro-2-((((5-methylfuran-2-yl)methyl)imino)methyl)phenol (CFMP) to recognize metal ions as a chemosensor has been studied. According to thorough research on the several facets of metal sensing phenomena, the Schiff base ligand CFMP demonstrated selective colorimetric and fluorescence sensing behavior towards the Cd2+ ion in a methanol–water system with strong binding nature, which was easily visible to the human eye. Job's plot titrations were used to determine the metal–ligand complex's stoichiometry, and LCMS data served as further confirmation. The CFMP has a low detection limit (LOD) of 0.2345 µM and shown outstanding fluorescence sensing activity in buffer fluid with a pH of 7.2. Investigations into the fluorescence characteristics of the CFMP and the metal complex in the solution state revealed an improvement in fluorescence emission intensity following complexation. Additionally, utilizing electronic absorption spectroscopic techniques on samples of lake and tap water, the use of Cd2+ ion detection in real water samples was investigated.