Schiff Base Ligand Research Articles

In vitro and in vivo studies of a decanuclear Ni(II) complex as a potential anti-breast cancer agent

A non-platinum-metal decanuclear complex [Ni10L4(CH3COO)8 (C2H5OH)8]·8(C2H5OH) (Ni10 complex) has been developed with a tri-dentate 2,3-dihydroxybenzaldehyde-2-aminophenol Schiff base ligand (H3L). Single crystal X-ray analysis reveals that the Ni10 complex displays a sandwich loaf-shaped decanuclear structure and its anticancer activity was evaluated. The cell cytotoxicity results indicating that the Ni10 complex is most effective to human breast cancer cells MDA-MB-231 and its mechanism were further investigated. Flow cytometry analysis showed that the Ni10 complex triggered cell cycle arrest and induced apoptosis of MDA-MB-231 cells. Western blot analysis of the changes of intracellular protein expression showed that Ni10 triggers MDA-MB-231 apoptosis through mitochondrial mediated apoptosis signaling pathways. In vivo experiments showed that the Ni10 complex significantly suppressed breast tumor growth with low toxicity against major organs in a nude mice model. The good treatment effect, low toxicity and pharmacological mechanisms of the decanuclear NiII complex may provide a clue for the research and development of non-platinum multinuclear based chemotherapeutic drugs.

Synthesis, Spectral Characterization, Antimicrobial Activity, DFT Calculations, Molecular Docking and ADME Studies of Novel Schiff Base Co(II), Ni(II), Cu(II) and Zn(II) Complexes Derived from 4-nitro-ortho-phenylenediamine.

A condensation reaction was carried out between 4-nitro-ortho-phenylenediamine and 5-bromosalicyaldehyde to synthesize a novel Schiff base ligand 2,2'-[(1E,1'E)-(4-nitro-1,2-phenylene) bis (azaneylylidene) bis (methaneylylidene)] bis (4-bromophenol) [NB] in the current investigation. This was followed by the synthesis of metallic complexes comprising the Co(II), Ni(II), Cu(II) and Zn(II) transition metal ions. A hexadentate environment encircling metal complexes was corroborated by the results of varied spectroscopic methods that were employed to unravel the structure of the ligand and metal complexes. The Tauc's plot and Urbach energy were utilized for quantifying the optical energy band gap to provide insight into optical characteristics. The Coats-Redfern method of thermal analysis was implemented to do the kinetic and thermodynamic calculations. Furthermore, DFT studies were performed to predict geometrical structures and the stability of the compounds. Thorough investigation to evaluate their biological efficacies, docking studies was executed against COVID-19 main protease (PDB-7VAH), Dengue virus NS2B/NS3 protease (PDB-2FOM) and Mycobacterium Tuberculosis (PDB-5AF3). Apart from this, in silico ADMET studies were also accomplished for elucidation of drug likeness characteristics and the results attained disclose the significant proficiency of synthesized compounds. Besides this, antimicrobial studies were assessed with different microbial strains and result validates cobalt and zinc complexes as most potent against the selected bacterial and fungal strains.

Preparation and Antifungal Properties of Cyclopropyl Derivatives of 3-Aminoquinazolin-4(3H)-one and Salicylal Schiff Base Nickel(II) Chelate Complex

N-substituted 2-cyclopropyl-3-R-quinazoline-4()-ones [R: NH2 (1), N=CH(2-hydroxyphenyl) (2)] and Ni(II) chelate compound of 2-cyclopropyl-3-[(Z)-(2-hydroxybenzylidene)amino]quinazoline-4(3H)-one (3) were synthesized and their structures and properties were characterized using X-ray diffraction data, computational optimization, 1H and 13C NMR, IR spectroscopy, and diffuse reflectance spectra. Compounds 1 and 2 are monoclinic (space group P21/n). Unit cell parameters (a, b, c) are 9.2529; 4.7246; 22.3460 Å and 10.2811; 4.6959; 30.972 Å for 1 and 2, respectively. Nickel(II) chelate compound crystallizes in an orthorhombic crystal system (space group Pbca). Unit cell parameters (a, b, c) for 3 are 26.5010; 14.8791; 8.904975 Å, respectively. Schiff base 2 in the crystalline state exhibits two rotary isomers in a molar ratio of 1:3, among which only a minor component as a bidentate ligand can form compound 3 with Ni(II) ion. Nickel(II) ion in 3 is coordinated by N donor atoms and deprotonated O atoms of Schiff base ligands to form square-planar chelate node NiN2O2. All synthesized compounds revealed high antifungal activity against bread mold (Mucor mucedo).

Synthesis, Crystal Structures, Antimicrobial Activity, and Acute Toxicity Evaluation of Chiral Zn(II) Schiff Base Complexes

Four mononuclear bioefficient zinc coordination complexes [Zn(NN)3](ClO4)2 (A–D) involving chiral bidentate Schiff base ligands have been synthesized and characterized by IR, 1H, and 13C NMR spectroscopy and mass spectrometry. X-ray crystal structures of three of the zinc complexes revealed that the zinc metal ion is hexacoordinated, exhibiting a distorted octahedral geometry where both the nitrogen atoms (NN = pyridyl and imine) of imines are coordinated to the central zinc ion. The isolated zinc complexes were evaluated for their antimicrobial activity in vitro against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus, displaying varying levels of growth inhibition. An acute toxicity test conducted using Artemia salina and Swiss albino mice showed that the zinc complexes A–D were non-toxic towards A. salina at concentrations below 414, 564, 350, and 385 µM, respectively, and did not affect liver biochemical parameters, although pyknosis was induced in hepatocytes of the treated mice.

Eco-friendly Synthesis, Characterization, and Antimicrobial Evaluation of Transition Metal (II) Complexes with Thiophene-Derived Tridentate (S N N Donor) Heterocyclic Schiff Base Ligand

Eco-friendly Synthesis, Characterization, and Antimicrobial Evaluation of Transition Metal (II) Complexes with Thiophene-Derived Tridentate (S N N Donor) Heterocyclic Schiff Base Ligand

Qualitative and Quantitative Luminescence Detection of 2,6-Dipicolinic Acid and Levofloxacin Based on a High-Nuclearity Eu(III) Nanomolecular Sensor.

Rapid and accurate testing of 2,6-dipicolinic acid (DPA) and levofloxacin (LFX) has been attracting much attention due to the fact that the former is an important biomarker of anthrax spores and the latter is a third-generation fluoroquinolone drug and has been recognized as an important environmental pollutant. Herein, we report the preparation of a 13-metal Eu(III) nanomolecular sensor (molecular sizes: 2.0 × 2.4 × 3.2 nm) bearing a new flexible Schiff base ligand for luminescence testing of DPA and LFX with high selectivity and sensitivity. The rapid enhancement of the Eu(III) luminescence of 1 caused by DPA and LFX is expressed by fitting equation I615nm = k × [C] + a, which can be used to quantitatively detect DPA and LFX concentrations in CH3CN, fetal calf serum (FCS), and a real drug. The response times of 1 to DPA and LFX are less than ten seconds, with detection limits as low as 3.78 × 10-2 to 2.71 nM. The test strips containing 1, as well as 1@SA films, can be used to qualitatively detect DPA and LFX by the color changes under the irradiation of UV light.

Comparative Analysis of Tetravalent Actinide Schiff Base Complexes: Influence of Donor and Ligand Backbone on Molecular Geometry and Metal Binding.

A series of isostructural early actinide AnIV complexes was synthesized in order to investigate the influence of a conjugated framework in the ligand backbone on An bonding. Therefore, the AnIV complexes [An(pyrophen)2] (An = Th, U, Np, and Pu) with the pure N-donor ligand bis(2-pyrrolecarbonylaldehyde)-o-phenylenediamine referred to as pyrophen, were synthesized and characterized. Solid state analysis via single-crystal X-ray diffraction (SC-XRD) reveals two sets of ligands binding in an almost orthogonal arrangement to the actinide center. For the larger actinides Th and U, the coordination sphere allows for additional coordination by a solvent molecule. Nuclear magnetic resonance spectroscopy (NMR) studies show the presence of highly symmetrical complexes in solution in good agreement with the solvent-free solid structures. While SC-XRD suggests mainly ionic binding, an analysis of paramagnetic NMR contributions and quantum chemical bond analysis hint towards significant covalency in the U, Np, and Pu compounds. This series of An complexes allowed for a thorough structural and theoretical comparison of a conjugated system to a closely related N-donor ligand (pyren)[1] as well as to the mixed N,O Schiff base ligands salophen (conjugated) and salen (non-conjugated).

Homobimetallic Ruthenium(II) Complexes Catalysed Selective Transfer Hydrogenation of Aldehydes in Water.

Herein we report chemoselective transfer hydrogenation (TH) of aldehydes in aqueous medium using a series of homobimetallic Ru(II) catalysts. Two homobimetallic complexes (Ru1 and Ru3) and one monometallic complex (Ru2) have been employed in the catalytic reduction of aldehydes. Bimetallic complex [(p-cymene)2(RuCl)2L3] (Ru3) is obtained from the reaction of Schiff base ligand 2,2'-((1E,1'E)-((3,3',5,5'-tetraisopropyl-[1,1'-biphenyl]-4,4'diyl)bis(azaneylylidene))bis(methaneylylidene))bis(4-bromophenol) (H2L3) and characterized by various spectroscopic and analytical techniques. The use of formic acid/formate buffer as the hydride source and a catalyst loading of 0.01 mol% of Ru1 or Ru3 resulted in the conversion of various aldehydes to the corresponding alcohols in good to excellent yield. This method is very efficient for selective reduction of aldehydes in the presence of other reducible functional groups. A loading of 0.0001 mol% of Ru1 catalyst is sufficient to achieve a turnover frequency (TOF) of 5.5× 105 h-1. Furthermore, the catalyst can been recycled and reused for six consecutives cycles without sacrificing the efficiency. A comparison of results obtained between bimetallic and monometallic complexes offers valuable insights into the distinct reactivity patterns of the bimetallic complexes, presumably originating from a cooperative effect. We have explored the mechanistic pathway using DFT methods.

Well Defined Phosphine Free Ni-Catalyzed Dehydrogenation of Secondary Alcohols for the Synthesis of Ketones and Ketazines.

In this work, we unveil a novel synthesis of bench stable Ni (II) complexes supported by tetradentate Schiff-base ligands and the complexes were devoid of any phosphine or phosphine-based ligand. These Ni-complexes were successfully applied for the dehydrogenation of secondary alcohols for ketone and ketazine syntheses. Secondary alcohols with different functional groups were well tolerated during catalytic cycle. Moreover, we successfully extended this protocol for the synthesis of biologically significant ketones and ketazines. On the basis of various control experiments, probable reaction pathway was proposed and an acceptorless alcohol dehydrogenation mechanism was suggested.

Crystal structures and circular dichroism of {2,2′-[(1S,2S)-1,2-diphenylethane-1,2-diylbis(nitrilophenylmethanylylidene)]diphenolato}nickel(II) and its ethanol solvate

The title compound, [Ni(C40H30N2O2)] (1), with an optically active Schiff base ligand derived from 2-hydroxybenzophenone and (1S,2S)-1,2-diphenylethylenediamine, was crystallized as the solvent-free and ethanol solvate forms (1 and 1·2C2H5OH). In both structures, the two phenyl groups on the stereogenic centers of the O,N,N,O-tetradentate ligand are axially oriented, and the conformation of the central diamine chelate ring is λ. The circular dichroism (CD) spectra of 1 and the analogous nickel(II) complex [Ni(C30H26N2O2)] (2) in solution show partially similar patterns in the 350–450 nm range, but are mirror images in the longer wavelength region (450–650 nm). In the latter region, the sign of CD for these complexes is sensitive to the substituents on the C=N carbon atoms (phenyl for 1 and methyl for 2) rather than the diamine chelate ring conformation.

Synthesis, characterization and magnetic properties of a hexanuclear copper (II) complex with hydroxido, alkoxido and phenoxido bridges

A new CuII6 complex, formulated as [Cu6(L)3(µ3-OH)(H2O)(OH)(NO3)]·2H2O·7CH3OH (1) has been prepared using the symmetrical N2O3-donor Schiff-base ligand H3L = N,N′-(2-hydroxypropane-1,3-diyl)bis(2-hydroxyacetophenimine). Compound 1 has been structurally and spectroscopically characterized. Single crystal X-ray diffraction analysis reveals that 1 crystallizes in the triclinic space group P-1 and consists of a CuII6 complex where each deprotonated ligand chelates two CuII centres. Three of the six independent CuII centres are arranged in an almost equilateral triangle with double Cu-O-Cu bridges, formed by a μ3-hydroxido and phenoxido bridges. Each of the three CuII centres in the triangle is further connected to one CuII centre through a single alkoxido bridge. The magnetic properties indicate the presence of moderate and weak antiferromagnetic interactions through the double and single oxido bridges, respectively.

Synthesis, Spectroscopy and Biological Studies of Copper and Silver Complexes Derived from 2-Substituted Amino Propanoic Acid

Synthesis of copper and silver complexes were prepared from novel Schiff base ligand. These synthesized ligand and their metal complexes were characterized by elemental analysis, FT-IR, 1H NMR, UV-Vis and Mass spectrometry. The coordination of amino nitrogen, phenolic oxygen, and carboxylato oxygen atoms is shown by the infrared spectra.The Schiff bases and its complexes were screened for their in vitro antibacterial and antifungal studies against the bacteria Pseudomonas Aeruginosa (PA, Gram -ve), Bacillus Cirroflagellosus (BC, Gram +ve), Penicillium Notatium (PN) and Aspergillus Niger (AN) strains. The results of the antibacterial investigation show that the copper and silver complexes possess more potent bactericide and fungicide properties than the ligand.

Optical and surface properties of Schiff base ligands and Cu(II) and Co(II) complexes

Objectives. To study the transition of electrons in 1,2-phenyl(4’-carboxy)benzylidene Schiff base ligand and transition metal ions, optical properties, as well as the surface chemistry of supported transition metals using diffuse reflectance spectroscopy (DRS); to study the roughness and morphology of the Schiff base ligand and its complexes using atomic force microscopy (AFM).Methods. DRS, AFM, and Fourier-transform infrared spectroscopy instruments were used to identify electron transitions, optical properties, and surface morphology in Schiff base ligands and their complexes.Results. The DRS revealed the d–d transitions and charge transfer shifts of all compounds, and helped identify the structure of the ligand. One of the optical properties studied was the energy gap calculation of the ligand and its complexes. The copper complex exhibited more semiconducting behavior with surface morphology properties such as surface roughness parameters lower than those of the ligand and the cobalt complex. This can be attributed to the smaller size of the copper atom, as well as lower electron transitions compared to the cobalt complex and the square planar bonding shape.Conclusions. In Schiff base ligands, the reflectance spectrum bands reveal three electron transitions: n→π*, π→π*, and σ→σ* transitions. In cobalt complexes, four transitions are indicated: 4A2(F)→4T1(F), 4A2(F)→4T1(P), charge transfer bands, and tetrahedral geometry. Copper complexes exhibit three transitions: 2B1g→2A1g, 2B1g→2Eg, and charge transfer bands, with a square planar geometry for their structure. The energy gap calculations were 2.42, 2.29, and 2.30 eV, respectively. In the case of the SH ligands, copper complexes, and cobalt complexes, all compounds exhibited semiconductor properties. However, the complexes displayed increased conductivity due to the influence of the metal and coordination structure.

Synthesis, characterization and anticancer activity of zinc sulfide nanoparticle using heterocyclic Zn (II) thiosemicarbazone complex as a single source

The green synthesis of zinc sulphide nanoparticles (Zn S NPs) using Zn(II) complex as a single molecular precursor is gaining importance due to its simplicity, cost – effectiveness and pharmacologically active nature. Now – a- day’s nanobiotechnolgy is increasing at a fast rate due to its many possible applications in the biomedical and, pharmaceuticals fields. In this paper, we have reported the synthesis of Chalcogenide nanostructured pharmacologically active Zn S nanoparticles using Zn (II) Heterocyclic thiosemicarbazone Complex as a Single Source. Zn (II) complex was synthesized by the reaction between Schiff base ligand and Zinc acetate salt in 2:1 molar ratio. Thiosemicarbazone have a wide clinical antitumor spectrum with efficacy in various tumor types such as leukemia, pancreatic cancer, breast cancer, non- small cell lung cancer, cervical cancer, prostate cancer and bladder cancer. These compounds possessed significant antineoplastic activity when the carbonyl group attachment of the side chain was located at a position alpha to the heterocyclic nitrogen atom, whereas attachment of the side chain ꞵ or gamma to the heterocyclic nitrogen atom, resulted in inactive antitumor agents. In addition, replacement of the heterocyclic ring N with carbon also resulted in a biologically inactive compound suggesting that a conjugated N, N, S -tridentate donor set is essential for the biological activities of thiosemicarbazone ligands. In our study, for synthesis of Zn S nanoparticles, the synthesized Zn(II) complex of thiosemicarbazone ligand was treated with aqueous extract of Parmotrema perlatum flowers. The use of aqueous extract of Parmotrema perlatum flowers in the synthesis of ZnS particles plays a very important role in reducing reaction time, reducing minimum possibility of side reactions and conversion of metal complexes into its nanoparticles in a very less time. All synthesized compounds were characterized by various structural, morphological, electronic and vibrational spectroscopic techniques and also evaluate the pharmacological activities of compounds like antioxidant, anti-inflammatory and anticancer activities. The peaks at 3414.82 cm-1 in FT-IR spectra confirms the presence of –OH groups and other bioactive agents in the aqueous extract of Parmotrema perlatum flowers, which acts as a capping and stabilizing agents in the synthesis of Zn S nano particles. The effective results of anti-cancer activity of compounds showed that the ZnS nanoparticles shows good cytotoxic activity against human breast cancer cell lines (MCF-7) using MTT assay. In this study, normal human cell lines used as standard for comparison purpose. The CTC50 values of ZnS nanoparticles was found to be 49.375µg/ml respectively. Therefore, it could be concluded that this biogenic method is effective for synthesis of Zn S nanoparticles from Zn(II) complex with desirable properties for potential biomedical applications which can be consider as a good drug candidate for anti-cancer therapy

Effect of Substituents in Equatorial Hexaazamacrocyclic Schiff Base Ligands on the Construction and Magnetism of Pseudo D6h Single-Ion Magnets.

Three mononuclear DyIII compounds [DyL1(Ph3SiO)2][BPh4]·MeCN·2H2O (1), [DyL2(Ph3SiO)2][BPh4]·C2H5OH·H2O (2), and [DyL3(Ph3SiO)(OAc)][BPh4]·CH3OH·3H2O (3) and their corresponding YIII diluted analogues [Dy0.0967Y0.9033L1(Ph3SiO)2][BPh4]·MeCN·2H2O (1@Y), [Dy0.2668Y0.7332L2(Ph3SiO)2][BPh4]·C2H5OH·H2O (2@Y), and [Dy0.1260Y0.8740L3(Ph3SiO)(OAc)][BPh4]·CH3OH·3H2O (3@Y) were synthesized with hexaazamacrocyclic Schiff base ligands as an equatorial ligand. The substituents in the equatorial hexaazamacrocyclic Schiff base ligand show a significant effect on the replacement of the axial ligands. Compounds 1, 2, and 3 are typical zero dc field single-molecule magnets with effective energy barriers (Ueff) of 1092(6), 946.1(7), and 150.1(9) K, respectively. Although the effective energy barriers of 1 and 2 are close, the magnetic hysteresis remains open up to 20 K for 1, twice as large as that of 2 (10 K), which is different from the previously reported compounds, probably due to nonplanarity N6 in the equator. Ab initio calculations indicate that the ground states of compounds 1 and 2 exhibit high anisotropy and pure second and third excited states, while compound 3 exhibits pure ground-state anisotropy and highly mixed excited states, leading to the easy occurrence of quantum tunneling of magnetization between the ground and excited states in compound 3. This work indicates that the substituents in equatorial hexaazamacrocyclic Schiff base ligands have a significant effect on the construction and magnetic properties of DyIII SIMs with D6h symmetry.

Cold and Liquid Crystal Properties of Square-Planar Copper(II) Versus Nickel(II)- Iminophenolate/Naphthalen-2-Olate Schiff Base Complexes.

Reaction of the phenolate or naphthalen-2-olate based Schiff base ligands, (E)-1-((2-ethylphenylimino)methyl)phenol (HL1) or (E)-1-((2-ethylphenylimino)methyl)naphthalen-2-ol (HL2) with nickel(II) and copper(II) acetate provides the complexes bis[(E)-1-((2-ethylphenylimino)methyl)phenolato-ĸ2N,O]Ni/Cu(II), [Ni(L1)2] (1) and [Cu(L1)2] (2), or bis[(E)-1-((2-ethylphenylimino)methyl)naphthalen-2-olato-ĸ2N,O]Ni/Cu(II), [Ni(L2)2] (3) and [Cu(L2)2] (4), respectively. Single crystal X-ray structure determinations for 1, 3 and 4 reveal N2,O2-metal coordination of two chelating Schiff base ligands in a square-planar geometry. Powder X-ray diffractograms confirm the phase purity of the bulk microcrystalline samples. Thermal analyses by differential scanning calorimetry (DSC) and polarized light microscopic (PLM) indicate the copper(II) complexes to exhibit cold crystal (2) and liquid crystal (4) property. Cyclic voltammograms suggest an irreversible electrochemical process with two one electron charge transfer processes in N,N-dimethylformamide. Variable temperature magnetic measurements at the solid-state prove the diamagnetic nature of the low-spin Ni2+ centres in 1 or 3, as expected from the square-planar coordination geometry with rather strong ligands. The complexes expose medium level of antioxidant activity in methanol. Optimized geometry and excited state property by DFT/TD-DFT correspond well to the experimental results of the electronic and molecular structure at the ground state.

A Structure and Magnetism Study of {MnII3MnIVLnIII3} Coordination Complexes with Ln = Dy, Yb

We report the research results of polynuclear complexes consisting of 3d-4f mixed-metal cores that are maintained by acetate ligands and multidentate Schiff base ligands with structurally exposed thioether groups. The presence of the latter at the periphery of these neutral compounds enables their anchoring onto substrate surfaces. Specifically, we investigated the electronic and magnetic properties as well as the structural arrangement in {MnII3MnIVLnIII3} with Ln = Dy, Yb coordination complexes using various complementary methods. We studied the electronic and atomic structure of the target compounds using the XAS and XES techniques. The molecular structures of the compounds were determined using density functional theory, and the magnetic data were obtained as a function of the magnetic field. Using the XMCD method, we followed the changes in the electronic and magnetic properties of adsorbed magnetic compounds induced by the reaction of ligands through interaction with the substrate. The complexes show antiferromagnetic exchange interactions between Mn and Ln ions. The spectroscopic analyses confirmed the structural and electronic integrity of complexes in organic solution. This study provides important input for a full understanding of the dependence of the magnetic properties and the molecule–substrate interaction of single adsorbed molecules on the type of ligands. It highlights the importance of chemical synthesis for controlling and tailoring the magnetic properties of metalorganic molecules for their use as optimized building blocks of future molecular spin electronics.

Synthesis and characterization of new organometallic lanthanides metal complexes for photodynamic therapy

New Schiff base ligand: 4-methoxy salicaldhyde-2-2-phenyl-hydrazono acetaldehíyde prepared by facile method. The molecular structures characterized by elemental analysis and proton magnetic resonance spectra (1H-NMR spectra). This spectra at the chemical shifts (3.5–10.39 ppm) confirmed the types and the numbers of protons. The sharp melting point at the range 110–112 °C confirmed purity. New optically active metal (samarium, terbium and gadolinium) complexes of the Schiff base synthesized in a one pot reaction. Vibrational IR spectra confirmed functional groups. Scanning electron microscopy micrographs confirmed that the modified microstructure of the metal complexes differed in morphology than the ligand. Powder X-ray diffraction patterns confirmed good crystalline structure. The optically activity of the solid metal complexes confirmed from electronic absorption spectra. The UV absorbance band at the wavelength range 280–390 nm and the intense phosphorescence bands up to 830 nm enabled application in photo dynamic therapy for apoptosis cancer cells by conversion triplet oxygen in the tissues into reactive singlet oxygen. Low charge transfer energy: 2.59–2.61 eV, high molar extinction coefficients (ε) at the order of magnitude \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\:{10}^{6}$$\\end{document} M− 1 cm− 1 and the intense phosphorescence bands reflected good photodynamic activity. The metal complexes are thermally stable.

Advancement in schiff base complexes for treatment of colon cancer

Abstract Schiff bases have proven to be beneficial in medicine and have interesting complexation capabilities with transition metals. The +4, +5, and +6 oxidation states of schiff base metal complexes have been the subject of recent review, which have highlighted their notable cytotoxic effects against various colon cancer cell lines (HT-29, HCT-116, SW-480, Coco-2, CT-26, LT-174, LoVo). Extensive research has focused on schiff base metal complexes in the +4 and +6 oxidation states, exhibiting distinct geometries and significant thermodynamic stability. These studies provide IC50 values for these complexes in colon cancer cell lines along with comprehensive structural representations that shed light on how different substituents affect cytotoxicity. When compared to schiff base ligands alone, metal complexes of schiff bases have been shown to significantly reduce colon cancer cell invasion and proliferation. The studied literature emphasizes schiff base metal complexe’s potential in biological applications and suggests that more study may be necessary to fully comprehend their biology. To enable more sophisticated multidisciplinary study in this field, future investigations should focus on synthesizing novel complexes with enhanced bioavailability, solubility, and low toxicity.

Enhancement of Circularly Polarized Luminescence Brightness of Schiff‐Base Diphenylboron and 9‐Borafluoren‐9‐yl Complexes

AbstractA series of diphenylboron and 9‐borafluoren‐9‐yl complexes with chiral Schiff‐base ligands was synthesized and characterized by NMR spectroscopy. X‐ray diffraction analysis revealed that their boron centers were adapted to tetrahedral coordination geometry. Although boron complexes with salicylideneimine backbones exhibited a weak circularly polarized luminescence (CPL), the CPL brightness (BCPL) was enhanced more than 9‐fold by the π‐extension of the Schiff base ligands. Time‐resolved emission decay analysis and theoretical calculations based on density functional theory (DFT) were conducted to further understand their luminescent properties.