Azomethine Group Research Articles

SYNTHESIS AND STUDIES OF Cu(II),Ni(II),Co(II) COMPLEXES WITH bis(SALICILIDEN)HYDRAZON

New complexes of Cu(II), Co(II), and Ni(II) with bis(salicylidene)hydrazone have been obtained. It has been shown that bis(salicylidene)hydrazone forms bi-nuclear complexes with the ions of these metals. The structure and physicochemical properties of these complexes have been studied by IR, UV spec-troscopy, EPR and thermogravimetric analysis. IR spectra show that coordination of ligand with metal ion is carried out through oxygen atom of phenolic group and nitrogen atom of C=N group. In the elec-tronic spectra of the ligand there are absorption bands of the aromatic ring transition at ~240 and 290 nm (related to π→π* and n- π transitions). The absorption bands at 340 and 380 nm can be attributed to the absorption of the azomethine group conjugated to the benzene ring. On the basis of thermogravimetric analysis the stages of thermal decomposition of synthesized complexes and the composition of solid reaction products obtained at these stages have been determined. It has been shown that the final products of thermal decomposition consist of Co, Ni, Cu oxides. In the EPR spectrum of the copper complex a very weakly asymmetric signal with g=2.10 is observed, which may indicate a tetrahedral (pseudotetrahedral) structure of the complex

Small thiophene-based molecules with favorable properties as HTMs for perovskite solar cells or as active materials in organic solar cells

Computational investigations are carried out to design new molecules based on thiophene cores substituted in several positions using different end-capped electron-donating groups formed from triphenylamine or OMe-triphenylamine that can be used as HTMs in Perovskite Solar Cells (PSCs), or as an active layer in Organic Solar Cells. The influence of π-extension on the charge transfer process is also probed by inserting two azomethine groups between acceptor and donor (D-π-A-π-D) moieties. The designed molecules (T10,12,13,15) were compared with the two synthesized molecules (T11,14) that have been applied as HTMs in a PSC. Density functional theory (DFT) and time-dependent DFT (TD-DFT) were chosen to calculate different chemical parameters of these molecules. Different chemical parameters were calculated to make the link between geometrical parameters and the efficiency, solubility, and stability of the under-probed compounds. The results show that all molecules can be used adequately with the perovskite matrix because of their sufficient deep HOMOs levels. The optoelectronic properties of the D-A-D molecules show no competition with the light-harvesting of the perovskite layer, while D-π-A-π-D compounds show a slight overlap with the absorption band of perovskites. All molecules indicate a faster hole-transport rate and an easy electron-hole pairs dissociation into free charge carriers, which facilitates the hole transport and enhances open-circuit voltage. Adding a second thiophene unit in the central core reinforces the structure's flexibility and improves Frontier Molecular Orbital's electronic density distribution, while inserting azomethine groups is advantageous for the molecule's solubility. Their short gaps, higher radiative lifetimes, and visible light absorbance make T12,15 good candidates for their usage in organic solar cell applications. A spontaneous solvation process within dichloromethane for all the investigated molecules was proved based on the high negative free energies.

New homo‐bimetallic complexes of dihydrazone‐oxime ligand incorporating isatinic moiety: Preparation, characterization, theoretical, microbicidal, and anticancer investigation

A new series of dihydrazone‐oxime ligand's homo‐bimetallic complexes of formulas [M2LCl5(H2O)3].nH2O (M=Fe3+, n=0; Ru3+, n=2), [M2L((O)CH3COO)3(H2O)5].nH2O (M=Co2+, Mn2+, Zn2+ or UO22+, n=4, 6, or 1) and [Cu2L(NO3)3(H2O)3] is designated from the reaction of 3‐((3‐(hydroxyimino)butan‐2‐ylidene)hydrazono)indolin‐2‐one (HL,1) with the salts of Fe3+, Ru3+, Co2+, Cu2+, Mn2+, Zn2+, and UO22+. The newly prepared compounds' structure was elucidated based on traditional techniques such as molar conductance, magnetic measurements, elemental, thermogravimetric (TGA) analyses, and mass spectrometry, as well as spectroscopic tools such as electronic absorption, infrared, nuclear magnetic resonance, mass, and electron spin resonance spectra. The values of complexes molar conductance in DMSO indicated that they were non‐electrolytes. The elemental analysis, in conjunction with other data obtained, confirmed that the ligand performed as a uni‐negative tetradentate chelator that bound two metal cations via the indoline carbonyl; deprotonated oximatic and azomethine groups adopt distorted octahedral or square pyramidal geometries. The chemical formula of these complexes was corroborated by TG analysis, which verified that the homo‐bimetallic complexes were degraded in three or four decaying steps in temperature range 50–596°C ended with the formation of metallic oxide. The prepared compounds' structural characterization was verified by DFT calculations utilizing DFT‐B3LYP technique with a basis set (6–311++G[d,p]). Theoretical calculations' results demonstrated that the homo‐bimetallic complexes' reactivity is higher than un‐complexed ligand's reactivity. The anticancer activity was determined versus three cell lines, namely, SKOV3, PC‐3, and HeLa cell lines. The assignment data revealed that the Zn2+ complex has a stronger inhibitory effect against the three cell lines. Additionally, the synthesized substances' in vitro microbicidal activity was performed versus a variety of bacterial and fungal species.

Bivalent Metal Chelates with Pentadentate Azo-Schiff Base Derived from Nicotinic Hydrazide: Preparation, Structural Elucidation, and Pharmacological Activity.

Azo-Schiff base ligand (N'-((E)-2-hydroxy-5-((E)-(2-hydroxyphenyl)diazenyl)benzylidene)nicotinohydrazide) and its Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Pd(II) chelates were prepared and elucidated. The geometrical structures of the prepared chelates were characterized by several spectroanalytical techniques and thermogravimetric analysis. The obtained data revealed that the chelates have (1M:1L), (1M:2L), (1M:3L), and (1M:4L) molar ratios. The infrared spectra displayed that the H2 L ligand behaves in a pentacoordinate fashion in chelates of Mn(II), Ni(II), and Cu(II) ions. However, in Zn(II) and Pd(II) chelates, the ligand is coordinated as a tetradentate species (NONO) through nitrogen atoms of azomethine and azo groups as well as oxygen atoms of phenolic hydroxy, and carbonyl groups. Besides, it was concluded that the oxygen atoms of carbonyl and hydroxy groups along with the azomethine nitrogen atom of the ligand are bounded with Co(II) ion in metal chelate (2). According to the measured molar conductance values, the chelates of Cu(II), Zn(II), and Pd(II) are weak electrolytes, but Mn(II), Co(II), and Ni(II) chelates are ionic. The azo-Schiff base ligand and its prepared metal chelates were tested for their antioxidant and antibacterial properties. The Ni(II) chelate was found to be considered an effective antioxidant agent. In addition, the available antibacterial data suggest that the Ni(II) and Co(II) chelates may be employed as inhibitor agents against Proteus vulgaris, Escherichia coli, and Bacillus subtilis bacteria. Furthermore, the data showed that, in comparison to the ligand and other metal chelates, copper(II) chelate (4) exhibited higher action against Bacillus subtilis bacteria.

SYNTHESIS, CHARACTERIZATION OF COPPER(II) COMPLEX WITH TETRADENTATE N2O2 AND POTENTIAL CONTRIBUTION AS PROMISING ANTIBACTERIAL STUDIES

A square planar Schiff base complex, Cu(H2L) namely N,N’-bis(4-methyl-α-salicylidene)propane-1,3-diaminecopper(II) through the condensation reaction of ligand with copper(II) acetate in the molar ratio of 1:1 in acetonitrile solvent was successfully synthesized. The obtained complex was characterized using, elemental analysis of carbon, hydrogen and nitrogen (CHN), Fourier Transform Infrared spectroscopy (FTIR) and electronic spectra of ultraviolet-visible (UV-vis) spectroscopy. FTIR confirmed the coordinates the metal ion to form mononuclear complex via tetradentate (ONNO) atoms of the phenolic group and azomethine group, respectively. The antibacterial studies of H2L and its Cu(H2L) were determined by screening the compounds against selected various Gram (+) and Gram (-) bacterial strains such as Staphylococcus epidermidis, Bacillus subtilis, Staphylococcus aureus, Vibrio cholera, Enterobacter cloacae and Escherichia coli. Indeed, preliminary results exhibited Cu(H2L) more active than the free ligand and displayed promising antibacterial activity, while no effect has been observed on strains for H2L.

Synthesis and Characterization of Schiff Base of 2-Acetyl-5-Methylfuran Glyoxime Hydrazine and its Metal (II) Complexes and Their Evalution for Antibacterial and Antifungal Activities

Two hydrazone Schiff base was synthesized by the interaction of ethanolic solution of antiglyoxime hydrazine with 2-acetyl-5-methylfuran to obtain the Schiff base. The complexes of Mn(II), Fe(II), Ni(II) and Cu(II) and their Schiff base were synthesized and characterized based on solubility, percentage yield, elemental analysis, melting point and decomposition temperature, infra-red spectra (FT-IR), conductivity measurement, magnetic susceptibility and water of crystallisation. The ligand and the complexes were coloured and stable at room temperature. They were soluble in acetone, DMSO, ethanol, methanol, hexane, chloroform, carbontetrachloride, benzene and DMF but insoluble in distilled water. The melting point temperature of the ligand was 118oC while the decomposition temperatures for the complexes were found to be between 295-312oC. The molar magnetic susceptibility of the complexes were in the range of 3.55 x 10-3 – 1.42 x 10-2erg.G-2mol-1. Molar conductance values of 2.17 – 2.87Ω-1cm2mol-1 show non electrolytic nature of the complexes. The spectral data of the ligand showed bands in the range 1581–1607cm-1 revealing the formation of the azomethine group. A band between 760-795cm-1 indicates the metal nitrogen bonds. The elemental analysis of the complexes showed the metal ligand ratio of 1:2 (M:2L). The antibacterial and antifungal studies showed that the complexes exhibited higher antibacterial and antifungal activities than the ligand but lower than the reference drugs.

A REVIEW STUDY ON GREEN SYNTHESIS OF SCHIFF BASES

Green chemistry offers signicant nancial and environmental advantages over traditional synthesis methods. It accomplishes this by subtly suggesting methods and tools. The present interest in green chemistry has proposed a further necessity for organic synthesis, where novel reaction conditions must locate, lowering the demand for hazardous ingredients or damaging organic solvents. These green approaches must improve selectivity, speed up reaction times, and facilitate product separation as compared to traditional routes. The rst synthesis of Schiff bases was recorded by Hugo Schiff in the 19th century (imines). A primary amine and an aldehyde are often combined to form a Schiff base, which is an aldehyde with an azomethine group (C=N group) instead of a C=O group. In order to determine the best approach that gives greater yields in less time while maintaining an environmentally friendly atmosphere, this study aims to concentrate on the green synthetic techniques utilised for Schiff bases synthesis. The review considered a number of environmentally friendly synthetics methods, among which microwave irradiation is considered to be the best, followed by ultrasonic, employing natural acids, and grinding techniques.

Microwave assisted Schiff base metal complexes as potential anticancer and antimicrobial agents: A critical review

Schiff bases are organic compounds which contain azomethine group (-C=N-) by reacting primary amines and carbonyl compounds. The presence of an azomethine group in the Schiff base facilitates coordination with transition metal ions. The term Schiff base is normally applied to these compounds when they are being used as ligands to form coordination complexes with metal ions. Such complexes occur naturally, but the majority of Schiff bases are artificial and are used to form many important catalysts. Schiff base metal complexes prepared using microwave irradiation have gained more attention because of their excellent strategy in generating quick and stable products in higher yields by improving the speed of reaction with lesser energy and exhibits various biological activities including antifungal, antibacterial, anti-tubercular, antiviral, antimalarial, anti-diabetic, anticancer, antioxidant, antidiuretic, anti-inflammatory, antipyretic and anti-HIV agents. Apart from biological applications, they are also used as a catalyst in Aldol reactions, polymerization reactions, oxidation reactions and other chemical reactions. Imine-ligand containing transition metal complexes including copper, zinc and cadmium, have proven to be effective starting points for the synthesis of metal or metal chalcogenide nanoparticles. In this review, various metal complexes derived from Schiff bases synthesised using microwave approaches are discussed along with their antibacterial, antifungal and anticancer activities.

Experimental and theoretical insights about the effect of some newly designed azomethine group‐contained macroheterocycles on oxidative stress and DNA repair gene profiles in neuroblastoma cell lines

We report herein the synthesis of new azomethine group containing forty-, sixty-eight- and seventy-two-membered macroheterocyclic compounds and the investigation of their activity against the neuroblastoma cell line. The synthesis of targeted compounds was done by condensation of dialdehydes with polyamines and their structures were investigated by 1H and 13C NMR and MALDI MS methods. Anticancer activity of these newly synthesized molecules was studied in the neuroblastoma (SH-SY5Y) cell line at eight different concentrations (1–100 µg/ml) for 24 h, 48 ​​hrs and 72 h by MTT method. In addition to it, oxidative stress (GPX1, PRDX1, CAT, SOD1, NQO1) and DNA repair (ATR, ERCC1, CDKN1A, PRKDC) gene profiles were also investigated by RT-PCR method. It was found that all synthesized compounds showed the highest activity after 72 h of incubation. PRDX1 gene expression in the case of all investigated compounds was found to be higher than the control group, whereas ABCB1 (MDR) gene expression increased only in the case of molecule 1. Results also demonstrate that the expression levels of GPX and SOD1 genes were high in the case of molecule 2, whereas molecule 1 manifested low expression levels of ERCC1, ATR, CDKN1A, PRKDC, GPX1, ABCB1(MDR), CAT, SOD1 and NQO1 genes. Along with experimental studies, theoretical studies were also carried out. The String v11 program was used to determine the interaction of proteins involved in oxidative stress and DNA repair mechanisms with other proteins. The results of the molecular docking analysis were found to be in good agreement with the experiments.

Synthesis, spectral characterization and antimicrobial effect of Cu(II) complexes of schiff Base Ligand, N-(3,4- dimethoxybenzylidene)-3-aminopyridine (DMBAP) Derived from 3,4-dimethoxybenzaldehyde and 3-aminopyridine

The present study emphasizes strictly on the synthesis, and characterization of complex 3,4- dimethoxybenzaldehyde and 3-aminopyridine with Cu(II) using several techniques like Elemental Analysis, FTIR spectroscopy, NMR, HRMS, UV-vis spectroscopy, Magnetic Susceptibility and Conductivity Measurements. The Ligand [L] acts as bidentate and co-ordinates through Nitrogen atom of imine group [azomethine group] and Nitrogen atom of pyridine ring. Electronic data of the complexes suggest the probable geometry is octahedral in nature. All the complexes and ligand were screened for their antibacterial activity and behaved non-electrolytic in nature. The metal ligand ratio obeys 1:2 ratio. Antimicrobial studies of gram-positive bacteria (GPB)- (Bacillus subtilis), gram-negative bacteria (GNB)- (E. coli) and some antibiotic reveal the MIC value in the range of (6–20 mm) followed the order [Cu(L)2Cl2]>[Cu(L)2Br2]>Antibiotic>Ligand. Antimicrobial activity has been explained on the basis of Tweedy Chelation Theory (TCT) and Anil’s Conceptual Model of Inhibition (ACMI).

Synthesis, characterization, anticancer activity and molecular docking of metal complexes bearing a new Schiff base ligand

2-((E)-((4-(((E)-4-Nitrobenzylidene)amino)phenyl)imino)methyl)naphthalen-1-ol, was synthesised followed by metalation with Fe(III), Co(III), Cu(II), Zn(II) and Ni(II) metals. The compounds were characterised by different methods CHN, AAS, IR, NMR, XRD, TGA and UV–Vis. The results reveal that the ligand has bidentate behavior, and it is bound with metals by a coordination bond through both the nitrogen atom of the azomethine group and the oxygen atom, this provided an octahedral geometry. The X-ray diffraction of the compounds indicate that the ligands and complexes of Co(III), Fe(III) and Zn(II) have a crystalline nature, whereas the Ni(II) and Cu(II) have an amorphous structure. The agar diffusion method (hole plate) was used to evaluate the ligand’s and its complexes’ antibacterial and antifungal effects on Salmonella enterica serovar typhi and Candida albicans, respectively. It was observed that the Fe(III) complex had the best activity among the compounds against microbial strains. Cytotoxicity of new metal complexes was also assessed against A549, HepG-2 and PC-3 cancer cells. Results demonstrated that the Cu(II) complex displayed the preeminent activity among the synthesised compounds against all the tested cell lines. Furthermore, molecular docking simulation revealed that the Fe(III) complex is shown to have a high affinity with the active sites of two targets of microbial strains. Also, the Cu(II) complex shown to has a high affinity with the active sites of three targets of A-549, HepG-2 and PC-3 cancer cells, which was confirmed by the formation of the different modes of interaction. Communicated by Ramaswamy H. Sarma

Synthesis and Spectral, Thermal and Antimicrobial Investigation of Mixed Ligand Metal Complexes of N-Salicylidene Aniline and 1,10-Phenanthroline

Coordination compounds of Co(II), Cu(II), Y(III), Zr(IV) and La(III) ions were synthesized from the N-salicylidene aniline (L) derived from the condensation of aniline with salicylaldhyde and 1,10-phenanthroline (phen) as a secondary mixed ligand. L, phen and their complexes were characterized using various physiochemical methods, such as elemental analyses (CHN), Fourier-transform infrared spectroscopy (FT-IR), molar conductance (Λ), magnetic susceptibility (μeff), proton nuclear magnetic resonance (1H NMR), ultraviolet–visible spectroscopy (UV–Vis) and thermogravimetric analysis (TG/DTG). The analytical and spectroscopic data supporting the chemical formulas of the metal complexes and chelation of L and phen with the metal ions forming octahedral complexes. FT-IR spectra demonstrated that L chelated with metal ions as a bidentate ligand via the oxygen atom of the phenolic group with a band in the range 3378–3437 cm−1 and the nitrogen atom of the azomethine group at 1612 cm−1. In addition, phen chelated through two nitrogen atoms in the range 1525–1565 cm−1. The 1H NMR results confirmed the IR assumption that the ligand connected to the metal ions via the phenolic’s oxygen atom. The molar conductance measurements of the complexes revealed high values of the electrolytic nature of these complexes in the range of 90.40–125.80 S cm2 mol−1. Thermal analysis (TG/DTG) was used to differentiate between coordinated and hydrated water molecules and the thermal stability of the complexes. Finally, the anti-microbial activities of the complexes were investigated against fungi (Candida albicans), Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) and Gram-positive bacteria (Staphylococcus aureus and Micrococcus sp.) using the disc diffusion method. The La(III) complex was significant against C. albicans compared with all other compounds and reference standard control.

Synthetic methodologies and pharmacological applications of sulphonamide containing Schiff bases and their metal complexes: A comprehensive review

Schiff bases are useful chemical compounds with a wide range of applications. The Schiff bases are synthesized via the condensation reaction between carbonyl compounds (aldehydes or ketones) and compounds having an amine group and the Schiff base is characterised by an imine or azomethine (-C=N-) group. These compounds are extensively used as ligands to form coordination complexes with metal ions and are widely utilized in the treatment of various ailments. Sulphonamides are biologically significant class of drug-like chemical derivatives due to their good oral absorption and urine excretion. Sulphonamides are widely used as antimicrobial, anti-inflammatory, anticancer and antiviral drugs in addition to acting as powerful Carbonic anhydrase hCA inhibitors, HIV protease inhibitors, anti-obesity and anti-thyroid agents because of their less poisonous, more reactive and cost-effective nature. Sulphonamide-based Schiff bases and their metal chelates have attracted the focus of researchers due to their broad range of pharmacological characteristics. In this review, various pharmacological uses of Schiff base metal complexes generated from sulphonamide derivatives are discussed.

Physico-Chemical Study of Mn(II), Co(II), Cu(II), Cr(III), and Pd(II) Complexes with Schiff-Base and Aminopyrimidyl Derivatives and Anti-Cancer, Antioxidant, Antimicrobial Applications.

A new class of biologically active mineral complexes was synthesized by reacting the following metal salts: MnCl2·4H2O, CoCl2·6H2O, CuCl2·2H2O, CrCl3·6H2O, and PdCl2 respectively with 2-amino-4,6-dimethyl pyrimidine (ADMPY) and Schiff's base resulting from the condensation reaction between benzaldehyde with p-phenylenediamine and 2-hydroxy-1-naphthaldehyde as ligands have been synthesized and characterized on the basis of their CHN, thermal analysis, XRD, SEM and magnetic measurements along with their FT-IR and UV-vis spectra. The scanning electron microscope SEM measurements and the calculations on the powder XRD data indicate the nano-sized nature of the prepared complexes (average size 32-88 nm). The spectral data confirmed the coordinated ligand (HL) via a nitrogen atom of an azomethine group (-C=N-) and phenolic -OH group and NH2-ADMPY ligand with the metal ions. An octahedral geometry for all complexes has been proposed based on magnetic and electronic spectral data except Pd(II) complex, which has a tetrahedral geometry. Molecular modeling was performed for Cu(II) complex using the density functional method DFT/B3LYP to study the structures and the frontier molecular orbitals (HOMO and LUMO). The antioxidant of the complexes was studied using the 2,2-diphenyl-1-picrylhydrazyl (DPPH)-free radical-scavenging assays. The metal complexes were tested in vitro for anticancer activities against two cancer lines A-549 and MRC-5 cells. Cu(II) and Pd(II) complexes showed the highest cytotoxicity effect, comparable to that of other cis-platinum-based drugs. The complexes showed significant activity against fungi and bacteria.

New Dual Inhibitors of SARS-CoV-2 Based on Metal Complexes with Schiff-Base 4-Chloro-3-Methyl Phenyl Hydrazine: Synthesis, DFT, Antibacterial Properties and Molecular Docking Studies

This paper explores a dual inhibition of main protease (Mpro) and nonstructural protein 10/nonstructural protein 16 (NSP16) methyltransferase complex as the key targets for COVID-19 therapy. These are based on the new Schiff-base ligand that was obtained from the condensation of (4-chloro-3-methyl phenyl) hydrazine with 2-pyridine-carboxaldehyde and its novel Schiff-base metal complexes. These include Ni(II), Pd(II), Pt(II), Zn(II), and Hg(II). The newly synthesized compounds have been characterized using FT-IR, 1H NMR, 13C NMR, and elemental analysis. The results suggested that the Schiff-base ligand is coordinated as a bidentate ligand through the nitrogen atoms of the azomethine group and pyridyl ring. In addition, the biological activity of the prepared complexes was examined against Pseudomonas aeruginosa and Staphylococcus aureus, and the results showed that the Zn(II) complex has the highest activity compared with other compounds. The active sites were found by looking at the molecular electrostatic potential (MEP) maps of the above ligands and complexes. The activity of the compound and its Ni(II) and Zn(II) complexes against Mpro and NSP10/ NSP16 was investigated using a molecular docking approach. They showed excellent binding energies ranging from −5.9 to −7.2 kcal/mol and −5.8 to −7.2 for Mpro and NSP16, respectively. All conformers of the metal complexes were docked with the active site of the NSP16 receptor, showing a binding affinity of 100%. According to our knowledge, this was the first report of these metal complexes as dual inhibitors for Mpro and NSP16 of SARS-CoV-2.

Preparation of zwitterionic ionic surfactants-based sulphonyl for steel protections: Experimental and theoretical insights

Abstract Designating an organic inhibitor with a specific chemical structure that actively participates in steel protection by increasing adsorption on the steel surface. Based on that, we synthesized three zwitterionic surfactants based on azomethine with different hydrophobic chain lengths labeled ZWSO, ZWSD, and ZWSH. The presence of azomethine group, electrons, and heteroatoms in the zwitterionic surfactant’s amphipathic structure helped to improve C-steel protection. Their inhibitory activity toward steel corrosion was investigated utilizing electrochemical impedance spectroscopy (EIS), gravimetrical, and potentiodynamic polarization techniques. Importantly, the surfactant tail influenced corrosion inhibition performance; as surfactant tail length increased, so did inhibition efficiency due to increased adsorption affinity. The inhibition efficiencies of ZWSO, ZWSD, and ZWSH are 87.15, 89.82, and 91.36%, respectively. Tafel data clarified that ZWSO, ZWSD, and ZWSH inhibitors behave as mixed-type inhibitors following the modified Langmuir isotherm. The inhibitors can adsorb physiochemically on the steel surface with ∆G ads ranges from −38.48 to −44.6 kJ mol−1. The SEM confirms that the morphology of C-steel becomes smoother because of inhibitor adsorption. The DFT and MCs output data supported the experimental performance of the tested ZWSO, ZWSD, and ZWSH inhibitors and especially their dependence on surfactant tail length.

New iron(III) complexes with 2-formylpyridine thiosemicarbazones: Synthetic aspects, structural and spectral analyses and cytotoxicity screening against MCF-7 human cancer cells

2-Formylpyridine thiosemicarbazone - iron (III) chelates [FeL2] Cl•2H2O {L = L1 (C1) [HL1 = 4-(4-Nitrophenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide] and L = L2 (C2) [HL2 = 4-(2,5-Dimethoxyphenyl)-1-((pyridin-2-yl)methylene)thiosemicarbazide]} were prepared. The two ligand anions in each complex resulted in saturation of the iron coordination number and consequently the existence of these complexes as 1:1 electrolytes. As well, the iron in these complexes exhibits low-spin electronic configuration. X-ray crystallography of complex C1 indicated its triclinic crystal system and P 1‾ space group. In addition, it proved the ligation through a thiol sulfur atom and two nitrogen atoms of pyridine and azomethine groups. This is while the presence of two water molecules of crystallization in the complex structure was also indicated. The ligand HL1 was selected for cytotoxicity screening against human MCF-7, A-549, HEPG-2 and HCT-116 cancer cells and the most enhanced activities were detected against the breast cells. Against these cells, the compounds HL1, HL2, C1 and C2 induced cytotoxicity, respectively, with IC50 values of 52.4, 145.4, 34.3 and 62.0 μM. However, against the healthy BHK cells, HL1 and HL2 caused cytotoxicity, respectively, with IC50 values of 54.8 and 110.6 μM and cytotoxicity with percent viabilities of 56.7 and 55.4% of the BHK cells by the complexes (137.4 μM of C1 and 131.9 μM of C2) was determined. These activities against MCF-7 cells are less significant compared with the measured value for doxorubicin. But this standard is more toxic to normal cells than the thiosemicarbazones (IC50 (doxorubicin) = 9.66 μM against MCF-7 cells and 36.42 μM against BHK cells).

Schiff Bases having A Triazole Ring Bearing a Pyridyl Moiety are Synthesised, and their Biological Activities are Studied

The most frequently used organic compounds are Schiff bases. They have been demonstrated to have a broad variety of biological activities. Using a thermal method, the synthesis of a series of imine derivatives 4a-f from Amino triazole thiol (3) as starting material with six different aldehydes. Target compounds' full characteriszation was achieved using 1H and 13C- NMR, mass spectra, and FT-IR. In the 1H-NMR spectra of compounds (4a-f), an isotope with a proton signal for the CH of the azomethine group that ranged from 8 to 10.30 ppm was observed. Due to labile hydrogen bonds with nitrogen and sulfur, compound 3 exists in two tautomeric forms. Synthesis compounds' antibacterial activity was investigated against the bacteria Klebsiella, E. coli and, S. aureus

Effect of Gel Electrolyte, Paste and Electrode on the Efficiency of Dye-Sensitized Solar Cell using Schiff Base Dye Compound

The low cost and ease of production have led to widespread adoption of dye-sensitized solar cells (DSSCs). Therefore, this study aims to synthesize Schiff base compounds from salicylaldehyde and ethylenediamine as a sensitizer in DSSC. The Shiff base compound was synthesized using the condensation method with mol ratio of 1:1 and the results showed yellow crystals with a yield of 81.14%. Furthermore, the UV-Vis spectrometer analysis showed that the Schiff base compound has bathochromic shift with a maximum wavelength change from 324 and 328 nm to 335 nm with transition n→π, while the IR spectrum at wavenumber of 1610 cm-1 indicated the presence of an azomethine group (–C=N–). The TG-DTA analysis showed a mass loss stage of the Schiff base molecule at 97.2% in the temperature range of 180-300 ºC. Based on UV-Vis, IR and TG-DTA data, the synthesized Schiff base has the potential to be used as a sensitizer in DSSC. The fabrication was then carried out using two variations of semiconductor namely TiO2 and ZnO, three variations of PEG gel electrolyte with 0.05 M, 0.1 M and 0.15 M, as well as three counter electrodes including graphite from a pencil, candle flame and a combination of both. Based on the results, DSSC based on TiO2 semiconductor with 0.15 M PEG gel electrolyte and candle flame counter electrode produced the highest efficiency of 0.29 % with maximum voltage (Vmax) of 370 mV and maximum current strength (Imax) of 0.8 mA.

Biological applications of Schiff bases: An overview

Schiff bases are the compounds containing the azomethine group (-HC=N-). They are formed by the condensation of ketones or aldehydes with a primary amine. Formation of Schiff base generally takes place under acid/base catalysis or with heat. The common Schiff bases are crystalline solids, which are basic but at least some form insoluble salts with strong acids. Schiff bases are used as intermediates for the synthesis of amino acids or as ligands for the preparation of metal complexes having a series of different structures. The electrophilic carbon and nucleophilic nitrogen in the C=N imine bond provide excellent binding opportunities with different nucleophiles and electrophiles thereby inhibiting targeted diseases, enzymes or DNA replication. These Schiff bases are synthesized from various aldehydes and amines under stirring conditions, catalyst-free, reflux conditions, microwave irradiation and ultrasonic conditions. These compounds serve a wide range of applications in pharmaceutical industries as well as chemical industries. There are a series of biological activities exhibited by these compounds which include antimicrobial, anti-inflammatory, antiviral and antioxidant activities. Apart from exhibiting medicinal properties, Schiff base compounds play an important role as ligands in coordination chemistry. Thus, Schiff bases and their derivatives may be further used for enormous biological applications with potent effects.