Nitrogen Oxygen Donor Research Articles

Synthesis, structural characterization and DFT calculations of a diphenyl-2-pyridylphosphine complex of copper(II)

The reaction of Cu(NO3)2·3H2O with a potentially bidentate P,N-donor ligand, diphenyl-2-pyridylphosphine (PPh2Py), in 1:2 molar ratio resulted in formation of a κ 2N,O-chelated complex, [Cu(κ 2N,O-P(O)Ph2Py)2(NO3)2] (1). A single-crystal X-ray study confirmed the formation of a five-membered κ 2N, O-chelate involving pyridyl nitrogen and phosphine oxide oxygen donor sites. A DFT study was carried out on 1 to understand the chelate ring expansion process upon oxidation with PPh2Py. DFT analysis revealed that 1 contains a relatively strong M-N bond compared to its M-P bond, facilitating the oxidation of the P atom followed by chelate ring expansion.

Antimicrobial screening involving Helicobacter pylori of nano-therapeutic compounds based on the amoxicillin antibiotic drug.

Nano-structure Cu(II) complex [Cu(AMAB)2 ]Cl2 with Schiff base (AMAB) derived from the condensation between 4-(dimethylamino)benzaldehyde and amoxicillin trihydrate was prepared. (AMAB) Schiff base and its Cu(II) complex were identified and confirmed by different physicochemical techniques. The Schiff base (AMAB) was coordinated to copper ion through carbonyl oxygen and imine nitrogen donor sites. X-ray powder diffraction shows a cubic crystal system of the Cu(II) complex. The density functional theory was used to optimize the structure geometries of the investigated compounds. The molecular docking of the active amino acids of the investigated proteins' interactions with the tested compounds was evaluated. The bactericidal or bacteriostatic effect of the compounds was screened against some bacterial strains. The activity of Cu-chelate against Gram-negative bacteria was mainly more effective than its (AMAB) ligand and vice versa in the case of Gram-positive bacteria. The biological activity of the prepared compounds with biomolecules calf thymus DNA (CT-DNA) was determined by electronic absorption spectra and DNA gel electrophoresis technique. All studies revealed that the Cu-chelate derivative exhibited better binding affinity to both CT-DNA than the AMAB and amoxicillin itself. The anti-inflammatory effect of the designed compounds was determined by testing their protein denaturation inhibitory activity spectrophotometrically. All obtained data supported that the designed nano-Cu(II) complex with Schiff base (AMAB) is a potent bactericide against H. pylori, and exhibits anti-inflammatory activity. The dual inhibition effects of the designed compound represent a modern therapeutic approach with extended spectrum of action. Therefore, it can act as good drug target in antimicrobial and anti-inflammtory therapies. Finally, H. pylori resistance to amoxicillin is absent or rare in many countries, thus amoxicillin nanoparticles may be beneficial for countries where amoxicillin resistance is reported.

Ligational behavior of bidentate nitrogen–oxygen donor 8‐quinolinolazodye toward Ni2+ and Zn2+ ions: Preparation, spectral, thermal, experimental, theoretical, and docking studies

The 5‐(4‐aryl azo)‐8‐hydroxyquinolines (L1–L3) and their metal complexes with Ni2+ and Zn2+ have been produced. Various spectroscopic techniques have been employed to analyze the ligand and complexes. The structures of the prepared compounds have been confirmed by Fourier transform infrared (FT‐IR), proton nuclear magnetic resonance (1H NMR), molar conductance, magnetic measurements, thermal gravimetric and differential thermal analyses (TG and DTA), and electronic transition. The FT‐IR spectra showed that the ligands are coordinated to the metal ions in a bidentate manner with donor sites of the azomethine‐N and phenolic‐OH. The FT‐IR and UV–Visible spectra were compared with the calculated results and showed a good agreement. The mass spectra concluded that the ligands' molecular weights and the calculated estimated m/z values match well. The complexes contain coordinated and hydrated water as confirmed by the TG results. The complexes are tetrahedral, trigonal bipyramid, and octahedral geometrical structures and act as non‐electrolytes in dimethylformamide (DMF) solvent. Using density functional theory (DFT) at the B3LYP level of theory and the 6‐311G** basis set for the C, H, N, Cl, and O atoms and the LANL2DZ basis set for the Ni and Zn atoms. Natural bond orbital (NBO) analysis was used to compute and describe the natural charge population and precise electronic configuration. The small energy gap between HOMO and LUMO energies suggests that charge transfer occurs within Ni2+ and Zn2+ complexes. The first‐order hyperpolarizability (β) of the complexes and the anisotropy of polarizability (α) values show promising optical properties. The electronic transitions of the prepared complexes were computed by time‐dependent density functional theory (TD‐DFT/PCM) with the B3LYP method using a 6‐31G** basis set. The ethanol polarizable continuum model (PCM) was used to simulate the solvent effect. Utilizing a computer virtual screening technique through molecular docking, the anticipation of binding of 8‐quinolinolazodye derivatives and their complexes with human CORONA virus protein (PDB ID: 5epw) was done.

Ligational behavior of a new bis (bidentate NO) donor hydrazone towards Co (II), Ni (II), and Cu (II) ions: Preparation, spectral, thermal, biological, docking, and theoretical studies

Reaction of 4,6‐bis(1‐hydrazonoethyl)benzene‐1,3‐diol with 3‐nitrobenzaldehyde gave the new bis (bidentate) hydrazone ligand; 4,6‐bis(3‐nitrobenzalen‐1‐yl)methylene)hydrazono)ethyl)benzene‐1,3‐diol (H2L; H2BisBD). Binuclear Co (II), Ni (II), and Cu (II) complexes of general formula ([M2BisBD(H2O)x (EtOH)y].nH2O; M = Co, Ni or Cu, x = 4 or 6, y = 2 or 0; n = 1 or 0) have been successfully prepared. The structures of H2BisBD and its complexes have been characterized by means of analytical, spectroscopic (infrared, proton nuclear magnetic resonance, mass, UV–Vis, and electron spin resonance), molar conductivity, and magnetic susceptibility measurements and thermal gravimetric analysis. Octahedral geometrical structures were proposed for all complexes in which the hydrazone ligand behaves as a bis (monoanionic bidentate) via azomethine nitrogen and phenolic oxygen donor atoms. The scanning electron microscopy refers that the copper (II) complex is in the nano scale. The ligand and its complexes showed antitumor activity against Hepatocellular carcinoma. Complexation process improved the antitumor activity, and copper (II) complex showed a promising activity, which agree with docking data. Theoretical studies for the prepared compounds were calculated using Hyperchem program at PM3.

Supramolecular diorganotin(IV) complexes of N′-(2-hydroxynaphthalen-1-yl)methylene)formohydrazide: Synthesis, spectroscopic characterization, X-ray structure, antibacterial screening, cytotoxicity and docking study

Three organotin(IV) complexes [Me2SnL(1), Ph2SnL(2), tert-Bu2SnL(3)] have been synthesized by the reaction of a novel ligand N'-(2-hydroxynaphthalen-1-yl)methylene)formohydrazide (H2L) with dialkyltin(IV) dichlorides [R2SnCl2 (R = Me, Ph, tert-Bu) in presence of Et3N. The ligand and complexes have been characterized by elemental analysis, mass spectrometry, FT-IR, 1H, 13C and 119Sn NMR spectroscopic techniques. The spectroscopic data suggests coordination of ligand to the diorganotin(IV) moieties via oxygen nitrogen donor sites and five coordinated tin centers. The molecular structures of ligand (H2L) and complexes (1, 3) were also confirmed by single crystal X-ray analysis. The solid state structure of ligand showed it to be in the amido form whereas the single crystal X-ray analysis of complexes revealed the dibasic tridentate nature of ligand and monometallic nature of complexes. In both the complexes (1, 3) the Sn atom is in a distorted five-coordinate square pyramidal geometry with trigonality index(τ) 0.33 and 0.41, respectively. Packing diagrams reveal the important role of H…H, CH…π and O…H interactions in generating the supramolecular assembly. The antibacterial potential of all the compounds was investigated against two gram-positive bacteria (Bacillus subtilis, Stephlococcus aureus) and four gram-negative bacterial strains (Escherichia coli, Shigella flexenari, Pseudomonas aeruginosa, Salmonella typhi), using imipenem as the standard drug. Complex 2 exhibited highest activity against Bacillus subtilis and highest cytotoxicity against brine shrimp nauplii with LD50 1.01 μg/mL. Molecular Docking investigations revealed the best target protein, the positive impact of diphenyltin(IV) moiety on the compound-protein binding and the important role of hydrogen bonding, pi-pi and hydrophobic forces in such type of interaction.

Synthesis, characterization, in vitro antioxidant and antimicrobial activities of diorganotin(IV) complexes derived from hydrazide Schiff base ligands

We have synthesized new diorganotin(IV) complexes of the type R2SnL (where R; methyl, ethyl, butyl and phenyl) of Schiff base ligands N'-(5-chloro-2-hydroxybenzylidene)thiophene-2-carbohydrazide (H2L1), N'-(4-(diethylamino)-2-hydroxybenzylidene)thiophene-2-carbohydrazide (H2L2), N'-(3,5-dibromo-2-hydroxybenzylidene)thiophene-2-carbohydrazide (H2L3) and N'-(2-hydroxy-5-methoxy-3-nitrobenzylidene)thiophene-2-carbohydrazide (H2L4). Spectroscopic methods (FT-IR, UV–vis, 1H, 13C and 119Sn NMR), elemental analysis, mass spectrometry, melting point and molar conductance measurements were used to elucidate the structures of compounds (1-20). The spectroscopic data indicated that the Schiff bases are tridentate (NOO) in nature and coordinated to the tin metal through enolic oxygen, azomethine nitrogen and aromatic hydroxyl oxygen donor atoms to display pentacoordinated geometry around the central tin metal. To examine the biological profile, the synthesized compounds were tested for in vitro antimicrobial activity against different bacterial and fungal strains by using serial dilution method which revealed that compounds Bu2SnL3 (15) and Ph2SnL3 (16) were most active antimicrobial agent. The compounds were further tested for antioxidant activity by using DPPH (1,1-diphenyl-2-picrylhydrazyl) assay. Complex Ph2SnL3 (16) exhibited highest antioxidant potential with lowest IC50 value (2.95 μM) among all the tested compounds.

English

The Schiff base of isatin and sulphanilamide (L1; C14H11N3O3S) was prepared and reacted with Re(CO)5X (X = Cl and Br) in toluene to give [Re(C14H10N2O)(CO)3X] (X = Cl, 1 and X = Br, 2). The prepared Schiff base of isatin and 4-methoxyaniline (L2; C15H12N2O2) was reacted with Re(CO)5X in toluene to give [Re(C14H10N2O)(CO)3X], where X = Cl, 3 and X = Br, 4. L2 and Re(CO)5Br were refluxed in dry toluene under nitrogen and recrystallized to give [Re(C15H12N2O2)(CO)3Br].1/2C2H5OH (5). Spectroscopic characterization of compounds was done using FTIR, UV-Visible, NMR and Mass spectra analyses. Magnetic susceptibility measurements and melting points were also determined. Elemental analysis of 5 revealed it was a solvate molecule of 4. The in-vitro antimicrobial activities of compounds were evaluated against Staphylococcus aureus, Bacillus subtilis, Haemolytic Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella sp., Aspergillus niger, Trichoderma viride and Penicillium citrinum. Spectroscopic analyses revealed new terminal carbonyl bands formed between 1900 and 2030 cm-1, as L1 and L2 coordinated through their azomethine nitrogen and keto oxygen donor atoms towards Re(I). Results of the antimicrobial studies revealed immerse improved activities upon coordination against tested microorganisms especially gram-negative bacteria, therefore they are recommended for further studies in cell imaging.   Key words: Isatin Schiff bases, rhenium (I) tricarbonyl complexes, antimicrobial, antifungal.

Green approach to synthesize, spectral investigation and biological applications of potentially active ternary schiff base copper(II) complexes

Abstract In this paper, a novel series of 4 mononucleate copper(II) complexes were synthesize from nitrogen-oxygen donor contain ternary Schiff base via environmentally green chemistry technique. The ternary schiff base copper(II) complexes were ready as of tyrosine, isoluecine with 2,4-dihydroxybenzaldehyde by grinding technique. 1,10-Phenanthroline/thiourea as a co-ligand were utilised in co-appointment with the schiff base in equimolar proportion. The complex be charaterized by means of basic analysis, magnetic moment, conduction measurements, IR along with UV–Visible spectral investigations. The synthesized complexes are neutral. From the infra-red spectral information of complexes, the value of Δν (νasCOO- − νsCOO-) is 177–220 cm−1 showing monodentate bringing together the carboxylate gathering. Experimental info established to facilitate the copper atom be co-ordinated to the ligand moiety, organizing toward the metal through oxygen and nitrogen present in the ligand as well as with co-ligand. Complexes 1–4 show a slectron spin resonance vary by g|| > g⊥ showing d(x2-y2)1 state recommends sq. pyramidal geometry. oxidation–reduction potential of complex erstwhile explored by cyclic voltammetry. The complexes show higher inhibitor action against DPPH radicals. The in-vitro antibacterial drug and antifungal examinations were in addition performed for the complexes and also the outcomes disclosed that the Cu(II) complexes were more and more powerful against all the microorganisms beneath analysis.

Photophysical Studies of a Catechol Based Polyfunctional Dipodal Chelator: Application for Optical Probe for Selective Detection of Fe(III).

A novel catechol based dipodal fluorescent chelator N,N'-bis[3-[(E)-(2,3-dihydroxyphenyl)methyleneamino]propyl]propanediamide(MPC), has been developed and its photophysical behaviour was studied by experimental (UV-VIS and fluorescence) and DFT method. The design of the molecule has been inspired from the naturally occurring siderophore enterobactin, a catechol based chelator with amide linkage, that shows an excellent binding efficiency towards Fe(III). The dipodal molecule (MPC) presented here, carries two catechol pendant binding moieties linked to the malonate central unit through propylene spacers by amide linkage. MPC showed good selectivity for Fe(III) at 10-4M concentration in aqueous medium amongst the biologically and environmentally important metal ions chosen viz., Na(I), K(I), Al(III), Cr(III), Fe(III), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II), by demonstrating a remarkable quenching in the fluorescent emission from 262a.u. to 55a.u. at λmax = 477nm. Also, the pre-organized assembled ligand favored an efficient Fe (III) encapsulation through coordination by imine nitrogen and catecholate oxygen donors. High formation constant (log β = 31.3) for 1:1 metal-ligand complex evaluated by both potentiometric and spectrophotometric methods, established the strong binding efficiency of the ligand for Fe(III) metal ion. The binding stoichiometry in the complex was also confirmed from Stern -Volmer and Hill Plot analysis. Further investigation on the emission behavior of MPC in a completely DMSO system explored its suitability for extensive applications in the areas such as, metallurgy, material science, iron contamination remedial in the materials etc.. DFT studies suggest that the ligand displays a U-shaped geometry with a parallel π-stacking and the hydrogen bond between two arms. The experimental infrared, electronic, fluorescence, 1H nmr, 13C nmr spectra were correlated with the theoretical results. The nature of electronic transitions were identified from the TDDFT calculation. The ligand forms a hexa-coordinated complex with six Fe-O bonds extending an orthorhombic geometry due distortion from a regular octahedron.

ZnO modified by urea–hydrogen peroxide adduct as photocatalyst for 2-propanol photooxidation in the gas phase under different irradiations

Zinc oxide nanoparticles were synthesized via sol–gel process using zinc acetate dihydrate, ethanol and oxalic acid as precursor, solvent and complexing agent, respectively. Urea-hydrogen peroxide (UHP) and urea were added as modification agents. UHP played, simultaneously, the role of nitrogen precursor and oxygen donor. Structural, morphological, textural and optical properties of zinc oxide samples were studied using XRD, SEM, BET, UV–Vis–DRS and Raman techniques. The XRD patterns and Raman spectroscopy results showed that the products consisted of ZnO and revealed that nitrogen was doped in the lattice of ZnO. SEM images revealed the occurrence of agglomeration and aggregation of ZnO nanoparticles. The photocatalytic activity of ZnO samples was estimated based on the photooxidation of 2-propanol in gaseous phase under UV and solar irradiations. Under both UV and solar irradiations, ZnO doped with UHP showed higher photocatalytic activity in comparison with bare ZnO and ZnO doped with only urea. The results showed that increasing the crystallite size has a direct effect on the improvement of the photocatalytic activity of ZnO.

Synthesis, Characterization and Magnetic Studies of Cobalt (II), Manganese (II) and Copper (II) Complexes containing Nitrogen-Oxygen Donor Ligands

Transition metal complexes, [M(COOPh)2(TMEDA)�(OH2)], (where M=Co+2 and Mn+2) and [Cu3(COOPh)2(TEA)2(CH3COO)2] have been synthesized by using sodium benzoate, tetramethyl-ethylenediamine and triethanolamine. The bonding nature and structure of complexes (1), (2) and (3) were explored through X-ray crystallography, IR, elemental analysis and magnetic studies. Single crystal X-ray analysis showed that in (1) and (2) complexes, each M (II) is bridged by two benzoate ions, one TMEDA and one water molecule while in (3) complex, Cu1 is coordinated by four oxygen atoms, two from TEA and two from carboxylate group while Cu2 is coordinated by three oxygen atoms and one nitrogen atom. All three complexes displayed triclinic system with space group P-1. Vibrating sample magnetometer measurement justified that these complexes are soft magnetic materials and can retain a certain value of magnetization even when magnetic field is removed.

Synthesis and Characterization of Tetranuclear Metal Complexes with an Octadentate Azodye Ligand

An octadentate azodye ligand containing phenolic/ketonic oxygen and azo nitrogen donor atoms when complexed with divalent metal ions forms tetranuclear complexes of composition [M4LCl4(H2O)12] and [ $$ M_{4}^{/} $$ LCl4(H2O)4] where, M = CoII,CuII, NiII, MnII and M/ = Zn II,, CdII and LH4 = 4,4/-bis(2,4/-dihydroxy-5/-acylphenylazo)diphenylsulphone (BDHAPADPS). The metal complexes were characterised by analytical, magnetic moment, conductance, I.R., electronic spectra, thermal, ESI–MS, ESR, XRD, SEM and EDX. DFT calculations of the ligand and metal complexes have been made by GAUSSIAN 03 rev. A.01 programme package. The antibacterial study of the ligand and the complexes has been made using Gram positive and Gram negative bacteria.

Synthesis, spectroscopic characterization, X-ray structure, DFT calculations, and antimicrobial studies of diorganotin (IV) complexes of monotopic oxygen nitrogen donor Schiff base

Seven new diorganotin(IV) complexes, [Me2SnL] (1), [Et2SnL] (2), [(n-Bu2SnL] (3), [Ph2SnL] (4), [(n-Oct2SnL] (5), [tert-Bu2SnL] (6), and [n-BuClSnL] (7) have been synthesized from the reaction of N′-(2-hydroybenzylidene)-4-tert-butylbenzohydrazide (H2L) with the corresponding diorganotin(IV) dichloride/oxide or organotin(IV) chloride dihydroxide. The synthesized compounds were structurally characterized by FT-IR, multinuclear NMR (1H and 13C) spectroscopies, elemental analysis, mass spectrometry, DFT/(B3LYP) calculations, and, for ligand single crystal, X-ray diffraction analysis. Spectroscopic evidence affirms coordination of ligand to the dialkyltin(IV) moieties through oxygen nitrogen donor sites in iminol form. The 1 J(119Sn, 13C) coupling constants, 584-655 Hz and 2 J(119Sn-1H) coupling constant, 79 Hz for complex (1), suggest pentacoordination around Sn atom in solution. Single-crystal X-ray structure of ligand show its existence in amido form. Supramolecular architecture mediated by N(2)-H···O(2) and C-H…π interactions is formed in solid state. The DFT calculations have been performed to obtain various structure-based molecular properties as well as to support experimental results. The synthesized compounds were screened in vitro against various human pathogenic microbial strains. Escherichia coli and Staphylococcus aureus were most visibly inhibited by complexes (4) and (7). Highest antifungal activity was shown by compound (6) against Fusarium solani. Compound (3) displayed highest cytotoxicity among synthesized compounds with LD50 0.44μg/mL.

Zinc Bioavailability from Phytate-Rich Foods and Zinc Supplements. Modeling the Effects of Food Components with Oxygen, Nitrogen, and Sulfur Donor Ligands.

Aqueous solubility of zinc phytate (Ksp = (2.6 ± 0.2) × 10-47 mol7/L7), essential for zinc bioavailability from plant foods, was found to decrease with increasing temperature corresponding to ΔHdis of -301 ± 22 kJ/mol and ΔSdis of -1901 ± 72 J/(mol K). Binding of zinc to phytate was found to be exothermic for the stronger binding site and endothermic for the weaker binding site. The solubility of the slightly soluble zinc citrate and insoluble zinc phytate was found to be considerably enhanced by the food components with oxygen donor, nitrogen donor, and sulfur donor ligands. The driving force for the enhanced solubility is mainly due to the complex formation between zinc and the investigated food components rather than ligand exchange and ternary complex formation as revealed by quantum mechanical calculations and isothermal titration calorimetry. Histidine and citrate are promising ligands for improving zinc absorption from phytate-rich foods.

Pd(II) Complexes with Nitrogen-oxygen Donor Ligands: Synthesis, Characterization and Catalytic Activity for Suzuki-Miyaura Cross-coupling Reaction

Inexpensive bidentate Schiff base ligands (O1, O3) and their Pd(II) complexes (OPd1, OPd3) were successfully synthesized and characterized using CHN elemental analysis, FTIR, 1H and 13C NMR, melting point determination, molar conductivity and magnetic moment. It revealed that these Schiff bases behaved as bidentate ligands in their complexes. The spectral data indicated that the ligands co-ordinated through the phenolic oxygen and the azomethine nitrogen atoms. Magnetic momentdata suggested the existence of square planar Pd(II) complexes, while non-electrolytic behaviour indicated the absence of counter ions in chloroform. The Pd(II) complexes showed good catalytic activities for Suzuki-Miyaura cross-coupling reaction between iodobenzene with phenylboronic acid at 1.0 mmol% catalyst loading.

A New Type of Palladium-Pincer Complexes Generated via Hydrolytic Ring-Opening of Imidazole-2-ylidenes

The reaction of a series of pyridine-appended imidazolium salts with Pd(COD)Cl2 in the presence of KOtBu as base led to hydrolytic ring-opening followed by a new type of pincer tridentate (N,C,O) bonding of the in situ generated formamide-based new ligands toward the metal center. This unprecedented type of bonding resulted from a vinylic C–H activation by palladium stabilized with coordination from the pyridine nitrogen and aldehyde oxygen donors in a pincer fashion. The new stable, square-planar palladium(II) complexes (1–3) were characterized by 1D and 2D NMR spectroscopic and high-resolution mass spectrometric (HRMS) methods. The single-crystal X-ray structure of a representative complex (2) confirmed the above interesting bonding features.

Synthesis and characterization of a chitosan ligand for the removal of copper from aqueous media

ABSTRACTA novel chitosan derivative, 8‐hydroxyquinioline‐2‐carboxaldehydechitosan (CSHQ) Schiff base, was synthesized by a simple condensation process. The structure of the resulting product was confirmed by Fourier transform infrared spectroscopy, solid‐state 13C‐NMR, differential scanning calorimetry, scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy. Further, the synthesized CSHQ Schiff base was used as an adsorbent for the removal of Cu(II) from aqueous solution. The adsorption of Cu(II) onto CSHQ was strongly dependent on the pH value, and the optimum pH value obtained was pH 5. Among the pseudo‐first‐order (PFO), pseudo‐second‐order (PSO), and intraparticle diffusion model simulation, the experimental data followed PSO kinetics well. The Cu(II) adsorption process onto CSHQ obeyed the Langmuir isotherm model well rather than the Freundlich and Sips isotherm models; this suggested that a monolayer adsorption occurred on the surface of CSHQ. From the overall results, we found that Cu(II) was adsorbed onto CSHQ through oxygen, nitrogen and pyridine nitrogen donor atoms and that CSHQ could be a promising adsorbent for water treatment. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4542–4550, 2013

ChemInform Abstract: Carbonyl Complexes of Rhodium‐ and Iridium‐Containing Nitrogen and Nitrogen—Oxygen Donor Ligands: Reactivity and Catalytic Carbonylation of Alcohol

AbstractReview: 114 refs.

Synthesis, spectroscopic and structural characterization of charge transfer complexes of 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane with iodine, TCNE and TCNQ

Abstract The charge transfer interaction of the interesting mixed nitrogen–oxygen donor 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane (HODABCHC) with σ-electron acceptor iodine and π-acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been investigated spectrophotometrically in chloroform. FT-IR, thermal and elemental analysis measurements are performed for the solid CT-interaction products. The reaction stoichiometries were found to be 1:4, 1:6 and 1:3 donor:acceptor molar ratio for iodine, TCNE and TCNQ reaction systems, respectively. The obtained relatively high reaction stoichiometry values are expected due to the expected high electron donation of the donor (HODABCHC). It contains six oxygen and two nitrogen donor atoms. Accordingly, the formed charge transfer complexes could be formulated as [ ( HODABCHC ) I ] + I 7 - , [(HODABCHC)(TCNE) 6 ] and [(HODABCHC)(TCNQ) 3 ].

Cytotoxic and Antimicrobial Activities of Cu(II), Co(II), Pt(II) and Zn(II) Complexes with N,O‐Chelating Heterocyclic Carboxylates

A series of Cu(II), Co(II), Pt(II) and Zn(II) coordination compounds has been prepared by the reaction of the metal chlorides with pyrazine-2-carboxylic acid, pyridine-2-carboxylic acid, imidazole-4-carboxylic acid, benzimidazole-2-carboxylic acid and 1-methylimidazole-2-carboxylic acid. The complexes were characterized by IR, UV-VIS, elemental analysis, and some by (1) H-NMR, X-ray crystallography, HPLC and LC/MS spectroscopy. All complexes consist of a 2:1 ratio of ligand to metal ion. IR and X-ray crystallography show that coordination is through the nitrogen and carboxylate oxygen donor atoms of the ligand to form chelating rings. DFT calculations predict that the trans-coordinated isomers are thermodynamically more stable than their cis-forms. Only one of five complexes studied by X-ray crystallography, Cu(II) complex of 1-methylimidazole-2-carboxylic acid showed a cis-configured metal ion center. HPLC analysis indicated that Pt(II) complex of 1-methylimidazole-2-carboxylic acid is dominated (>90%) by the trans-configured complex. All other complexes showed one isomer, presumably the trans-form. The cytotoxic activity was investigated in human cancer cell lines in vitro; only the Pt(II) complexes were active. The antimicrobial activity against four bacterial strains and one fungi was estimated by the MIC method and best results were found amongst the Co(II) complexes. These results indicate that trans-coordinated bischelating N,O-heterocyclic carboxylates of Pt(II) are an interesting new class of potential antitumor agents.