Complexes In DMSO Research Articles

Tetrel Bonds between Phenyltrifluorosilane and Dimethyl Sulfoxide: Influence of Basis Sets, Substitution and Competition.

Ab initio calculations have been performed for the complexes of DMSO and phenyltrifluorosilane (PTS) and its derivatives with a substituent of NH3, OCH3, CH3, OH, F, CHO, CN, NO2, and SO3H. It is necessary to use sufficiently flexible basis sets, such as aug’-cc-pVTZ, to get reliable results for the Si···O tetrel bonds. The tetrel bond in these complexes has been characterized in views of geometries, interaction energies, orbital interactions and topological parameters. The electron-donating group in PTS weakens this interaction and the electron-withdrawing group prominently strengthens it to the point where it exceeds that of the majority of hydrogen bonds. The largest interaction energy occurs in the p-HO3S-PhSiF3···DMSO complex, amounting to −122 kJ/mol. The strong Si···O tetrel bond depends to a large extent on the charge transfer from the O lone pair into the empty p orbital of Si, although it has a dominant electrostatic character. For the PTS derivatives of NH2, OH, CHO and NO2, the hydrogen bonded complex is favorable to the tetrel bonded complex for the NH2 and OH derivatives, while the σ-hole interaction prefers the π-hole interaction for the CHO and NO2 derivatives.

Unprecedented formation of a μ‐oxobridged dimeric copper (II) complex: Evaluation of structural, spectroscopic, and electronic properties by using theoretical studies and investigations biological activity studies of new Schiff bases derived from pyrazolone

Novel Schiff base Cu (II) complex was synthesized in the present work through condensation of salicylaldehyde with 4‐aminoantipyrine derivative and characterized by spectral and analytical techniques. Crystal structure of the Cu (II) complex was determined by single‐crystal X‐ray diffraction technique. The structure of the complex is quite unexpected and unprecedented. The observation can be due to the in situ oxidation of the methyl groups of the 4‐aminoantipyrine of the Schiff base ligand to CH2OH. Cu2L2 is a two‐centered Ci‐symmetry complex that is bridged by two oxygen atoms from two ligand molecules, with four‐coordinated Cu (II) ion's in a very regular square‐planar fashion. The electrochemical properties of complex in DMSO displayed the electronic effects on the groups on redox potential. Various computational studies such as DFT (density functional theory), MEPs (molecular electrostatic potential), and HS (Hirshfeld surface analysis) were performed to understand the properties of different interactions of the compounds. The DFT computations, geometry optimization of the ligand, and Cu (II) complex (1) were optimized using the B3LYP method with (6‐311G) basis set. Also, HS analysis is used for decoding intermolecular interactions in the crystal system and contribution of component units for the construction of the 3D architecture. Anticancer effects of the ligand and complex in MTT assay against cancer cell lines SW480 were studied. The antioxidant activity results show that the ligand and complex have antioxidant and anticancer activity. Molecular docking study was also carried out for the complex to find its binding affinity to protein B‐cell lymphorna (BCL‐2, PDB ID: 4LXD).

Effects of metal ion in cationic Pd(II) and Ni(II) phthalocyanines on physicochemical and photodynamic inactivation properties

Four novel tetra non-peripheral 2-hydroxypyridine substituted palladium (II) and nickel (II) phthalocyanines and their quaternized derivatives were synthesized. The phthalocyanines were fully characterized by different spectroscopic methods such as UV-Vis, FT-IR, 1H NMR and MALDI-TOF mass spectrometry. The quaternized phthalocyanines showed solubility in DMSO and water within a wide concentration range and with lack of aggregation behavior. The singlet oxygen generation properties were determined for quaternized phthalocyanine complexes in DMSO, water, and water + TritonX 100 solutions. The uptake capability and in vitro photodynamic activity studies performed on two pathogenic bacteria namely Gram (+) Methicillin-resistant Staphylococcus aureus (MRSA) and Gram (-) Aeromonas hydrophila suggested good potential of palladium (II) phthalocyanine complex (5) for the uptake and inactivation of planktonic cultured bacteria. Significant localization of water-soluble Pd(II) phthalocyanine complex was observed for MRSA biofilms. However, this resulted in low efficiency of pathogen inactivation. The newly synthesized nickel (II) phthalocyanine (6) showed lack of inactivation towards both bacterial strains under the applied mild treatment conditions.

Further exploration of the reaction between cis‐[Fe(CO)4I2] and alkylamines: An aminium salt of fac‐[Fe(CO)3I3]− or an amine‐bound complex of fac‐[Fe(CO)3I2(NH2R)

Four new monoiron (II) tricarbonyl complexes with the amine bound, fac‐[Fe(CO)3I2(NH2R)] (R = Et, 1; nPr, 2; nBu, 3; nPent, 4), were reported using cis‐[Fe(CO)4I2] as the precursor. All the complexes 1–4 were structurally confirmed by various techniques such as ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), and nuclear magnetic resonance (NMR) spectra and elemental analysis of which complexes 1 and 2 are crystallographically determined. The reaction of the precursor with alkylamines proceeded in two main parallel pathways to form both aminium salts of fac‐[Fe(CO)3I3]− and the amine‐bound complexes (1–4). Their dominances altered with the reaction time. These complexes in DMSO undergo quick decomposition with complex 1 as the relatively most stable one (t1/2 = 7.3 min) although they are stable in solid status. Unlike the triiodo anion and pyridinyl analogs showing severe cytotoxicity due to the generation of iodine radical during the decomposition, no iodine radicals were detected from the fac‐[Fe(CO)3I2(NH2R)] complexes. Therefore, the cell viability of RT112 cells was not affected by the presence of the amine‐bound iron complex (1) up to 100 μmol L−1.

Antioxidant vs. Prooxidant Properties of the Flavonoid, Kaempferol, in the Presence of Cu(II) Ions: A ROS-Scavenging Activity, Fenton Reaction and DNA Damage Study.

Kaempferol is a flavonoid that occurs in tea and in many vegetables and fruits, including broccoli, cabbage, beans, grapes, apples, and strawberries. The efficacy of Kaempferol has been demonstrated in the treatment of breast, esophageal, cervical, ovarian, and liver cancers and leukemia, which very likely arises from its prooxidant properties and the activation of pro-apoptotic pathways. Indeed, this matter has already been the focus of a number of published studies and reviews. The aim of the present study was to elucidate the antioxidant vs. prooxidant properties of flavonoids in the presence of the redox-active metal, copper (II) ion, by means of the Fenton reaction. The specific motivation of this work is that, since an increased level of Cu(II) ions is known to be associated with many disease states such as neurological conditions (Alzheimer’s disease) and cancer, any interaction between these ions and flavonoids might affect the outcome of therapeutic uses of the latter. The structure of the Cu-kaempferol complex in DMSO was investigated by means of low temperature EPR spectroscopy, which confirmed the existence of at least two distinct coordination environments around the copper (II) ion. UV vis-spectra of kaempferol and its Cu(II) complex in DMSO revealed an interaction between the 5-OH (A ring) group and the 4-CO (C ring) group of kaempferol with Cu(II) ions. An ABTS assay confirmed that kaempferol acted as an effective radical scavenger, and that this effect was further enhanced in the form of the Cu(II)-kaempferol complex. Quantitative EPR spin trapping experiments, using DMPO as the spin trap, confirmed suppression of the formation of a mixture of hydroxyl, superoxide, and methyl radicals, in a Fenton reaction system, upon coordination of kaempferol to the redox-active Cu(II) ions, by 80% with respect to the free Cu(II) ions. A viscometric study revealed a better DNA-intercalating ability of the Cu-kaempferol complex than for free kaempferol, essential for conferring anticancer activity of these substances. The results of the viscometric measurements were compared with those from a DNA damage study of Cu-kaempferol complexes in a Fenton reaction system, using gel electrophoresis. At low concentrations of kaempferol (Cu–kaempferol ratios of 1:1 and 1:2), a very weak protective effect on DNA was noted, whereas when kaempferol was present in excess, a significant DNA-protective effect was found. This can be explained if the weakly intercalated kaempferol molecules present at the surface of DNA provide protection against attack by ROS that originate from the Fenton reaction involving intercalated Cu(II)-kaempferol complexes. Following the application of ROS scavengers, L-histidine, DMSO, and SOD, gel electrophoresis confirmed the formation of singlet oxygen, hydroxyl radicals, and superoxide radical anions, respectively. We propose that the prooxidant properties of Cu-kaempferol complexes may provide anticancer activity of these substances. When present in excess, kaempferol displays antioxidant properties under Cu-Fenton conditions. This suggests that kaempferol might prove a suitable candidate for the prevention or treatment of oxidative stress related medical conditions that involve a disturbed metabolism of redox metals such as copper, for example, Menkes disease, and neurological disorders, including Alzheimer’s disease. For the potential use of kaempferol in clinical practice, it will be necessary to optimize the dose size and critical age of the patient so that this flavonoid may be beneficial as a preventive drug against cancer and neurological disorders.

Synthesis, spectroscopic study, biological activity and dyeing application of curcumin - Schiff base with various metal ions complexes

A tetradentate (N2O2) Schiff base (H2Ldfm) was successfully synthesized via condensation of curcumin / diferuloylmethane (dfm) and L-leucine amino acid (HL). There were three different methods that used for synthesizing H2Ldfm; (refluxing, grading, and fusion). Ten different metal complexes were also successfully synthesized by combination of the Schiff base (H2Ldfm) and 1,10-phenanthroline (phen) ligand to form a hexadentate (N4O2) mixed ligands (Ldfm, phen) with ten different metal salts (M) where{ M= Al(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Ag(I), Cd(II), Hg(II), and Pb(II)}. The molar ratio of reactants was (1:1:1) (M: H2Ldfm : phen). The new Schiff base and its new complexes were characterized by different physicochemical techniques such as FT-IR, UV-Visible, elemental analysis (C.H.N), 13C-NMR, 1H-NMR, molar conductivity, mass spectroscopy, magnetic susceptibility, and thermal analysis. All complexes exhibited octahedral geometry. The solution conductivity of (Al (III), Fe (III), and Ag(I)) complexes in DMSO shows an electrolytic behavior, while the solution conductivity of (Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Hg(II) and Pb(II)) complexes shows non-electrolytic attitude. The Schiff base (H2Ldfm) and its metal complexes were used for industrial and biological application such as dyeing cotton fibers testing and two types of bacteria testing like (Staphylococcus aureus and Escherichia Coli).

On the molecular basis of H2O/DMSO eutectic mixtures by using phenol compounds as molecular sensors: a combined NMR and DFT study.

NMR and DFT studies of phenol compounds as molecular sensors were carried out to investigate H2O/DMSO eutectic mixtures at a molecular level. The experimental 1H NMR chemical shifts of the OH groups, δexp(OH), of phenol, paracoumaric acid, and vanillic acid show maximum deshielding and, thus, hydrogen bond interactions in the range of mole fractions 0.20 < χ(DMSO) < 0.33. In the mole fractions χ(DMSO) < 0.2, a progressive decrease in δexp(OH) was observed which demonstrates a decrease in hydrogen bond interactions at infinite dilution in H2O, despite the increase in the number of available hydrogen bond acceptor and donor sites. DFT calculated δcalc(OH) of minimum energy solvation clusters were shown to be in reasonable agreement with the pattern in experimental δexp(OH) data. The chemical shift deshielding and, thus, increased hydrogen bond interactions in the natural product + DMSO + nH2O (n = 2, 3) solvation clusters, relative to complexes in DMSO or H2O solutions, cannot be attributed to a single structural parameter of the cooperative interactions between H2O and DMSO molecules with the phenol OH groups of the natural products. The minimum energy conformers of phenol compounds + 2H2O + DMSO complexes are in excellent agreement with a recent low temperature neutron diffraction experiment of 3D2O + DMSO and demonstrate a general structural motif of solvation complexes. The combined use of 1H NMR and DFT studies with emphasis on δ(OH) of phenol compounds, as molecular sensors, can provide an effective method for the study of solute-solvent interactions at the atomic level.

Determination of Stability constants Nickel binary and ternary complexes in aquesous DMSO by Pontentiometric method

The stability constants of some of the binary and ternary system involving Nickel(II) have been studied. Bis-(pyridyl) benzilidene acts as a primary ligand. Glycine, L-alanine, L-phenylalanine, L-leucine and L-valine were acts as a secondary ligand. The stability constants of complex are calculated by SCOGS computer program. The reported values are ± 0.02 log unit accuracy. The protonation constants values increase with an increasing percentage of dimethyl sulphoxide. Protanation constants values for the glycine, L-valine ternary complexes higher stability constants indicate that inductive effect is predominant than steric effect. Whereas L-Phenylalanine ternary system has high stability constants than other ternary complexes due to stacking interaction between phenyl ring of phenylalanine and phenyl ring of primary ligand. The order of stability constant of ternary systems is Ni(bpb)(phe)2 > Ni(bpb)(leu)2 > Ni(bpb)(val)2 > Ni(bpb)(gly)2.

Synthesis, characterization, DNA binding ability, in vitro cytotoxicity, electrochemical properties and theoretical studies of copper(II) carboxylate complexes

Four copper(II) carboxylate complexes, namely [Cu2(μ-3,5-dinitrobenzoate-O,O')4(4-(dimethylamino)benzaldehyde)2] (1), [Cu2(μ-benzoate-O,O')4(benzoic acid)2] (2), [Cu2(μ-benzoate-O,O')4(H2O)2] [Cu(benzoate-O,O')2(imz)2].2H2O (3) and [Cu(benzoate-O,O')2(2-Me-imz)2] (4) (imz = imidazole, 2-Me-imz = 2-methyl-imidazole), were synthesized and comprehensively characterized by elemental analysis, spectroscopic methods, single crystal X-ray diffraction, cyclic voltammetry (CV), topological analysis as well as theoretical studies. Single crystal X-ray diffraction revealed that products 1 and 2 are dinuclear paddle-wheel complexes, compound 3 is a co-crystal containing mononuclear and dinuclear blocks, while compound 4 is a mononuclear complex. Hirshfeld surface analysis of the compounds rationalized different types of hydrogen bonds, which also lead to the generation of H-bonded networks in 3 and 4. Their topological analysis disclosed a uninodal 4-connected 2D layer with sql topology in 3 and a uninodal 2-connected 1D chain with 2C1 topology in 4. The interaction of 1–4 with calf thymus DNA was investigated by UV–visible and fluorescence spectroscopy, revealing a moderately strong non-intercalative mode of interaction. In vitro cytotoxicity study of the complexes on HepG2 (human liver hepatocellular carcinoma) cell lines revealed a significant inhibition activity. Electrochemical study of the complexes in CH3CN (1–3) and DMSO (4) solution showed a one electron transfer corresponding to Cu(III)Cu(II)/Cu(II)Cu(II) and Cu(II)Cu(II)/Cu(I)Cu(II) redox couples. The ΔE and Ipa/Ipc values suggest that the redox couples are quasireversible. The DFT study was performed to further rationalize the crystal structures and nuclearity of the obtained copper(II) complexes.

Bonding Energetics of Palladium Amido/Aryloxide Complexes in DMSO: Implications for Palladium-Mediated Aniline Activation.

Thermodynamic knowledge of the metal-ligand (M-L) σ-bond strength is crucial to understanding metal-mediated transformations. Here, we developed a method for determining the Pd-X (X=OR and NHAr) bond heterolysis energies (ΔGhet (Pd-X)) in DMSO taking [(tmeda)PdArX] (tmeda=N,N,N',N'-tetramethylethylenediamine) as the model complexes. The ΔGhet (Pd-X) scales span a range of 2.6-9.0 kcal mol-1 for ΔGhet (Pd-O) values and of 14.5-19.5 kcal mol-1 for ΔGhet (Pd-N) values, respectively, implying a facile heterolytic detachment of the Pd ligands. Structure-reactivity analyses of a modeling Pd-mediated X-H bond activation reveal that the M-X bond metathesis is dominated by differences of the X-H and Pd-X bond strengths, the former being more influential. The ΔGhet (Pd-X) and pKa (X-H) parameters enable regulation of reaction thermodynamics and chemoselectivity and diagnosing the probability of aniline activation with Pd-X complexes.

Bonding Energetics of Palladium Amido/Aryloxide Complexes in DMSO: Implications for Palladium‐Mediated Aniline Activation

AbstractThermodynamic knowledge of the metal–ligand (M−L) σ‐bond strength is crucial to understanding metal‐mediated transformations. Here, we developed a method for determining the Pd−X (X=OR and NHAr) bond heterolysis energies (ΔGhet(Pd−X)) in DMSO taking [(tmeda)PdArX] (tmeda=N,N,N′,N′‐tetramethylethylenediamine) as the model complexes. The ΔGhet(Pd−X) scales span a range of 2.6–9.0 kcal mol−1 for ΔGhet(Pd−O) values and of 14.5–19.5 kcal mol−1 for ΔGhet(Pd−N) values, respectively, implying a facile heterolytic detachment of the Pd ligands. Structure‐reactivity analyses of a modeling Pd‐mediated X−H bond activation reveal that the M−X bond metathesis is dominated by differences of the X−H and Pd−X bond strengths, the former being more influential. The ΔGhet(Pd−X) and pKa(X−H) parameters enable regulation of reaction thermodynamics and chemoselectivity and diagnosing the probability of aniline activation with Pd−X complexes.

New Palladium(II) and Platinum(II) Complexes Based on Pyrrole Schiff Bases: Synthesis, Characterization, X-ray Structure, and Anticancer Activity.

New palladium (Pd)II and platinum (Pt)II complexes (C1–C5) from the Schiff base ligands, R-(phenyl)methanamine (L1), R-(pyridin-2-yl)methanamine (L2), and R-(furan-2-yl)methanamine (L3) (R-(E)-N-((1H-pyrrol-2-yl) methylene)) are herein reported. The complexes (C1–C5) were characterized by FTIR, 1H and 13C NMR, UV–vis, and microanalyses. Single-crystal X-ray crystallographic analysis was performed for the two ligands (L1–L2) and a Pt complex. Both L1 and L2 belong to P21/n monoclinic and P-1 triclinic space systems, respectively. The complex C5 belongs to the P21/c monoclinic space group. The investigated molar conductivity of the complexes in DMSO gave the range 4.0–8.8 μS/cm, suggesting neutrality, with log P values ≥ 1.2692 ± 0.004, suggesting lipophilicity. The anticancer activity and mechanism of the complexes were investigated against various human cancerous (Caco-2, HeLa, HepG2, MCF-7, and PC-3) and noncancerous (MCF-12A) cell lines using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Apopercentage assays, respectively. C5 demonstrated strong DNA-binding affinity for calf thymus DNA (CT-DNA) with a binding constant of 8.049 × 104 M–1. C3 reduced cell viability of all the six cell lines, which included five cancerous cell lines, by more than 80%. The C5 complex also demonstrated remarkably high selectivity with no cytotoxic activity toward the noncancerous breast cell line but reduced the viability of the five cancerous cell lines, which included one breast cancer cell line, by more than 60%. Further studies are required to evaluate the selective toxicity of these two complexes and to fully understand their mechanism of action.

Tetra-2,3-pyrazinoporphyrazines with peripherally appended pyridine rings. 21. Mono- and pentanuclear FeII complexes: Solid state and solution studies

New Fe[Formula: see text] complexes of formula [Py8TPyzPzFe] · xH2O, its bis-pyridine adduct [Py8TPyzPzFe(py)2] · xH2O, the pentanuclear species [(MCl[Formula: see text]Py8TPyzPzFe] · xH2O (M [Formula: see text] Pd[Formula: see text], Pt[Formula: see text] and the bis-DABCO adducts [Py8TPyzPzFe(DABCO)2] · 11H2O and [(PdCl[Formula: see text]Py8TPyzPzFe(DABCO)2] · H2O (Py8TPyzPz [Formula: see text] octapyridino-tetrapyrazinoporphyrazinato dianion; DABCO [Formula: see text] 1,4-diazabiciclo[2.2.2]octane) were synthesized and characterized by elemental and thermogravimetric analysis, IR and UV-vis spectroscopy, with added studies on the starting complex [Py8TPyzPzFe] · xH2O regarding magnetic and electrochemical behavior. Clathrated water molecules are present in all compounds and have little to no effect on their physicochemical behavior as was observed for all previously reported analogs. UV-vis spectra of the mononuclear [Py8PyzPzFe] · xH2O complex in DMSO and pyridine are indicative of aggregation immediately after dissolving the compound. However, the spectra change slowly over time leading to formation of a porphyrazine species having spectral features typical of a monomer. UV-vis spectra of the parent pentanuclear [(MCl[Formula: see text]Py8TPyzPzFe] · xH2O (M [Formula: see text] Pd[Formula: see text], Pt[Formula: see text] complexes show a smaller degree of aggregation upon dissolution in DMSO or pyridine and the spectra of these solutions also change over time to those of a monomer. The presence of aggregation, spectral evolution with time and final species formed from the N-base adducts [Py8TPyzPzFe(DABCO)2] · 11H2O and [(PdCl[Formula: see text]Py8TPyzPzFe(DABCO)2] · H2O are reported and discussed.

Low-dimensional compounds containing bioactive ligands. Part XIV: High selective antiproliferative activity of tris(5-chloro-8-quinolinolato)gallium(III) complex against human cancer cell lines

Four gallium(III) complexes, [Ga(ClQ)3]⋅MeOH (1 – MeOH), [Ga(ClQ)3] (1), [Ga(BrQ)3] (2), [Ga(dIQ)3] (3) and [Ga(CQ)3] (4), were prepared (H-ClQ = 5-chloro-8-quinolinol, H-BrQ = 7-bromo-8-quinolinol, H-dIQ = 5,7-diiodo-8-quinolinol, H-CQ = 5-chloro-7-iodo-8-quinolinol) and characterised by elemental analysis, IR and NMR spectroscopy. Single crystal structure analysis of 1 – MeOH confirmed that the complex has a molecular structure with gallium(III) metal ion coordinated in mer-fashion by N- and O-donor atoms of three ClQ ligands. Stability of all complexes in DMSO was proved by 1H NMR spectroscopy. The in vitro antiproliferative activity of 1 was evaluated against the A2780, MBA-MB-231 and HCT116 cell lines. Complex 1 displays higher antiproliferative activity (IC50 values in the range 2.1–6 μm) compared to the ClQ ligand and cisplatin; and a significant selective antiproliferative potency (IC50 = 136 μm, for normal MRC5pd30 cell line). Radical scavenging experiments revealed that complex 1 exhibits the highest antioxidant activity of the prepared complexes as well as the ligands.

Development of highly potent Arene-Ru (II)-ninhydrin complexes for inhibition of cancer cell growth

In this communication, two new Ru(II)-arene-ninhydrin complexes [(η6-p-cymene)RuCl(k2-N,O-2-(1,3-dioxo-1,3-dihydro-2H-inden-2-ylidene)hydrazine-1-carboxamide (Ru-1) and [(η6-p-cymene)RuCl(k2-N,S-2-(1,3-dioxo-1,3-dihydro-2H-inden-2-ylidene)hydrazine-1-carbothioamide (Ru-2) have been prepared and analyzed by different analytical and spectroscopic techniques. The studies show that Ru(II) complexes have “piano stool” coordination geometry, comprises of one π-bonded arene centroid, two σ-bonded nitrogen atoms and one chlorine atom from ninhydrin thiosemicarbazole and Ru(II) metal centre respectively. The molar conductivity study of these complexes in DMSO:water (9:1, v/v) media reveals that complexes are ionic in nature. The photo-physical properties of Ru-1 and Ru-2 with calf thymus deoxyribonucleic acid (CT-DNA) and bovine serum albumin (BSA) were explored. The intrinsic binding constant (Kb) of Ru-1 and Ru-2 with DNA/BSA was found to be 4.5 × 105 M−1/1.3 × 105 M−1 and 2.1 × 105 M−1/1.2 × 105 M−1 respectively. The competitive displacement of ethidium bromide (EtBr) from DNA in the presence of Ru-1 and Ru-2 quantified by quenching constant and viscosity studies. This high binding ability is due to groove binding or intercalation of Ru(II) complexes with CT-DNA which is well supported with in-silico studies. The effect of the Ru-1 and Ru-2 were examined on two different cancer cell lines (HeLa and MDA-MB-231) using the MTT assay. The obtained results show that Ru-1 and Ru-2 exhibits high potency and selectivity with HeLa (IC50 = 9.5 × 10−6 mol/L) and MDA-MB-231(IC50 = 14.7 × 10−6 mol/L) cell lines respectively.

Synthesis, spectral characterization and DFT calculations of novel Ag(I) π-coordination polymeric complexes based on N-allylmorpholine-4-carbothioamide

Two complexes of Ag(I) with the N-allylmorpholine-4-carbothioamide (HL) with general formula ([Ag(HL)NO3]·3H2O)n (1) and [Ag(HL)NO3]n (2) were synthesized and isolated in crystalline state. X-ray diffraction study of compounds showed that both complexes are coordination polymers which differ by coordination manners of nitrate anions and presence of cocrystallized water molecules. In solid state in both complexes the ligand molecules are coordinated in bridging mode by μ2-S atom and the CC double bond of the allyl moiety with formation of stable six-membered chelate metallocycles and 1D Ag–S–Ag polymeric chains. However dissolution of the complexes in DMSO leads to cleavage of polymeric chains as well as Ag-(CC) π-coordination bonds, as evidenced by the 1H and 13C NMR spectroscopy data. Crystallographic data have also revealed so-called “additional” coordination of Ag+ ions, which complements the “usual” coordination polyhedra of Ag+ expanding its coordination numbers from 3 to 5 and 6, leading to stabilization of such compounds in solid state. Results of DFT calculation of IR spectra were compared with experimental data and fragmentation of complexes was investigated by MALDI-TOF mass spectrometry and TPD MS methods.

Ultrafast excited state dynamics of biliverdin dimethyl ester coordinate with zinc ions

As one of the biological endogenous pigments, biliverdin (BV) and its dimethyl ester (BVE) have extremely weak fluorescence in solution with quantum yield less than 0.01%. However, the situation reverses with the addition of zinc ions. The strength for fluorescence of BVE-Zn2+ complex is greatly enhanced and fluorescence quantum yield can increase to 5%. Herein, we studied ultrafast excited state dynamics of BVE-Zn2+ complex in ethanol, n-propanol, and DMSO solutions in order to reveal the mechanism of fluorescence quantum yield enhancement. The results show that BVE can form a stable coordination complex with zinc with 1:1 stoichiometry in solution. BVE is structurally and energetically more stable in the complex. Using picosecond time-resolve fluorescence and femtosecond transient absorption spectroscopy, we show that smaller non-radiative rate constant of BVE-Zn2+ complex in DMSO is the key to increasing its fluorescence quantum yield and the excited state decay mechanism is also revealed. These results provide valuable information about the fluorescence property change after BVE binding to metal ions and may provide a guidance for the study of phytochromes or other fluorescence proteins in which BV/BVE acts as chromophores.

Synthesis, Structural and Biological Studies of Some Metal Complexes derived from Tridentate Pyrazole-based Ligand

The new derivatives of heterocyclic resulting, studying spectral Cobalt(II), Nickel(II), Copper(II), and Cadmium (II) with new tridentate ligand namely [3-(1-acetyl-4-[4- (dimethylamino)phenyl]-1H-pyrazol-3-yl)-4-hydroxy-6-methyl-5,6-dihydro-2H-pyran-2-one] which was formed by the (E)-3-(3-(4-(dimethylamino) phenyl)acryloyl)-4-hydroxy-6-methyl- 2H-pyran-2-one with excess of hydrazine monohydrate in glacial acetic acid. NMR, FTIR, MS spectra as well as the elemental analyses, identified the new ligand and TLC was carried out to confirm their structures. The Cobalt (II), Nickel (II), Copper (II) and Cadmium (II) were precipitated by direct reactions of their chlorides with the solution of the ligand in 2:1 molar ratios. All complexes have been identified on the basis of the preliminary analysis, infrared, ultraviolet spectra of the visible moments of magnetic conductivity measurements were conducted for radiation conclude the octahedral geometry around Cobalt (II), Copper (II), and Nickel (II). The Cadmium (II) complex was investigated as tetrahedral in 1:1 ratio. The biological activity of the ligand and its metal complexes in DMSO against some bacterial strains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli and P. aeruginosa). Effected of the syntheses of HL ligand, [Co(L)2] and [Cu(L)2] complexes were studied on Acetylcholinesterase (AChE) in healthy human serum. Results indicated that all of the compounds displayed moderate and selective AChE inhibitory activity. The complexes of [Cu(L)2] and [Co(L)2] showed inhibition constant in the range (Ki: 8.333×10-4, 3.159×10–12, 2.5×10-6, 3.333×10-4 M respectively) higher than HL ligand (1.1×10-4, 1.964×10–12 respectively) M for AChE.

Mononuclear and binuclear dioxidomolybdenum(VI) complexes of ONO appended aroylhydrazone: Crystal structures, interaction energy calculation and cytotoxicity

Mono- and binuclear cis-MoO2 complexes (1–3) having the general formula [MoO2(ISF)D] (D = H2O (complex 1), DMSO (complex 2) and 4,4ꞌ-bipyridine (complex 3) ISF = 3,5-diiodosalicyaldehyde-2-furoichydrazone) have been synthesized and fully characterized by different physico-chemical methods. The molecular structures were confirmed unambiguously by single crystal X-ray diffraction studies. The octahedral geometry around the Mo(VI) central atom is satisfied by O, N, O donor atoms of dideprotonated dianionic hydrazone moiety, two oxido oxygens and oxygen/nitrogen atoms of the coordinated solvent molecules. The asymmetric unit of complexes 1 and 2 contains one molecule whereas complex 3 contains only half of the molecule. The 4,4ꞌ-bipyridine molecule acts as a linker that links the two asymmetric MoO2D moieties to form the binuclear dioxidomolybdenum(VI) in complex 3 with Mo⋯Mo non-bonding distance of 12.01(10) Å. The relevance of hydrogen bonding and non-bonding interactions in the construction of supramolecular architectures were investigated. The upshots of single crystal studies were reproduced with the aid Hirshfeld surface studies. The pre-eminence of dispersion energy component over other components was established by interaction energy calculations and the energy framework analysis. The average interaction energy values for complexes 2 and 3 are found to be −282.3 and −228.3 kJ mol−1 respectively. Furthermore the in vitro cytotoxicity of all the synthesized compounds was evaluated against lymphoma ascites cell line.

Tetra-2,3-pyrazinoporphyrazines with Peripherally Appended Pyridine Rings. 20. Mono- and Pentanuclear AlIII and GaIII Complexes: Synthesis and Physicochemical and Photoactivity Studies.

The autocyclotetramerization of the precursor 2,3-dicyano-5,6-di(2'-pyridyl)pyrazine [(CN)2Py2Pyz] in the presence of MCl3 compounds (M = AlIII, GaIII) leads to the formation of the new mononuclear porphyrazine complexes [Py8TPyzPzMCl]·xH2O (Py8TPyzPz = tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazinato anion). From these species, the hydroxide analogues [Py8TPyzPzMOH]·xH2O were obtained by contact with hot water, and their corresponding pentanuclear species [(PdCl2)4Py8TPyzPzMCl]·xH2O could be easily formed by the reaction with PdCl2. Physicochemical characterization of the mono- and pentanuclear macrocycles was based on elemental analysis, and mass, powder X-ray, and IR spectra. UV-vis spectral studies of the mononuclear species in solutions of DMF, DMSO, or pyridine (c ≈ 10-5-10-6 M) indicate (mainly in DMF and DMSO) the initial presence of aggregation, in some cases accompanied by the concomitant occurrence for the complex of a one-electron reduction. While disaggregation into a single species evolves spontaneously over time, the -1 charged species, eventually also found present, can be brought back to its neutral form by addition of a slight amount of HCl, the final spectrum showing the presence of the starting neutral species in its pure monomeric form. Similar aspects were faced also for the parent pentanuclear complexes. Cyclic voltammetry experiments, conducted for the mono-/pentanuclear complexes in DMF and DMSO (c ≈ 10-4 M), exhibit progressive one-electron reductions (1 → 4) characterized by E1/2 values (V vs SCE) positioned to significantly less negative values than those known for the phthalocyanine (Pc) analogues, these data confirming the previously already proven higher electron-deficient character of the MII derivatives of the Py8TPyzPz macrocycle with respect to Pc. The role of the present new series of AlIII and GaIII macrocyclic species to act as photosensitizers for the generation of singlet oxygen, 1O2, the cytotoxic agent in the anticancer treatment known as photodynamic therapy (PDT), has been explored in DMF/HCl. Among the quantum yields ΦΔ, the value found for the GaIII complex [Py8TPyzPzGaCl] (0.68), practically coincident with that observed for the TTDPz analogue (0.69), is well above those of most porphyrazines analogues (ΦΔ = 0.4-0.6), a result encouraging further research work for potential applications in the biochemical field.