Synthesis,structure, and DNA-binding studies of a dicopper(II) complex with N-phenolato-N′-[2-(dimethylamino) ethyl]oxamide as ligand

A new µ-oxamido-bridged dicopper(II) complex, [Cu₂(pdmaeox)(bpy)(H₂O)](pic)?·?H₂O [H₃pdmaeox?=?N-phenolato-N′-[2-(dimethylamino)ethyl]oxamide, Hpic?=?2,4,6-trinitrophenol, bpy?=?2,2′-bipyridine], has been synthesized and characterized by elemental analyses, molar conductivity measurement, infrared, and electronic spectra studies, and X-ray single-crystal diffraction. The complex crystallizes in the triclinic system, P 1 space group, with crystallographic data: a?=?10.7815(2)?Å, b?=?11.3598(2)?Å, c?=?14.1389(3)?Å, and z?=?2. In [Cu₂(pdmaeox)(bpy)(H₂O)]⁺, one copper(II) resides in the inner site with a square-planar coordination geometry and the other is chelated by the two exo-oxygen atoms of the cis-pdmaeox^3? ligand in a square-pyramidal environment. The Cu···Cu separation through cis-pdmaeox^3? bridge is 5.1834(4)?Å. The crystal structure is stabilized by hydrogen bonds and π–π stacking interactions. The interaction of the dicopper(II) complex with herring sperm-DNA (HS-DNA) has been investigated by electronic absorption titration, fluorescence titration, electrochemical titration, and viscosity measurements. The results reveal that the interaction of the dicopper(II) complex with HS-DNA might be electrostatic binding. The effects of bridging ligand on the interaction of the dinuclear complex with HS-DNA were preliminarily investigated.     

Radical cyclization of α-bromo aluminum acetals onto alkenes and alkynes (radic[Al] process): a simple access to γ-lactols and 4-methylene-γ-lactols

An efficient preparation of γ-lactols and methylene-γ-lactols is described. Highly acid-sensitive lactols are prepared in a concise manner by using a radical cyclization of aluminum acetals. The precursors for the radical reactions are readily prepared from allyl or propargyl alcohols and α-bromo acids. Functionalization of the resulting γ-lactols and methylene-γ-lactols can be achieved following isolation, leading to synthetically useful building blocks, such as 1,4-diols, 1,4-dienes, γ-lactones, and polysubstituted tetrahydrofurans.     

Synthesis,Structure and DFT Calculations of a Novel Copper(Ⅱ) Complex Based on Tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate

A novel copper(Ⅱ) complex with tert-butyl 2-[N-(tert-butyloxycarbonylmethyl)-2-picolyamino]acetate(ampy) was synthesized and structurally characterized by elemental analysis, FT-IR spectrum, electrospray ionization-mass spectrometry, UV-vis spectrum and single-crystal X-ray diffraction, respectively. A mononuclear copper(II) complex with ampy, [Cu(ampy)Cl2](1), was formed irrespective of the metal-to-ligand molar ratios([Cu2+]:[ampy] = 0.5:1, 1:1, and 2:1) as a single product. Complex 1 crystallizes in the orthorhombic system, space group Pbca with a = 12.343(2), b = 18.928(3), c = 20.058(4) ?, V = 4686.1(14) ?3, Z = 8, Dc = 1.3349(4) g/cm~3, F(000) = 1920, S = 1.016, R = 0.0693 and w R = 0.1721 for 3151 observed reflections with I 2σ(I). X-ray diffraction analysis reveals that the central copper(II) ion is bound by pyridyl N, tertiary amine N and carbonyl O atoms of the quadridentate ampy as well as two Cl anions, constructing a slightly distorted octahedral geometry. Complex 1 further constructs a stable 3D supramolecular architecture by intermolecular C–H···Cl hydrogen bonds. In addition, the molecular geometry was calculated by density functional theory(DFT/B3LYP) method with the basis sets(6-31+G(d,p) for H, C, N, O and Cl atoms, and LANL2 DZ for Cu atom, respectively). The calculated results show that the optimized geometrical parameters are in good agreement with the experimental data. Natural bond orbital(NBO) analysis and frontier molecular orbitals(FMOs) analysis were investigated at the same level.     

Crystal Structure and Antitumor Activity of Tri[2- [N-(4''''-methyl-benzylsulfonyl)amino]ethyl]-amine

1 INTRODUCTION The supramolecular architectures of tripodal ligands with special cavities have attracted much attention of chemists and biochemists because of their interesting structures and possible properties such as ion and molecular recognition, selective inclusion and important biological function[1～5]. However, their potential applications in supra- molecular and biological chemistry for constructing various complexes have not been clearly realized until recent years. Few crystal…     

Synthesis, characterization and electrical conductivity of poly [ethyl trifluorobuty-2-noate]

Poly[ethyl trifluorobuty-2-noate] (PETFB) was prepared from ethyltrifluorobuty-2-noate by anionic polymerization.The polymer was examined by UV-Vis,IR and NMR spec-trometries.It possessed π-conjugated backbone in the main chain.No significant variation in the electrical conductivity of BF3-doped PETFB was observed after more than three months' storage,indicating improved conductive stability in air as compared with polyacetylene.     

4,5-Dihydroxyimidazolidin-2-ones in an α-ureidoalkylation reaction of N-(carboxyalkyl)-, N-(hydroxyalkyl)-, and N-(aminoalkyl)ureas 3. α-Ureidoalkylation of N-[2-(dimethylamino)ethyl]urea

α-Ureidoalkylation of N-[2-(dimethylamino)ethyl]urea with 1,3-unsubstituted, 1,3-dialkyl-, and 1,3-dimethyl-4,5-diphenyl-4,5-dihydroxyimidazolidin-2-ones(thiones) was systematically studied. Hitherto unknown N-[2-(dimethylamino)ethyl]glycolurils and their hydrochlorides were synthesized. The yields of the target glycoluril hydrochlorides decreased on going from 1,3-H₂- to 1,3-dialkyl-4,5-dihydroxyimidazolidin-2-ones and increased with the introduction of phenyl groups at the positions 4 and 5 of the starting 4,5-dihydroxyimidazolidin-2-one. X-ray diffraction study showed that 2-[2-(dimethylamino)ethyl]glycoluril crystallizes in the form of a conglomerate.     

Crystal structure and DNA interaction of a nickel(II) complex with N-benzyl-N ′-[2-(benzylamino)ethyl]ethane-1,2-diamine

N-Benzyl-N′-[2-(benzylamino)ethyl]ethane-1,2-diamine was prepared by reduction of its Schiff base analog. Its Ni(II) complex was synthesized and characterized. The crystal structure of the complex showed a square pyramidal structure in which a chlorine atom bridges two Ni(II) atoms in the common apical position. The dinuclear complex has two identical five-coordinate Ni(II) atoms. Interaction of the complex with calf thymus DNA was investigated by UV spectroscopy and fluorescence spectroscopy, and the results suggest that the complex binds to DNA by electrostatic interactions only. The binding constant is 1.02 × 10⁴ mol⁻¹ L.     

Synthesis and Solvolysis of [(ω-(Dimethylphenoxysilyl)alkyl]-diphenylphosphines,Phosphine Oxides and Phosphine Sulfides

Abstract

Kinetics of base catalysed solvolytic cleavage of phenoxy group from compounds of general structure X (CH₂)nSiMe₂OPh, where n=1,2,3 and X=Me,Ph₂P, Ph₂P (p), Ph₂P(s) has been investigated. The main purpose was to study the effect of phosphorus groups on the reactivity in substitution reaction at silicon. We wanted to answer the question whether there is any direct interaction of the phosphorus groups with silicon moiety, modifying this reactivity. Complementary NMR studies have also been performed for this purpose.     

Synthesis,characterisation and photoswitchability of a new [2]rotaxane of α-cyclodextrin with a diazobenzene containing π-conjugated molecular dumbbell

In this work, a new [2]rotaxane consisted of a diazobenzene containing π-conjugated linear compartment, including the 4,4′-bipyridyl moiety and α-cyclodextrin (α-CD) as the macrocyclic compartment, was synthesised with yields of nearly 57% and fully characterised. α-CD easily assembled with the linear compartment and suitable bulky ends (stoppers) in water to give a new [2]rotaxane. The characterisation of this supramolecular compound was accomplished using several spectroscopic techniques such as ¹H NMR, ¹³C NMR and 2D NMR spectroscopy, powder X-ray diffraction, fourier transform infrared spectroscopy, induced circular dichroism and UV–vis spectrophotometry, as well as scanning electron microscopy and Energy Dispersive X-ray. Furthermore, the reversible E–Z photoisomerisation of both [2]rotaxane and its molecular dumbbell was investigated by irradiation with UV light.     

Synthesis of α-[2-(2, 4-Dichlorophenoxy) Propionyloxy] Alkyl Phosphonates

Somenewphosphonatederivativeshaveshownexcellentbiologicalactivityandthusdrewourincreasingattention.DUringpastfewyears,wehavesynthesizedandstudiedseveralseriesofthiskindofcompoundswhichhaveherbicidalactivity.['1Amongthem,astriesofsubstitutedphenoxyacetoxyalkylphosphonatesisatypicalone,andsomecompoundsexhibitbetterherbicidalactivities.Inordertoexaminefurtherintotheher-bicidalactivitiesofnewphosphonatederivatives,wedesignedanothernewcompoundsQ-L2-(2,4-dichlorophenoxypropionyloxy)Jalkylphosphona…     

Mechanism and selectivity of nickel-catalyzed [3 + 2] cycloaddition of cyclopropenones and α,β-unsaturated ketones: A computational study

Density functional theory calculations have been performed to investigate the nickel-catalyzed [3 + 2] cycloaddition of cyclopropenones and α,β-unsaturated ketones. The computations show that the overall catalytic cycle consists of four major steps, including: (1) C-C oxidative addition of the cyclopropenone to afford the four-membered nickelacycle, (2) isomerization, (3) migratory insertion via a 4,1-insertion fashion, and (4) C-C reductive elimination to deliver the [3 + 2] cycloaddition product. The enantioselectivity is mainly attributed to the π-π interaction between the diphenylcyclopropenone moiety and the phenyl substituent of the oxazoline ring of the ligand. The chemoselectivity of the C = O versus C = C insertion was rationalized in terms of the steric effect.     

Reaction of [HO(CH2)3]3P with α,β-Unsaturated Ketones Containing a Phenylpropanoid Backbone

Abstract

Interaction of 3,4-(MeO)₂-benzylideneacetone with [HO(CH₂)₃]₃P (THPP) was studied in CD₃OD by NMR to compare reactivity of a phenylpropanoid α,β-unsaturated ketone with a corresponding α,β-unsaturated aldehyde. In the presence of HCl, both the ketone and a related cinnamaldehyde first establish an equilibrium with the product formed by nucleophilic attack of the THPP at the C?O bond, [ArCH?CHCX(OD)PR₃]⁺Cl^?(X?H or CH₃, Ar?Ph or 3,4-(MeO)₂C₆H₃). The ketone salt then slowly transforms into [R₃PCH(Ar)CH(D)C(O)CD₃]⁺Cl^?, the phosphonium product of nucleophilic attack of THPP at the C?C bond, whereas the final product from the aldehyde is the (α-ether)phosphonium chloride [ArCH?CHCH(OCD₃)PR₃]⁺Cl^?. In aqueous media, in the absence of HCl, 4-HO-benzylideneacetone, which is similar to a lignin-type, α,β-unsaturated aldehyde model compound, interacts with THPP to afford a stable phosphonium zwitterion, in contrast to the previously studied aldehyde model, which forms dimeric, bisphosphonium products.     

Synthesis, crystal structure, cytotoxicities and DNA-binding properties of a tetracopper(II) complex with N-benzoato-N′-[2-(2-hydroxyethylamino)ethyl-amino]oxamide ligand

A new dissymmetrical N,N??-bis(substituted)oxamide ligand, N-benzoato-N??-[2-(2- hydroxyethylamino)ethyl]oxamide (H₃bhyox), and its tetranuclear copper(II) complex, [Cu₄(bhyox)₂(dabt)₂](ClO₄)₂ (1) have been synthesized and characterized (dabt?=?2,2??-diamino- 4,4??-bithiazole). The crystal structures of H₃bhyox and complex 1 have been determined by X-ray single-crystal diffraction. Complex 1 has a cyclic tetranuclear cation with an embedded inversion center, in which the Cu?CCu separations through the oxamido and carboxyl bridges are 5.2246(6) and 5.3141(6) ?, respectively. Both Cu(II) centers at the inner and outer sites of the cis-bhyox^3? ligand have square pyramidal geometries. There is a 3D hydrogen-bonding network in the crystal. The cytotoxicities and DNA-binding properties of H₃bhyox and complex 1 were studied. Both compounds can interact with HS?CDNA by intercalation, and the DNA-binding affinities are consistent with their in vitro cytotoxicities.     

Understanding the regio- and chemoselective polar [3+2] cycloaddition of the Padwa carbonyl ylides with α-methylene ketones. A DFT study

The regio- and chemoselective polar [3+2] cycloaddition (32CA) of the Padwa carbonyl ylide (CY) with α-methylene ketone (αMK) to yield the oxa-bridged spirocycloadduct has been studied using the DFT method at the B3LYP/6-31G(d) computational level. Six reactive channels associated to the stereo-, regio-, and chemoselective approach modes of the CY to the CC and CO reactive sites of the αMK have been analyzed. DFT calculations for this cycloaddition are in complete agreement with the experimental outcome, explaining the reactivity and selectivity of the formation of the [3+2] cycloadduct. Analysis of the global and local electrophilicity and nucleophilicity indices allows an explanation about the regio- and chemoselectivity of this 32CA reaction. Intrinsic reaction coordinate (IRC) calculations and the topological analysis of the electron localization function (ELF) of the relevant points of the favored reactive channel explain the one-step two-stage nature of the mechanism of this cycloaddition.     

2-[1-(Dimethylamino)ethyl]ferrocenylphosphinic acid as an organocatalyst of Michael and Friedel—Crafts reactions

Russian Chemical Bulletin - Racemic 2-[1-(dimethylamino)ethyl]ferrocenylphosphinic acid was tested as an organocatalyst in the Michael and Friedel—Crafts reactions. The use of this zwitterion...     

Hydrogen fluoride adsorption and reaction on the α-Al2O3(0001) surface: a density functional theory study

The adsorption and reaction behaviors of HF on the α-Al(2)O(3)(0001) surface are systematically investigated using density functional theory method. By increasing the number of HF molecules in a p(2 × 1) α-Al(2)O(3)(0001) slab, we find that HF is chemically dissociated at low coverage; while both physical and dissociative adsorption occurs at a 3/2 monolayer (ML) coverage. At the same coverage (1.0 ML), diverse configurations of the dissociated HF are obtained in the p(2 × 1) model; while only one is observed in the p(1 × 1) slab due to its smaller surface area compared with the former one. Preliminary fluorination reaction study suggests that the total energy of two dissociated HF in the p(2 × 1) slab increases by 1.00 and 0.72 eV for the formation and desorption of water intermediate, respectively. The coadsorption behaviors of HF and H(2)O indicate that the pre-adsorbed water is unfavorable for the fluorination of Al(2)O(3), which is well consistent with the experimental results. The calculated density of states show that the peak of σ(H-F) disappears, while the peaks of σ(H-O) and σ(Al-F) are observed at -8.4 and -5 to -3 eV for the dissociated HF. Charge density difference analysis indicates that the dissociated F atom attracts electrons, while no obvious changes on electrons are observed for the surface Al atoms.     

Host–guest complexation of a nitroheterocyclic compound with cyclodextrins: a spectrofluorimetric and molecular modeling study

Nitroheterocyclic compounds (NC) were candidate drugs proposed for Chagas disease chemotherapy. In this study, we investigated the complexation of hydroxymethylnitrofurazone (NFOH), a potential antichagasic compound, with α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), Hydroxypropyl-β-cyclodextrin (HP-β-CD), Dimethyl-β-cyclodextrin (DM-β-CD) and γ-cyclodextrin (γ-CD) by fluorescence spectroscopy and molecular modeling studies. Hildebrand–Benesi equation was used to calculate the formation constants of NFOH with cyclodextrins based on the fluorescence differences in the CDs solution. The complexing capacity of NFOH with different CDs was compared through the results of association constant according to the following order: DM-β-CD > β-CD > α-CD > HP-β-CD > γ-CD. Molecular modeling studies give support for the experimental assignments, in favor of the formation of an inclusion complex between cyclodextrins with NFOH. This is an important study to investigate the effects of different kinds of cyclodextrins on the inclusion complex formation with NFOH and to better characterize a potential formulations to be used as therapeutic options for the oral treatment of Chagas disease.     

Iridium-catalyzed [2 + 2 + 2] cycloaddition of α,ω-diynes with nitriles

[Ir(cod)Cl](2)/DPPF or BINAP efficiently catalyzed the cycloaddition of α,ω-diynes with nitriles to give pyridines. The reaction can accommodate a very wide range of nitriles. Both aliphatic and aromatic nitriles smoothly reacted with α,ω-diynes to give pyridines. Ten equivalents of unactivated aliphatic nitrile were enough to give the product in high yield. Aliphatic nitriles bearing an acetal or amino moiety could be used for the reaction. The highly regioselective cycloaddition of unsymmetrical diyne bearing two different internal alkyne moieties was achieved. The observed regioselectivity could be reasonably explained by considering the different reactivities of the α-position in iridacyclopentadiene. Regioselective cycloaddition was successfully applied to the synthesis of terpyridine and quinquepyridine. This chemistry was extended to a new and efficient synthesis of oligoheteroarenes. Five aromatic or heteroaromatic rings were connected in a single operation. [Ir(cod)Cl](2)/chiral diphosphine catalyst can be applied to enantioselective synthesis. Kinetic resolution of the racemic secondary benzyl nitrile catalyzed by [Ir(cod)Cl](2)/SEGPHOS gave a central carbon chiral pyridine in 80% ee. The mechanism was analyzed on the basis of the B3LYP level of density functional calculations.