The interaction of Cu^2+ complex of N,N'-bis(2-aminoethyl)-2,6-pyridinedicarboxamide (BAP) with DNA was studied by agarose gel electrophoresis analysis. The results indicate that the BAP-Cu^2+ complex can promote the cleavage of phosphodiester bond of supercoiled DNA at physiological condition, which is 3.2 × 10^6 times higher than DNA natural degradation. A hydrolytic cleaving mechanism through the cooperation of copper ions and functional amino groups was proposed. 相似文献
Hydrazone-based receptor containing electron-withdrawing chromogenic substituents 1,10-phenanthroline-2,9-di-carboxaldehydic-(2,4-dinitrophenyl)-hydrazone
(1) has been synthesized. The interaction with different anions via hydrogen bonding was demonstrated by UV-Vis absorption spectroscopy
to give a purple 1:1 complexes in DMSO, whose association constant decreases in line with the following order of the studied
anions (AcO− > F− > H2PO4− > OH− >>Cl−∼Br−∼I−). As a naked-eyes colorimetric sensor for anions, the study has a latent application importance.
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In the present study, structures and electronic properties of inclusion complexes of TMeQ[6] with PZ+ and CHCl3 were investigated, using the density functional theory calculations and molecular dynamic (MD) simulations. Theoretical results at the M05-2X-D3/6-31G(d) level clearly confirm that the inclusion complex formation is energetically feasible, and PZ+@TMeQ[6] formation is more favorable than CHCl3@TMeQ[6]. Natural bond orbital and quantum theory of atoms in molecules analyses were applied to investigate the electron transfer and topological properties of the interactions of TMeQ[6] and guest compounds. Non-covalence nature, van der Waals, of the host–guest interactions was confirmed by non-covalent interactions–reduced density gradient method. Finally, the effect of solvent was taken into account by using the MD simulations. According to H-bond analysis in the MD simulations, the importance of hydrogen bonding interactions was confirmed only in PZ+@TMeQ[6] complex, the studied inclusion complexes are more stable in chloroform, because of a high value of van der Waals interactions. This study show that TMeQ[6] as a good candidate for sensing.
Graphical Abstract
A joint MD/QM study confirms the side chain effect of PZ+ on the response ability improvement of TMeQ[6].
Macro-cyclic ligands from adipic acid, ethylenediamine with diethyloxalate and diethylmalonate and their respective metal complexes of Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) with macro cyclic ligands (LO) and (LM) L [N,N′-bis(2-aminoethyl)hexanediamide] were synthesized successfully. These metal complexes were characterized by Fourier transform infrared, ultraviolet visible spectrometry, proton nuclear magnetic resonance spectroscopy, and mass Spectrometry, CHNS and thermogravimetric analysis. The elemental analysis confirms the structures for Mn(II), Co(II) and Ni(II) complexes similar to octahedral geometry, Cu(II) complexes as a square planar geometry and Zn(II) complexes in the tetrahedral geometry. The molar conductivities of all the metal complexes were taken in 10?3 M DMSO, and values of all the metal complexes showed their electrolytic nature which indicates the presence of chloride ions. Thermal analysis supports as the metal complexes are thermally stable. The result of antimicrobial activity against various microorganisms confirms that the metal complexes are potent bactericides and fungicides than the ligand. Metal complexes of LO with Cu(II) and Zn(II) were found to be highly active against S. typhimurium than the complexes of LM.
Circularly polarized luminescence (CPL) organic dyes are currently receiving a great interest, but there are still not many reported observations of CPL spectra of hydrophobic dyes from aqueous solution. We have prepared hydrophobic pyrene derivatives and dissolved them into aqueous solutions with γ-cyclodextrin (γ-CD) by using grinding technique. Among these derivatives, (pyrene-1-carbonyl)serine (PySer) forms a spatially restricted dimer in the hydrophobic chiral cavity of γ-CD and exhibits excimer emission with a high quantum yield of Φf?=?0.68. In addition, circular dichroism and CPL signals were induced for the complex. The strong gCPL value of gCPL?=?+?2.2?×?10?3 was obtained, which may be attributed to the interaction between the hydroxyl groups in the side chain of PySer with those of γ-CD and it strengthens the chiral dimeric structure.
We quantitatively modeled the volume phase transition of a hydrogel containing a crystalline colloidal array with a crown
ether ligand which binds Pb2+. The hydrogel volume response and the wavelength diffracted depend on the Pb2+ concentration and on both the ionic strength and the valence of the nonbinding ionic species. We successfully modeled the
response of this hydrogel Pb2+ sensor to ionic strength and the cation valence of the added salts.
Figure Cation identity dependence of crown ether photonic crystal Pb+ sensing 相似文献
Electron capture dissociation (ECD) and electron transfer dissociation (ETD) in metal-peptide complexes are dependent on the metal cation in the complex. The divalent transition metals Ni2+, Cu2+, and Zn2+ were used as charge carriers to produce metal-polyhistidine complexes in the absence of remote protons, since these metal cations strongly bind to neutral histidine residues in peptides. In the case of the ECD and ETD of Cu2+-polyhistidine complexes, the metal cation in the complex was reduced and the recombination energy was redistributed throughout the peptide to lead a zwitterionic peptide form having a protonated histidine residue and a deprotonated amide nitrogen. The zwitterion then underwent peptide bond cleavage, producing a and b fragment ions. In contrast, ECD and ETD induced different fragmentation processes in Zn2+-polyhistidine complexes. Although the N–Cα bond in the Zn2+-polyhistidine complex was cleaved by ETD, ECD of Zn2+-polyhistidine induced peptide bond cleavage accompanied with hydrogen atom release. The different fragmentation modes by ECD and ETD originated from the different electronic states of the charge-reduced complexes resulting from these processes. The details of the fragmentation processes were investigated by density functional theory.
The cyclen based pyridine complexes 1Ln-3Ln (Ln = La(III) and Eu(III)) were synthesised as metallo-ribonuclease mimics and their ability to hydrolytically cleave the phosphodiester of HPNP at 37 °C was investigated using UV-vis spectroscopy, whereas the binding of the substrate was evaluated using 31P NMR and Eu(III)-luminescent measurements. In contrast 2La gave rise to fast pH dependent hydrolysis of HPNP, with maximum efficiency at ca. pH 8.2, and with a half-lifetime of ∼1 h, the 1Ln and 3Ln complexes were found to be inactive, emphasizing the importance of the nature of the pyridine isomer as a cofactor in the hydrolytic process. 相似文献
Novel cyclen copper(II) complexes appending different side arms were synthesized as DNA cleavage agents. Both the intermediates
and mononuclear complexes were characterized by 1H NMR, ESI-HRMS, Elemental analyses and IR, and their catalytic activities for DNA cleavage and DNA binding abilities were
investigated. The results indicate that the copper(II) complexes could catalyze the cleavage of supercoiled DNA (pUC 19 plasmid
DNA) under physiological conditions to produce nicked DNA with high yields (nearly 100%) via an oxidative mechanism in the
absence of exogenous agents; The copper complex bearing an 9-anthryl group gave superior DNA interactions to those bearing
phenyl or methyl groups. 相似文献
Abstract Cholesterol complexes with tri-n-butyl phosphate, tri-n-octylamine, N,N-dimethylacetamide, and cyclohexanone in benzene and toluene solutions were studied using conventional IR spectroscopy. The
spectra were recorded in the region of fundamental OH stretching (3,700–3,100 cm−1) at 298 K. The experimental spectra were resolved into bands corresponding to the cholesterol monomer and particular oligomeric
and complex species. The formation constants of complexes were determined from the-least squares plots of the linearized expressions
of Bjerrum’s formation function. The stoichiometry of complexes was also identified in this way. The identification of the
particular resolved bands was performed from their location, and from the dependence of their intensity on the cholesterol
monomer and free base concentration.
Graphical Abstract
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Abstract A EuIII cryptate complex constructed from a CuII cryptand with an LtBu ligand, [EuIIICu2II(LtBu)2(NO3)3(MeOH)], and the corresponding CaII and NaI cryptates, [CaIICu2II(LtBu)2(NO3)2(MeOH)2] and [NaICu2II(LtBu)2(Me2CO)](BPh4), have been synthesized and characterized in order to shed light on the essential role of CuII in the luminescence of a EuIII cryptate. The unprecedented role of a CuII cryptand makes it possible to produce lanthanide luminescence in a EuIII cryptate complex and is successfully elucidated by comparison with the corresponding CaII and NaI cryptates.
Graphical abstract
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Understanding the molecular mechanism of HIV-1 integrase (IN) activity is critical to find functional inhibitors for an effective
AIDS therapy. A robust, fast, and sensitive method for studying IN activity is required. In this work, an assay for real-time
label-free monitoring of the IN activity based on surface plasmon resonance was developed. This assay enabled direct monitoring
of the integration of a viral doubled-stranded (ds) DNA into the host genome. The strand transfer reaction was detected by
using two different DNA targets: supercoiled plasmid (pUC 19) and short palindrome oligonucleotide. The effect of the length
of the DNA target on the possibility to monitor the actual process of the strand transfer reaction is discussed. The surface
density of integrated ds-DNA was determined. IN binding to the oligonucleotide complexes and model DNA triplexes in the presence
of various divalent ions as metal cofactors was investigated as well. The assay developed can serve as an important analytical
tool to search for potential strand transfer reaction inhibitors as well as for the study of compounds interfering with the
binding of ds long terminal repeats–IN complexes with the host DNA.
HIV-1 integrase strand transfer activity was monitored in real time using a multichannel surface plasmon resonance biosensor.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
Stability constants of 1 : 1 16-crown-5 (16C5)-metal ion complexes were determined in water at 25°C by conductometry and potentiometry with ion-selective electrodes. The selectivity sequences of 16C5 in water for univalent and bivalent metal ions are Ag+ > Na+ Tl+ > K+ and Sr2+ > Ba2+ Pb2+, respectively. The stability of a given 16C5-metal ion complex in water is much lower than might be expected on the basis of the solvation power (i.e. relative solubility of the metal ion) of water for the metal ion. The same tendency is observed for the cases of 15-crown-5 (15C5) -metal ion complexes. Transfer activity coefficients () of 15C5 and 16C5 for tetradecane (TD)/water, TD/methanol, TD/acetonitrile, and propylene carbonate/water systems were determined at 25°C. From these data, contributions of a methylene group and an ether oxygen atom to the log value of a crown ether were then obtained. The values from water to acetonitrile, propylene carbonate, and methanol of 15C5- and 16C5-univalent metal ion complexes
were calculated, s, M+, and L being a solvent, a univalent metal ion, and a crown ether, respectively. The log
value is greater than the corresponding log
value. The log
values are negative. This indicates that, although the M- ions are more soluble in water than in the nonaqueous solvents, when the crown ether forms a complex with the M+ ion, the complex becomes more soluble in the nonaqueous solvents than in water, compared with the free crown ether. It was concluded from this finding that the unexpectedly low stability of the crown ether-M+ complex in water is attributed to strong hydrogen bonding between ether oxygen atoms of the free crown ether and water. 相似文献
A new method for the highly sensitive and selective determination of boron at nanograms per cubic decimeter levels has been
developed based on the derivatization reaction of boron using salicylaldehyde and 1-amino-8-naphtol-3,6-disulfonate with reversed-phase
partition high-performance liquid chromatography. A detection limit as low as 2.0 nmol/dm3 (22 ng/dm3) was achieved without any preconcentration. No significant interference was observed in the determination of 16 μmol/dm3 of boron with the addition of nine metal ions (AlIII, CuII, CoII, FeII, FeIII, NiII, MnII, VV, ZnII) at concentrations 100 times greater than that of boron without any masking procedure. The proposed method was successfully
applied to the determination of boron in river water, tap water, doubly distilled water, and highly purified water.
Figure Scheme of formation of boron-azomethine-H complex with salicylaldehyde and 1-amino-8-naphthol-3, 6-disulfonate 相似文献
This work demonstrates the capabilities of nanoscale secondary-ion mass spectrometry, using the Cameca NanoSIMS50 ion microprobe,
to detect and image the copper-ion distribution in microalgal cells exposed to nanomolar and micromolar copper concentrations.
In parallel to 63Cu− secondary-ion maps, images of 12C−, 12C14N−, and 31P− secondary ions were collected and analysed. A correlation of 63Cu− secondary-ion maps with those found for 12C14N− and 31P− demonstrated the possible association of Cu with cell components rich in proteins and phosphorus. The results highlighted
the potential of NanoSIMS for intracellular tracking of essential trace elements such as Cu in single cells of the microalga
Chlorella kesslerii.
Figure
12C14N-, 63Cu- secondary-ion distributions in algal cell 相似文献
Abstract The stability constant of the dibenzo-18-crown-6·H3O+ cationic complex species dissolved in nitrobenzene saturated with water has been determined from extraction experiments in
the two-phase water–nitrobenzene system and from γ-activity measurements. Various structures of protonated dibenzo-18-crown-6 are discussed.
Graphical abstract
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Abstract The interaction of cobalt(II)-glutathione (CoGSH) with deoxyribonucleic acid (DNA) has been studied by UV–vis, fluorescence,
circular dichroism (CD), thin-film infrared (IR), and viscometric techniques. From the UV-spectroscopic method, binding constant
(Kb) was determined and was found to be 2.3 × 106 M−1. In fluorimetric analysis, the quenching of fluorescence intensity of DNA bound to ethidium bromide (EB) was investigated.
The Stern–Volmer quenching constant (Ksv) was also estimated from this study and was found to be 2.8 × 106 M−1at 37 °C. The solution CD spectra of DNA and DNA–CoGSH indicate that in each case, DNA exists in the ‘B’ conformation and
suggested an intercalative binding mode. Thin-film IR data also reveal that DNA attains the ‘B’ family of conformations after
interaction with CoGSH complex. The increase in DNA viscosity in the presence of CoGSH complexes is attributed to the lengthening
of DNA helix due to intercalation.
Graphical Abstract The spectrophotometric, CD, thin film IR, viscometric and fluorimetric studies
on the interaction of CoGSH with DNA indicated an intercalative binding mode with the
retention of ‘B’ conformation of DNA.
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Abstract From extraction experiments in the two-phase water–nitrobenzene system and γ-activity measurements, the stability constant
of protonated tetraethyl p-tert-butylcalix[4]arene tetraacetate in nitrobenzene saturated with water was determined. By using DFT calculations, the most
probable structure of the tetraethyl p-tert-butylcalix[4]arene tetraacetate·H3O+ complex species was derived.
Graphical Abstract
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Abstract A series of dinuclear Fe(III) complexes was synthesized in which the Schiff-base blocking ligand L5 coordinates each of the centers which are linked by a bidentate, bipyridine-type ligand. For these systems, [L5FeIII{bridge}FeIIIL5](BPh4)2, thermally induced spin crossover is observed. The corollary of the systems is that the spin crossover interferes with the
magnetic exchange interaction. The overlap of the energy bands of the LL and HH reference states (L, low-spin; H, high-spin)
causes the exchange interaction to act against the spin crossover (leading to incompleteness or gradual behavior).
Graphical abstract
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