共查询到20条相似文献,搜索用时 750 毫秒
1.
Yata PK Shilpa M Nagababu P Reddy MR Kotha LR Gabra NM Satyanarayana S 《Journal of fluorescence》2012,22(3):835-847
The three Ru(II) complexes of [Ru(phen)2dppca]2+ (1) [Ru(bpy)2dppca]2+ (2) and [Ru(dmb)2dppca]2+ (3) (where phen = 1,10 phenanthroline, bpy = 2,2-bipyridine, dmb = 2 ,2-dimethyl 2′,2′-bipyridine and polypyridyl ligand
containing a single carboxylate functionality dppca ligand (dipyridophenazine-11-carboxylic acid) have been synthesized and
characterized. These complexes have been shown to act as promising calf thymus DNA intercalators and a new class of DNA light
switches, as evidenced by UV-visible and luminescence titrations with Co2+ and EDTA, steady-state emission quenching by [Fe(CN)6]4− and KI, DNA competitive binding with ethidium bromide, viscosity measurements, and DNA melting experiments. The results suggest
that 1, 2, and 3 complexes bind to CT-DNA through intercalation and follows the order 1 > 2 > 3. Under irradiation at 365 nm,
the three complexes have also been found to promote the photocleavage of plasmid pBR322 DNA. 相似文献
2.
Michail N. Elinson Valentina M. Merkulova Alexey I. Ilovaisky Dmitry V. Demchuk Pavel A. Belyakov Gennady I. Nikishin 《Molecular diversity》2010,14(4):833-839
Electrochemically induced catalytic multicomponent transformation of isatins, 4-hydroxyquinolin-2(1H)-one and malononitrile in ethanol in an undivided cell in the presence of sodium bromide as an electrolyte results in the
formation of spirooxindoles with fused functionalized indole-3,4′-pyrano[3,2-c]quinoline] scaffold in 75–91% substance yields
and 500-600% current yield. The developed efficient electrocatalytic approach to medicinally relevant [indole-3,4′-pyrano[3,2-c]quinoline]
scaffold is beneficial from the viewpoint of diversity-oriented large-scale processes and represents a novel example of facile
environmentally benign synthetic concept for electrocatalytic multicomponent reactions. 相似文献
3.
We studied the spectral-luminescent characteristics of the luminescence of mixed-ligand polypyridine-phosphine complexes of
ruthenium(II) cis-[Ru(bpy)2(PPh3)X](BF4)
n
with ligands 2,2′-bipyridyl (bpy) and triphenylphosphine (PPh3) and X = Cl−, Br−, CN−, NO2−, NH3, MeCN, pyridine (py), 4-aminopyridine (pyNH2), and 4,4′-bipyridyl (4,4′-bpy) in a 4: 1 EtOH-MeOH alcoholic mixture at 77 K. The radiative and nonradiative deactivation
rate constants of the lowest electronically excited state of the complexes are determined. We find that triphenylphosphine
has a greater effect on the photophysical characteristics of ruthenium(II) complexes compared to π-acceptor strong-field ligands,
such as MeCN, CN−, and NO2−. At the same time, the characteristics of complexes cis-[Ru(bpy)2(PPh3)X]
n+ considerably depend on the nature of the second monodentate ligand X, which is coordinated to ruthenium(II), and correlate
with its position in the spectrochemical series of ligands. 相似文献
4.
Woo Suk Hwang Yun Hong Jung Woo Sung Son Byeng Wha Son Jung Sook Kang 《Journal of fluorescence》2011,21(1):231-237
The metal-ligand complexes, [Ru(bpy)2(dppz)]2+ (bpy = 2,2??-bipyridine, dppz = dipyrido[3,2-a:2??,3??-c]phenazine) (RuBD) and [Ru(phen)2(dppz)]2+ (phen = 1,10-phenanthroline) (RuPD), display favorable photophysical properties including long lifetime, polarized emission, and very little background fluorescence. To check if RuBD and RuPD reflect the overall rotational mobility of small nucleic acid, we measured the intensity and anisotropy decays of RuBD and RuPD when intercalated into tRNAtyr using pBC SK(+) phagemid as a control. We used frequency-domain fluorometry with a blue light-emitting diode (LED) as the modulated light source. We observed shorter lifetimes for tRNAtyr than those for the pBC SK(+) phagemid for both probes, however, RuPD showed much larger decrease in the mean lifetime values (64%). The slow rotational correlation time of RuBD (31.3 ns) and the fast rotational correlation time of RuPD (26.0 ns) reflected the overall rotational mobility of tRNAtyr. In addition, the steady-state anisotropy and time-resolved anisotropy decay data showed a clear difference between tRNAtyr and pBC SK(+) phagemid. This suggests the possibility of a homogeneous assay for identifying target nucleic acids and/or nucleic acid binding proteins. 相似文献
5.
Mohammad A. Khalilzadeh Zinatossadat Hossaini Faramarz Rostami Charati Sara Hallajian Mehdi Rajabi 《Molecular diversity》2011,15(2):445-450
An efficient synthesis of 2-hydroxy-3-[2-oxo-2-phenylethylidene]-2-phenyl-2, 3-dihydro-4 H-furo[3, 2-c]chromene-4(2H)-one is described. This involves the reaction between dibenzoylacetylene and 4-hydroxycoumarine in the presence of NaH (10 mol
%) in nearly quantitative yield. Treatment of this heterocyclic system with trimethyl chlorosilane in CHCl3 leads quantitatively to 4-oxo-3-[2-oxo-2-phenylethylidene]-2-phenyl-3H, 4H-furo[3,2-c]chromene-1-ium chloride. Direct addition of nucleophiles, such as alcohols, amines or trialkyl phosphites to this
salt in water as the solvent produces functionalized 2-phenyl-4H-furo[3,2-c] chromen derivatives in excellent yields. 相似文献
6.
Four novel copper(II) complexes of the composition [CuLX] where L = 2,6-bis(benzimidazole-2yl)pyridine, X = dipyridophenazine
(L1), 1,10-phenanthroline (L2), hydroxyproline (L3) and 2,6-pyridine dicarboxylic acid (L4) were synthesized and characterized by using elemental analysis, FT-IR, UV–vis, ESI-MS, molar conductance and magnetic susceptibility
measurements. The complexes [CuLL1](NO3)2 [1], [CuLL2](NO3)2 [2], [CuLL3](NO3) [3] and [CuLL4] (NO3) [4] are stable at room temperature. In DMSO the complexes [1] and [2] are 1:2 electrolytes, [3] and [4] are 1:1 electrolytes. Based on elemental and spectral studies five coordinated geometry is assigned to all the four complexes.
The interaction of four copper ion complexes with calf thymus DNA were carried out by UV–vis titrations, fluorescence spectroscopy,
thermal melting and viscosity measurements .The binding constant (Kb) of the above four metal complexes were determined as 5.43 × 104 M,−1 2.56 × 104 M−1, 1.21 × 104 M−1 and 1.57 × 104 M−1 respectively. Quenching studies of the four complexes indicates that these complexes strongly bind to DNA, out of all complex
1 is binding more strongly. Viscosity measurements indicate the binding mode of complexes with CT DNA by intercalation through
groove. Thermal melting studies also support intercalative binding. The nuclease activity of the above metal complexes shows
that 1, 2 and 3 complexes cleave DNA through redox chemistry. 相似文献
7.
M. S. Khakhalina D. N. Musaeva I. Yu. Tikhomirova M. V. Puzyk 《Optics and Spectroscopy》2010,108(4):571-573
The surface of a cation-exchange membrane was modified by the [PtEnPpy]+, [PtEnBt]+, [PtEnTpy]+, [RuBpy3]+2, and NB+, (En is ethylenediamine; Ppy, Bt, Tpy are α-deprotonated forms of 2-phenylpyridine, 2-phenylbenzothiazole, and 2-(2′-thienyl)pyridine,
respectively; Bpy is 2,2′-bipyridyl, and NB+ is Nile blue) ions, which exhibit intense luminescence. It is found that the quenching of the luminescence of the modified
cation-exchange membrane by water vapors depends on the nature of the excited electronic state of the immobilized cation. 相似文献
8.
6-Hydroxy chromone-3-carbaldehyde-(4′-hydroxy) benzoyl hydrazone (L) and its Ln (III) complexes, [Ln = La, Nd, Eu and Tb]
have been prepared and characterized on the basis of elemental analyses, molar conductivities, mass spectra, 1H NMR, thermogravimety/differential thermal analysis (TG-DTA), UV-vis spectra, fluorescence spectra and IR spectra. The formula
of the complex is [Ln L·(NO3)2]·NO3. Spectrometric titration, ethidium bromide displacement experiments and viscosity measurements indicate that Eu (III) complex
bind with calf-thymus DNA, presumably via an intercalation mechanism. The intrinsic binding constant of Eu (III) with DNA
was 2.48 × 105 M−1 through fluorescence titration data. 相似文献
9.
Y. Zhang C. Y. Chen M. Huang Y. S. Wang Y. M. Zou 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,56(2):157-166
Ab initio calculations of the total dielectronic
recombination (DR) rate coefficients for thirteen ions along the NiI
isoelectronic sequence in the ground state (Kr8+, Mo14+,
Ag19+, Sn22+, Xe26+, Nd32+, Gd36+,
Yb42+, W46+, Au51+, Pb54+, At57+, and
U64+) have been performed using the flexible atomic code. The
level-by-level calculations are performed for evaluating the DR
contributions through the relevant Cu-like autoionizing inner-shell
excited 3l174l′n′′l′′ and 3l175l′n′′l′′ configuration complexes with n′′
≤15, which are associated with Δn=1 and Δn=2
core-excitations, respectively. The usual (n′′)-3 scaling
law is found to be invalid for low-Z ions. A level-by-level
extrapolation procedure is employed to obtain the contributions
through higher n′′ complexes. The decays to autoionizing
levels followed possibly by radiative cascades could enlarge the
rates at relatively high temperature by a factor up to about 23%.
For the whole isoelectronic ions the contributions from
3s23p63d9 4l′n′′l′′ dominate the total DR
rates while the contributions from the 3s23p63d9 5l′n′′l′′ configuration complexes are about 10-20% at
relatively high temperature. On the basis of the calculated results,
a general analytic formula for the total DR rate coefficients of all
the ions with 36≤Z ≤92 along the NiI isoelectronic
sequence is constructed. The comparisons of the rates obtained from
the general formula with those from the detailed calculations show
that the formula is of high precision, generally better than 3%
accuracy for electron temperatures kT≥0.1EI, where EI is
the ionization energy of the Cu-like ion. The present DR rates at
temperature above 1.0EI are larger than the previously published
data by a factor above 30%. The commonly used semiempirical formula
proposed by Burgess and modified by Merts may overestimate the rates
at high temperature by a factor of about 2 for low-Z ions. 相似文献
10.
The [Pd(C∧N)(4,4′-bpy)Cl], [Pd(C∧N)NO3]2(μ-4,4′-bpy) and [Pd(C∧N)(μ-4,4′-bpy)]4(NO3)4 complexes (C∧N− are deprotonated forms of 2-phenylpyridine (ppy), 2-(2′’-thienyl)pyridine (tpy), and 2-phenylbenzothiazole (bt); bpy is 4,4′
bipyridyl) are synthesized and characterized by 1H NMR spectroscopy, electronic absorption and emission spectroscopy, and cyclic voltammetry. The upfield shifts of the chemical
shift of a proton in the ortho-position to the donor carbon atom of the cyclopalladated ligand of complexes (Δδ = −(1.1–1.5)
ppm) is assigned to the anisotropic effect of the circular current of the pyridine rings of 4,4′-bipyridyl orthogonal to the
coordination plane. The characteristic long-wavelength absorption and phosphorescence bands of the complexes are assigned
to the chromophore metal-complex fragment {M(C∧N)}. The quasi-reversible reduction waves of complexes are assigned to the
ligand-centered processes of successive electron transfer to the π*-orbitals localized mainly on the coordinated pyridine
components of 4,4′-bipyridyl. 相似文献
11.
Two new ligands derived from phloroglucinol 2-{[(4-methoxy benzoyl ) oxy ] } methyl benzoic acid[L1] and 2-{[(4-methyl benzoyl
)oxy] methyl} benzoic acid[L2] were synthesized. The solid complex Eu(III)-L2 has been synthesised and characterized by elemental
analysis ,UV and IR spectra. The reaction of Eu(III) with the two synthesized ligands has been investigated in I = 0.1 mol dm-3 p-toluene sulfonate by cyclic voltammetry and square wave voltammetry. The reaction of Eu (III)–L1 and Eu (III)–L2 binary
complexes with nucleotide 5′-AMP , 5′-ADP ,5′-ATP , 5′- GMP , 5′-IMP , and 5′-CMP has been investigated using UV, fluorescence
and electrochemical methods. The experimental conditions were selected such that self-association of the nucleotides and their
complexes was negligibly small, that is, the monomeric complexes were studied. The interaction of the Eu(III)–L1 or L 2 solid
complexes with calf-thymus DNA has been investigated by fluorescence and electrochemical methods including cyclic voltammetery(CV)
,differential pulse polarography (DPP) and square wave voltammetry (SWV) on a glassy carbon electrode. The fluorescence intensity
of Eu(III)-L2 complex was enhanced with the addition of DNA. Under optimal conditions in phosphate buffer pH 7.0 at 25 °C
the linear range is 3–20 μM for calf thymus DNA (CT–DNA) and the corresponding determination limit is 1.8 μM. 相似文献
12.
The field dependence of the nuclear spin-lattice relaxation (SLR) of cold implanted 82Br (T ≤ 25 mK) in α-Fe single crystals was investigated with nuclear magnetic resonance of oriented nuclei (NMR/ON) at low temperatures
as experimental technique. The SLR at the lattice sites with the hyperfine fields found by earlier NMR/ON experiments was
measured as a function of the applied external magnetic field B
ext parallel to the three principle axes [100], [110] and [111] of the iron single crystal. The data were evaluated with the
full relaxation formalism in the single impurity limit and for comparison also with the often employed model of a single exponential function with an effective relaxation time
T
1′. With a phenomenological model the high field values of the relaxation rates r
∞, [100]′ = 6.6(2) · 10−15 T2sK−1, r
∞, [110] = 5.4(2) · 10−15 T2sK−1 and r
∞, [111] = 5.2(1) · 10−15 T2sK−1 were obtained. 相似文献
13.
Dipyrido[3,2-a:2′,3′-c]-phenazine (L) was employed as a selectively fluorescent chemosensor for Hg2+ in DMF solution under buffered conditions with its fluorescence being strongly increased. The fluorescence increasing was attributed to the formation of L–Hg2+ by 1:1 complex ratio (K=3.7×105 M−1), which constitutes the basis for the determination of Hg2+ with the prepared chemosensor. The experiment results also show that the response behavior of L to Hg2+ is pH independent in the range of pH 6.0–9.0 and show excellent sensitivity and selectivity for Hg2+ over other examined metal ions. 相似文献
14.
Jalilzadeh M Noroozi Pesyan N Rezaee F Rastgar S Hosseini Y Sahin E 《Molecular diversity》2011,15(3):721-731
Reaction of barbituric acid (BA), 1,3-dimethyl barbituric acid (DMBA) and 2-thiobarbituric acid (TBA) with cyanogen bromide
and various aldehydes in presence of triethylamine afforded a new class of heterocyclic stable 5-alkyl and/or 5-aryl-1H, 1′H-spiro[furo[2,3-d]pyrimidine-6,5′-pyrimidine]2,2′,4,4′,6′(3H,3′H,5H)-pentaones which are dimeric forms of barbiturate (uracil and thiouracil derivatives) at 0 °C to ambient temperatures. Structure
elucidation is proved by X-ray crystallography, 1H NMR, 13C NMR, FT-IR, CHN and mass analyses techniques. Mechanisms of the formations are discussed. 相似文献
15.
1-(4-Aminoantipyrine)-3-tosylurea (H2L) and its three lanthanide (III) complexes, M(H2L)3 3NO3 [where M = Nd(III), Sm(III) and Eu(III)], have been synthesized and characterized. In addition, the DNA-binding properties
of the three complexes have been investigated by UV–vis (ultraviolet and visible) absorption spectroscopy, fluorescence spectroscopy,
circular dichroism (CD) spectroscopy, cyclic voltammetry, and viscosity measurements. Results suggest that the three complexes
bind to DNA via a groove binding mode. Furthermore, the antioxidant activity (superoxide and hydroxyl radical) of the metal
complexes was determined by using spectrophotometer methods in vitro. These complexes were found to possess potent antioxidant
activity and be better than standard antioxidants like vitamin C and mannitol.
Absorption spectra of the complex 3 inTris-HCl buffer upon addition of calf-thymus DNA. [complex]=1×10-5 M, [DNA]=(0-1) ×10-5 M. Arrow shows the absorbance changing upon increasing DNA concentrations. Inset: plots of [DNA]/(εa – εf) versus [DNA] for the titration of DNA with the complex. 相似文献
16.
L. Lis 《Il Nuovo Cimento D》1990,12(7):935-940
Summary In this report investigations are presented of laser generations at 3391 nm and 3391 and 7699 nm, or rather of changes induced
by them in populations of the 5s′ [1/2]
1
0
, 4p′[3/2]2 and 3d′[5/2]
3
0
levels, depending upon the angle of the tilted mirror of the He−Ne laser system. This writer has discovered that the above
laser generations develop at a strongly tilted mirror, when the beam reflected from one mirror, in order to reach the other,
has to be reflected many times on the inside walls of the discharge tube.
The work was supported by CPBR 8.14. 相似文献
17.
F. B. Mushenok A. I. Dmitriev M. V. Kirman S. M. Aldoshin N. A. Sanina R. B. Morgunov 《Physics of the Solid State》2010,52(10):2135-2141
Ordered arrays of nanowires of the photochromic antiferromagnet SpFeMn(C2O4)3 (where Sp is 1-{(1′,3′,3′-trimethyl-6-nitro-5′-chlorospiro[2H-1-benzopyran-2,2′-indolin]-8-yl)methyl}pyridinium) have been fabricated in anodized aluminum oxide pores with diameters of
20 and 200 nm. It has been revealed that the growth of the spin-glass phase with noncollinear ordering of spins in nanowires
is suppressed in favor of the uniaxial antiferromagnetic phase. A decrease in the nanowire diameter leads to an increase in
the anisotropy of the magnetic resonance spectra. This is associated with the magnetocrystalline anisotropy that considerably
exceeds the anisotropy of the nanowire shape. 相似文献
18.
Moamen S. Refat Mohamed M. Ibrahim Mohamed A. A. Moussa 《Journal of Applied Spectroscopy》2012,78(6):772-781
Charge-transfer complexes (CTC) resulting from interactions of 1,3-di[(E)-1-(2-hydroxyphenyl) methylideneamino]-2-propanol Schiff base with some acceptors such as iodine (I2), bromine (Br2), and picric acid (PiA) have been isolated in the solid state in a chloroform solvent at room temperature.
Based on elemental analysis, UV-Vis, infrared, and 1H NMR spectra, and thermogravimetric analysis (TG/DTG) of the solid CTC, [(Schiff)(I2)] (1), [(Schiff)(Br2)] complexes with a ratio of 1:1 and [(Schiff)(PiA)3] complexes with 1:3 have been prepared. In the picric acid complex, infrared and 1H NMR spectroscopic data indicate that the charge-transfer interaction is associated with a hydrogen bonding, whereas the
iodine and bromine complexes were interpreted in terms of the formation of dative ion pairs [Schiff+, I2∙−] and [Schiff+, Br2∙−], respectively. Kinetic parameters were obtained for each stage of thermal degradation of the CT complexes using Coats–Redfern
and Horowitz–Metzger methods. DC electrical properties as a function of temperature of these charge transfer complexes have
been studied. 相似文献
19.
Summary The planarity and electron delocalization of the 2, 2′:6′, 2″-terpyridine (terpy) moiety in salts of the type [Pt(terpy)Me]X
leads to extensive stacking interactions in aqueous solution. UV/VIS,1H NMR and resonance light scattering spectra provide evidence for the tendency of the complex to form large aggregates even
under low ionic strength conditions. The interaction of the cationic complex with calf thymus DNA was investigated by spectroscopic
techniques and mobility assays. At highr
f ratios the complex seems to form extended aggregates on the surface of the nucleic acid but at lowerr
f evidence was obtained for intercalation.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. 相似文献
20.
Quadrupolar interactions in [IR(CN)5]3−, [Ir(CN)5Cl]4− and [Ir(CN)4Cl2]4− paramagnece a complexes in alkali halide host lattices are systematically analysed by ESR spectroscopy. The measured quadrupolar
interactions are shown to have no clear correlation to the measured unpaired electron populations. 相似文献