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51.
P. Udhayakala S. Seshadri T.V. Rajendiran S. Gunasekaran 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2010,75(2):567-573
The FTIR and FT Raman spectra of 3′-chloropropiophenone and 3′-nitropropiophenone have been recorded in the regions 4000–400 and 3500–100 cm?1 respectively. The optimized geometry, frequency and intensity of the vibrational bands of 3′-chloropropiophenone and 3′-nitropropiophenone were obtained by ab initio and DFT levels of theory with complete relaxation in the potential energy surface using 6-31G (d,p) basis set. A complete vibrational assignment aided by the theoretical harmonic frequency analysis has been proposed. The harmonic vibrational frequencies calculated have been compared with experimental FTIR and FT Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The experimental spectra also coincide satisfactorily with those of theoretically constructed simulated spectrograms. 相似文献
52.
A. Antony Muthu Prabhu S. Siva R. K. Sankaranarayanan N. Rajendiran 《Journal of fluorescence》2010,20(1):43-54
The photophysical behaviour of 2,6-diaminopyridine (DAP) has been studied in solvents of different polarity, pH, β-cyclodextrin
(β-CD) and compared with 2-amino pyridine (2AP). The inclusion complex of both molecules with β-CD are analysed by UV-visible,
fluorimetry, FT-IR, 1H NMR, SEM and AM1 methods. The solvent studies shows i) DAP gives more red shifted absorption and emission maxima than 2AP
molecule and ii) addition of amino group in 2AP effectively increase the resonance interaction in the pyridine ring. A regular
red shift observed in acidic pH solutions suggests intramolecular proton transfer (IPT) present in both molecules. β-CD studies
indicates i) in pH ~ 7, a regular red shifted absorption and emission maxima observed in AP molecules suggests pyridine ring
encapsulated in to the β-CD cavity (1:1 inclusion complex formed) and ii) in pH ~ 1, a blue shifted absorption maxima noticed
in 2AP, is due to protonated amino group deeply encapsulated in to the hydrophobic part of the β-CD cavity. 相似文献
53.
The absorption and fluorescence spectra of imipramine and carbamazepine have been recorded in solvents of different polarity
and β-cyclodextrin (β-CD). The inclusion complexes for both drugs are investigated by UV-visible, fluorimetry and DFT. Solvents
study shows isotropic polarizability structure is present in imipramine while the amide group inhibits the above structure
in carbamazepine. The band width half a maximum of carbamazepine decreased in polar solvents suggest that different species
present in non-polar solvents and among that one of this species is affected in protic solvents. Both drugs form two different
1:2 inclusion complexes with β-CD. The structured longer wavelength emission in β-CD solution suggests viscosity plays major
roles in the inclusion complex. This study also confirms van der Waals forces and hydrophobic interactions are the driving
forces in imipramine and hydrogen bonding interactions play major roles in carbamazepine. 相似文献
54.
Phyllanthin-assisted biosynthesis of silver and gold nanoparticles: a novel biological approach 总被引:2,自引:0,他引:2
Abstract The anisotropic gold and spherical–quasi-spherical silver nanoparticles (NPs) were synthesized by reducing aqueous chloroauric
acid (HAuCl4) and silver nitrate (AgNO3) solution with the extract of phyllanthin at room temperature. The rate of reduction of HAuCl4 is greater than the AgNO3 at constant amount of phyllanthin extract. The size and shape of the NPs can be controlled by varying the concentration of
phyllanthin extract and thereby to tune their optical properties in the near-infrared region of the electromagnetic spectrum.
The case of low concentration of extract with HAuCl4 offers slow reduction rate along with the aid of electron-donating group containing extract leads to formation of hexagonal-
or triangular-shaped gold NPs. Transmission electron microscopy (TEM) analysis revealed that the shape changes on the gold
NPs from hexagonal to spherical particles with increasing initial concentration of phyllanthin extract. The Fourier transform
infrared spectroscopy and thermogravimetric analyses reveal that the interaction between NPs and phyllanthin extract. The
cyclic voltammograms of silver and gold NPs confirms the conversion of higher oxidation state to zero oxidation state.
Graphical abstract Anisotropic gold and silver nanoparticles were synthesized by a simple procedure using phyllanthin extract as reducing agent.
The rate of bioreduction of AgNO3 is lower than the HAuCl4 at constant concentration of phyllanthin extract. The required size of the nanoparticles can be prepared by varying the concentration
of phyllanthin with AgNO3 and HAuCl4.
相似文献
55.
The X-ray crystal structure of the complex rac-[Ru(5,6-dmp)(3)]Cl(2) (5,6-dmp = 5,6-dimethyl-1,10-phenanthroline) reveals a distorted octahedral coordination geometry with the Ru-N bond distances shorter than in its phen analogue. Absorption spectral titrations with CT DNA reveal that rac-[Ru(5,6-dmp)(3)](2+) interacts (K(b), (8.0 +/- 0.2) x 10(4) M(-1)) much more strongly than its phen analogue. The emission intensity of the 5,6-dmp complex is dramatically enhanced on binding to DNA, which is higher than that of the phen analogue. Also, interestingly, time-resolved emission measurements on the DNA-bound complex shows biexponential decay of the excited states with the lifetimes of short- and long-lived components being higher than those for the phen analogue. The CD spectral studies of rac-[Ru(5,6-dmp)(3)](2+) bound to CT DNA provide a definite and elegant evidence for the enantiospecific interaction of the complex with B-form DNA. Competitive DNA binding studies using rac-[Ru(phen)(3)](2+) provide support for the strong binding of the complex with DNA. The Delta-enantiomer of rac-[Ru(5,6-dmp)(3)](2+) binds specifically to the right-handed B-form of poly d(GC)(12) at lower ionic strength (0.05 M NaCl), and the Lambda-enantiomer binds specifically to the left-handed Z-form of poly d(GC)(12) generated by treating the B-form with 5 M NaCl. The strong electronic coupling of the DNA-bound complex with the unbound complex facilitates the change in its enantiospecificity upon changing the conformation of DNA. The (1)H NMR spectra of rac-[Ru(5,6-dmp)(3)](2+) bound to poly d(GC)(12) reveal that the complex closely interacts most possibly in the major grooves of DNA. Electrochemical studies using ITO electrode show that the 5,6-dmp complex stabilizes CT DNA from electrocatalytic oxidation of its guanine base more than the phen analogue does. 相似文献
56.
Rajendiran Thangaraj Annamalai Senthil Kumar 《Journal of Solid State Electrochemistry》2013,17(3):583-590
A graphitized mesoporous carbon modified glassy carbon electrode (GCE/GMC) prepared by drop coating method without any pre-anodization of the underlying GCE or external binder/matrix, has been demonstrated for simultaneous electrochemical oxidation of guanine (G) and adenine (A) at oxidation potentials 0.60 and 0.85 V vs. Ag/AgCl, respectively, in the presence of thymine (T) by differential pulse voltammetric method in pH 7 phosphate buffer solution. Control voltammetric experiments with unmodified GCE, graphite nanopowder and multiwalled carbon nanotube modified electrodes yielded either feeble or with high-background current responses. Interestingly, the GCE/GMC showed highly efficient, stable and well-defined voltammetric signals. Thymine oxidation signal noticed discretely at 1.15 V vs. Ag/AgCl on the GCE/GMC was not influenced for the simultaneous determination of G and A. Constructed DPV calibration graphs were linear in the range of 25–200 and 25–150 μM, respectively, for the G and A. Corresponding detection limit (S/N?=?3) values are 0.76 and 0.63 μM. Real sample analyses for the detection of G and A concentrations in calf-thymus DNA (detected [G]/[A] ratio?=?0.82), beef brain and beef liver were successfully demonstrated with recovery values ~100 %. 相似文献
57.
S. Karthikeyan T. M. Rajendiran R. Kannappan R. Mahalakshmy R. Venkatesan P. Sambasiva Rao 《Journal of Chemical Sciences》2001,113(4):245-256
Preparation of the ligands HL1 = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-ethylphenol; HL2 = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-methoxyphenol and HL3 = 2,6-[(N-phenylpiperazin-1-yl)methyl]-p-nitrophenol are described together with their Cu(II) complexes with different bridging units. The exogenous bridges incorporated
into the complexes are: hydroxo [Cu2L(OH)(H2O)2](ClO4)2.H2O (L1=1a, L2 =1b, L3 =1c), acetato [Cu2L(OAc)2]ClO4.H2O (L1 =2a, L2 =2b, L3 =2c) and nitrito [Cu2L1(NO2)2(H2O)2]ClO4.H2O (L1=3a, L2 =3b, L3 =3c). Complexes1a,1b,1c and2a,2b,2c contain bridging exogenous groups, while3a,3b,3c possess only open μ-phenolate structures. Both the ligands and complexes were characterized by spectral studies. Cyclic voltammetric
investigation of these complexes revealed that the reaction process involves two successive quasireversible one-electron steps
at different potentials. The first reduction potential is sensitive to electronic effects of the substituents at the aromatic
ring of the ligand system, shifting to positive potentials when the substituents are replaced by more electrophilic groups.
EPR studies indicate very weak interaction between the two copper atoms. Various covalency parameters have been calculated. 相似文献
58.
Rajendiran V Karthik R Palaniandavar M Stoeckli-Evans H Periasamy VS Akbarsha MA Srinag BS Krishnamurthy H 《Inorganic chemistry》2007,46(20):8208-8221
The copper(II) complex [Cu(tdp)(ClO4)].0.5H2O (1), where H(tdp) is the tetradentate ligand 2-[(2-(2-hydroxyethylamino)ethylimino)methyl]phenol, and the mixed ligand complexes [Cu(tdp)(diimine)]+ (2-5), where diimine is 2,2'-bipyridine (bpy) (2), 1,10-phenanthroline (phen) (3), 3,4,7,8-tetramethyl-1,10-phenanthroline (tmp) (4), and dipyrido-[3,2-d:2',3'-f]-quinoxaline (dpq) (5), have been isolated and characterized by analytical and spectral methods. Complexes 1 and [Cu(tdp)(phen)]ClO4 (3) have been structurally characterized, and their coordination geometries around copper(II) are described as distorted octahedral. The equatorially coordinated ethanolic oxygen in 1 is displaced to an axial position upon incorporating the strongly chelating phen, as in 3. The solution structures of all the complexes have been assessed to be square-based using electronic absorption and electron paramagnetic resonance (EPR) spectroscopy. The interaction of the complexes with calf thymus DNA (CT DNA) has been explored by using absorption, emission, and circular dichroic spectral and viscometric studies, and modes of DNA binding for the complexes have been proposed. Absorption spectral (Kb = 0.071 +/- 0.005 (2), 0.90 +/- 0.03 (3), 7.0 +/- 0.2 (4), 9.0 +/- 0.1 x 10(5) M(-1) (5)), emission spectral (Kapp = 4.6 (1), 7.8 (2), 10.0 (3), 12.5 (4), 25.0 x 10(5) M(-1) (5)), and viscosity measurements reveal that 5 interacts with DNA more strongly than the other complexes through partial intercalation of the extended planar ring of the coordinated dpq with the DNA base stack. Interestingly, only complex 4 causes a B to A conformational change upon binding DNA. All the complexes hydrolytically cleave pBR322 supercoiled DNA in 10% DMF/5 mM Tris-HCl/50 mM NaCl buffer at pH 7.1 in the absence of an activating agent, and the cleavage efficiency varies in the order 5 > 3 > 2 > 4 > 1 with 5 displaying the highest Kcat value (5.47 +/- 0.10 h(-1)). The same order of cleavage is observed for the oxidative cleavage of DNA in the presence of ascorbic acid as a reducing agent. Interestingly, of all the complexes, only 5 displays efficient photonuclease activity through double-strand DNA breaks upon irradiation with 365 nm light through a mechanistic pathway involving hydroxyl radicals. The protein binding ability of 1-5 has been also monitored by using the plasma protein bovine serum albumin (BSA), and 4 exhibits a protein binding higher than that of the other complexes. Further, the anticancer activity of the complexes on human cervical epidermoid carcinoma cell line (ME180) has been examined. Interestingly, the observed IC50 values reveal that complex 4, which effects conformational change on DNA and binds to BSA more strongly, exhibits a cytotoxicity higher than the other complexes. It also exhibits approximately 100 and 6 times more potency than cisplatin and mitomycin C for 24 and 48 h incubation times, respectively, suggesting that 4 can be explored further as a potential anticancer drug. Complexes 4 and 5 mediate the arrest of S and G2/M phases in the cell cycle progression at 24 h harvesting time, which progress into apoptosis. 相似文献
59.
The mixed-ligand copper(II) complex [Cu(tdp)(tmp)](ClO4), where H(tdp) is 2-[(2-(2-hydroxyethylamino)ethylimino)methyl]phenol and tmp is 3,4,7,8-tetramethyl-1,10-phenanthroline, exhibits cleavage of the proteins bovine serum albumin and lysozyme, producing approximately 5 and 4 kDa protein fragments respectively within a few minutes at micromolar concentrations. The hydrophobic tmp ligand recognizes the hydrophobic site and enhances protein binding and cleavage even at physiological pH and temperature. 相似文献
60.
Govindasamy Balasubramani Paramasivam Deepak Rajamani Sowmiya Rajendiran Ramkumar 《Natural product research》2015,29(10):958-960
This study pertains to the phytochemical components and the biological properties of the weed, Antigonon leptopus Hook. & Arn. (AUT/PUS/064). Phytochemical screening of methanolic leaf extract of A. leptopus revealed the presence of saponin, phenolic compounds, tannins, flavonoids, alkaloids, fixed oils and amino acids. Accordingly, 12 phytochemical components were analysed and characterised by GC–MS. Antibacterial activity was evaluated against fish and clinical pathogens. Fish pathogens, Providencia vermicola (MTCC 5578) and Aeromonas hydrophila (MTCC 646) were more sensitive to the methanolic leaf extract than clinical pathogens. A useful information was obtained from the phytochemistry of A. leptopus leaves, which would pave way to further applications to treat fish diseases and for utility in the pharmaceutical field. 相似文献