Studies of charge transfer interaction of nucleotides with proflavine
04 Jan 1995-Journal of Photochemistry and Photobiology A-chemistry (Elsevier)-Vol. 85, Iss: 43467, pp 89-92
TL;DR: In this article, the interaction of several nucleosides with proflavine hemisulphate was investigated by absorption and fluorescence spectroscopy in solvents with different dielectric constants.
Abstract: The interaction of several nucleosides with proflavine hemisulphate was investigated by absorption and fluorescence spectroscopy in solvents with different dielectric constants. In each case, the ground state charge transfer complex was formed (observed from the difference absorption spectra) and the formation constants were calculated using the Benesi-Hildebrand equation (H.A. Benesi and J.H. Hildebrand, J. Am. Chem. Soc., 71 (1949) 2703). Fluorescence spectroscopy ruled out the possibility of exciplex formation as no new band was observed. However, static quenching occurred within a limited range of acceptor to donor concentration ratio. The formation constants calculated were found to be higher than those observed by adsorption spectroscopy.
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TL;DR: In this article, the solvent effects in the structure and electronic spectra of some cationic dyes: acridine orange, proflavine, safranine, neutral red, thionine and methylene blue were studied.
Abstract: We present a quantum-mechanical study on the solvent effects in the structure and electronic spectra of some cationic dyes: acridine orange, proflavine, safranine, neutral red, thionine and methylene blue. The geometry optimizations were carried out with the AM1 and DFT (with B3LYP functional) methods and the theoretical spectra of the dyes under study were obtained with Zindo time-dependent methods (TD–DFT and TD–HF). The solvation methodology adopted was the integral equation formulation (IEF) version of the polarizable continuum model (PCM).
68 citations
TL;DR: The binding of the polyaromatic guest, 3,6-diaminoacridine (Proflavine) to cucurbit[n]uril (CB[n]) where n = 6, 7 and 8 has been studied by fluorescence spectrophotometry and binding constants determined using a least squares fitting method.
Abstract: The binding of the polyaromatic guest, 3,6-diaminoacridine (Proflavine) to cucurbit[n]uril (CB[n]) where n = 6, 7 and 8 has been studied by fluorescence spectrophotometry and binding constants determined using a least squares fitting method. Titration of CB[8] into a solution of Proflavine results in a 95% decrease in fluorescence up to a CB[8] to Proflavine ratio of 2:1. From the induced fluorescence spectra a binding constant of 1.9 × 107 M− 1 was determined. When Proflavine is titrated into a solution of CB[8] a similar binding constant is calculated (1.3 × 107 M− 1). Titration of CB[6] into a solution of Proflavine yields a decrease in fluorescence of 18–20%, but no binding is observed beyond what is seen within experimental error. Finally, titration of CB[7] into a solution of Proflavine results in an increase in fluorescence (32%) and a blue-shift of the emission wavelength from 509 nm to 485 nm. From the induced fluorescence spectra a binding constant of 1.65 × 107 M− 1 was determined. From 1H NMR ...
34 citations
TL;DR: In this paper, an aqueous suspension of pyrene nanoparticles (PyNPs) stabilized by sodium lauryl sulfate exhibit red shifted aggregation induced enhanced emission (AIEE) in the spectral region where Rhodamine 6G absorbs strongly.
Abstract: An aqueous suspension of pyrene nanoparticles (PyNPs) stabilized by sodium lauryl sulfate exhibit red shifted aggregation induced enhanced emission (AIEE) in the spectral region where Rhodamine 6G (R6G) absorbs strongly. Dynamic light scattering results of the aqueous suspension show a narrow particle size distribution with an average size of 38 nm and the zeta potential of −22 mV predicted a high degree of stability and surface charge modification of the nanoparticles. The negative zeta potential allowed cationic R6G to adsorb on the oppositely charged surface of the nanoparticles and both the molecules bind within the close distance required for efficient fluorescence resonance energy transfer (FRET) to take place from PyNPs to R6G. Systematic FRET experiments performed by measuring quenching of fluorescence of PyNPs with successive addition of R6G solution exploited the use of the PyNPs as a novel probe first time for the detection and estimation of R6G from textile effluents with a Limit of Detection (LOD) equal to 8.905 × 10−6 mol L−1 by fluorimetric measurements. The quenching results obtained at different constant temperatures were found to fit the well-known Stern–Volmer relation and were used further to estimate photokinetic and thermodynamic parameters such as quenching rate constant, enthalpy change (ΔH), Gibbs free energy change (ΔG) and entropy change (ΔS). The mechanism of binding and quenching of fluorescence of PyNPs by R6G is proposed based on the thermodynamic parameter, the energy transfer efficiency, critical energy transfer distance (R0) and distance of approach between donor–acceptor molecules (r). The fluorescence quenching results are used further to develop analytical methods for estimation of R6G from industrial textile effluents.
27 citations
TL;DR: In this article, the structure and electronic spectra of three cationic dyes monomers and dimers were analyzed using the Integral Equation Formalism (IEF) version of the Polarizable Continuum Model (PCM).
Abstract: In this work we present a quantum-mechanical study on the structure and electronic spectra of three cationic dyes monomers and dimers: acridine orange (AO), proflavine (PF) and methylene blue (MB). The geometries were obtained from crystallographic data, the electronic properties were calculated with DFT (B3LYP functional) and the theoretical spectra were obtained with ZINDO. The solvation methodology adopted was the Integral Equation Formalism (IEF) version of the Polarizable Continuum Model (PCM). This study shows that the differences, even small, between optimized and crystal geometries are responsible for important spectral characteristics. Also, it indicates possible structures for interacting dimers.
17 citations
TL;DR: This work was made as overview of all significant structure characteristics for specific action of acridine derivatives, including antimalarial or antiviral activity, and antitumor activity.
Abstract: Acridine ring can be found in molecules used in man y different spheres, including industry and medicine. Nowadays, even acr idines with antibacterial activity are of research interest due to increasing bacterial re sistance. Some acridine derivatives showed antimalarial or antiviral activity. Acridine derivatives were also investigated for antitumor activity due to the interaction with topo isomerase II and DNA base pairs. Considering these possible uses of acridine derivat ives, this work was made as overview of all significant structure characteristics for sp ecific action of these compounds.
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References
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TL;DR: In this paper, it was shown that the position of the absorption bands of iodine solutions in the visible region moved gradually from violet to brown, the shift being only small in the case of benzene in which the color of iodine is a red-violet.
Abstract: Introduction The various colors of iodine in different solvents have attracted the attention of investigators for over half a century. Beckmann’ showed that the differences are not due to any change in the molecular weight of iodine and suggested solvation as the cause of brown color. Lachman2 supported this explanation, pointing out that the solvents which give a violet color are saturated, those which give brown colors are unsaturated. He stated that small additions of alcohol to a solution of iodine in chloroform suffice to shift the color stepwise from violet to brown. Hildebrand and Glascock3 found that when iodine and an alcohol were both added to a “violet” solvent, bromoform or ethylene bromide, the molal lowering of the freezing point was considerably less than additive, indicating combination of iodine with alcohol. Furthermore, they investigated colorimetrically the equilibria of iodine with ethyl alcohol, ethyl acetate and nitrobenzene dissolved together in a “violet” solvent such as carbon tetrachloride, chloroform or carbon disulfide, and found in each case an equilibrium constant corresponding to a 1 : 1 compound. They calculated the heat of combination in one case. There followed a long series of investigations of the general problem, well summarized by Gmelin4 and in a recent review by Kleinberg and Davidson.6 But the original division of iodine solutions into two or more distinct color classes became untenable with the work of Waentig, Groh’ and \\X7alkers which showed that the position of the absorption bands of iodine solutions in the visible region moved gradually from violet to brown, the shift being only small in the case of benzene in which the color of iodine is a red-violet. We have long been curious about the chemical basis for iodine solvates. It is not a question of dipole moment, as Walkers concluded, for we have recently shown rather conclusively that the iodine solubility, which would be altered by solvation effects, bears little or no relation to the dipole moment of the solvent mole~ule .~ The alcohols are extraordinary dipoles, and their effect is readily understandable, but the case of benzene seemed
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509 citations
01 Feb 1967
TL;DR: Parker et al. as discussed by the authors outline the principles of all these techniques and draw attention to some unusual results obtained with them, including the observation of delayed fluorescence, which was until recently of interest only to the photochemist, but it has now been shown to have potential value as an analytical technique also.
Abstract: From its first analytical applications (Bowman et al, 1955: Parker, et al, 1957) the technique of fluorescence photoelectric spectrometry developed within a decade to become a standard technique for trace organic and inorganic analysis. Reviews and text-books (Bartholomew, 1958: Parker, et al, 1962: Hercules, 1966) deal with the principles of its analytical application and the excellent text book of Udenfriend (1962) covers the applications in the biochemical field. The possibility of using phosphorescence measurement for analytical purposes was first suggested by Lewis and Kasha (1944) and was subsequently taken up by Freed and Salmre (1958) and by Parker and Hatchard (1962). It now promises to rival fluorescence measurement as a method for the trace analysis of organic materials. The observation of delayed fluorescence was until recently of interest only to the photo-chemist, but it has now been shown to have potential value as an analytical technique also (Parker et al, 1965). The object of this paper is to outline briefly the principles of all these techniques and to draw attention to some unusual results obtained with them.
191 citations
TL;DR: It is concluded that the location of the strongly bound dye depends on the nature of the bases involved in the binding site, and the binding is more external in G.C rich than in A.T rich regions.
51 citations