Bichromophoric fluorescent dyes with rigid molecular structure: fluorescence ability regulation by the photoinduced intramolecular electron transfer
15 Jul 2004-Journal of Photochemistry and Photobiology A-chemistry (Elsevier)-Vol. 165, Iss: 1, pp 59-68
TL;DR: Bichromophoric 3-diethylamino-7-phenyl-7H-benzo-[4,5]-imidazo-[1,2-c]-chromeno-[3,2e]-pyrimidines were synthesized by the condensation of 7-diagramnino-3-(2-benzimidazolyl)-iminochromene with several aromatic aldehydes as discussed by the authors.
Abstract: Bichromophoric 3-diethylamino-7-phenyl-7H-benzo-[4,5]-imidazo-[1,2-c]-chromeno-[3,2-e]-pyrimidines were synthesized by the condensation of 7-diethylamino-3-(2-benzimidazolyl)-iminochromene with several aromatic aldehydes. Fluorescence properties of these compounds were studied in solvents of various polarity and acidity. The excited state intramolecular electron transfer was shown as the reason for the fluorescence quenching of the studied dyes with electron donor substituents in the minor chromophoric moiety. Prospects for the usage of these compounds as fluorescence probes sensitive to polarity and pH of their surrounding were elucidated.
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TL;DR: A new family of coumarin-based pH indicators was synthesized, sensitive to pH in either weakly acidic or weakly basic solution, which possess moderate to high brightness, excellent photostability and compatibility with light-emitting diodes.
Abstract: A new family of coumarin-based pH indicators was synthesized. They are sensitive to pH in either weakly acidic or weakly basic solution. The indicators possess moderate to high brightness, excellent photostability and compatibility with light-emitting diodes. The indicators were covalently immobilized on the surface of amino-modified polymer microbeads which in turn were incorporated into a hydrogel matrix to obtain novel pH-sensitive materials. When a mixture of two different microbeads is used, the membranes are capable of optical pH sensing over a very wide range comparable to the dynamic range of the glass electrode (pH 1-11).
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TL;DR: In this paper, a dye-sensitized nanocrystalline TiO2 solar cells (DSSCs) with carboxyl and hydroxyl anchoring groups was designed and synthesized for the application of DSSC.
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TL;DR: Turki et al. as discussed by the authors showed that iminocoumarin derivatives can advantageously replace coumarins in this type of solvents, and confirms that substitution on the imino group is a convenient way to obtain good fluorescent probes designed for various purposes.
42 citations
TL;DR: The results show that the absorption maxima and fluorescence emission maxima calculated using the Time-Dependent Density Functional Theory is in good agreement with the available experimental results.
Abstract: The electronic structures and photophysical properties of rigid coumarin dyes have been studied by using quantum chemical methods. The ground-state geometries of these dyes were optimized using the Density Functional Theory (DFT) methods. The lowest singlet excited state was optimized using Time -Dependent Density Functional Theory [TD-B3LYP/6-31G(d)]. On the basis of ground- and excited-state geometries, the absorption and emission spectra have been calculated using the DFT and TD-DFT method. All the calculations were carried out in gas phase and in acetonitrile medium. The results show that the absorption maxima and fluorescence emission maxima calculated using the Time-Dependent Density Functional Theory is in good agreement with the available experimental results. To understand the Non- Linear Optical properties of coumarin dyes we computed dipole moment (μ), electronic polarizability (α), mean first hyperpolarizability (βo) and second hyperpolarizability (γ) using B3LYP density functional theory method in conjunction with 6-31G(d) basis set.
32 citations
Cites background from "Bichromophoric fluorescent dyes wit..."
...a absorption maxima value taken from ref [1], b f=oscillator strength...
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...99) [1, 2], high molar extinction coefficients (10,000–54,300) [1, 3] and large Stokes shifts (up to 160 nm) [4]....
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...reported bichromophoric fluorescent coumarin dyes with rigid molecular structure; these compounds are very sensitive to solvent polarity and pH [1]....
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...All experimental values were taken from reference [1]....
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TL;DR: A series of novel long-wavelength, fluorescent, novel iminocoumarin derived dyes were synthesized by extending the π-conjugation and spatial location of the benzimidazolic and iminochromene rings in a planar structure.
28 citations
References
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Book•
01 Jan 1983
TL;DR: This book describes the fundamental aspects of fluorescence, the biochemical applications of this methodology, and the instrumentation used in fluorescence spectroscopy.
Abstract: Fluorescence methods are being used increasingly in biochemical, medical, and chemical research. This is because of the inherent sensitivity of this technique. and the favorable time scale of the phenomenon of fluorescence. 8 Fluorescence emission occurs about 10- sec (10 nsec) after light absorp tion. During this period of time a wide range of molecular processes can occur, and these can effect the spectral characteristics of the fluorescent compound. This combination of sensitivity and a favorable time scale allows fluorescence methods to be generally useful for studies of proteins and membranes and their interactions with other macromolecules. This book describes the fundamental aspects of fluorescence. and the biochemical applications of this methodology. Each chapter starts with the -theoreticalbasis of each phenomenon of fluorescence, followed by examples which illustrate the use of the phenomenon in the study of biochemical problems. The book contains numerous figures. It is felt that such graphical presentations contribute to pleasurable reading and increased understand ing. Separate chapters are devoted to fluorescence polarization, lifetimes, quenching, energy transfer, solvent effects, and excited state reactions. To enhance the usefulness of this work as a textbook, problems are included which illustrate the concepts described in each chapter. Furthermore, a separate chapter is devoted to the instrumentation used in fluorescence spectroscopy. This chapter will be especially valuable for those perform ing or contemplating fluorescence measurements. Such measurements are easily compromised by failure to consider a number of simple principles."
28,073 citations
"Bichromophoric fluorescent dyes wit..." refers background in this paper
...Owing to the sensitivity of their spectral properties to the acidity of the media, coumarins were recommended as fluorescent pH indicators [6,7] and fluorescent sensors for pH estimation in biological objects on the micro-level [8]....
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TL;DR: In this paper, an algorithm for the accurate calculation of dielectric screening effects in solvents is presented, which leads to rather simple expressions for the screening energy and its analytic gradient with respect to the solute coordinates.
Abstract: Starting from the screening in conductors, an algorithm for the accurate calculation of dielectric screening effects in solvents is presented, which leads to rather simple explicit expressions for the screening energy and its analytic gradient with respect to the solute coordinates. Thus geometry optimization of a solute within a realistic dielectric continuum model becomes practicable for the first time. The algorithm is suited for molecular mechanics as well as for any molecular orbital algorithm. The implementation into MOPAC and some example applications are reported.
7,865 citations
"Bichromophoric fluorescent dyes wit..." refers background in this paper
...The media polarity effects were not taken into account in such calculations, therefore they were repeated in the dielectric continuum model (COSMO [26]) with ε = 37 (arbitrary modeling the aqueous ethyl alcohol surrounding)....
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TL;DR: In this paper, a new method for obtaining optimized parameters for semi-empirical methods has been developed and applied to the modified neglect of diatomic overlap (MNDO) method.
Abstract: A new method for obtaining optimized parameters for semiempirical methods has been developed and applied to the modified neglect of diatomic overlap (MNDO) method. The method uses derivatives of calculated values for properties with respect to adjustable parameters to obtain the optimized values of parameters. The large increase in speed is a result of using a simple series expression for calculated values of properties rather than employing full semiempirical calculations. With this optimization procedure, the rate-determining step for parameterizing elements changes from the mechanics of parameterization to the assembling of experimental reference data.
7,125 citations
TL;DR: In this paper, a review compiles positively and negatively solvatochromic compounds which have been used to establish empirical scales of solvent polarity by means of UV/vis/near-IR spectroscopic measurements in solution.
Abstract: This review compiles positively and negatively solvatochromic compounds which have been used to establish empirical scales of solvent polarity by means of UV/vis/near-IR spectroscopic measurements in solution-with particular emphasis on the E ~ ( 3 0 ) scale derived from negatively solvatochromic pyridinium N-phenolate betaine dyes. This requires a short discussion of the concept of solvent polarity and how empirical parameters of solvent polarity can be derived and understood in the framework of linear free-energy relationships. The preconditions for the occurrence of solvatochromism, and further requirements of solvatochromic compounds for them to be useful as solvent polarity indicators will be discussed. In addition to spectroscopically based single parameters of solvent polarity, multiparameter treatments of solvent effects by means of solvatochromic parameters will also be mentioned. The mutual interrelation between some of the more important W/vis/near-IR spectroscopically derived solvent scales, and their correlations with solvatochromic multiparameter equations will be exemplarily given.
4,512 citations
"Bichromophoric fluorescent dyes wit..." refers background or methods in this paper
...This thesis is supported by the better correspondence of the reversed lifetime of IId and Lippert solvatochromic function (L = ((ε − 1)/(ε + 1)) − ((n2 − 1)/(n2 + 1)) [24], which takes into account only universal interactions), rather than empirical Reichardt polarity parameter EN T (30) [25], which includes both specific and universal interactions between...
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...ε, dielectric constants; n, refraction indices of the solvents; L, Lippert solvent polarity [24]; EN T (30), Reichardt solvent polarity [25] functions; τ, fluorescence lifetime....
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TL;DR: In this article, the rate constants of 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process.
Abstract: Fluorescence quenching rate constants, kq, ranging from 106 to 2 × 1010 M−1 sec−1, of more than 60 typical electron donor-acceptor systems have been measured in de-oxygenated acetonitrile and are shown to be correlated with the free enthalpy change, ΔG23, involved in the actual electron transfer process
in the encounter complex and varying between + 5 and −60 kcal/mole. The correlation which is based on the mechanism of adiabatic outer-sphere electron transfer requires ΔG≠23, the activation free enthalpy of this process to be a monotonous function of ΔG23 and allows the calculation of rate constants of electron transfer quenching from spectroscopic and electrochemical data.
A detailed study of some systems where the calculated quenching constants differ from the experimental ones by several orders of magnitude revealed that the quenching mechanism operative in these cases was hydrogen-atom rather than electron transfer.
The conditions under which these different mechanisms apply and their consequences are discussed.
3,485 citations
"Bichromophoric fluorescent dyes wit..." refers background in this paper
...Taking into account the bichromophoric character of IId and IIe, the absence of any conjugation between the -electron subsystems of these molecules, we assume the intramolecular electron transfer [20,21] from the dialkylamino-phenyl to 3-benzimidazolyl-iminochromene moieties as a possible reason of the discussed quenching....
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