The green fluorescent protein (GFP) and its mutants are important fluorescent markers for the microscopy of biological specimens. Their photodynamics are governed by transitions between the neutral and anionic form of the light emitting chromophore. We used two-color fluorescence excitation spectroscopy to show that this is also true for mutants such as EGFP and E222Q, which in their ground state do not show any absorption attributable to the neutral chromophore. The photodynamics of E222Q are described within the framework of a 4-level system comprising two dark states. Two-color fluorescence correlation spectroscopy (FCS) has been employed to determine the rate constants for this system. The first of these states has a population rate of 3 × 105 s-1 and a lifetime of 50 μs, indicating that this is the triplet state. The second state, which we identified as the neutral chromophore, has a population rate of 4 × 105 s-1 and a lifetime of 500 μs. Our data allude to the fact that, already at low intensities, a large fraction of the molecules are in the dark states.

Fluorescence excitation lines of single terrylenediimide (TDI) molecules were recorded in the matrices polyethylene (PE) and hexadecane (HD) in the temperature range between 1.4 and 13 K. From line width distributions at 2.5 K in both matrices it was concluded that the disorder, theoretically modeled by a distribution of two-level systems (TLSs), is about three times stronger in PE. Temperature-dependent measurements of the line shape of single chromophores showed a reversible broadening and shift of the zero-phonon lines. We attributed this behavior to dephasing caused by pseudolocal phonons and to spectral diffusion caused by fluctuating TLSs of the disordered host. Following these assumptions, the data could be well approximated with the pertinent expressions. The specific environments of the individual molecules are reflected by different behaviors of their `homogeneous' lines.

The method of fluorescence excitation spectroscopy of single molecules isolated in frequency space at liquid helium temperature was used to examine Terrylenediimide (TDI). The chromophore shows sharp zero-phonon lines and high fluorescence count rates which could be demonstrated by saturation studies. Additionally fluorescence spectra of single TDI molecules in the solid host matrix hexadecane will be discussed. As the structure of TDI allows further attachment to other molecules, TDI is a promising chromophore for e.g., fluorescence labeling.

The photophysical properties of terrylenediimide (TDI) make this novel fluorophore an ideal candidate for single-molecule studies in solid matrices using various optical techniques. By employing frequency selective high-resolution laser spectroscopy at liquid helium temperatures, we could isolate the fluorescence excitation lines of single TDI molecules. Additionally, vibrational modes of the molecule were examined and the population and depopulation rates of the triplet state determined. At temperatures between 100 K and room temperature single TDI molecules were imaged by confocal fluorescence microscopy. In these investigations one-step irreversible bleaching and “on−off” transitions of the fluorescence were observed.

Dependence on the Substituents of the Photoconduction from Arylamines Aromatic amines are often used as charge transporting agents in electrophotographic two-layer-systems. Structure-property-relations of this substance class are discussed on the basis of homogeneously sensitized polycarbonat-layers containing derivatives of anilines. Substituent variation of the actinic compounds has a significant influence on the electrophotographic sensitivity. Correlations between Hammett substituents constants and electrophotographic sensitivity are useful for the preselection of arylamin structures. Dibenzylamino groups lie out of these correlations and induce an unexpected high photoconductivity. This fact was investigated by cyclovoltammetric measurements of 22 various dibenzylanilines. Low half-peakpotentials and reversible one-electron oxidation steps of dibenzylanilines are necessary for outstanding photoconductor properties.

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Starting from analyses of the patent situation, trends and important material types of subject monomeric organic photoconductors are recorded. An introduction to N-benzhydrylanilines and important possibilities of synthesis are given. 23 compounds are described in this paper. Structure-properties relations and correlations between the electrophotographic sensitivity and the Hammett-constants of the substituents are discussed.

Journal für Praktische Chemie/Chemiker-ZeitungVolume 334, Issue 5 p. 437-440 Arbeitsvorschriften Und MeßWerte Synthese, Charakterisierung und UV-VIS-spektroskopisches Verhalten von 4-benzhydrylamino-substituierten Azobenzolen Synthesis, Characterization and UV-VIS-spectral Behaviour of 4-Benzhydrylamino-substituted Azobenzenes Prof. Dr. J. Epperlein, Corresponding Author Prof. Dr. J. Epperlein Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandFachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this authorS. Mais, S. Mais Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this authorB. Blau, B. Blau Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this author Prof. Dr. J. Epperlein, Corresponding Author Prof. Dr. J. Epperlein Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandFachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this authorS. Mais, S. Mais Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this authorB. Blau, B. Blau Fachbereich Chemie der Technischen Universität Chemnitz, Straße der Nationen 62 O-9010 Chemnitz, Bundesrepublik DeutschlandSearch for more papers by this author First published: 1992 https://doi.org/10.1002/prac.19923340513Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume334, Issue51992Pages 437-440 RelatedInformation