Conformational rearrangements in and twisting of a single molecule

Hofkens, Johan; Vosch, Tom; Maus, Michael; Köhn, F.; Cotlet, Mircea; Weil, Tanja; Herrmann, Andreas; Müllen, Kläus; Schryver, F. C. De

doi:10.1016/s0009-2614(00)01349-x

Cited by 133 publications

(199 citation statements)

References 21 publications

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“…Fluorescence was focused onto an intensified frame transfer camera (Pentamax Roper Scientific), whereas excitation laser light was suppressed by a long pass filter (Omega "3RD530LP"). [22], and toluene (606 nm) [9]. The spectrum in toluene shows a pronounced vibronic side band (as has been observed in all other solution spectra), which is less pronounced for PP in PMMA and on SiO 2 .…”

Section: Methodssupporting

confidence: 64%

“…Perylene bisimide (PBI) type molecules are one of those dye molecules which show on one hand a sufficiently high photostability. On the other hand they are due to various (bay) groups subject to intramolecular dynamics [9,10]. In a recent publication [11] a comparison of time resolved fluorescence and molecular dynamics calculations has demonstrated, that these bay groups control the formation and interconversion of two limiting classes of conformations.…”

Section: Introductionmentioning

confidence: 99%

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Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films

2009

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Section: Methodssupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films

2009

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“…In ZE, an apolar matrix, we do not expect ET to occur at all. Indeed, single molecules of PN16 and PN8 display a behavior reminiscent of that of single dye molecules (20)(21)(22). Fluorescence is emitted with one stable level of intensity at an average photon count rate of 100-175 counts per 10 ms (Fig.…”

Section: Methodsmentioning

confidence: 99%

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer

Cotlet

Masuo

Luo

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

111

102

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S ingle-molecule detection (SMD) has been extensively used to answer questions of both biophysical chemistry and chemical physics relevance (1-5). An elegant way to probe conformational changes is to take advantage of distance-dependent processes involving pairs of fluorophores. Förster resonant energy transfer (FRET) between two fluorophores has gained popularity as a sensitive tool to probe distance changes in the nanometer range (5-8). With an efficiency scaling with the inverse of the 6th power of the interchromophore distance, FRET can be used to track distance changes in the 2-to 8-nm range in various biological structures (5). The distance scale can be downsized to the ångstrom scale if one uses photoinduced electron transfer (ET). ET usually involves a pair of electron donor (D) and acceptor (A) chromophores spatially separated by an edge-toedge distance of Ϸ1 nm or less (9). Because the efficiency scales exponentially with the D-A distance, ET can probe distance changes with subångstrom resolution. However, whereas highly efficient FRET results in fluorescence emitted mainly from the acceptor fluorophore, highly efficient ET usually leads to a strong quenching of the fluorescence of the emitting chromophore. Thus, reports on single-molecule photoinduced ET are rather limited (10-14), in contrast to reports on singlemolecule FRET. A particular situation of ET refers to the case in which the locally excited state (LES) and the charge-separated state (CSS) are relatively close in energy (Fig. 1A, with CSS in position 2). In this case, upon optical excitation, the LES deactivates mainly by forward ET to the CSS and, if the radiationless deactivation of the CSS to the ground state (GS) is inefficient (see below), the CSS is forced to decay through the LES by reverse ET (14, 15). The fluorescence is delayed but can retain a high quantum yield. If present, reversible ET can be probed by SMD if the excited chromophore shows bright fluorescence and high photostability. In some cases, competition between the deactivation of the CSS to the LES or to the GS may be influenced by molecular oxygen (15).Here we use single-molecule fluorescence decay times to probe the dynamics of reversible ET between an excited perylenediimide (acceptor, P) and triphenylamine (donor, N) as parts in a dendritic structure. Triphenylamines are attached to the core perylenediimide by means of a polyphenylene skeleton that imposes some rigidity on the whole structure. The D-A distance is thus modified, in a controlled way, from the first (PN8, Fig. 1B with R ϭ R1) to the second (PN16, Fig. 1B with R ϭ R2) generation; hence, we expected that the parameters of the ET change as well. Materials and MethodsEnsemble stationary and time-resolved fluorescence spectroscopy was performed on 10 Ϫ6 M solutions of PN8 and PN16 (16) in solvents of different polarity: methylcyclohexane, toluene, and ethyl acetate, all of spectral-grade purity. Before measurements, solutions were degassed by freeze-pump-thaw cycling. Fluorescence decays were recorded at 5...

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“…Additionally, oxidation or even partial oxidation of a silver cluster has been shown to have a very large effect on the emission spectrum, usually a clear blueshift outside the region where we can still excite the C24-AgNCs [ 40,41 ] The changes observed in this case are generally below 100 nm. Fluorophores can undergo small changes to their conformation, even when suspended in a polymer matrix, [ 42,43 ] which can lead to changes in their inherent fl uorescent properties. Although it has been shown that DNA conformation is relatively stable in PVA fi lms, [ 44 ] small fl uctuations are likely given the large void size and inhomogeneous nature of PVA fi lms.…”

Section: Single Molecule Measurements: Antibunchingmentioning

confidence: 99%

Single‐Molecule Characterization of Near‐Infrared‐Emitting Silver Nanoclusters

Hooley

Paolucci

Liao

et al. 2015

Advanced Optical Materials

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In this paper, single molecule spectroscopy is used to probe the photophysical heterogeneity of near‐infrared emitting silver nanoclusters stabilized in single stranded DNA containing 24 cytosines (C24‐AgNCs). Focusing on this subset of emitters allows us to address and correlate their photophysical parameters. The results suggest that for these near‐infrared emitting C24‐AgNCs, the broad range of observed photophysical properties is due to the spectral heterogeneity of two species, one of which has a broad range of emission maxima and decay times. This conclusion is drawn by analyzing the results of a large number of single C24‐AgNCs where, for the first time, emission maxima, fluorescence decay times, fluorescence intensity, blinking, and photon antibunching are determined simultaneously. The single molecule measurements also reveal that some of the C24‐AgNCs can change their spectral properties during the measurement, while photon antibunching measurements verified that all the analyzed C24‐AgNCs behave as single emitters. While the overall spectral heterogeneity can be related to the immobilization in the polymer film and/or intrinsic heterogeneity of the C24‐AgNCs emitters, the exact origin of the dynamical changes has not been fully determined. However, changes in the AgNCs geometry, local environment, or changes in the DNA conformation are possible explanations.

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Conformational rearrangements in and twisting of a single molecule

Cited by 133 publications

References 21 publications

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer

Single‐Molecule Characterization of Near‐Infrared‐Emitting Silver Nanoclusters

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Conformational rearrangements in and twisting of a single molecule

Cited by 133 publications

References 21 publications

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO2surfaces and in thin polymer films

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO2surfaces and in thin polymer films

Probing conformational dynamics in single donor-acceptor synthetic molecules by means of photoinduced reversible electron transfer

Single‐Molecule Characterization of Near‐Infrared‐Emitting Silver Nanoclusters

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Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO₂surfaces and in thin polymer films