scholarly journals Directional and regioselective hole injection of spiropyran photoswitches intercalated into A/T-duplex DNA

2019 ◽  
Vol 21 (32) ◽  
pp. 17971-17977 ◽  
Author(s):  
Davide Avagliano ◽  
Pedro A. Sánchez-Murcia ◽  
Leticia González
Keyword(s):  
Electron Transfer ◽  
Hole Injection ◽  
Duplex Dna ◽  
Multiscale Computations

The hole electron transfer of UV excited spiropyran intercalated in dsDNA is directional, asymmetric and regioselective, as shown by quantitative multiscale computations.

Distance-Dependent Activation Energies for Hole Injection from Protonated 9-Amino-6-chloro-2-methoxyacridine into Duplex DNA

2002 ◽  
Vol 124 (11) ◽  
pp. 2422-2423 ◽  
Author(s):  
William B. Davis ◽  
Stephan Hess ◽  
Izabela Naydenova ◽  
Reinhard Haselsberger ◽  
Alexander Ogrodnik ◽  
...  
Keyword(s):  
Activation Energies ◽  
Hole Injection ◽  
Duplex Dna

Zur Ladungstrennung bei der sensibilisierten Löcherinjektion in Anthracenkristallen / Charge Separation and Sensitized Hole Injection into Anthracene Crystals

1975 ◽  
Vol 30 (4) ◽  
pp. 506-514
Author(s):  
M. E. Michel-Beyerle ◽  
W. Bube ◽  
R. Haberkorn
Keyword(s):  
Electron Transfer ◽  
Surface Recombination ◽  
Delayed Fluorescence ◽  
Injection Current ◽  
Hole Injection ◽  
Recombination Rates ◽  
Crystal Water ◽  
Injection Process ◽  
Current Voltage ◽  
Anthracene Crystal

Abstract The dependence of the sensitized injection current and of the crystal's sensitized delayed fluorescence on the electric and magnetic field is utilized to examine the process of charge separa-tion at the phase boundary crystal/water electrode. Hole currents, sensitized by electron transfer interaction between rhodamine B molecules in their lowest excited singlet state and the anthracene crystal, can be shown to originate from a thermal injection process. This conclusion is further supported by the changed phenomenology of the injection current and the delayed fluorescence in the presence of molecular oxygen in the aqueous electrode. In this case an alternative injection reaction predominates due to the oxygen enhancement of the intersystem crossing rate and thus of the sensitized population of triplet excitons in the crystal, the latter ones injecting holes through electron transfer to oxygen present at the surface.Neglecting image-and Coulomb forces at the interface crystal/electrolyte, an analytical ex-pression for the current-voltage relation can be given which includes the influence of the space charge. This expression does well agree with the experimental current-voltage characteristics ob-served for different surface recombination rates of charge carriers.

DNA photonics

2006 ◽  
Vol 78 (12) ◽  
pp. 2287-2295 ◽  
Author(s):  
Frederick D. Lewis
Keyword(s):  
Electron Transfer ◽  
Energy Transfer ◽  
Dihedral Angle ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Single Step ◽  
Hole Injection ◽  
Electronic Interaction ◽  
Base Pairs ◽  
Donor And Acceptor

Short DNA duplexes can be stabilized by the presence of organic chromophores, which serve as hairpin linkers or end-capping groups. Capped hairpins possessing one or more base pairs form stable folded structures in aqueous solution. Increasing the number of base pairs separating the two chromophores increases both the distance between the two chromophores and the dihedral angle between their electronic transition dipoles. Thus, duplex DNA can serve as a helical scaffold for the study of electronic interactions between two chromophores. Three types of electronic interaction have been investigated: (a) exciton coupling (EC) between two identical chromophores, as probed by exciton-coupled circular dichroism (EC-CD); (b) fluorescence resonance energy transfer (FRET) between a fluorescent donor and acceptor; and (c) photoinduced electron transfer (PET) between an electron donor and acceptor. EC and the efficiency of fluorescence energy transfer are dependent upon both the distance and dihedral angle separating the two chromophores. Electron transfer occurs via both single-step superexchange and bridge-mediated hopping mechanisms, neither of which displays angular dependence. The competition between these mechanisms is dependent upon both the energetics of hole injection into the base-pair bridge and the distance between the donor and acceptor chromophores, superexchange dominating at short distance and hole hopping at longer distances.

Dynamics of superexchange photoinduced electron transfer in duplex DNA

2001 ◽  
Vol 2 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Frederick D Lewis ◽  
Yansheng Wu
Keyword(s):  
Electron Transfer ◽  
Photoinduced Electron Transfer ◽  
Duplex Dna

Naphthalenedicarboxamides as Fluorescent Probes of Inter- and Intramolecular Electron Transfer in Single Strand, Hairpin, and Duplex DNA

1999 ◽  
Vol 103 (13) ◽  
pp. 2570-2578 ◽  
Author(s):  
Frederick D. Lewis ◽  
Yifan Zhang ◽  
Xiaoyang Liu ◽  
Ning Xu ◽  
Robert L. Letsinger
Keyword(s):  
Electron Transfer ◽  
Fluorescent Probes ◽  
Single Strand ◽  
Intramolecular Electron Transfer ◽  
Duplex Dna

A light optical diffractometer for electron microscopical images operating in line

1978 ◽  
Vol 36 (1) ◽  
pp. 86-87
Author(s):  
P. Bonhomme ◽  
A. Beorchia
Keyword(s):  
Electron Microscopy ◽  
Electron Transfer ◽  
Electron Microscope ◽  
Image Converter ◽  
Coherent Light ◽  
Spatial Filters ◽  
Electron Image ◽  
Electron Microscopical ◽  
Working Parameters ◽  
Amorphous Part

We have already described (1.2.3) a device using a pockel's effect light valve as a microscopical electron image converter. This converter can be read out with incoherent or coherent light. In the last case we can set in line with the converter an optical diffractometer. Now, electron microscopy developments have pointed out different advantages of diffractometry. Indeed diffractogram of an image of a thin amorphous part of a specimen gives information about electron transfer function and a single look at a diffractogram informs on focus, drift, residual astigmatism, and after standardizing, on periods resolved (4.5.6). These informations are obvious from diffractogram but are usualy obtained from a micrograph, so that a correction of electron microscope parameters cannot be realized before recording the micrograph. Diffractometer allows also processing of images by setting spatial filters in diffractogram plane (7) or by reconstruction of Fraunhofer image (8). Using Electrotitus read out with coherent light and fitted to a diffractometer; all these possibilities may be realized in pseudoreal time, so that working parameters may be optimally adjusted before recording a micrograph or before processing an image.

Sign in / Sign up

Export Citation Format

Share Document