FRANCK-CONDON-LIKE PATTERNS OBSERVED IN THE INFRARED SPECTRA OF PHENOL-ALKYLSILANE DIHYDROGEN-BONDED CLUSTERS IN THE EXCITED STATES

Recent experimental and theoretical investigations dealing with model DNA double helices, composed of either adenine–thymine (A–T) or guanine–cytosine (G–C) base pairs, and G quadruplexes shed some light on the excited states populated by photon absorption and their relaxation, energy transfer among bases, and one-photon ionization. These studies revealed that the Franck–Condon excited states of DNA helices cannot be considered as the sum of their monomeric constituents because electronic coupling induces delocalization of the excitation over a few bases. Energy transfer takes place via intraband scattering in less than 100 fs. The fluorescence lifetimes of DNA helices detected by fluorescence upconversion and corresponding mainly to ππ* transitions are longer than that of an equimolar mixture of nucleotides; the only exception was observed for alternating G–C polymers. Moreover, nanosecond flash photolysis experiments showed that organization of bases within single and double helices may lead to a lowering of their ionization potential. Finally, the first determination regarding the time-scale needed for the formation of T dimers, the (6–4) adducts, was determined for the single strand (dT)20.

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Franck–Condon-like Progressions in Infrared Spectra of Biological Molecules

The Journal of Physical Chemistry A ◽

10.1021/acs.jpca.5b08801 ◽

2015 ◽

Vol 119 (42) ◽

pp. 10494-10501 ◽

Cited By ~ 7

Author(s):

Aleksandra V. Zabuga ◽

Michael Z. Kamrath ◽

Thomas R. Rizzo

Keyword(s):

Infrared Spectra ◽

Biological Molecules ◽

Franck Condon

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Exploring ultraviolet photoinduced charge-transfer dynamics in a model dinucleotide of guanine and thymine

Physical Chemistry Chemical Physics ◽

10.1039/c8cp07864e ◽

2019 ◽

Vol 21 (26) ◽

pp. 14407-14417 ◽

Cited By ~ 4

Author(s):

Marta Duchi ◽

Michael P. O’Hagan ◽

Rhea Kumar ◽

Simon J. Bennie ◽

M. Carmen Galan ◽

...

Keyword(s):

Charge Transfer ◽

Excited States ◽

Product Formation ◽

Photoinduced Charge Transfer ◽

Charge Transfer Dynamics ◽

Franck Condon ◽

Photoinduced Charge

We unequivocally demonstrate that the Franck–Condon excited states of 2′-deoxyguanosine 3′-monophospate 5′-thymidine are significantly delocalised across both nucleobases, and mediate ultrafast exciplex product formation.

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Abinitio calculation of the vibrational structure in the electronic spectra of HCN and DCN between 1700 and 2000 Å

Canadian Journal of Chemistry ◽

10.1139/v77-514 ◽

1977 ◽

Vol 55 (20) ◽

pp. 3664-3675 ◽

Cited By ~ 34

Author(s):

M. Perić ◽

S. D. Peyerimhoff ◽

R. J. Buenker

Keyword(s):

Excited States ◽

Band System ◽

Vibrational Structure ◽

Electronic Transitions ◽

Dissociation Limit ◽

Potential Surfaces ◽

Double Zeta ◽

Polarization Functions ◽

Franck Condon ◽

Ci Calculations

Ab initio SCF and CI calculations for the potential surfaces of HCN in ground and various 1(π,π*) excited states are carried out using an AO basis of double-zeta quality augmented with various polarization functions. These results are then combined with transition moment data to allow for a Franck-Condon analysis of the vibrational structure of the lowest three electronic transitions in both HCN and DCN. The resulting intensity distribution is then compared with the corresponding experimental data reported by Herzberg and Innes. This work confirms the earlier conclusion of Schwenzer et al. that the upper state in the [Formula: see text] band system is the 1∑−−1A″species, and not the 1Δ as originally believed. In addition a detailed mechanism for the observed predissociation of the α state is outlined, in which the gradual conversion of the π* MO of bent HCN into a pure hydrogenic 1s AO plays a key role. Arguments are also presented in favor of assigning the [Formula: see text]transition seen in DCN to a 1Δ-21A′ upper state with the same D + CN dissociation limit as for the 1∑−−1A″ species.

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