Peculiarities in the elementary step of electronic energy transfer in macromolecules

2012

Ukr. J. Phys.

The present work discusses the results of comparative investigations of the optical absorption, luminescence, and photostability of the biomacromolecules (DNA, RNA), as well as synthetic poly- and oligonucleotides. The separate nucleotides in DNA and RNA are examined as almost independent absorbing centers. It is confirmed that the main triplet excitons traps responsible for the DNA phosphorescence emission are AT-complexes in DNA. In contrast toDNA, the main triplet excitons traps in RNA are adenosine bases. These bases are the most photostable against UV-irradiation as compared with all other nucleotides in both DNA and RNA. The fact of the photostability of adenosine bases and the AT-complex provides the existence of the DNA/RNA self-protection mechanisms against a damage caused by UV-irradiation. It is found the deoxyribonucleotides are more photostable than the correspondingribonucleotides. So, the results presented here show that DNA is more photostable than RNA.

Section: Resultsmentioning

confidence: 97%

The Spectral Properties and Photostability of DNA, RNA, and Oligonucleotides

Kudrya

2012

Ukr. J. Phys.

“…After such localization the EEET is possible along the DNA macromolecule through C-and G-bases. Earlier [40] it was shown, for synthetic PVCa-type macromolecules, that the value of the critical length for an elementary singlet exciton jump was close to 18 A. Thus, the singlet EEET in DNA could be rather efficient, but it was not the case.…”

Section: Fluorescence: the Singlet Eeet And The Nature Of Capturing C...mentioning

confidence: 97%

“…Thus, this S-jump is realized not only with the help of a dipole-dipole (Foerster) mechanism, but due to Dexter mechanism (see, e.g. [40,45]). So, the EEET dominates along the DNA macromolecule.…”

Section: The Singlet Eeet In Dnamentioning

confidence: 99%

“…The singlet EEET in DNA was the subject of a number of works [24,26,[33][34][35][36][37][38][39][40][41]. Most of them only prove the existence of singlet EEET [33][34][35][36][37] and examine very sophisticated models of these processes based on experimental data obtained with the help of femtosecond techniques at ambient temperatures [33,37,38].…”

Section: The Singlet Eeet In Dnamentioning

confidence: 99%

See 1 more Smart Citation

The spectral properties of DNA and RNA macromolecules at low temperatures: fundamental and applied aspects

Methods Appl. Fluoresc.

Kudrya

2017

This paper summarizes the results of studies of the spectral properties-optical absorption, fluorescence and phosphorescence-of DNA and RNA macromolecules and synthetic poly-, oligo- and mono-nucleotides, which have been carried out in our laboratory. The system of first excited singlet and triplet energy levels for DNA and RNA is evaluated using low-temperature (4.2 K-77 K) luminescent measurements. The traps of the singlet and triplet electronic excitations in these compounds are identified. An important self-protection mechanism against photo-damage of DNA and RNA by UV photons or penetrative radiation based on the capture of triplet electronic-energy excitations by the most photostable centers-in DNA, the complex formed by neighboring adenosine (A) and thymidine (T) links; in RNA, the adenosine links-is described. It is confirmed that despite similarities in the chemical and partly energy structures DNA is more stable than RNA. The spectral manifestation of the telomeres (the important functional system) in DNA macromolecules is examined. The results obtained on telomere fragments provide the possibility of finding the configuration peculiarities of the triplet excitations traps in DNA macromolecules. The resulting spreading length of the migrating singlet (l ) and triplet (l) excitations for DNA and RNA macromolecules are evaluated.

“…2) with maxima ∼350, 370, and ∼380–390 nm is also typical for low‐molecular weight carbazole containing polymers,2, 4, 5 and it is associated with fast emission of carbazole π‐electron system. At any rate, one can conclude that the nature of absorption and emitting centers is the same for PCEM and carbazole containing macromolecules that manifest only monomer fluorescence (excimer emission is absent); for example, the copolymer of N‐vinylcarbazole with octhyl methacrylate16, 18, 19 or poly[9‐(2,3‐epoxypropyl)‐carbazole] 17. The absorption spectra of PCCEM and PBCEM are red‐shifted over ∼600 cm −1 in comparison with the absorption spectrum of PCEM , but the shape of spectra and vibrational structures are similar (Fig.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and spectral investigation of alkyl methacrylates with halogenated carbazolyl pendant groups for photonics applications

Bogdał

J of Applied Polymer Sci

Pielichowski

et al. 2002

ABSTRACT:The alkyl methacrylates with halogenated carbazolyl pendant groups were prepared, and the analysis of their absorption and emission spectra showed that the polymers containing monohalogenatged carbazole rings were capable of exhibiting a high singlet-triplet (S-T) conversion. The reasons that mainly triplet excitons could be observed in such polymers and additional bands appearance in the spectra of the polymers with dihalogenated carbazole rings are discussed.