Triplet-triplet energy transfer in a copper(II) porphyrin-free-base porphyrin dimer

1987 ◽  
Vol 91 (16) ◽  
pp. 4269-4273 ◽  
Author(s):  
Osamu. Ohno ◽  
Yoshiharu. Ogasawara ◽  
Motoko. Asano ◽  
Yoshizumi. Kajii ◽  
Youkoh. Kaizu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Free Base ◽  
Triplet Energy ◽  
Triplet Energy Transfer ◽  
Porphyrin Dimer

Synthesis, spectroscopy and photochemistry of dyads and triads with porphyrins and bis(terpyridine)ruthenium(II) complex

2006 ◽  
Vol 10 (08) ◽  
pp. 1049-1060 ◽  
Author(s):  
Prashanth Kumar Poddutoori ◽  
Premaladha Poddutoori ◽  
Bhaskar G. Maiya
Keyword(s):  
Energy Transfer ◽  
Photophysical Properties ◽  
Soret Band ◽  
Differential Pulse ◽  
Free Base ◽  
Triplet Energy ◽  
Polar Solvents ◽  
H Nmr ◽  
Ligand Charge Transfer ◽  
Triplet Energy Transfer

A bis(terpyridine)ruthenium(II) complex ([Ru]2+) was covalently connected via a floppy - OCH 2 CH 2 O - spacer to the free-base porphyrin (H) or zinc(II) porphyrin (Zn) or both, to obtain dyads ([HRu]2+, [ZnRu]2+) and triads ([HRuH]2+, [ZnRuH]2+, [ZnRuZn]2+). These compounds have been fully characterized by MALDI, UV-vis, 1 H NMR (1D and 1 H -1 H COSY) spectroscopies, and also by the cyclic and differential pulse voltammetric techniques. Absorption spectroscopy of these newly synthesized compounds shows that significant exciton coupling exists in non-polar solvents (cyclohexane and toluene) between the porphyrin ring and the bis(terpyridine)ruthenium(II) complex. Upon excitation within the Soret band of [HRu]2+/[HRuH]2+, free-base porphyrin fluorescence was found to be strongly quenched in non-polar and weakly quenched in polar solvents, probably due to ‘singlet-triplet’ energy transfer from the free-base porphyrin to the [Ru]2+ complex. Whereas, in [ZnRu]2+/[ZnRuZn]2+, zinc(II) porphyrin fluorescence was quantitatively and reasonably quenched in non-polar and polar solvents, respectively by mainly electron transfer from the zinc(II) porphyrin to the [Ru]2+ complex. The solvent plays a crucial role in the photophysical properties of these compounds, since the energy of the triplet metal-to-ligand charge-transfer (3MLCT) excited state is influenced by the polarity of the medium. Finally, [ZnRuH]2+ exhibits the combined fluorescence properties of [HRu]2+ and [ZnRu]2+ but the observed additional quenching in non-polar solvents for the zinc(II) porphyrin component is explained by energy transfer from the zinc(II) porphyrin to the free-base porphyrin and/or the bis(terpyridine)ruthenium(II) complex.

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

Triplet energy transfer in conjugated polymers. II. A polaron theory description addressing the influence of disorder

2008 ◽  
Vol 78 (4) ◽  
Author(s):  
Ivan I. Fishchuk ◽  
Andrey Kadashchuk ◽  
Lekshmi Sudha Devi ◽  
Paul Heremans ◽  
Heinz Bässler ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Conjugated Polymers ◽  
Triplet Energy ◽  
Polaron Theory ◽  
Triplet Energy Transfer

Triplet Energy Transfer Insight in Coordination of Unsaturated Hydrocarbons by d0Bent Metallocenes (Zr, Hf)

2007 ◽  
Vol 111 (43) ◽  
pp. 10928-10937 ◽  
Author(s):  
Galina V. Loukova ◽  
Svetlana E. Starodubova ◽  
Vyatcheslav A. Smirnov
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Unsaturated Hydrocarbons ◽  
Triplet Energy Transfer

Triplet-Triplet Energy Transfer from a UV-A Absorber Butylmethoxydibenzoylmethane to UV-B Absorbers

2014 ◽  
Vol 90 (3) ◽  
pp. 511-516 ◽  
Author(s):  
Azusa Kikuchi ◽  
Nozomi Oguchi-Fujiyama ◽  
Kazuyuki Miyazawa ◽  
Mikio Yagi
Keyword(s):  
Energy Transfer ◽  
Triplet Energy ◽  
Triplet Energy Transfer
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