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41.
Dr. Jérôme Fortage Dr. Fabien Tuyèras Dr. Philippe Ochsenbein Dr. Fausto Puntoriero Dr. Francesco Nastasi Prof. Dr. Sebastiano Campagna Dr. Sophie Griveau Dr. Fethi Bedioui Dr. Ilaria Ciofini Dr. Philippe P. Lainé 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(36):11047-11063
This study evaluates the impact of the extension of the π‐conjugated system of pyridiniums on their various properties. The molecular scaffold of aryl‐substituted expanded pyridiniums (referred to as branched species) can be photochemically bis‐cyclized into the corresponding fused polycyclic derivatives (referred to as pericondensed species). The representative 1,2,4,6‐tetraphenylpyridinium ( 1H ) and 1,2,3,5,6‐pentaphenyl‐4‐(p‐tolyl)pyridinium ( 2Me ) tetra‐ and hexa‐branched pyridiniums are herein compared with their corresponding pericondensed derivatives, the fully fused 9‐phenylbenzo[1,2]quinolizino[3,4,5,6‐def]phenanthridinium ( 1H f ) and the hitherto unknown hemifused 9‐methyl‐1,2,3‐triphenylbenzo[h]phenanthro[9,10,1‐def]isoquinolinium ( 2Me f ). Combined solid‐state X‐ray crystallography and solution NMR experiments showed that stacking interactions are barely efficient when the pericondensed pyridiniums are not appropriately substituted. The electrochemical study revealed that the first reduction process of all the expanded pyridiniums occurs at around ?1 V vs. SCE, which indicates that the lowest unoccupied molecular orbital (LUMO) remains essentially localized on the pyridinium core regardless of pericondensation. In contrast, the electronic and photophysical properties are significantly affected on going from branched to pericondensed pyridiniums. Typically, the number of absorption bands increases with extended activity towards the visible region (down to ca. 450 nm in MeCN), whereas emission quantum yields are increased by three orders of magnitude (at ca. 0.25 on average). A relationship is established between the observed differential impact of the pericondensation and the importance of the localized LUMO on the properties considered: predominant for the first reduction process compared with secondary for the optical and photophysical properties. 相似文献
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M. Palumbo P. Rodighiero O. Gia A. Guiotto S. Marciani Magno 《Photochemistry and photobiology》1986,44(1):1-4
Abstract— The tetracyclic furocoumarin 2H-benzofuro[3,2-g]-1-benzo-pyran-2-one and its 4 and/or II methyl analogues have been investigated in their DN A-photobinding properties. Spectrophotometric and radioactivity measurements show that these compounds exhibit prominent ability to bind to the polynucleotide double helix by covalent photoaddition of the furocoumarin 3,4 double bond.
Denaturation-renaturation experiments demonstrate that no cross-link of DNA chains occurs. Benzopsoralens can thus be considered as a new class of monofunctional DNA-photobinding agents. 相似文献
Denaturation-renaturation experiments demonstrate that no cross-link of DNA chains occurs. Benzopsoralens can thus be considered as a new class of monofunctional DNA-photobinding agents. 相似文献
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In this contribution, a pulse sequence is described for recording accordion-optimized DEPT experiments. The proposed ACCORDEPT experiment detects a wide range of one-bond coupling constants using accordion optimization. As a proof of concept, this strategy has been applied to a mesogen containing a large range of one-bond (1)J(CH) coupling constants associated with the various structural elements. The ACCORDEPT experiment afforded significant enhancements for the resonances with the larger (1)J(CH) couplings, similar SNR for aliphatic resonances, but reduced SNR for aliphatic resonances as compared with the standard DEPT experiment. In addition, the ACCORDEPT is straightforward to implement, does not require any supplementary calibration procedures and can be used under automated conditions without difficulty by inexperienced users. 相似文献
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Santoni MP Hanan GS Hasenknopf B Proust A Nastasi F Serroni S Campagna S 《Chemical communications (Cambridge, England)》2011,47(12):3586-3588
A planar bis-dipyrid-2'-yltriazine (bis-dpt) bridging ligand forms dinuclear Ru(II) complexes able to store up to eight electrons upon electrochemical reduction. 相似文献
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