- Dynamics of the higher lying excited states of cyanine dyes. An ultrafast fluorescence study
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The electronic relaxation dynamics of the second singlet excited states of several cyanine dyes was studied through the femtosecond fluorescence up-conversion technique. Our interest in these molecules comes from the potential applications of systems with upper excited singlet states with a long lifetime, which can include electron and energy transfer from the higher lying singlets after one- or two-photon absorption. We studied three series of cyanines with 4-quinolyl, 2-quinolyl, or benzothiazolyl type end groups, each with varying sp2 carbon conjugation lengths in the methinic bridge. The dynamics after electronic excitation to singlet states above the fluorescent state vary significantly as a function of cyanine structure and conjugation length. In particular, for the 4-quinolyl series the cyanine with an intermediate conjugation length (three methinic carbons) has the slowest S 2 decays with lifetimes of 5.4 ps in ethanol and 6.6 ps in ethylene glycol. On the other hand, we observed that the 2-quinolyl family has S 2 decay times in the subpicosecond range independent of the conjugation length between the end groups. The slowest internal conversion was observed for the benzothiazolyl type cyanine with five methinic carbons, with an S2 lifetime of 17.3 ps in ethanol. For the planar cyanines of this study we observed for the first time a clear systematic trend in the S 2 decay times which closely follow the energy gap law. It was also demonstrated that a slow S2 decay is as well observed upon excitation through degenerate two-photon absorption with near-IR pulses. The present study isolates the most important variables for the design of cyanines with long S2 lifetimes.
- Guarin, Cesar A.,Villabona-Monsalve, Juan. P.,López-Arteaga, Rafael,Peon, Jorge
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- A self-immolative near-infrared probe based on hemi-benzothiazolecyanine for visualizing hydrogen peroxide in living cells and mice
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Hemicyanine dyes including hemi-indocyanine and hemi-benzindocyanine have been attracted considerable attentions to develop near infrared probes for in vivo fluorescence imaging. However, hemi-benzothiazolecyanine dye (MTR) is rarely reported for detection analytes. In this work, to extend the sensing applications of MTR, we present an optimized route for facile preparation of the dye. And as a proof-of-concept, a self-immolative NIR probe MTR-HH based on hemi-benzothiazolecyanine dye was designed and synthesized for H2O2. The probe exhibited a 284-fold fluorescent enhancement to H2O2 with a detection limit of 0.32 μM over other biospecies. Moreover, MTR-HH was successfully applied for visualizing endogenous H2O2 in living cells and mice.
- Gong, Yi?Jun,Feng, Dan?Dan,Liu, Wei?Ning,Fang, Jing?Kun,Feng, Suling
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- CHEMISTRY OF ENOL ETHERS. LII. REACTION OF THE VINYLOGS OF THE VILSMEIER COMPLEX WITH HETEROCYCLIC COMPOUNDS AS A NEW METHOD FOR THE SYNTHESIS OF CYANINE DYES
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During the condensation of the vinylogs of the Vilsmeier complex with quaternary salts of heterocyclic bases containing an active methyl group the meso-substituted di- and tricarbocyanine dyes are formed.
- Makin, S. M.,Pomogaev, A. I.
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p. 2020 - 2024
(2007/10/02)
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