Exciplex formation in alcohol and water solutions of 7-azaindole

Collins, Susan

doi:10.1021/j100240a009

Cited by 36 publications

(39 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This emis sion band, ini tially as signed to a strongly red-shifted nor mal emis sion, 194 has been al ter natively sug gested to re sult from an exciplex (7AI/wa ter) forma tion. 195 Later, Negrerie et al 174 re as signed the en tire 385 nm band to the tau to mer emis sion re sult ing from ESDPT. Sub se quently, Chou and co-workers 196 in ves ti gated 7AI in ethers ti trated by wa ter and re solved a weak tau to mer emission max i mum at ~ 500 nm which was pro posed to orig i nate from ESDPT of the 1:1 cy clic 7AI/wa ter HB com plex in the di luted wa ter con cen tra tion.…”

Section: Ivc 7-azaindoles In Aque Ous So Lu Tionmentioning

confidence: 99%

“…The steady-state ob ser va tion of the well-resolved tauto mer emis sion dis cards the pro posed mech a nism of the prohi bi tion of ESDPT dur ing the life time of the ex cited 7AI in pure wa ter. 174,[194][195][196] That the unique rise time of the tau to mer emis sion cor re lated well with the en tire de cay of the nor mal emis sion dis counts the pro posed mech a nism that only a minor part of the nearly cor rect 1:1 cy clic com plex un der goes ESDPT, while the nor mal emis sion orig i nates from the polysolvated 7AI. 78,177,197 Al ter na tively, the ex per i men tal results can be more plau si bly ra tio nal ized by the mech a nism pro posed by Maroncelli and co-workers 181 that the dy nam ics of ESDPT are as so ci ated with en tire solvated 7AI where the ki netic scheme can be de scribed within the frame work of 7AI in al co hols (see Fig.…”

Section: Ivc 7-azaindoles In Aque Ous So Lu Tionmentioning

confidence: 99%

See 1 more Smart Citation

The Host/Guest Type of Excited‐State Proton Transfer; a General Review

Chou

2001

J Chinese Chemical Soc

View full text Add to dashboard Cite

Contemporary progress regarding guest/host types of excited‐state double proton transfer has been reviewed, among which are the biprotonic transfer within doubly H‐bonded host/guest complexes, the transfer through a solvent bridge relay, the intramolecular double proton transfer and solvation dynamics coupled proton transfer. Of particular emphases are the photophysical and photochemical properties of excited‐state double proton transfer (ESDPT) in 7‐azaindole and its corresponding analogues. From the chemical aspect, two types of ESDPT reaction, namely the catalytic and non‐catalytic types of ESDPT, have been classified and reviewed separately. For the case of static host/guest hydrogen‐bonded complexes both hydrogen‐bonding strength and configuration (i.e. geometry) play key roles in accounting for the reaction dynamics. In addition to the dynamical concern, excited‐state thermodynamics are of importance to fine‐tune the proton transfer reaction in the non‐catalytic host/guest type of ESDPT. The mechanisms of protic solvent assisted ESDPT, depending on host molecules and proton‐transfer models, have been reviewed where the plausible resolution is deduced. Particular attention has been given to the excited‐state proton transfer dynamics in pure water, aiming at its future perspective in biological applications. Finally, the differentiation in mechanism between solvent diffusive reorganization and solvent relaxation to affect the host/guest ESPT dynamics is made and discussed in de tail.

show abstract

Section: Ivc 7-azaindoles In Aque Ous So Lu Tionmentioning

confidence: 99%

Section: Ivc 7-azaindoles In Aque Ous So Lu Tionmentioning

confidence: 99%

The Host/Guest Type of Excited‐State Proton Transfer; a General Review

Chou

2001

J Chinese Chemical Soc

View full text Add to dashboard Cite

show abstract

“…The exciplex between alcohols and 7-azaindole has not been as well characterized as the tautomeric equilibria. This alcohol and 7-azaindole exciplex has been studied in liquids (Collins, 1983). Through kinetic analysis, the exciplex was found to result from a single alcohol complex formation with a single 7-azaindole molecule.…”

Section: Hydrogen Bonding Interactions Polar Cosolventsmentioning

confidence: 99%

“…The shift has been determined relative to the emission maximum in pure C02 within & 300 cm-1. Figure 19 shows the dependence of the peak shift on methanol concentration for several different densities and in liquid solvent (Collins, 1983). The steep initial shift with methanol concentration is the formation of the exaplex, while the lesser slope at higher alcohol concentrations in the liquid is the non-specific dielectric shift of the exciplex.…”

Section: Hydrogen Bonding Interactions Polar Cosolventsmentioning

confidence: 99%

Supercritical thermodynamics of sulfur and nitrogen species. Final technical report, October 1, 1991--September 30, 1994

Eckert¹

1994

View full text Add to dashboard Cite

“…Although the origin of this band has been the subject of conflicting interpretations [3][4][5][6][7][8][9], it is generally accepted that the photophysics of 7-azaindole in water is mainly dominated by 7AI hydrates [5,7] that, because of their 'blocked' structures for the ESDPT process, are unable to phototautomerize. However, a very small fraction of cyclic doubly hydrogen bonded 7AI monohydrates, possessing an appropriate hydrogen-bonded structure, are able to phototautomerize directly and rapidly, just as in the case of the dimer.…”

Section: Introductionmentioning

confidence: 99%

Spectral and Photophysical Properties of α-carboline (1-Azacarbazole) in Aqueous Solutions

et al. 2011

View full text Add to dashboard Cite

The absorption and fluorescence spectra of α-carboline, 9H-pyrido[2,3-b]indole, AC, in organic aprotic solvents containing different water proportions and in acid/base aqueous solutions inside and outside the pH range have been examined. In the organic aprotic solvents, the addition of increasing concentrations of water sequentially quenches and shifts to the red the fluorescence spectra of AC. These spectral changes have been rationalized assuming the formation, at the lower water concentrations, of a discrete ground state non-cyclic weakly fluorescent AC hydrate emitting at 376 nm that, upon increasing the water concentrations, evolves to a higher order AC poly hydrate emitting at 397 nm. The changes of the AC absorption spectra in aqueous acid/basic solutions indicate the existence of three ground state prototropic species; the pyridinic protonated cation, C (pK(a) = 4.10 ± 0.05), the neutral, N (pK(a) = 14.5 ± 0.2), and the pyrrolic deprotonated anion, A. Conversely, the changes of the AC fluorescence spectra in these media indicate the existence of four excited state species emitting at 376 nm, 397 nm, 460 nm and 465 nm. Since the emissions at 376 nm and 397 nm satisfactorily match those of the hydrates observed in the organic-water mixtures, they were consistently assigned to two differently hydrated ground state N species. The remaining emissions at 460 nm and 465 nm have been assigned without ambiguity, on the basis of their excitation spectra, to the C and A species, respectively. The excited-state pK(a)s of the prototropic species of AC have been estimated by using the Förster-Weller cycle.

show abstract

Exciplex formation in alcohol and water solutions of 7-azaindole

Cited by 36 publications

References 1 publication

The Host/Guest Type of Excited‐State Proton Transfer; a General Review

The Host/Guest Type of Excited‐State Proton Transfer; a General Review

Supercritical thermodynamics of sulfur and nitrogen species. Final technical report, October 1, 1991--September 30, 1994

Spectral and Photophysical Properties of α-carboline (1-Azacarbazole) in Aqueous Solutions

Contact Info

Product

Resources

About