Proton donor properties of pyrroles studied by IR spectroscopy

Narziev, B.N.; Mulloev, N. U.

doi:10.1007/bf02700648

Cited by 7 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vibration spectra of substituted isatins were studied earlier [ 56 , 57 , 58 ]. The main frequency assignment to the corresponding vibration mode has been accomplished based on the IR and Raman spectra and single crystal dichroism [ 56 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Structure on Charge Distribution in the Isatin Anions in Aprotic Environment: Spectral Study

et al. 2017

View full text Add to dashboard Cite

Five isatin anions were prepared by deprotonation of initial isatins in aprotic solvents using basic fluoride and acetate anions (F− and CH3COO−). The F− basicity is sufficient to deprotonate isatin NH hydrogen from all the studied compounds. This process is reversible. In the presence of proton donor solvents, the anions form the corresponding isatins. The isatin hydrogen acidity depends on the overall structure of the isatin derivatives. The anions were characterized by ultraviolet–visible (UV–Vis), Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Interestingly, the anions form aggregates at concentrations above 10−3 mol·dm−3. Further, the effect of cations on the UV–Vis spectra of the studied anions was studied. Charge transfer and its distribution in the anion depends on the radius and the cation electron configuration. The alkali metal cations, tetrabutylammonium (TBA+), Mg2+ and Ag+, interact with the C-2 carbonyl oxygen of the isatin anion. The interaction has a coulombic character. On the other hand, Cd2+, Zn2+, Hg2+, Co2+, and Cu+ cations form a coordinate bond with the isatin nitrogen.

show abstract

Section: Resultsmentioning

confidence: 99%

Effect of Structure on Charge Distribution in the Isatin Anions in Aprotic Environment: Spectral Study

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Because of geometry, a linear H‐bond is not possible. It is therefore weak, as indicated by the NH stretching frequency of 3462 cm −1 in CCl 4 , 27 not far from the value of 3497cm −1 , 28 reported for pyrrole in the same solvent. On the other hand, both proton donating properties of the NH group and the accepting capability of pyridine nitrogen strongly increase upon excitation to S 1 29 .…”

Section: Resultsmentioning

confidence: 60%

Tautomerization in Condensed Phases and in Isolated Molecules

Waluk

2009

Israel Journal of Chemistry

View full text Add to dashboard Cite

We review our recent investigations of systems revealing single or double proton (hydrogen) transfer in the ground or electronically-excited states. The results obtained for condensed phases are compared with the data provided by experiments carried out in the regime of molecular isolation, mainly by using supersonic jet spectroscopy techniques.Both intra-and intermolecular processes have been studied. Four different bifunctional chromophores are discussed, all sharing a common feature of possessing a proton-donating NH group and an acceptor nitrogen atom incorporated into a pyridine or pyrrolene ring.Porphycene and derivatives reveal, when isolated, coherent double hydrogen transfer manifested by vibration-specific tunneling splittings. In condensed phases, tautomerization occurs as a rate process; its dynamics can be probed by techniques using polarized light. Huge dependence of the tautomerization rate on the strength of intramolecular hydrogen bonds has been detected.2-(2¢-pyridyl)pyrrole provides a rare example of a molecule which undergoes both intramolecular excited-state single proton transfer and a solvent-assisted excited-state double proton transfer reaction. Supersonic jet studies allowed us to identify the vibrational modes that enhance the tautomerization.Photoinduced intramolecular proton transfer in 7-(2¢-pyridyl)indole is accompanied by twisting of the proton donor and acceptor subunits. The reaction occurs faster in the supersonic beam than in room temperature solutions.1H-pyrrolo[3,2-h]quinoline forms 1:1 and 1:2 complexes with alcohols and water. The stoichiometries and vibrational structure could be determined for jet-isolated complexes. The 1:1 cyclic, doubly hydrogen-bonded species reveal rapid photoinduced tautomerization both in condensed phases and when isolated in supersonic beams.

show abstract