| Autor: |
Pozharskii AF; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation., Ozeryanskii VA; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation., Filatova EA; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation., Dyablo OV; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation., Pogosova OG; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation., Borodkin GS; Institute of Physical and Organic Chemistry , Southern Federal University , Stachki Avenue 194/2 , 344090 Rostov-on-Don , Russian Federation., Filarowski A; Faculty of Chemistry , University of Wroclaw , F. Joliot-Curie 14 , 50-383 Wroclaw , Poland.; Department of Physics , Industrial University of Tyumen , Volodarskogo 38 , 625000 Tyumen , Russian Federation., Steglenko DV; Department of Organic Chemistry , Southern Federal University , Zorge str. 7 , 344090 Rostov-on-Don , Russian Federation.; Institute of Physical and Organic Chemistry , Southern Federal University , Stachki Avenue 194/2 , 344090 Rostov-on-Don , Russian Federation. |
| Abstrakt: |
9-Dimethylaminobenzo[ g]indoles 3-6 and 1-dimethylamino-8-(pyrrolyl-1)naphthalene 7 were examined as possible models for establishing the ability of the pyrrole nitrogen atom to participate in [NHN] + hydrogen bonding as a proton acceptor. Indoles 3-5 (to a lesser extent 6) form rather stable tetrafluoroborates, with the proton mostly located on the NMe 2 group but simultaneously engaged in the formation of a charged intramolecular [NHN] + hydrogen bond (IHB) with the pyrrole N atom. The theoretically estimated energies of IHB in salts 3H + BF 4 - -6H + BF 4 - vary between 7.0-10.7 and 6.2-7.0 kcal mol -1 in vapor and MeCN, respectively. The pyrrole N atom undergoes a perceptible pyramidalization but still remains involved in the 6π-electron aromatic system, suggesting that the hydrogen bonding in salts 3H + BF 4 - -6H + BF 4 - represents a previously unknown mixed NH···N(n,π) interaction. Despite the favorable orientation of the N-H bond and the pyrrole ring in salt 7H + BF 4 - , no signs of NH···N(n) bonding in it were noticed, and the existing interaction was classified as pure NH···N(π). The results obtained may be useful in studies of secondary protein structures, especially those α-helix sections which contain tryptophan residues. |
