The acid-base properties of selected derivatives of the [1,2,4]triazolo[3,2-c][1,2,4]triazole fused aromatic system have been investigated by UV–vis spectroscopy. Neutral heterobicycles (HL) exhibit amphoteric behavior (they can deliver the N–H proton forming the conjugated base L- and can accept up to two protons, forming the species H2L+ and H3L++) and show an unprecedented tautomeric switching upon protonation, as revealed by single crystal X-ray analysis and confirmed by theoretical calculations. By varying the groups attached at the heterocycle, a remarkable shift of pKai values, up to 5–6 units, is observed. In particular, with strong electron attractor groups at position 7 (e.g. p-nitrophenyl or pentafluorophenyl) the neutral compounds are stronger acids than phenol or p-nitrophenol.

Proton induced tautomeric switching in N-rich aromatics with tunable acid-base character / Centore, Roberto; Manfredi, Carla; Fusco, Sandra; Maglione, Cira; Carella, Antonio; Capobianco, Amedeo; Peluso, Andrea; Colonna, Daniele; Di Carlo, Aldo. - In: JOURNAL OF MOLECULAR STRUCTURE. - ISSN 0022-2860. - 1093:(2015), pp. 119-124. [10.1016/j.molstruc.2015.03.030]

Proton induced tautomeric switching in N-rich aromatics with tunable acid-base character

CENTORE, ROBERTO;MANFREDI, CARLA;FUSCO, SANDRA;MAGLIONE, CIRA;CARELLA, ANTONIO;
2015

Abstract

The acid-base properties of selected derivatives of the [1,2,4]triazolo[3,2-c][1,2,4]triazole fused aromatic system have been investigated by UV–vis spectroscopy. Neutral heterobicycles (HL) exhibit amphoteric behavior (they can deliver the N–H proton forming the conjugated base L- and can accept up to two protons, forming the species H2L+ and H3L++) and show an unprecedented tautomeric switching upon protonation, as revealed by single crystal X-ray analysis and confirmed by theoretical calculations. By varying the groups attached at the heterocycle, a remarkable shift of pKai values, up to 5–6 units, is observed. In particular, with strong electron attractor groups at position 7 (e.g. p-nitrophenyl or pentafluorophenyl) the neutral compounds are stronger acids than phenol or p-nitrophenol.
2015
Proton induced tautomeric switching in N-rich aromatics with tunable acid-base character / Centore, Roberto; Manfredi, Carla; Fusco, Sandra; Maglione, Cira; Carella, Antonio; Capobianco, Amedeo; Peluso, Andrea; Colonna, Daniele; Di Carlo, Aldo. - In: JOURNAL OF MOLECULAR STRUCTURE. - ISSN 0022-2860. - 1093:(2015), pp. 119-124. [10.1016/j.molstruc.2015.03.030]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/608274
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