Premium
Modulation of Lactam‐Lactim Tautomerism of Quinoxalin‐2‐one Induced by Cucurbit[7]uril: A Comparative Study with Oxazin‐2‐one
Author(s) -
Aliaga Margarita E.,
De la Fuente Julio R.,
GarcíaRio Luis,
RojasRomo Carlos,
Uribe Iván,
DíazHernández Dafne,
Fierro Angélica,
Cañete. Álvaro
Publication year - 2018
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201801628
Subject(s) - tautomer , bathochromic shift , chemistry , lactam , stereochemistry , photodissociation , photochemistry , computational chemistry , fluorescence , physics , quantum mechanics
Abstract The formation of inclusion complexes between cucurbit[7]uril (CB7) and N , N ‐(dimethylamino)styrylquinoxalin‐2‐one ( Me 2 NSQx ) or the N , N ‐(dimethylamino)styryloxazin‐2‐one ( Me 2 NSOxa ) dyes, was carried out using spectroscopy techniques (UV‐vis, fluorescence and NMR), flash photolysis, mass spectrometry and docking studies. Results show that: ( i ) both dyes form inclusion complexes with a CB7 excess, which depicts huge bathochromic shifts (>100 nm); ( ii ) Me 2 NSQx and Me 2 NSOxa , firstly form a 1:1 complex and at higher CB7 concentrations, a 2:1 host:guest complex is generated; ( iii ) the inclusion complex for Me 2 NSQx changes from its stable lactam form to the lactim tautomer, while for Me 2 NSOxa the equilibrium is shifted to the oxazinium tautomer. Finally, in the case of Me 2 NSQx dye, spectroscopic and docking studies indicate that the most stable complex is Me 2 NSQx @CB7 (1:2) in its lactim form, while in Me 2 NSOxa the equilibrium is shifted to the oxazinium containing complex. Therefore, our results evidence the importance of the interaction of CB7 as another form of controlling the tautomerism equilibrium of lactam or lactones derivatives.