The diels-alder cycloaddition reaction of substituted hemifullerenes with 1,3-butadiene: Effect of electron-donating and electron-withdrawing substituents

Producción CientíficaThe Diels-Alder (DA) reaction provides an attractive route to increase the number of six member rings in substituted Polycyclic Aromatic Hydrocarbons (PAHs). The density functional theory (DFT) B3LYP method has been used in this work to inquire if the substitution of H over the edge of triindenetriphenylene (pristine hemifullerene 1) and pentacyclopentacorannulene (pristine hemifullerene 2), could improve the DA cycloaddition reaction with 1,3-butadiene. The substituents tested include electron-donating (NH2, OMe, OH, Me, i-Pr) and electron-withdrawing groups (F, COOH, CF3, CHO, CN, NO2). The electronic, kinetic and thermodynamic parameters of the DA reactions of the substituted hemifullerenes with 1,3-butadiene have been analyzed. The most promising results were obtained for the NO2 substituent; the activation energy barriers for reactions using this substituent were lower than the barriers for the pristine hemifullerenes. This leads us to expect that the cycloadditions to a starting fullerene fragment will be possible.Ministerio de Asuntos Económicos y Transformación Digital (MINECO y European Regional Development Fund (proyectos MAT2011-22781 y MAT2014-54378-R))Junta de Castilla y León (Grant VA050U14)CONACyT-México (project grants 180523 and 163234) and (postdoctoral fellowship CB-2012/180523