[1] Univ Papaloapan, Dept Quim, Circuito Cent 200, Tuxtepec 68301, Oaxaca, Mexico
[2] Inst Ciencia & Tecnol Polimeros ICTP, C Juan de la Cierva 3, Madrid 28006, Spain
[3] Univ Guanajuato, Div Ciencias Exactas, Dept Quim, Noria Alta S-N, Guanajuato 36050, Mexico