A compound selected from the group consisting of PU-BSI12, PU-BSI8, PU-BSI6, PU-BSI11, PU-BSI7, PUBSI13, PU-BSI14, PU-BSI5, PU-HZ150, PU-HZ151, PU-DZ13, PU-DZ14 and PU-DZ16, which has the following formulas ** Formula **Un compuesto seleccionado del grupo que consiste en PU-BSI12, PU-BSI8, PU-BSI6, PU-BSI11, PU-BSI7, PUBSI13, PU-BSI14, PU-BSI5, PU-HZ150, PU-HZ151, PU-DZ13, PU-DZ14 y PU-DZ16, que tiene las siguientes fórmulas **Fórmula**