Esquema 9. Síntesis propuesta para los complejos de interés.
6. CONCLUSIONES Y PERSPECTIVAS
La PCL es un polímero biodegradable con propiedades que permiten una amplia aplicación sin causar un impacto negativo en el medio ambiente. Entre sus propiedades se encuentran la termoplasticidad, impermeabilidad, baja toxicidad y alta cristalinidad. Sin embargo, la propiedad con mayor relevancia es la biodegradación, la cual se basa en dos etapas: hidrólisis de los enlaces ésteres por difusión de agua y fragmentación catalizada por las enzimas depolimerasas. Estas propiedades permiten que la PCL sea utilizada en diversas aplicaciones como la liberación controlada de medicamentos, en ingeniería de tejidos y material de empaque. Por otro lado, este polímero se puede sintetizar por diferentes rutas como PCA, ROP de CL y ROP vía radical de MD. No obstante, la ROP de CL es uno de los métodos que permite obtener PCL con mayor peso molecular y por ello, se han utilizado diferentes catalizadores con el propósito de hacer el método más eficiente, entre ellos se encuentran aniones, cationes, ácidos de Lewis, alcoholes primarios, complejos de coordinación y enzimas.
Entre estas variantes de catalizadores, los complejos de coordinación han sido los más estudiados debido a que permiten obtener PCL con mayor grado de cristalinidad y con polidispersidad cercana a 1. Por tal motivo, se realizó una propuesta de nuevos complejos de coordinación que posiblemente presentan potencial catalítico para la ROP de CL vía coordinación-inserción. Estos complejos se componen de ligandos derivados de L1, los cuales fueron seleccionados debido a su naturaleza 𝜎 donores y 𝜋 aceptores (retrodonación) y permiten una mejor activación del catalizador. En cuanto al centro metálico se propuso utilizar el Zn(II) debido a su baja toxicidad, biocompatibilidad, bajo costo y óptima degradación, por lo que permitirá que la PCL tenga un método de síntesis menos tóxico y biocompatible. Por lo cual, los complejos propuestos pueden tener una eficiente actividad catalítica para la ROP de CL y deberían ser evaluados en trabajos futuros. Finalmente, se realizó la síntesis de los ligandos L1-L4, con su respectiva caracterización por 1H-RMN y la
síntesis del complejo dicloro[bis(3,5-dimetilpirazol-1-il)metano-NN]zinc(II), el cual se caracterizó por 13C-RMN.
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Como perspectivas de este trabajo se propone terminar la síntesis de los complejos propuestos con su respectiva caracterización y aplicarlos como catalizadores para la obtención de la PCL. Adicionalmente, caracterizar la PCL obtenida con el fin de verificar el potencial catalítico de estos complejos propuestos y la posible aplicación de la PCL que se obtenga.
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8. Anexo
1. Metodología de síntesis de ligandos derivados de bis(3,5-dimetil-1-