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Asociación estereoselectiva de metaciclos binucleares en los polímeros de coordinación
Andrei N Khlobystov1, Matthew T Brett, Alexander J Blake
1School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD, U.K.
Journal of the American Chemical Society
|May 29, 2003
Resumen
Los investigadores sintetizaron metaciclos de cadmio y estudiaron su ensamblaje en polímeros. La agregación estereoselectiva produce estructuras helicoidales o no helicoidales, influenciadas por las condiciones de ensamblaje y las propiedades de los ligandos, siendo la asociación homoquiral energéticamente menos favorable.
Área de la Ciencia:
- Coordinación Química de la Coordinación
- Ciencia de los materiales Ciencia de los materiales.
- Química supramolecular de las moléculas.
Sus antecedentes:
- Los metaciclos binucleares con centros metálicos quirales coordinadamente insaturados son de interés para la construcción de arquitecturas complejas.
- Comprender el autoensamblaje de estos metaciclos en marcos poliméricos es crucial para el diseño de nuevos materiales.
Objetivo del estudio:
- Para sintetizar metaciclos de cadmio binucleares estructuralmente relacionados utilizando ligandos exo-bidentados angulares.
- Estudiar sistemáticamente el autoensamblaje de estos metaciclos en estructuras estructurales poliméricas por primera vez.
- Investigar la influencia de la agregación estereoselectiva en la formación de polímeros de coordinación helicoidales y no helicoidales.
Principales métodos:
- Síntesis de cíclos metálicos de cadmio binucleares [Cd(NO(3))(2)L](2) donde L es un ligando exo-bidentado angular.
- Experimentos controlados de autoensamblaje bajo condiciones variables (temperatura, funcionalidad del ligando).
- Aislamiento y caracterización de complejos poliméricos helicoidales y no helicoidales.
- Cálculos teóricos de la energía de la red cristalina para confirmar la favorabilidad termodinámica.
Principales resultados:
- Síntesis exitosa de una serie de cíclos metálicos binucleares de cadmio.
- Demostración de que la asociación homoquiral estereoselectiva conduce a polímeros de coordinación helicoidales, mientras que la asociación meso produce cadenas no helicoidales.
- Identificación de las condiciones específicas (temperatura) que favorecen la asociación homoquiral frente a la meso para el ciclo metálico [Cd{\displaystyle {Cd{\displaystyle {NO}{\displaystyle {Cd}{\displaystyle {NO}}}{\displaystyle {Cd}{\displaystyle {Cd}{\displaystyle {D}{\displaystyle {D}}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\displaystyle {D}{\frac {D}}{\displaystyle {D}{\frac {D}}}}{\displaystyle {D}{\frac {D}}}{\displaystyle {D}{\frac {D}}}{\displaystyle {D}{\frac {D}}}
- Confirmación de que la asociación homoquiral es energéticamente menos favorable que la asociación meso a través de cálculos teóricos.
Conclusiones:
- La agregación estereoselectiva de los cíclos metálicos de cadmio binucleares es controlable, lo que lleva a estructuras poliméricas helicoidales o no helicoidales distintas.
- El diseño de ligandos y las condiciones de autoensamblaje son factores críticos para dirigir la formación de arquitecturas supramoleculares específicas.
- El paisaje energético favorece la asociación meso sobre la asociación homoquíra en estos sistemas de ciclo metálico.
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