Publication: Polimerización supramolecular de moléculas sencillas. Transferencia y amplificación de quiralidad
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2018-09-13
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Universidad Complutense de Madrid
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Abstract
El objetivo general de la presente Tesis Doctoral consiste en el estudio de los procesos de polimerización supramolecular de moléculas orgánicas relativamente sencillas capaces de autoensamblar formando agregados supramoleculares altamente organizados. La combinación de estudios en disolución, junto con la visualización de los agregados formados mediante diferentes técnicas microscópicas, permitirá obtener los parámetros termodinámicos que definen el proceso de agregación y, a su vez, comprobar la morfología de las estructuras supramoleculares formadas. La presencia de distintos tipos de quiralidad en estas moléculas debe dirigir su organización en estructuras supramoleculares helicoidales, que permitirán llevar a cabo el estudio de la influencia de la quiralidad molecular en la quiralidad supramolecular. Además, abre nuevas vías para la investigación del origen de la homoquiralidad en la naturaleza.Con esta idea en mente, la primera parte de esta Tesis se centra en el estudio de dos tricarboxamidas anfifílicas radiales derivadas de oligofenilenetinileno (OPE). Experimentos de UV-vis a temperatura variable demuestran la polimerización supramolecular cooperativa de estas tricarboxamidas que autoensamblan mediante enlaces de hidrógeno C=O···H-N entre los grupos amida e interacciones entre las unidades aromáticas. La organización helicoidal de los agregados formados se ha demostrado mediante dicroísmo circular en acetonitrilo. La tricarboxamida aquiral 18 autoensambla en estructuras con forma de cintas planas que experimentan una amplificación de quiralidad mediante la adición de una pequeña cantidad del compuesto quiral (S)-19, generando tiras retorcidas...
The overall aim of this Thesis is based on the detailed study of the supramolecular polymerization processes of relatively simple organic molecules that self-assemble into highly organized aggregates. The combination of these studies in solution together with the visualization of the aggregates formed by different microscopic techniques allow obtaining the thermodynamic parameters that define the aggregation process and, at the same time, confirming the morphology of the supramolecular structures. Additionally, the presence of different types of chirality in these molecules directs the supramolecular organization into helical structures, which allows to carry out the study of the influence of molecular chirality on the supramolecular chirality and opens new avenues for the investigation of the origin of homochirality in Nature.With that idea in mind, the first part of this Thesis focuses on the study of two radial amphiphilic C3-symmetric oligo(phenylene ethynylene) (OPE) based tricarboxamides. Variable temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these tricarboxamides that self-assemble by the operation of triple C=O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism in acetonitrile. Achiral tricarboxamide 18 self-assembles into flat ribbon-like structures that experience an amplification of chirality...
The overall aim of this Thesis is based on the detailed study of the supramolecular polymerization processes of relatively simple organic molecules that self-assemble into highly organized aggregates. The combination of these studies in solution together with the visualization of the aggregates formed by different microscopic techniques allow obtaining the thermodynamic parameters that define the aggregation process and, at the same time, confirming the morphology of the supramolecular structures. Additionally, the presence of different types of chirality in these molecules directs the supramolecular organization into helical structures, which allows to carry out the study of the influence of molecular chirality on the supramolecular chirality and opens new avenues for the investigation of the origin of homochirality in Nature.With that idea in mind, the first part of this Thesis focuses on the study of two radial amphiphilic C3-symmetric oligo(phenylene ethynylene) (OPE) based tricarboxamides. Variable temperature UV-vis experiments demonstrate the cooperative supramolecular polymerization of these tricarboxamides that self-assemble by the operation of triple C=O···H-N H-bonding arrays between the amide functional groups and π-π stacking between the aromatic units. The helical organization of the aggregates has been demonstrated by circular dichroism in acetonitrile. Achiral tricarboxamide 18 self-assembles into flat ribbon-like structures that experience an amplification of chirality...
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Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Química Orgánica I, leída el 10-03-2017