[en] The work presented herein describes the design and synthesis of new ditapic lígands structurally related to A-monoalkyl-4,4'-bipyridium and N,,v'-dialkyl-4,4' -bipyridium ligands, and their use on the self-assembly of dinuclear Pd(lI) and Pt(II) metallacycles, Here, by controlling the geometry of the starting materials on the self-assembly tWQ difTerent molecular polygons were obtained, L-shaped ligands, derived from N-monoalkyl-4,4'-bipyridium lead to rectangular metallacyeles, whilst the C-shaped ligands, derived from N,N '-dialkyl-4,4'-bipyridium, yield hexagonal geometries, Some of the L-shaped ligands could be further modified, incorporatiung npendant groups which allow functionalization of the resulting metallaeycles with hydroxyl or esther groups. AH the new ligands have been obtained as organic saIts by Zincke reaction, and with their solubility in aqueous or organic media adjusted by the counterions. Alkylation of at least one of the pyridines on the Iigands. confer rr-deficient properties to the obtained metallaeycles, That effeet, in eonjunetion with generation of a hydrophobic cavity with adjustable size, make them suitable to 3Ct as molecular hast for aromatic compounds. The complexation process has been studied using NMR techniques, enabling the determination of the insertion modes in solution of different PAHs into rectangular cavities. Those insertion modes were found to be quite dependent on the establishment of[C-H00 ',,] interaetions between the pyridine rings on the receptors and aromatic guest protons. In some cases, these binding modes have been found lo be in good agreement with those found in the salid state by single crystal X-ray diffraction, On the other hand, association constants {Ka} were determined using UV-vis and fluorescence techniques, allowing to quantifY the host-guest affinities. Hexagonal metallaeycles have being found to be worse molecular receptors than rectangular hosts, a fact anributed to less efficient binding interactions. [2]catenanes were also prepared using electron rich aromatic cyclophanes and a ligand based on a diazapyrenium system, Finally a dynamic system was designed. which can be interconverted between three supramolecules of different sizes by applying external stimuli (temperature, concentration, and ionic strength). These three structures in equilibrium have been identified as: metallacycle, ring into the ring and a Borromean knot. The polarity influence ofthe media on the dynamie system has been supported by calculations of SAS.

[gl] Neste traballo preséntase o deseno e a síntese de novas ligandos ditópicos estruturalmente relacionados con N·monoalquil·4,4'·bipiridinio e N,N'-dialquil-4,4'-bipiridinio, e O seu emprego no autoensamblaxe de metalociclos dinucleares de Pd(ll) e Pt(II). Asi, mediante o control da xeometría dos compoi\entes de partida obtivéronse dous tipos de polígonos moleculares diferentes. Os ligandos con forma de "L", derivados de ,N.monoalquil-4,4'-bipiridinio. conducen ó ensamblaxe de metalociclos rectangulares. mentres que os ligandos en forma de "e", derivados de N.N'-dialquiIA,4'-bipiridinio, a xeometrias hexagonais. Sobre algúns dos ligandos de partida puidéronse incorporar novas grupos funcionais que penniten a derivatización dos metalociclos con grupos hidroxilo ou éster. Todos os novas ligandos obtivéronse como sales orgánicas empregando a reacción de Zincke e modulándose a sua solubilidade en medio acuoso ou orgánico en función do contraión empregado. A alquílación de polo menos un dos átomos de nitróxeno piridínicos nos ligandos preparados, confirenlles ós metalociclos resultantes propiedades lCdeficientes que xunto ca cavidade hidrofóbica xerada e o tamai\o axustable, fanos adecuados para actuar como receptores moleculares de substratos aromáticos. O proceso de complexación estudouse utilizando técnicas de RMN, pennitíndonos coñecer o modo de inserción en disolución de diferentes PAHs nas cavidades dos receptores, inserción que está condicionada palas interaccións [C~H···lC] entre os aneis de piridina e os prolóns do substrato aromático. Os modos de unión puidéronse contrastar, nalgún dos casos, co atopado en estado sólido mediante difracción de raios X de monocristal. Por outra banda, determináronse constantes de asociación empregando técnicas de UV~vis e fluorescencia, pennitindo cuantificar a afinidade entre as dúas especies. Os metalociclos hexagonais demostraron ser peores receptores moleculares, o cal se atribue ás interaccións menos eficientes entre receptor-sustrato. Tamén se preparon [21catenanos, empregando ciclofanos derivados dos sustratos anteriores e un ligando baseado en un sistema de diazapirenio no calo proceso de ensamblaje está dirixido por centros de Pd(II). Por último, desei\ouse un sistema dinámico con posibilidad de interconversión entre tres especies de distinto tamaño mediante a aplicación de diferentes estímulos externos (temperatura, concentración e forza iónica do medio). Estas tres especies en equilibrio foron identificadas como: metalociclo. anel dentro de anet e un nó de Borromeo. A influenza que supón a polaridad do medio no sistema dinámico foi apoiada por cálculos de SAS (superficie accesible ó disolvente).