Study Of Responsive Colloidal Metallosupramolecular Particles Based On Bis-terpyridine Ligand

Supramolecular polymers are macromolecules that are interconnected by non-covalent weak bonds,and organic units?or monomers?consist of these weak bonds.Our study mainly focuses on supramolecular polymers in which the monomer units are interconnected by coordination complexes.Their specific geometry and reversible character brings interesting properties and functionalities to coordination polymers like controlled self-assembly and stimuli-responsiveness.Moreover,additional various functionalities have been brought to coordination polymers by the utilization of a functional monomer.In this study,one coordination polymer is made of a pH-responsive monomer,another made of a redox-responsive monomer.During the last decade,researchers were dedicated to synthesized micro-or nano-particles made of coordination polymers and their potential development in nanotechnologies,biomedicine and environmental science.The present report presents two kinds of colloidal micro-particles made of responsive coordination polymers.The first type is a coordination polymer made of monomer units are interconnected by Cu²⁺-terpyridine complexes and for which the monomer units themselves contain a Cu²⁺ions trapped in a chelating cage.When the pH decreases to acidic values,the Cu²⁺ions are released from their cages and react with the Cu²⁺-terpyridine complexes,changing their stoichiometry ratio from 1:1 to 1:2 and triggering the depolymerization.Water is the bad solvent for such macrocyclic structure,colloidal spherical particles are synthesized by simple transfer of the polymer solubilized in methanol into water.Great control of the sizes of the particles is achieved by tuning the concentration.Evidence was made by laser light scattering particle size analysis and UV-visible absorption analysis that the colloidal particles auto-dissolved by depolymerization of the coordination polymer they are made of in acidic condition.Additionally,a photo-acid generator?a molecule which release proton when illuminated?was used to induce the dissolution of the particles in water by exposure to light.The second type of colloidal particles presents in this thesis is redox responsive coordination polymer.The monomer units,interconnected by Zn²⁺-terpyridine coordination complexes,incorporate bis-viologen units.Those bis-viologen units are made of two viologen groups separated by an alkyl spacer that is made of either two or three carbons?ethyl or n-propyl?.Once reduced,bis-viologen units containing a n-propyl spacer self-fold and form a?-dimer with a violet color whereas bis-viologen units containing an ethyl spacer stay in a linear conformation,as a blue colored bis-viologen^2?+·?radical,because of the inflexibility of the ethyl spacer.Consequently,coordination polymer chains containing n-propyl spacer?ZnL₃polymer?can self-fold in solution whereas polymer made of ethyl spacer?ZnL₂ polymer?cannot.Based on these two polymers solubilized in acetonitrile,colloidal particles are made by transferred from acetonitril into water.Depending on the concentration during the synthesis,the obtained ZnL_n particles are spherical with diameters about 200 nm or have more regular shapes with larger diameter and can also be clusters of nanocrystals.ZnL_n particles were analyzed by grazing incident X-ray diffraction?GI-XRD?,small angle X-ray scattering?SAXS?and electron microscopies.It was found that all types of particles were polycrystalline with crystalline domains ranging from 4 nm to 14 nm.Inter-planar distances were found to be comprised between 0.22 and 0.46 nm,corresponding to the distances separating adjacent chains.