Supramolecular chemistryand nanodevices basedon terpyridine complexes

Author(s)

Juliano Alves Bonacin

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Conjunto das Químicas (IQ e FCF) (CQ/DBDCQ)
• Defense date: 2007-05-22

Examining board members

Henrique Eisi Toma; Paola Corio; Breno Pannia Espósito; Ana Flávia Nogueira; Vagner Roberto de Souza

• Advisor: Henrique Eisi Toma

Abstract

This thesis deals with the development of new metal-organic supramolecular systems based on functionalized terpyridine compounds, including their application in nanotechnological devices. New iron and ruthenium coordination compounds incorporating terpyridine ligands have been obtained, and their ability to generate thin films and participate in host-guest interactions has been conveniently explored. Such complexes have been employed in the modification of titanium dioxide surfaces, for applications in sensors and photoeletrochemical cells. By combining nanocrystalline titanium dioxide with carboxy-methyl-β-cyclodextrin, a novel, efficient strategy has been devised for photodegradation of aromatic compounds, and successfully demonstrated after anchoring the bis(4\'-(4-bromophenyl)-2,2\':6\'2\'\'-terpyridine)iron(II) complex and monitoring its bleaching by exposing to UV radiation. In this way, this system has been successfully employed in the design of a novel, versatile UV dosimeter. Electropolymerization studies have also been carried out on this complex, in order to generate molecular films for use in amperometric sensors, capable of probing relevant species, such as the nitrite ions. Another compound dealt with in this work was [Ru(c-ph-terpy)(Q)(NCS)], where c-ph-terpy = 4\'-(4-carboxy-pheny)-2,2\':6\',2\'\'-terpyridine, and Q = 8-oxyquinolinate ligand. This terpyridine complex has been designed as fotosensitizer in Grätzel\'s photoelectrochemical cells, by its direct coating on the titanium dioxide nanoparticles or by performing their previous treatment with carboxi-methyl-β-cyclodextrin. It has been shown that the inclusion into the cyclodextrin cavity improves the performance of the photosensitizer for energy conversion. Finally, a new supermolecule encompassing a central tetrapyridylporphyrin unity attached to four chloro(oxalate)(4-chloro-2,2\':6\',2\'\'-terpyridine)ruthenium(II) complexes, has been synthesized. This species exhibits catalytic activity in the oxidation of organic compounds. The reported study, involving several systems, has contributed to the available molecular engineering strategies, through the building up of new connecting groups and molecular films, and has also allowed the exploitation of some of their possible nanotechnological applications (AU)