New Materials to Solve Energy Issues through Photochemical and Photophysical Processes: The Kinetics Involved

Kinetic rates of energy production are extremely controlled by the competing processes that occur in systems capable of energy transfer. Besides organic and inorganic compounds already known as electronically actives, supramolecular systems can be thought to form energy transfer complexes to efficiently convert, for instance, light into electricity and the mechanisms for that can be of any kind. Photophysical and photochemical processes can simultaneously occur in such systems to provide energy conversion, by competing mechanisms or collaborative ones. Thus, to investigate the kinetic rates of each process and to understand the dynamics of the electronic excited states population and depopulation in strategically structured materials, can offer important tools to efficiently make use of this not always so evident power of supramolecular materials. In this chapter, we present the state-of-the-art of the use of photophysical processes and photochemical changes, presented by new materials and devices to provide a control of energy transfer processes and enable distinct applications, since energy conversion to sensing and imaging techniques to material characterization

Phe–Phe Di-Peptide Nanostructure Self-Assembling Modulated by Luminescent Additives

In this work, supramolecular L-L-diphenylalanine (Phe-Phe) nanostructures were self-assembled in solvents of distinct polarity and in the presence of luminescent additives of distinct conjugation length that physically adhere to the nanostructures to provide growth environments of distinct properties. When the additive is poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene], an electron donor polymer, and solvent is tetrahydrofuran (THF), Phe-Phe vesicle-like structures are obtained, whereas in water and in the presence of a similar additive in structure, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene], nano-tubes are formed. In contrast, when 9-vinyl-carbazole, an electron acceptor additive is used, nano-tubes are formed even when THF is the solvent. The same structures are obtained when the additive is the macromolecule poly(vinyl carbazole). The morphologies of these self-assembled structures were observed by scanning electron microscopy, and their photophysical behavior was determined by steady-state fluorescence spectroscopy and time-resolved fluorescence spectroscopy. These data analyzed altogether inform about the formation mechanisms of such structures and about the influence that distinct interactions exert on self-assembling and charge-transfer processes through formation of complexes between the luminescent additives and the Phe-Phe nano- and microstructures41606619CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE GOIÁS - FAPEG407619/2013-5sem informaçã