Isabel Cabral

Exploring geometric morphology in shape memory textiles: design of dynamic light filters

Thermo-responsive Shape Memory Alloys are able to adopt a temporary configuration and return to their programmed shape when heated to a determined activation temperature. The possibility to integrate them in textile substrates creates potential to develop smart textiles whose shape change explores functional and expressive purposes. The aim of this research is to develop shape memory woven textiles in which dynamic behavior achieves predefined geometric shapes. The requirement of geometric morphology was addressed through origami techniques. Combining foldability properties with shape change, it is possible to design textile structures with a variable number of layers. Difference in light transmittance is analyzed according to layer variation. Experiments conducted explore methodological processes aimed at future developments in dynamic light filters research. The results highlight a process to design textiles with predefined geometric morphologies that can be activated electrically, and delineate a further study in order to improve the shape memory textile behavior.

A new and efficient approach to the synthesis of 6-amidino-2-oxopurines

The reaction of 5-amino-4-cyanoformimidoylimidazoles 1a and 1b with tosyl isocyanate proved to be a mild and efficient method for the synthesis of the corresponding 6-amidino-2-oxopurines 5. These compounds, which were isolated in almost quantitative yield, rearrange in the presence of acetic acid–DMF to give a pyrimido[5,4-d]pyrimidin-2-one 6. The structure of compound 6 was confirmed by X-ray crystallography. The pathway for both reactions is discussed. Studies on the reactivity of tosyl isocyanate with imidazoles 2, 7, 8 and 16, obtained from 1 by selective acylation of the amino or imino nitrogen atoms, enabled clarification of the mechanism for purine formation.