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New optic fibre sensors capable of detecting organic compounds

October 26, 2004

This new research is presented in the Navarre chemist, Mar'�a Asunci'�n Luquin's PhD, "Synthesis and characterisation of de vapochromic substances for their implementation in optic fibre environmental sensors". The PhD has been presented in Public University of Navarre.

One of the principal contributions of this thesis is that it has managed to develop optic fibre sensors capable of detecting the presence of Volatile Organic Compounds (VOC), not only in the air, but also in solution.

Compounds that change colour

The results of a vapochromic derivative, i.e., one capable of changing colour in the presence of vapours from volatile organic compounds, has been previously outlined in a PhD defended at the University.

Nevertheless, a number of aspects thereof remained unknown, such as the motive for which a change of colour takes place and also the reason why, at times, the reaction does not produce the desired product.

The thesis by this Navarre chemist tries to respond to these unanswered questions and thus to know better the derivatives known as vapochromic compounds.

The PhD thesis is structured in five main parts. After a theoretical analysis of sensors and phosphines, Ms Luquin carried out experiments with the preparation both of vapochromic and related derivatives as well as new, 2-phenylthiolate phenylphosphine and 2-thioanisol phenylphosphine derivatives. The study ends with the chapter on conclusions.

Thus, on concluding this research, the properties of vapochromism were reproduced in other systems.
Moreover, it was able to be demonstrated that, in order to employ a vapochromic derivative as a sensor de volatile organic compounds (VOC) in optic fibre sensor systems, it is not necessary for a spectacular colour change to occur as the systems employed are capable of detecting small modifications.

Working with some of these compounds capable of detecting colour change, optic fibre environmental sensors have been developed.
In this way, in the PhD thesis, new sensors for volatile organic compounds have been developed, some of which are capable of detecting organic compounds even in aqueous solutions.

Recovery of catalyst

Together with this contribution, the thesis presents other applications for a number of ligands with synthesised transition metals. Tests on catalytic carbon-carbon link formation reactions, particularly the Heck reaction, have helped us conclude that a number of synthesised compounds turn out to be good catalysts in carbon-carbon coupling reactions. These involve highly important reactions in Organic Chemistry as they can synthesise a great number of biarylic compounds - of great interest in natural products, polymers, advanced materials, liquid crystals, ligands and even in molecules of medical interest.

Moreover, until now, ligands containing atoms of sulphur have not been greatly employed in catalytic reactions because sulphur may poison the catalyst. But, in the PhD, it has been shown that, not only is the catalyst not poisoned, but that very good results are obtained - even in reactions in air and in the presence of water, which has led to the trying to recover the catalyst.

Elhuyar Fundazioa

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