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No description available.

It is not often that a single experiment opens up a new direction of research. In this report, the optical properties of a series of organic molecules, of the form 2,4-bis((N-methyl-N-alkylamino)phenyl)squarine, which are symmetrical about their centre point, are investigated. By conventional thinking, these molecules should not show any even order non-linear optical effects; the generation of second, fourth or sixth harmonics of the incident light. In fact, significant second harmonics are generated by the materials, x(2)=25-pm v-1. This fact in itself is noteworthy, but the additional fact that the efficiency of the conversion is over two times greater than any other previously reported material is exceptional. The door is now open to an entirely new class of non-linear optical materials. In this report a thorough characterisation of the organic molecules is made by a variety of techniques; polarised second harmonic generation, quartz crystal micro balance and grazing angle X-ray diffraction. A mechanism for this new phenomenon, based on intermolecular charge transfer is developed. In a world of ever tightening pollution control legislation the need for sensors which can accurately measure the concentrations of various pollutant gases is becoming more important. In this report the pollutant sensing properties of a series of organic molecules, 2,4-bis((N-methyl-N-alkylamino)phenyl)squarine, are investigated. The series of compounds was found to be sensitive to nitrogen dioxide in concentrations of as little as 1 part per million in air, but the changes produced in the molecules were non-reversible. It is very rare to accidentally stumble across a molecule with ideal properties. A molecule must usually be modified to achieve optimum properties. In this report the steps taken in the molecular engineering of a new selective and reversible gas sending molecule are also reported. 1-(4-hydroxyphenyl)-2-(1-octadecyl-4-quinolinium iodide) ethene shows sensitivity to ammonia gas in concentrations as low as 25 parts per million in air. The response is fully reversible and can be detected using a surface plasmon resonance based sensor. In the search for new technical solutions to old problems simple solutions are often overlooked. The final section off this report describes a simple gas sensing technique, which had been available in many research institutions, but overlooked in favour of more complex solutions.

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No description available.

Cette étude vise à conforter l’apport de matière organique extraterrestre via les météorites et les micrométéorites. Elle permet de mieux cerner les conditions dans lesquelles les molécules organiques, synthétisées dans l’espace, ont contribué à l’émergence de la vie sur Terre il y a environ quatre milliards d’années. Pour cela, des molécules organiques ont été exposées aux conditions de l’espace à bord de la station spatiale internationale et également irradiées en laboratoire lors d’expériences au sol. Par ailleurs, des molécules organiques associées à une argile, ont été soumises à des chocs mécaniques pour simuler des impacts météoritiques. Des acides aminés et des dipeptides ont été choisis pour ces études en raison de leur intérêt prébiotique et de la diversité des groupements fonctionnels qu’ils offrent. Des méthodes de fonctionnalisation pour l’analyse chirale ou non chirale de ces molécules par chromatographie gazeuse couplée à un spectromètre de masse ont été développées. Les expériences démontrent que la résistance des molécules à l’irradiation et à l’impact est fonction de la nature chimique des composés. De ce fait, le transport dans l’espace et l’impact météoritique pourraient servir de filtres moléculaires en favorisant certaines molécules au détriment d’autres. / This study concerns the transport to Earth of exogenic organic matter by meteorites or micrometeorites in order to better determine the conditions under which organic molecules synthesized in space contributed to the emergence of the life on Earth four billion years ago or more. Organic molecules were exposed to space conditions on board the international space station as well as in laboratory experiments. Moreover, simulated meteorite impacts on organic molecules associated with a clay were carried out to determine the survival of the organic components. Amino-acids and dipeptides were selected for these studies because of their prebiotic interest and for the diversity of their functional groups. Methods of derivatization for chiral and not chiral analysis of these molecules by gas chromatography coupled to a mass spectrometer were developed. The results of the experiments show that the resistance of the molecules to irradiation and to impact is a function of their chemical nature, and that transport in the space environment as well meteoritic impact could be used as molecular filters by favouring the survival of certain molecules rather than others.

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In this study, the interaction energies between aromatic organic molecules (AOMs) and cellulose are explored using density functional theory (DFT) through the software SIESTA and the exchange-correlational functional VDW-DRSLL. Three AOMs will be modelled: benzene, benzamide and benzoic acid. Firstly, the interaction energies of the dimers of the AOMs are determined. Then, the obtained interaction energies of the cellulose-AOM complexes are compared to the former in order to decide which interaction is stronger. It is found that the studied AOMs are more likely to interact with cellulose than with another identical monomer; benzamide has the highest propensity to interact, followed by benzoic acid and benzene. Furthermore, for all interaction energy calculations a counterpoise correction term will be introduced as an addition to the SIESTA optimisation and it will be shown that without this correction the acquired energy minima will deviate significantly from accepted values from previous studies.

We present here the hypothesis of a possible relationship between metal atom clusters and the formation of organic molecules in the interstellar medium and on small bodies as a possible pathway to the origin of such molecules. Two distinct stages are díscussed: a) the possible formation and presence of atom clusters in space and on the primitive Earth, and b) the synthesis of interstellar and terrestrial prebiotic organic molecules, a process in which metalclusters could be the active catalysts. The confirmatíon of these suggestions might be very important in arder to explain the presence of extra-terrestrial organic molecules in the interstellar medium, small bodies and planetary systems, and therefore would have great relevance in cosmochemistry and in the current theories about the origins of life.

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