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abstracts
Non-centrosymmetric Metal Organic Frameworks (MOF) based on coordination of carbohydrates on alkaline metal ion represent an ideal category of compounds to plan functional materials with interesting second-order non-linear optics properties. Two MOFs obtained from fructose and calcium chloride, [Ca(C6H12O6)(H2O)2]Cl2 (1) and [Ca(C6H12O6)2(H2O)2]Cl2·H2O (2), have been synthetized in ethanol and by solid-solid interactions and have been characterized with X-ray diffraction and IR and RAMAN spectroscopy. The two compounds have also been studied with DFT theoretical calculations to investigate their relative stability and foresee their optical properties. Finally, the second harmonic generation (SHG) properties have been evaluated by SHG microscopy. It has been demonstrated that the coordination of fructose on the calcium ion causes an improvement of the SHG intensity with respect to the fructose itself and that there is a strictly correlation between the calculated dipole moment and the first static hyperpolarizability values and intensity of the SHG signal. Furthermore, the remarkable difference in the SHG intensity of the two compounds studied, suggests that this physical property can be "controlled" not only by tuning the composition of the system, but also by the disposition of the MOF's building units in the crystal. The metal-carbohydrate based MOFs analyzed in this work have a favorable combination of thermal and chemical stability, transparency, and second-order optical non-linearity and are thus potential candidates for applications in electro-optic devices.
abstracts
The Interdepartmental Research Centre for the Development of Crystallography (CrisDi) aims to be an institution of reference for researchers at the University of Turin interested on the field of diffraction (X-rays, neutrons and electrons), to promote the knowledge and dissemination of crystallography, and to facilitate the access to available laboratory instrumentation (diffractometers and TEM) and to large scale facilities (synchrotron and neutron sources). CrisDi hosts scientists with interest in the fields of solid state chemistry and physics, organic, inorganic, organometallic and theoretical chemistry, mineralogy, biology, pharmaceutical and agricultural sciences. The Centre encourages the design and the development of new methodologies and applications, and supports the enhancement of the available instruments. The submission of proposals at large scale instruments is encouraged specially for young researchers and PhD students. The cultural and scientific interchange among crystallographers coming from different disciplines is strongly encouraged by CrisDi. A main task of the CrisDi is the annual organization of a post-grade level School with a series of courses dedicated to: (i) basic level crystallography (symmetry, theory of diffraction, crystal-chemistry), diffraction techniques (single crystal and powder X-ray diffraction, neutron and electron scattering); (ii) advanced level (high temperature and high pressure structural studies, macromolecular crystallography, time resolved crystallography and kinetic studies); (iii) spectroscopic approaches (XAFS, XANES, XES and NMR) in crystallography. The school, which is held every year in May for about 20 ECTS equivalent, has no tuition fees and is also open to non-academia people.
