Odd-Even Effect in the Elastic Modulii of α,ω-Alkanedicarboxylic Acids

Nanoindentation is a probe used to quantitatively assess mechanical behavior of small volume materials. In this technique, load applied vs. the depth of penetration of the indenter into the specimen are measured simultaneously and with high precision and resolution. By analyzing the data, one can obtain the elastic modulus and hardness of crystals. Though this technique has been extensively used to characterize inorganic and engineering materials, we have recently extended its utility to study weak interactions and to establish structure-property relationships in molecular crystals. Being able to assess the relative strength of weak interactions such a technique has become relevant to the subject of crystal engineering which is concerned with the design of molecular solids with desired properties and functions. In our recent studies through nanoindentation on the alkanedicarboxylic acids reveals that the elastic modulus shows similar alternation property as the melting point alternation. Our results are endorsing the strained molecular conformations hypothesis for the melting point alternation of diacids, proposed by Thalladi et al. These results support the development of crystal engineering because nanoindentation may be used as a direct measure of molecular and crystal energies of molecular crystals.

The International Year of Crystallography

IYCr2014 aims at improving public awareness of the field, boost access to instrumentation and high-level research, nurture "home-grown" crystallographers in developing nations, and increase international collaborations for the benefit of future generations. The IUCr-UNESCO OpenLab is a network of operational crystallographic laboratories based mainly in Africa, Asia and South America, and implemented in partnership with industry. The OpenLabs will enable students in far-flung lands to have hands-on training in modern techniques and expose them to cutting-edge research in the field. Such project was started based on the strong experience gained through the IUCr Initiative in Africa . The Summit meetings are intended to bring together scientists from countries in three widely separated parts of the world. Karachi (Pakistan), Campinas (Brazil) and Bloemfontein (South Africa). These meetings, attended by scientists from academia and industry and by science administrators, will focus on high-level science, and also highlight the difficulties and problems of conducting competitive scientific research in different parts of the developing world. Moreover, a worldwide crystal-growing competition aims at attracting and inspiring youngsters.