The central theme of our research is the kinetic and thermodynamic control of the solid-state structure of materials. In our work, we use X-ray and neutron powder diffraction methods for crystal structure solution and Rietveld refinements, and total X-ray scattering methods for local structure and disorder analyses. To test for dynamics in the solid state, and to complement the diffraction studies, we use inelastic and quasielastic neutron scattering, as well as Raman/IR spectroscopy. To study the thermoanalytic equilibria, we use various calorimetry methods. Finally, we develop in situ characterization methods for following phase transformations and chemical reactions. We are grateful for a continued support from the CNR NIST and the APS Argonne. Our current research projects are summarized bellow.
Organic Crystals in Nature
We are interested in organic crystals naturally occurring on Earth and on extraterrestrial bodies. Currently, we are focused on the organic mineralogy of Titan, Saturn’s moon. The surface of Titan features lakes and seas made of ethane, rain and storms of methane and snow of hydrocarbons. Pure hydrocarbons precipitate on the surface as planetary ices. We study the stability and phase equilibria of planetary ices in the Titanean environment. There is imminent need for this research considering the next NASA New Frontiers mission to Titan, slated for 2026 launch. On Earth, similar materials exist as petroleum and organic minerals. We study the liquid-solid equilibria of petroleum components and design experimental models to help discover new organic minerals and organic carbon-bearing matter on Earth.
Latest paper on Titanean minerals in Chem.Commun. 2020
We explore strategies to improve the physicochemical properties of crystalline materials by tuning the molecular composition, chemical potentials and intermolecular bonding. Currently, we aim to increase the solubility of poorly soluble pharmaceuticals and fitness supplements and to improve their bioavailability. On the contrary, we aim to decrease the aqueous solubility of fungicides and other pesticides. Upon rain, fungicides are washed from the crops into the soil, poorly soluble formulations would provide longer retention time, better crop protection and less contamination of the environment. We are also interested in the exploring the possibilities to alter the color of pigments and dyes based on pigment-pigment cocrystal formation (“molecular mixing” of colors).
Latest paper on fungicides in Cryst. Growth Des. 2020
We explore strategies to introduce structural defects and/or to induce amorphization in various classes of functional materials, particularly in metal-organic frameworks. Controlled introduction of defects elicits new and desirable physicochemical properties; for example, linker dislocation in the canonical MOF-74 leads to formation of new active sites and bight-light luminescence.
Latest paper on defects in MOFs in J. Mater. Chem. A 2021
Our current projects are supported by NASA (2020-2023), the Welch Foundation (2019-2022) and startup funding from SMU.