Marialore Sulpizi: Research

Interfaces: structure, reactivity, spectroscopy

Liquid-solid interfaces are ubiquitous and responsible for a number of phenomena encountered in biological, chemical and physical processes. Surface-induced changes of material properties are not only important for the solid support but also for the liquid itself. The complex chemistry at solid-liquid interfaces is fundamental to heterogeneous catalysis and electrochemistry and has become especially topical in connection with the search for new materials for energy production. The interactions at solid/liquid interface control crystallization and shape selective crystal growth. This is fundamental for example to the synthesis of nanoparticles with specific tailored shape/size. In life science, the most important solid-liquid interfaces are the cell-membrane / water interfaces. Phenomena occurring at the surface of phospholipid bilayers control the docking of proteins, the transmission of signals as well as transport of molecules in and out of the cell. More recently the development of bio-compatible materials has lead to research on the interface between bio-compatible material and lipid/proteins in aqueous solution.

Interface Selective Vibrational Spectroscopy

Confined water at nanoscale shows properties which are remarkably different from bulk. Vibrational Sum Frequency Generation Spectroscopy (VSFG) has contributed to a large extent to draw the attention on the new physical and chemical properties at interfaces, thanks to its ability to selectively probe non-centrosymmetric systems. However, the microscopic characterization of the VSFG spectra remains hard even with the development of some improvements like Phase-Sensitive VSFG. Molecular dynamics simulations can play a key role to provide a molecular interpretation of the spectra. In particular DFT-based simulations which do not require a priori parametrization, are particularly suitable to address the heterogeneous environment at interfaces. Our aim is to advance computational spectrscopy methods in order to provide a microscopic understanding of the special water structure and dynamics at interfaces. For more information, please contact Marialore Sulpizi.
Collaborators: Ellen Backus, Mischa Bonn and Yuki Nagata (MPIP).

How the Interface Interactions Influence the Crystal Growth

We investigate how the properties at the interface influence the crystal growth in a few selected example. In particular one topic is related to the understanding of the microscopic origin of the asymmetric growth mechanism in gold nanorods (Collaborators: C. Sönnichsen, Chemistry, JGU). The second topic is related to understanding how bio-polymers such as polyacrylate, poly-aspartate and poly-glutamate influence the crystalline phase, morphology and growth rate of calcium oxalate. Ab initio molecular dynamics study of the interactions of the water/mineral and water/polymer/mineral interfaces shed light on the biomineralization process and on the mechanisms responsible for its inhibition. For more information, please contact Marialore Sulpizi.
(Collaborators: D. Donadio, UCLA).

Solid/Water Interface Structure and Reactivity

We aim to a detailed understanding of the molecular behaviour of the different solid–water interfaces, using density functional theory based molecular dynamics (DFTMD) simulations, where a consistent treatment of the electronic structure of solvent and surface is provided. Our interest includes oxide water interfaces (such as silica, alumina, clays) as well as ionic salts/water interfaces, such as the fluoride/water interface. For more information, please contact Marialore Sulpizi.

Computational Electrochemistry in Extended Systems

We calculate the redox potential and reorganisation free energy for molecules in complex environments. In particular we elucidated the role of the environment (solvent, protein scaffold) and its H-bond network on the electrochemical properties of several systems such as quinones and metalloproteins. Further works involves electrochemical properties of solid/liquid interfaces. For more information, please contact Marialore Sulpizi.