Application of molecular structure and reactivity to challenges in catalysis, materials, and biological chemistries
The Nava lab is fundamentally interested in understanding how to efficiently translate molecular structure and reactivity to address challenges at the frontiers of materials, biological and energy conversion chemistries. An ever increasing area of importance is the efficient transduction of energy at the molecular level; advances in energy efficiency lessens the demand on legacy energy and drive the viability of energy from renewable sources. Two broad thrusts will form the basis of the program: understanding the role of metals, particularly those in unusual oxidation states, in materials or biological systems and facilitating reversible chemical conversions to enable new energy storage technologies. In order to achieve these idealized goals, advancements must be made in the art of synthetic inorganic chemistry and accordingly, work in the Nava lab will focus at the interface of chemical synthesis and application.
From molecules to materials
The diversity of nanomaterial compositions available to researchers is influenced, and in many cases gated, by their synthetic precursors. Few strategies exist to access large swathes of the periodic table in a uniform, controllable, and predictable manner. New transition metal complexes encompassing the d- and f-block will be developed as metal (0) precursors for preparation of materials such as metastable colloidal nanoparticles, high entropy alloys, intermetallics and quantum dots. New ligand classes and utilization of redox buffering with molecular precursors will be implemented to precisely control the composition, oxidation state, and interfacial chemistry of materials. With a controllable, well-defined route to varied nanomaterials, the synthesis of materials for use in energy conversion chemistries and catalysis will be greatly aided and diversified.
Hydrogen Interconversion chemistry
Hydrogen is the simplest atom from an electronic perspective. However, this simplicity belies the importance of this element as an energy carrier, both in biology as exemplified by proton gradients and modern life as exemplified by the hydrocarbon fuels which drive industry. Hydrogen is unique among the elements in that the (ionic) radius of its common oxidation states, the proton, the hydrogen atom, and hydride, vary by over six orders of magnitude. Such a drastic change in size may manifest as the difficult and inefficient reversable redox cycling of hydrogen. We seek to develop strategies to stabilize the redox interconversions of hydrogen atom at a molecular level. Initial targets include investigating the interconversion of hydrogen gas to hydrides; advances in this area may one day enable practical hydrogen storage.
Zero-valent metals in biology
Transition metals fulfill varied structural, catalytic, and energy carrying tasks throughout the cell, roles which are frequently enabled by the metal’s ability to change formal oxidation states. While considerable progress has been made in understanding the role of a transition metal’s oxidation state in biological processes, this understanding has not come uniformly across all oxidation states of a given metal. The low formal oxidation states of biogenic metals such as Fe(0) and Cu(0) are largely unknown in a biological context. We seek to investigate the biological machinery that generates elemental metal nanoparticles in a bacterial model system with the goal of understanding how metal coordination environment is utilized to favor M(0) formation and how the nanoparticle surface is stabilized by proteins.
Minimalist models of heterogenous active sites
Heterogeneous materials play a central role in modern catalysis, yet the active site(s) of many catalytically-active materials are often thinly dispersed or present at interfaces in inactive bulk matrices, obfuscating hypothesis-driven mechanistic analysis of these sites. While aluminosilicates are widely used catalyst supports, few readily tunable homogeneous molecular models of this class of materials exist due to fundamental challenges in synthetic chemistry. We will develop tunable, oxidation-resistant homogeneous models of silicate and aluminosilicate metal binding sites in these heterogeneous materials. Complexes relevant to C–H activation will be prepared and utilized as spectroscopic references for heterogeneous systems. Further elaboration of these platform will allow the rapid screening of catalyst motifs and identification of new targets for heterogeneous materials syntheses.