Research
Research approach
Metalloenzymes constitute a paradigmatic example of ideal catalysts. Fine tuning of the first and second coordination spheres in combination with the use of preferred readily available first row metal ions permit them to carry out a wide range of synthetic transformations. Especially relevant are the processes in which dioxygen is implicated, i) used as H+/e- acceptor to oxidize a wide range of organic substrates with an exquisite selectivity, and ii) found as final product in the photosynthetic water oxidation. In this research program, we will take inspiration of the complex enzymatic machinery to develop low-weight metal complexes that can mimic some crucial aspects of these processes. Detailed study of physical and chemical properties of relevant metal/dioxygen derived intermediate species will led to rational design of new sustainable, efficient and selective catalytic systems with useful energetic and synthetic applications beyond the enzymatic activity.
Synthesis, Characterization and Reactivity of High-Valent M(O2)/M(O) Species
Metal-superoxo, metal-(hydro)peroxo and metal-(hydro)oxo species are proposed to be involved in several natural and industrial catalytic processes such C-H hydroxylation, dioxygen reduction and water oxidation. Due to the importance of these intermediates in organic synthesis, renewable energy sources and drugs metabolism, the detection, characterization and study of these reactive species have interested researchers from a wide range of disciplines. In this research plan, small-molecule model systems will be used to disclose some crucial aspects of these short-lived intermediates. We will take advantage of rational ligand design, cryogenic control and spectroscopic characterization to study in detail the geometric and electronic features of these high-valent metal species along with their reactivity, leading to the development of novel catalytic processes.
1st Row Metal Systems For Enhanced Catalytic O2-Reduction/H2O-Oxidation
One of the main concerns human civilization will face is replacing the use of oil-based energy sources with cheap, universal, envionmentally benign technologies. Taking inspiration from two natural complementary processes (photosynthesis and cellular respiration), the scientific community is developing novel energetic sources based on: i) photochemical cells that combine water, light and a catalyst to generate molecular hydrogen to be used as fuel and; ii) fuel cells, which makes use of hydrocarbons, H2O2 and/or H2 to generate energy with higher efficiency (60%) than simple combustion (30%). First row metal complexes have emerged as an appealing alternative in homogenous catalytic water oxidation (WO) and dioxygen reduction (O2Red) because they are cheap, they can be systematically improved through ligand design and more importantly, the catalytic reaction mechanism can be studied with spectroscopic techniques. On the other hand, it is essential to develop new catalysts that will be optimized for high turnover frequency and robustness. In this part of the program, discrete first row metal cataysts inspired by the natural WO and O2Red processes will be synthesized, focusing on a better understanding of the O-O cleavage/formation mechanism that will lead to the design of improved catalytic systems.
New Bio-Inspired Catalysts for Practical Organic Synthesis
Enzymatic catalytic transformations have inspired synthetic chemists to design simplified catalytic systems that could emulate and/or overcome these natural processes. Many researchers have expended efforts to explore new routes in the conversion of inert C-H bonds to value-added products. This part of the scientific project will focus on the development of catalysts based on the methodical design of first row metal complexes for the catalytic transformation of C-H and C=C bonds to selective C-O bond formation (hydroxylations, cis-dihydroxylatyion and epoxidation), C-N formation (aminations, aziridinations), C-C formation (cyclopropanation), and C-X halogenations (X = F, Cl, Br, I). Our efforts will concentrate on building a library of synthetic tools for cheap, environmentally sustainable, chemo- and stereoselective chemical transformations of complex molecules.