OUR RESEARCH

Brief synopsis:

Research in the Handford lab is centered on the development of soluble, molecular inorganic species that inform the understanding of structure and reactivity in complex catalytic systems, including heterogeneous and bioinorganic active sites. Molecular "models" provide unparalleled insights towards the structural and electronic aspects of reaction centers, owing to their suitability for atomically-resolved characterization methods, including chemical crystallography and spectroscopy.

In spite of their utility, molecular active-site models are often limited in simultaneously capturing both the reactive and structural elements of "real" reaction centers. These shortcomings are associated with challenges of ligand design and electronic structure, which impose fundamental limitations in the level of insight offered by synthetic inorganic molecules. Within the Handford group, we seek to identify new strategies that enable the isolation of highly reactive inorganic molecules which fully describe the underpinnings of cooperative reactivity found in heterogeneous and bioinorganic active sites.

We will utilize a broad suite of experimental and theoretical tools as we explore the fundamental properties and reaction chemistry of these systems, and students within this lab will become proficient in a diverse array of synthetic, spectroscopic, and computational techniques.

You can expect:

That you'll find yourself in an intellectually enriching environment; one which challenges and supports you as you expand the bounds of your scientific practice.
That you'll be respected as a colleague and collaborator, and that you're warmly invited to be a part of the lab's ever evolving culture.
That you'll be exposed to a breadth of synthetic, spectroscopic, and theoretical methods.
That you'll be supported along a career trajectory of your choosing, whether that lies in academia, industry, the professional sector, or elsewhere.

Research Areas

Multimetallic Reactivity

Polymetallic active sites are ubiquitous in industrial heterogeneous catalysts that convert inert small-molecules to chemically useful derivatives. Synthetic examinations of polymetallic molecules have resulted in the development of soluble clusters that capture aspects of the high reactivity and redox flexibility inherent to these polymetallic active sites. These studies have facilitated a greater understanding of the mechanistic underpinnings of multinuclear cooperativity, but synthetic polymetallic clusters remain broadly limited due to complex geometries and electronic structures that attenuate their reactivity.

In order to overcome these limitations, we are exploring cluster designs that possess prescribed nuclearities and electronic structures, with symmetry and simplicity as guiding principles. With these clusters in hand, we'll explore their characteristic behavior towards small-molecule substrates of relevance to fuel production and clean energy. Spectroscopic and structural studies will enable the development of step-by-step insights towards bond-activation and bond-forming steps.

Polar Heterobimetallics

Investigations of heterobimetallic units (LM—M’L’) have generated fundamental insights into the nature of intermetallic bonding, while uncovering new reaction pathways that take advantage of the divergent properties of the two metal centers. In particular, strongly polarized metal-metal multiple bonds have been a powerful driver in furthering our understanding of the d-block elements, by uncovering new trends in periodicity and reactivity that are directly tied to exotic bonding situations between distinct metal ions.

Existing heterobimetallic systems are generally limited to supported metal-metal bonds, buttressed by ligands that coordinatively saturate one or both of the metal centers, tempering the reactivity of these systems. My group seeks to address these limitations and to significantly expand this area by developing a generalizable synthetic route to access unsupported, polar metal-metal multiple bonds. My group will map the reaction chemistry of these species, uncovering how bond-activation mechanisms and catalytic processes are dictated by the oxidation state and bond order of the heterobimetallic unit.

Metal-Main Group Cooperativity

Transition-metal group element phases (MxEy) are highly active heterogeneous catalysts for numerous transformations that include hydrogen evolution, hydrogenation, and hydroformylation. The reactivity and robustness of these phases is attributed to cooperative effects involving both centers of the M—E linkage, and to the mobility of M and E ions in the bulk phase which gives rise to multiple stoichiometries within a single catalytic system. The flexibility of these phases has made identification of the reactive surface structures challenging, and structure-reactivity relationships in these phases remain an open question.

Insight towards these features from the molecular inorganic community is also limited, owing to the dearth of controlled synthetic methods to prepare model compounds that contain MxEy cores. My group is interested in establishing a generalizable method to prepare soluble MxEy clusters with prescribed M : E ratios, which will enable the discovery of a broad library of molecular structures with varying M,M’/E combinations. The systematic study of these species’ structures and reaction chemistry will establish how the identity of M and E influence the nature and behavior of the M—E bond, and in turn, the reactivity of the MxEy unit. By examining the transformations of these clusters with small-molecule substrates that are relevant to established transition-metal main group catalysts, my group will uncover the structural and mechanistic underpinnings of these materials’ high reactivity.