Understanding and Controlling the Reactivity of Complex Ions at Interfaces

About This Grant

With support from the Chemical Structure and Dynamics (CSD) program in the Division of Chemistry, Professor Julia Laskin at Purdue University is investigating the reactivity of well-defined transition metal complexes deposited onto self-assembled monolayer surfaces to gain fundamental insights into the stability, reactivity, and chemical degradation of complex solid interfaces. The limited molecular-level understanding of surface-mediated chemical transformations hinders progress in energy technologies, catalysis, and molecular electronics. This project addresses that gap by developing a generalizable approach that enables the controlled preparation of new interfaces for fundamental studies of interfacial processes. The work will employ sophisticated custom-built ion soft-landing instruments capable of depositing high currents of both intact ions and reactive fragments onto model surfaces with precise control over ion identity, charge state, and kinetic energy. Professor Laskin and her students will systematically examine how factors such as the gas-phase stability of precursor ions, structural rearrangements upon surface impact, and charge retention influence the reactivity of deposited species. By combining mass spectrometry with advanced spectroscopic and electrochemical techniques, the team will investigate ligand loss, charge transfer, and interfacial degradation mechanisms. Their discoveries will inform the design of stable, functional interfaces for applications in photovoltaics, spintronics, and quantum information science. The research will also contribute to the development of predictive models for surface reactivity guided by density functional theory (DFT). Broader impacts include integration of the research into undergraduate analytical chemistry education and hands-on outreach workshops, as well as a strong emphasis on workforce development. Undergraduate and graduate students will gain interdisciplinary training in surface science, mass spectrometry, and computational chemistry within a multidisciplinary, collaborative research environment—equipping them with the technical expertise and problem-solving skills needed for careers in academia, industry, and national laboratories. The technical objectives of this project are to: (1) determine how the relative gas-phase stability of fully coordinated and undercoordinated transition metal complexes affects their reactivity on surfaces; (2) assess how co-deposition of cations with weakly coordinating anions influences charge retention and structural stability; (3) probe reaction mechanisms using isotope-labeled ligands to trace ligand exchange pathways; and (4) compare surface reactivity with degradation induced by light or electrochemical stimulation. The experimental studies will focus on 3d-metal complexes (Fe, Co, Ni, Cu, Zn) ligated with bipyridine or phenanthroline, which are broadly relevant to applications in light harvesting and catalysis. The use of custom-designed ion deposition instruments will allow for precise control over experimental variables, and the resulting surface products will be characterized in situ and ex situ using a suite of spectroscopic and mass spectrometric techniques. These data will be interpreted in conjunction with DFT calculations to correlate reactivity with geometric and electronic structure. Collectively, this work will establish benchmark datasets and mechanistic frameworks to understand and control interfacial reactivity of complex ions, thereby enabling the rational design of robust functional materials. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.