About

Ian Gould is President's Professor in the School of Molecular Sciences at Arizona State University, a position he has held since joining ASU in 1998. His research interests are in organic geochemistry and geochemically inspired green organic chemistry. He has over 150 refereed publications and an H-index over 50. His work focuses on understanding the reactions of organic matter beneath the Earth's surface, which are significant for the deep geochemical carbon cycle, petroleum and natural gas processing, marine organic processes, and energy sources for microbial communities. Gould's research explores how these geochemically relevant organic reactions occur using water as the solvent and without exotic reagents, providing insights into Earth's natural organic chemistry processes.

Research topics

• Chemistry
• Organic chemistry
• Geology
• Inorganic chemistry
• Mineralogy
• Chemical physics
• Computational chemistry
• Thermodynamics
• Chemical engineering
• Astrobiology

Selected publications

• The Mycobacterium lipid transporter MmpL3 is dimeric in detergent solution, SMALPs and reconstituted nanodiscs

  bioRxiv (Cold Spring Harbor Laboratory) · 2024-05-07

  preprintOpen access

  Abstract The mycobacterial membrane protein large 3 (MmpL3) transports key precursor lipids to the outer membrane of Mycobacterium species. Multiple structures of MmpL3 from both M. tuberculosis and M. smegmatis in various conformational states indicate that the protein is both structurally and functionally monomeric. However, most other resistance, nodulation and cell division (RND) transporters structurally characterised to date are either dimeric or trimeric. Here we present an in depth biophysical and computational analysis revealing that MmpL3 from M. smegmatis exists as a dimer in a variety of membrane mimetic systems (SMALPs, detergent-based solution and nanodiscs). Sucrose gradient separation of MmpL3 populations from M. smegmatis, reconstituted into nanodiscs, identified monomeric and dimeric populations of the protein using laser induced liquid bead ion desorption (LILBID), a native mass spectrometry technique. Preliminary cryo-EM analysis confirmed that MmpL3 forms physiological dimers. Untargeted lipidomics experiments on membrane protein co-purified lipids revealed PE and PG lipid classes were predominant. Molecular dynamics simulations, in the presence of physiologically-relevant lipid compositions revealed the likely dimer interface.

  PublisherOA PDFDOI

• Author response for "The mycobacterium lipid transporter MmpL3 is dimeric in detergent solution, SMALPs and reconstituted nanodiscs"

  2024-07-24

  peer-review
  PublisherDOI

• Ethene-ethanol ratios as potential indicators of hydrothermal activity at Enceladus, Europa, and other icy ocean worlds

  Icarus · 2023-08-29 · 7 citations

  article
  PublisherDOI

• Kinetics and Mechanisms of Hydrothermal Dehydration of Cyclic 1,2- and 1,4-Diols

  The Journal of Organic Chemistry · 2022-10-13 · 6 citations

  articleSenior authorCorresponding

  Hydrothermal dehydration is an attractive method for deoxygenation and upgrading of biofuels because it requires no reagents or catalysts other than superheated water. Although mono-alcohols cleanly deoxygenate via dehydration under many conditions, polyols such as those derived from saccharides and related structures are known to be recalcitrant with respect to dehydration. Here, we describe detailed mechanistic and kinetic studies of hydrothermal dehydration of 1,2- and 1,4-cyclohexanediols as model compounds to investigate how interactions between the hydroxyls can control the reaction. The diols generally dehydrate more slowly and have more complex reaction pathways than simple cyclohexanol. Although hydrogen bonding between hydroxyls is an important feature of the diol reactions, hydrogen bonding on its own does not explain the reduced reactivity. Rather, it is the way that hydrogen bonding influences the balance between the E1 and E2 elimination mechanisms. We also describe the reaction pathways and follow-up secondary reactions for the slower-dehydrating diols.

  PublisherDOI

• Hydrothermal Experiments with Protonated Benzylamines Provide Predictions of Temperature-Dependent Deamination Rates for Geochemical Modeling

  ACS Earth and Space Chemistry · 2021-08-10 · 7 citations

  article

  In fluids of sufficient temperature and residence time, certain organic species are observed to equilibrate, and their abundances become diagnostic of reaction conditions, including temperature, redox state, and pH. Organic species released from remote geologic and planetary settings can therefore serve as geochemical tracers for environments that are difficult to observe directly. Here, we provide a framework for selecting organic compounds as geochemical tracers based on kinetic modeling. We characterized temperature-dependent rates of deamination substitution reactions for aqueous protonated benzylamines, i.e., benzylaminiums, to form benzyl alcohols and ammonium. Hydrothermal experiments were conducted at 200–300 °C at liquid–vapor water saturation pressures with ring-substituted benzylaminiums expected to have comparable deamination rates to environmentally abundant aminiums, e.g., amino acids. We compared rates extrapolated from experiments to idealized natural systems, taking into account fluid temperatures and residence times. Our results indicate that reversible deamination/hydration reactions may equilibrate over geologic time scales across diverse environments, including those approaching freezing temperatures for the most reactive benzylaminium. Therefore, similar reaction constituents may be useful targets for the exploration of potentially habitable subsurface environments, such as icy ocean worlds of the solar system. Our investigation supports previous findings that aqueous deamination of benzylaminiums operates via two simultaneous substitution mechanisms, SN1 and SN2. We find that for certain benzylaminiums, rates of each mechanism should be modeled individually to improve extrapolation across temperatures. Extrapolations of observed (i.e., bulk) deamination kinetics to near-ambient temperatures (∼50 °C) without mechanistic considerations can produce discrepancies in reaction half-lives on the order of a billion years.

  PublisherDOI

• Violation of fluctuation-dissipation relations for electron transfer in nonpolar solvents

  Physical Review Research · 2021-02-04 · 7 citations

  articleOpen access

  Nonpolar materials are increasingly employed as media for electron transfer, particularly in applications related to solar energy conversion. What should be the mechanism of activation for electron tunneling in the absence of rotating permanent dipoles considered in standard theories is not clear. We suggest that compression and decompression (density) fluctuations shifting positions of polarizable molecules of the medium is the mechanism for radiationless transitions. These fluctuations affect the induction interactions between the medium induced dipoles and the localized electron (induction forces). Solvent reorganization energy must be a signature of such fluctuations, but it has never been directly measured for electron transfer in nonpolar media. Here, absorption and emission spectra of a charge-transfer complex are analyzed as functions of temperature in cyclohexane. Significant reorganization energies, 0.2-0.5 eV, are found. They strongly differ between the ground and photoexcited charge-transfer states in violation of fluctuation-dissipation relations establishing the basis for modern theories of electron transfer. The reorganization energies are decaying functions of temperature, also in violation of the macroscopic fluctuation-dissipation relations.

  PublisherOA PDFDOI

• Hydrothermal One-Electron Oxidation of Carboxylic Acids in the Presence of Iron Oxide Minerals

  ACS Earth and Space Chemistry · 2021-09-17 · 7 citations

  article

  Hydrothermal experiments were undertaken to explore the reaction pathways of phenyl-containing carboxylic acids in the presence of iron oxide minerals. At 300 °C and 1 kbar (100 MPa), in addition to the previously reported decarboxylation and ketonic decarboxylation pathways, phenylacetic acid undergoes oxidation to form benzoic acid, which eventually forms 2-phenylacetophenone via ketonic decarboxylation with phenylacetic acid. The production of benzoic acid in the presence of magnetite (Fe3O4) or hematite (Fe2O3) parallels the production of benzoic acid in the presence of Cu(II) salt solutions observed in previous hydrothermal studies, which was attributed to a sequence of one-electron-transfer processes. We propose a similar one-electron oxidation reaction pathway in the presence of minerals. Complexity builds as the reaction options increase. Hydrothermal experiments with hydrocinnamic acid were performed to demonstrate the generality of the reaction pathways for carboxylic acids, although the rate of consumption of hydrocinnamic acid was slower than that of phenylacetic acid and yielded a complex variety of detected products. Hydrocarbons are produced at the longest observed time points of a reaction through either decomposition or C–C bond formation to larger compounds. These results indicate that minerals can enhance the complexity of organic product pathways for carboxylic acids and resulting products during hydrothermal transformations and may enable the production of hydrocarbons from organic acids and other precursors.

  PublisherDOI

• Quantifying the extent of amide and peptide bond synthesis across conditions relevant to geologic and planetary environments

  Geochimica et Cosmochimica Acta · 2021 · 20 citations

  • Chemistry
  • Astrobiology
  • Chemical physics
  PublisherDOI

• Motivation factors that contribute to student engagement in an electronic learning system

  International Conference of Learning Sciences · 2020-01-01

  article
  Publisher

• Kinetics and Mechanisms of Hydrothermal Ketonic Decarboxylation

  ACS Earth and Space Chemistry · 2020 · 9 citations

  • Chemistry
  • Inorganic chemistry
  • Organic chemistry

  The formation of ketone products from carboxylic acids in the presence of minerals has not been considered in the interpretations of aqueous geochemistry, even though the formation of ketones is a well-known industrial process that occurs on mineral surfaces. This study demonstrates the formation of ketone products through ketonic decarboxylation from phenylacetic and hydrocinnamic acid in the presence of the mineral surfaces of magnetite (Fe3O4), hematite (Fe2O3), corundum (Al2O3), and spinel (MgAl2O4) at hydrothermal conditions (300 °C, 1000 bar). These minerals were chosen to deconvolve the mechanism of ketonic decarboxylation and explore the difference in abundance and rate of product formation on different kinds of oxide minerals. The presence of minerals increased the number and variety of reaction paths available to phenylacetic acid, compared to reactions without minerals. Magnetite and spinel favored the ketonic decarboxylation reaction more strongly than hematite and corundum, resulting in greater product yields. In the case of spinel, the presence of mineral both increases the formation of dibenzylketone and the decomposition of the same ketone into toluene.

  PublisherDOI

Recent grants

• An Intelligent Tutoring System for Organic Chemistry

  NSF · $592k · 2015–2019

Frequent coauthors

• Samir Farid

  University of Rochester

  59 shared

• Everett L. Shock

  38 shared

• Hilairy E. Hartnett

  Arizona State University

  33 shared

• Nicholas J. Turro

  Columbia University

  29 shared

• Lynda B. Williams

  Arizona State University

  27 shared

• Robert A. Moss

  20 shared

• Joseph P. Dinnocenzo

  University of Rochester

  19 shared

• Edward D. Lorance

  Vanguard University

  18 shared

Education

• Ph.D.

  University of Manchester, U.K.

  1980

• M.S.

  University of Manchester, U.K.

  1978

• B.S.

  University of Manchester, U.K.

  1977