About

Jarad Mason is a Professor of Chemistry and Chemical Biology at Harvard University, joining the faculty in January 2018. He holds B.S. and M.S. degrees from the University of Pennsylvania and earned his Ph.D. from the University of California, Berkeley in 2015 under the guidance of Jeffrey Long. His research group applies the tools of coordination chemistry, materials science, and nanotechnology to the synthesis of materials that address basic science challenges in energy and sustainable development. His work emphasizes the development of chemical strategies to manipulate entropy, phase transitions, and porosity at different length scales in new classes of inorganic-organic materials. Notable projects include designing dense, crystalline solids capable of reversible, high-enthalpy phase transitions for thermal energy storage, as well as creating new classes of porous materials with novel behaviors and functionalities. The group also focuses on developing liquids with intrinsic microporosity, self-cooling adsorbents, and nanocrystal-based porous frameworks. Students in his group receive extensive training in synthetic chemistry and utilize a broad range of analytical tools such as diffraction, adsorption, electron microscopy, calorimetry, and spectroscopy.

Research topics

• Organic chemistry
• Chemistry
• Materials science
• Chemical engineering
• Nanotechnology
• Crystallography
• Chemical physics
• Thermodynamics

Selected publications

• An International Laboratory Comparison Study on Approximating the Enthalpy of Adsorption via the Clausius‐Clapeyron Approach

  ChemPhysChem · 2026-04-09 · 1 citations

  articleOpen access

  Materials-based gas capture and storage is an increasingly important area of research. Robust and accurate determination of material properties is required for judicial selection of materials for specific applications and for engineering materials-based systems at scale. One key property is the strength of the adsorbate-adsorbent interaction often quantified via the isosteric enthalpy of adsorption. The heat of adsorption can be measured directly through calorimetry; however, a more widely used approach is to apply the Clausius-Clapeyron (CC) equation to adsorption isotherms collected at different temperatures. While this approach appears to be straightforward, there exist multiple variants in the application of the methodologies employed. This raises the question on how these variations may or may not affect the determined results. Presented here is a discussion of the most common methodologies and a comparison of indirect determinations (via CC) of the isosteric enthalpy of adsorption by different laboratories on identical material. Included in that comparison are discussions on the measurement and analysis reproducibility. Importantly, details of the methodologies are shown to be critical when comparing enthalpies among laboratories, and different methodologies contribute to significant discrepancies and artifacts in the results. Recommendations are provided to promote robust determination and the reporting thereof.

  PublisherDOI

• The Impact of Silanol Defects on the Properties of Zeolite-Based Microporous Water

  The Journal of Physical Chemistry C · 2026-01-09 · 1 citations

  articleSenior authorCorresponding

  Microporous particles with hydrophobic internal surfaces and hydrophilic external surfaces can dramatically enhance the gas-carrying capacity and gas transfer kinetics of aqueous solutions. Pure-silica zeolites are particularly well suited to forming aqueous dispersions with dry and gas-filled micropores─termed “microporous water”─but the zeolite particles typically do not retain their full solid-state gas sorption capacity in the solution phase. Moreover, covalent surface functionalization through silanization reactions can lead to significant additional reductions in gas-carrying capacity. Here, we show that internal silanol defects are directly responsible for the lower O2-carrying capacities and that removal of these defects through an ammonium fluoride treatment restores the gas-carrying capacity of microporous water to 100% of its theoretical value. This further allows covalent surface functionalization to be carried out while preserving the internal porosity─and aqueous phase gas-carrying capacity─of the zeolite. In addition, we investigate how internal silanol defects impact the thermodynamics of noncovalent polymer intrusion into the zeolite particles in aqueous dispersions. Collectively, these results provide new insights into how silanol defects influence the bulk properties of zeolite-based microporous water.

  PublisherDOI

• Observation of Microscopic Domain Effects in the Metal–Insulator Transition of Thin-Film NdNiO ₃

  Nano Letters · 2026-03-16

  articleOpen access

  for thermal control and memory applications.

  PublisherOA PDFDOI

• Manipulating Hydrocarbon Chain-Melting Transitions in Dialkylammonium Halide Barocaloric Materials through Desymmetrization

  Journal of the American Chemical Society · 2025-05-30 · 6 citations

  articleSenior authorCorresponding

  Layered materials containing hydrocarbon bilayers capable of transitioning between an ordered and partially disordered state can exhibit large temperature and entropy changes─termed barocaloric effects─in response to a change in hydrostatic pressure. These barocaloric materials can, in principle, be used to drive heating and cooling cycles with higher efficiency and less environmental impact than conventional fluorocarbon refrigerants. However, much remains to be understood about how to manipulate the thermodynamics and kinetics of hydrocarbon order-disorder, or "chain-melting", transitions in the solid state in order to design materials with properties tailored for specific thermal applications. Here, we report a chain desymmetrization strategy to modulate the phase-change behavior of a new family of asymmetric dialkylammonium halide salts. In particular, we demonstrate that chain desymmetrization can lead to reduced phase-change thermal hysteresis while maintaining large entropy changes. This translates to a significant reduction in the pressure required to reversibly drive nonzero entropy changes, with asymmetric dialkylammonium salts able to access reversible entropy changes at pressures nearly 80% lower than their symmetric counterparts. This work expands the scope of chain-melting materials that exhibit strong barocaloric effects and offers insights into the factors that influence the reversibility of barocaloric materials.

  PublisherDOI

• Crossover from propagon to diffuson thermal transport in SnTe due to nanodiamond inclusions leads to ultra-low lattice thermal conductivity

  Journal of Applied Physics · 2025-10-22

  article

  The “phonon-glass electron-crystal” is an infamously challenging thermoelectric material design principle due to the interconnectedness of thermal and electronic transport in materials. Here, the incorporation of ∼5-nm particles of diamond—a phonon crystal—into the thermoelectric matrix of SnTe is explored as a route toward low lattice thermal conductivity. This counterintuitive strategy works because the large acoustic property mismatch at the SnTe–diamond interface blocks thermal transport. Between 300 and 773 K, SnTe with 1.0 vol. % nanodiamond inclusion exhibits the lowest average and absolute lattice thermal conductivities of any reported SnTe material in this temperature range. The ultra-low lattice thermal conductivity of the nanocomposites is investigated in the two-channel framework—recently advanced in the context of glassy and disordered materials—whereby heat is transported by propagating and non-propagating phonons termed propagons and diffusons, respectively. Above ∼650 K, calculations demonstrate the breakdown of the phonon gas (propagon-only) model for describing the nanocomposite conductivity. At ∼773 K, conductivity reaches the glassy limit where thermal transport is mediated by diffusons. Neutron spectroscopy reveals that with the increase in temperature, phonon modes in SnTe broaden and overlap in energy. We propose that linewidth broadening from nanodiamond-induced scattering and Umklapp processes promotes coupling and wave-like tunneling between overlapping modes, thereby enhancing diffuson-mediated transport at the expense of propagon transport. This progression toward diffuson-dominated conduction represents a novel transport paradigm in primarily crystalline nanocomposites.

  PublisherDOI

• Tunable thermal phase-change materials from common detergents

  Chem · 2025-11-18

  articleSenior author
  PublisherDOI

• Self-assembly of chiroptical ionic co-crystals from silver nanoclusters and organic macrocycles

  Nature Chemistry · 2025-01-08 · 24 citations

  articleOpen accessSenior author
  PublisherOA PDFDOI

• Protein Coatings Dictate the Dispersibility and Stability of Hydrophobic Zeolitic-Imidazolate Frameworks in Water

  The Journal of Physical Chemistry B · 2025-03-11 · 7 citations

  articleSenior authorCorresponding

  Metal-organic frameworks are promising materials for many biomedical technologies due to their ability to store and release large quantities of guest molecules in a predictable and tunable fashion. In biological fluids, proteins readily adsorb to the external surfaces of metal-organic framework particles through a combination of hydrophobic and electrostatic interactions. However, much remains to be understood about the nature of these protein coatings and how they influence the bulk properties of aqueous dispersions of metal-organic frameworks. Here, we show that a variety of proteins can be used to manipulate the properties of aqueous dispersions of zeolitic-imidazolate framework (ZIF) particles. Specifically, noncovalently associated protein coatings promote the formation of dispersions of hydrophobic ZIFs in water with high colloidal and hydrolytic stability, as long as the density of adsorbed proteins exceeds a critical, protein-dependent threshold. Further, these dispersions feature low viscosity and complete retention of gas carrying capacity. The wide range of properties accessible with protein coatings provides a highly modular approach to design hydrophobic metal-organic frameworks with properties tailored for specific biological applications.

  PublisherDOI

• Transferability and Accuracy of Ionic Liquid Simulations with Equivariant Machine Learning Interatomic Potentials

  arXiv (Cornell University) · 2024-03-04

  preprintOpen access

  Ionic liquids (ILs) are an exciting class of electrolytes finding applications in many areas from energy storage to solvents, where they have been touted as ``designer solvents'' as they can be mixed to precisely tailor the physiochemical properties. As using machine learning interatomic potentials (MLIPs) to simulate ILs is still relatively unexplored, several questions need to be answered to see if MLIPs can be transformative for ILs. Since ILs are often not pure, but are either mixed together or contain additives, we first demonstrate that a MLIP can be trained to be compositionally transferable, i.e., the MLIP can be applied to mixtures of ions not directly trained on, whilst only being trained on a few mixtures of the same ions. We also investigate the accuracy of MLIPs for a novel IL, which we experimentally synthesize and characterize. Our MLIP trained on $\sim$200 DFT frames is in reasonable agreement with our experiments and DFT.

  PublisherOA PDFDOI

• Barocaloric Effects in Dialkylammonium Halide Salts

  Journal of the American Chemical Society · 2024-01-16 · 23 citations

  articleSenior authorCorresponding

  Barocaloric effects─solid-state thermal changes induced by the application and removal of hydrostatic pressure─offer the potential for energy-efficient heating and cooling without relying on volatile refrigerants. Here, we report that dialkylammonium halides─organic salts featuring bilayers of alkyl chains templated through hydrogen bonds to halide anions─display large, reversible, and tunable barocaloric effects near ambient temperature. The conformational flexibility and soft nature of the weakly confined hydrocarbons give rise to order–disorder phase transitions in the solid state that are associated with substantial entropy changes (>200 J kg–1 K–1) and high sensitivity to pressure (>24 K kbar–1), the combination of which drives strong barocaloric effects at relatively low pressures. Through high-pressure calorimetry, X-ray diffraction, and Raman spectroscopy, we investigate the structural factors that influence pressure-induced phase transitions of select dialkylammonium halides and evaluate the magnitude and reversibility of their barocaloric effects. Furthermore, we characterize the cyclability of thin-film samples under aggressive conditions (heating rate of 3500 K s–1 and over 11,000 cycles) using nanocalorimetry. Taken together, these results establish dialkylammonium halides as a promising class of pressure-responsive thermal materials.

  PublisherDOI

Frequent coauthors

• Jeffrey R. Long

  University of California, Berkeley

  182 shared

• Miguel I. Gonzalez

  Harvard University

  152 shared

• Craig M. Brown

  NIST Center for Neutron Research

  122 shared

• Matthew R. Hudson

  NIST Center for Neutron Research

  114 shared

• Eric D. Bloch

  Indiana University Bloomington

  99 shared

• Wendy L. Queen

  École Polytechnique Fédérale de Lausanne

  94 shared

• Ryan D. McGillicuddy

  77 shared

• Simon J. Teat

  Lawrence Berkeley National Laboratory

  45 shared

Labs

• Mason GroupPI

Education

• Ph.D., Chemistry

  Harvard University

  2008

• B.S., Chemistry

  University of California, Berkeley

  2003

Awards & honors

• Dan David Prize
• International Institute for Nanotechnology postdoctoral fell…