DNA-Inspired Molecular Solar Thermal Storage (Pyrimidone)
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Summary

Researchers at UC Santa Barbara have developed a modified pyrimidone molecule that stores solar energy directly in its chemical bonds and releases it as heat on demand — achieving a record energy density of more than 1.6 MJ/kg, exceeding that of lithium-ion batteries. The breakthrough advances the field of Molecular Solar Thermal (MOST) energy storage and was published in Science in February 2026.

Key Facts

  • Developed by: Han Group, UC Santa Barbara (collaboration with UCLA for computational modeling)
  • Published: February 12, 2026, in Science (DOI: 10.1126/science.aec6413)
  • Molecule type: Modified pyrimidone (organic, water-soluble)
  • Field: Molecular Solar Thermal (MOST) energy storage
  • Energy density: >1.6 MJ/kg (vs. ~0.9 MJ/kg for lithium-ion batteries)
  • Theoretical storage lifetime: ~481 days at room temperature
  • Release mechanism: Acid catalyst triggers rapid heat release; sufficient to boil water in ~0.5 seconds under ambient conditions
  • Status: Laboratory research stage; pre-commercial

What It Is / How It Works

Molecular Solar Thermal (MOST) energy storage is an approach where a molecule absorbs photons from sunlight and undergoes a structural change that traps that energy in chemical bonds. The stored energy can later be released as heat when triggered — without the need for a battery or grid infrastructure. Unlike conventional solar panels, which require a separate battery system, a MOST material stores energy intrinsically in the liquid itself.

The UC Santa Barbara team drew inspiration from a photochemical process that occurs in DNA: when DNA nucleobases absorb ultraviolet light, they can form a ring structure called a pyrimidone. The researchers engineered this same type of structural transformation into a standalone molecule designed for stability and high energy density.

When exposed to sunlight, the pyrimidone molecule undergoes a photoisomerization — its atoms rearrange into a higher-energy configuration (the “charged” state) and remain locked there. The molecule is water-soluble and operates without toxic solvents, which distinguishes it from many earlier MOST candidates that relied on organic solvents or degraded quickly. Computational modeling by collaborators at UCLA helped optimize the molecular design.

To release the stored energy, an acid catalyst is added to trigger the reverse isomerization, rapidly returning the molecule to its lower-energy state and releasing heat. In laboratory demonstrations, this release was fast enough to bring water to a boil under ambient conditions in approximately 0.5 seconds. After discharge, the molecule can be recharged with light and reused in a closed-loop cycle.

The theoretical energy density of 1.65 MJ/kg makes it the highest-reported value in the MOST field and exceeds the energy density of lithium-ion batteries (~0.9 MJ/kg). Theoretical calculations project that the charged molecule could remain stable for around 481 days at room temperature — a significant advance over previous MOST materials that degraded within hours or days.

The Han group synthesized four pyrimidone derivatives with different substituents to test this design space. The best performer, designated molecule 3 (its charged Dewar isomer form is called D-3), combines two design principles identified as critical to its record performance: the photoinduced conversion to the Dewar isomer produces a total loss of aromaticity, forming two highly strained rings that store substantial energy in a strategic C–N bond, and the addition of lightweight methyl (CH3) groups lowers the barrier for fast, efficient heat release while maximizing energy density per unit mass. In the reported boiling demonstration, 107 mg of D-3 boiled 0.46 mL of water immediately upon addition of a hydrochloric acid catalyst. The Dewar isomer form was shown to remain stable for more than a year in DMSO solution across repeated storage/release cycles, consistent with the ~481-day theoretical room-temperature stability estimate.

Remaining challenges include broadening the molecule’s absorption spectrum to capture more of the visible solar spectrum (current designs are more responsive to UV) and demonstrating economic scalability for real-world applications. The Han and Houk groups say they are developing a machine-learning model to predict new heterocyclic systems and substituents aimed at broader-spectrum absorption and higher energy density.

Notable Developments

  • 2026-05-21: UCLA publishes detailed follow-up coverage naming the top-performing derivative (molecule 3 / D-3), disclosing the design mechanism (aromaticity loss + methyl substitution), and confirming Dewar-isomer stability of over a year in DMSO across repeated cycles. Han and Houk groups announce plans for an ML-guided search for broader-spectrum, higher-density successor molecules.
  • 2026-04-23: Study featured on the cover of Science (vol. 392, issue 6796).
  • 2026-02-12: Research published in Science. Team demonstrates boiling water under ambient conditions using stored solar heat; reports record MOST energy density of >1.6 MJ/kg.

Key People / Key Organizations

  • Grace Han — Associate Professor, UC Santa Barbara; principal investigator of the Han Group; leads MOST materials research; 2025 Moore Inventor Fellow (Gordon and Betty Moore Foundation), funding this work
  • Han Nguyen — Doctoral student, Han Group, UC Santa Barbara; lead author on the Science paper
  • Benjamin Baker — Co-author, UC Santa Barbara; Han Lab doctoral student
  • Ken Houk — Distinguished Research Professor, UCLA; leads computational modeling collaboration on molecular design optimization
  • Alexander Maertens — Third-year Ph.D. student, Houk Group, UCLA; co-author, contributed computational analysis of the design mechanism
  • Qingyang Zhou — Fourth-year Ph.D. student, Houk Group, UCLA; co-author, contributed computational analysis
  • UC Santa Barbara — Primary research institution
  • UCLA — Computational modeling collaborator (Houk Group)

Sources