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Microenvironment-Driven Charge Tuning at Microdroplet Interfaces Dictates Criegee Intermediate Reactivity
Ye-Guang Fang1, Yu Sun1, Yue Liu1
1Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China.
The Journal of Physical Chemistry Letters
|June 4, 2026
Summary
Water microdroplets significantly alter chemical reactions. The microenvironment, not just electric fields, controls reactivity of Criegee intermediates (CIs), with smaller CIs showing the largest rate enhancements.
Area of Science:
- Atmospheric Chemistry
- Physical Chemistry
- Chemical Physics
Background:
- Water microdroplets possess unique physicochemical properties.
- Interfacial electric fields are traditionally considered the main drivers of microdroplet reactivity.
- The role of other factors in regulating charge transfer and reaction activity remains unclear.
Purpose of the Study:
- To investigate how the interfacial microenvironment of water microdroplets influences the chemical reactivity of Criegee intermediates (CIs).
- To explore factors beyond electric fields that regulate charge transfer and reaction rates in microdroplets.
- To understand the molecular size selectivity of interfacial catalysis on CIs.
Main Methods:
- Quantum chemical calculations
- Enhanced sampling methods
- Ab initio molecular dynamics simulations
- Reaction kinetic theory
Main Results:
- The interfacial microenvironment modulates charge distribution on electrophilic carbon atoms.
- Interface-to-gas-phase reaction rate ratios for CIs vary by up to 6 orders of magnitude.
- Small CIs (e.g., CH2OO, CH3CHOO) show 4-6 order-of-magnitude rate enhancements, while larger CIs are less affected.
- Catalysis is attributed to differential regulation of charge distribution and dynamic fluctuations at the electrophilic center.
Conclusions:
- The microdroplet interfacial microenvironment plays a crucial role in regulating charge distribution and reactivity of CIs.
- This effect complements the established electric field perspective on microdroplet chemistry.
- Findings provide a theoretical basis for atmospheric particle-phase CIs chemistry.
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