Session 1C: Lectures by Fellows/Associates

Chairperson: Vijayamohanan Pillai, IISER Tirupati, Tirupati

The alchemy with water microdroplets

Water microdroplets are widespread in nature and create a remarkably distinct chemical environment compared to bulk water. While bulk water is a benign universal solvent for many substances, its microdroplet form features a unique air–water interface where molecules experience partial solvation, specific orientation, extreme local pH and polarity, and ultrahigh intrinsic electric fields. These factors collectively lower activation barriers and enhance the chemical reactivity of reagents confined within the small volume of each droplet. At the interface, water becomes redox-active, enabling simultaneous oxidation and reduction processes often driven by reactive oxygen species generated in situ. Our pioneering studies have unveiled and harnessed this multifaceted microenvironment to achieve remarkable outcomes: (i) accelerating chemical reactions by many orders of magnitude, (ii) triggering new chemical pathways inaccessible in bulk media, and (iii) capturing reactive intermediates normally too fleeting to detect. These advances underscore the critical role of the microdroplet surface in promoting unique chemical transformations without requiring external catalysts or harsh conditions. This chemistry points toward water microdroplets as green, efficient reactors for the synthesis of valueadded chemicals and pharmaceuticals, paving the way for the development of scalable and sustainable synthetic platforms. This presentation will delve into the mechanistic insights, experimental findings, and future opportunities in water microdroplet chemistry, underscoring its vital role in both fundamental and applied chemical sciences. It will spotlight the notion of 'Alchemy'—a metaphor that inspires curiosity and wonder—by illustrating how these minuscule reactors convert ordinary water into a potent medium capable of driving unprecedented chemical transformations.