Single crystals dance under UV light

24 Apr 2014. NUS scientists together with collaborators demonstrated photo-activated mechanical motion in three metal coordination complexes.

Prof Jagadese J. VITTAL’s group in the Department of Chemistry NUS has collaborated with Prof Panče Naumov’s group in New York University Abu Dhabi and another team from the Max Plank Institute for Solid State Research, Stuttgart, Germany lead by Prof Dinnebier who demonstrated photo-activated mechanical motion in three metal coordination complexes during a chemical reaction under UV light for the first time. In other words, the so-called “bad” UV light has been utilized to convert to chemical energy and then to kinetic energy during a metal complex polymerization reaction.

This ‘photosalient’ behaviour is very important to understand the energy harvesting mechanism as well as the light-induced motility in biological systems. The major drawback in this system is that the mechanical motion stops once the reaction is completed. It would be nice if the light energy is directly converted to mechanical (kinetic) energy for a wide variety of practical applications and to solve the energy crisis! Currently the team is trying to understand the mechanism of the observed phenomenon by studying a series of new compounds. Their long term goal in this area is to find a system that converts light energy continuously to mechanical energy exclusively or chemical energy reversibly.

Crystals of three metal complexes pops out under UV light like corns on hot ovens. In the 60-year old solid-state [2+2] photo cycloaddition reaction history this has been observed for the first time. This reaction has utilized the conversion of UV light into mechanical motion through a chemical reaction and enhanced our understanding towards designing materials for alternative energy conversion. His research is being highlighted in Chemistry World: Popcorn-like explosion of single crystals explained


Picture of single crystal popping under UV light [Image credit: National University of Singapore]


Medishetty R, Husain A, Bai ZZ, Runčevski T, Dinnebier RE, Naumov P, Vittal JJ. "Single Crystals Popping Under UV Light: A Photosalient Effect Triggered by a [2+2] Cycloaddition Reaction." Angewandte Chemie International Edition 53 (2014) 5907.