He is noted for the development of new methods to construct rotaxanes, catenanes and molecular knots and for the invention of some of the first synthetic molecular motors and functional nanomachines. Using mechanically-interlocked molecular architectures he prepared a novel molecular information ratchet that employs a mechanism reminiscent of Maxwell's demon. He has developed a rotaxane based photoactive molecular switch with the capability of changing the hydrophobicity of a surface and thus causing small droplets of liquid to move up hill, against the force of gravity. In 2009 he reported the first small-molecule walker-track system in which a 'walker' can be transported directionally along a short molecular track in a manner reminiscent of the way that biological motor proteins 'walk' along biopolymers in the cell. In 2011 his research group described the smallest molecular knot prepared to date and also a 160-atom-loop pentafoil knot. The Leigh group have also reported the synthesis of an 819 knot, the most complex molecular knot made to date. In 2013 the Leigh group reported a small-molecule machine capable of detaching and assembling a series of amino acidbuilding blocks from a track into a peptide of specific sequence, a very primitive version of the task performed by the ribosome. They also invented the first autonomous chemically-fuelled synthetic molecular motor and demonstrated a small-molecule 'robotic arm' able to transport molecular fragments between sites 2 nm apart on a molecular platform, marking the start of so-called 'small-molecule robotics'. In 2017 the Leigh group reported the first molecular robot that can be programmed to build different molecules. The molecular robot could be programmed to construct any one of four different stereoisomers of a molecular product, a significant step towards a 'molecular assembler'. The achievement was hailed as 'science fiction becomes fact'. In September 2016 Leigh was suggested as one of three candidates for the potential award of a Nobel Prize for synthetic molecular machines. However, on 5 October 2016 the Nobel Prize in Chemistry was awarded to J. Fraser Stoddart, Ben Feringa and Jean-Pierre Sauvage for the design and synthesis of molecular machines.
Public engagement
Leigh’s 819 molecular knot features in the 2019 Guinness Book of World Records. In 2018 he commissioned and collaborated with acapellascience on ‘Nanobot’, a parody of ‘Havana’ by Camila Cabello aimed at the general public, describing the science behind nanorobotics. The ‘Professor David Leigh Prize for Chemistry’ at Codsall Community High School encourages girls and disadvantaged children to study science at university. Leigh is a Director and Governor of Withington Girls' School. Leigh is a former national champion contract bridge player and an accomplished magician, well known for blending magic, humour and science in his public lectures.
