The Nature of the Mechanical Bond: From Molecules to Machines. By Carson J. Bruns & J. Fraser Stoddart. Wiley, 2016. Hardback, Pp. 786. Price GBP 180.00, EUR 216.00. ISBN 978‐1‐119‐04400‐0

This book is a monumental review of the area of chemistry embracing the fascinating world of mechanically interlocked molecules (MIM). This field emerged about fifty years ago and the recognition of its achievements culminated by the attribution of the Nobel prize for chemistry to Jean-Pierre Sauvage, J. Fraser Stoddart (one of the authors of this book) and Bernard L. Feringa in 2016. Starting in the mid-1980s, this field developed rapidly thanks to the efforts of numerous researchers. This book is a tribute to the work of all these chemists. The first chapter of The Nature of the Mechanical Bond: From Molecules to Machines clearly defines the concepts. It introduces the mechanical bond (interlocked molecules which cannot be separated without breaking a chemical bond) and presents the two main types of mechanically interlocked molecules, namely catenane (interlocked rings) and rotaxane (a ring around a rod with two big stoppers at its ends). The chapter presents an historical perspective of the mechanical bond and makes fascinating connections with patterns analogous to chemical bonds in nature, ancient and modern civilizations, and art. This opening chapter can be read with pleasure and interest not only by chemists but also by any curious person. Chapter 2 reviews the different synthesis strategies used to build molecular structures containing mechanical bonds under kinetic control with a specific emphasis on templatedirected synthesis (noncovalent bonding interactions serve as templates instead of covalent bonds) and active template synthesis (a species – usually a transition metal centre – acts as a template and a catalyst). These template strategies have proven to be very efficient for obtaining catenanes and rotaxanes. Chapter 3 presents the strategies used to make mechanical bonds under thermodynamical control, which rely on reversible bond breaking–bond forming steps. Techniques such as slippage, self-assembling of metallo-organic MIMs, condensation, olefin methathesis and reversible nucleophilic reactions are described and illustrated by many examples. Chapter 4 is devoted to the analysis of catenane topologies and rotaxane architectures. Topological isomerism concerns molecular ensembles containing the same atoms and chemical bonds which cannot be interconverted by any deformations that do not involve the breaking and forming of chemical bonds. In topology, rotaxanes differ from catenanes in the sense that they are topologically trivial (components can be separated without any bond breaking). This chapter describes numerous catenane and rotaxane structures with potentially interesting chemical and physicochemical properties. Chapter 5 explains and illustrates the concepts of stereochemistry in mechanomolecules. Mechanostereoisomers are isomers which have the same interlocked component parts, but their positions in space differ. The ability of mechanostereoisomers to interconvert through a dynamical process distinguishes the dynamical mechanostereoisomers from the static ones which generally cannot be interconverted without the breaking and making of bonds. The last chapter of the book describes the molecular switches (systems changing their conformation in response to a stimulus) and molecular machines (systems performing mechanical work) which can be designed from mechanostereoisomers interconverting through a dynamical process driven by a chemical reaction (acid–base, redox or covalent), light, solvation effect, molecular recognition, heat, pressure, and so on. ISSN 2053-2296