Professor John Sherwood: An appreciation ORGANIC crystalline materials are ubiquitous in our everyday life, from pharmaceuticals, fuels and soap and candles to chocolate and ice cream, crop protection products and electro-optic materials. Crystals are periodic structures of 3D ordered molecules, though they can be imperfect due to missing or misplaced molecules or the same when dimensionally extended. Such defects are highly important as they affect the material’s properties and, hence, performance. Understanding, characterising and defining the crystal growth of these materials and, in particular, the pivotal inter-relationship between their growth conditions, defect types and resulting properties owes so very much to the seminal work, spanning six decades, of Professor John N Sherwood of the University of Strathclyde, who died, aged 87, last month.