It's a nightmarish amount of work to figure out how to build a molecule from scratch. Now machines can do it and it will mean a bounty of new drugs and materials

Bruno Mangyoku

CHEMISTS have a unique power to manipulate matter. Imagine any arrangement of atoms you like and a chemist will have a good shot at stitching them together. Over the decades, their round-bottomed flasks have helped bring all sorts of new compounds into being, from dazzling pigments to miracle pills and wonder materials. But they don’t come easy, not least because chemists must do it all backwards.

The tried-and-tested method for planning how to create a sophisticated molecule starts where you would like to end up. You draw out the web of connected atoms you want to make, then pick it apart, working backwards to plot out a series of reactions that, if performed in the reverse order, will get you to your goal.

It is a simple, old and indispensable idea that won its inventor a Nobel prize. Plenty of the last century’s finest drugs have chemical structures so fiendishly complicated that they could never have been made without a logical reverse engineering.

“Chess and chemistry are very similar. They’re both about plotting moves”

Yet with thousands of possible ways to make compounds of even middling complexity, it is tough for humans to spot the best routes. That is why a few chemists think the quickest path to molecules more wondrous than ever lies in taking themselves out of the equation.

Most of the biological world is built of organic, or carbon-containing, molecules. From hormones to vitamins to poisons, organic chemists have long tried to both divine their structures and find ways to make them in the laboratory.

In the middle of the 20th century, chemists generally tried …