A way to link carbon rings thought impossible for a century has now been done, and could have medical applications. For exactly 100 years, chemists have considered double bonds impossible – or nearly so – in organic chemistry under specific circumstances. Known as Bredt’s rule, this axiom was based not on theory, but decades of previous observations of molecules where such bonds were lacking. Confidence was high enough that it has widely been published in textbooks. New research shows it’s not true, and will encourage chemists to look for molecules they previously thought couldn’t exist. Carbon is such an immensely...