Molecules of the year 2025

Snub cube supramolecule This whopping piece of molecular architecture incorporates 2,712 atoms across 12 identical macrocycles held together by 144 hydrogen bonds (Nature 2025, DOI: 10.1038/s41586-024-08266-3). It’s not the first time anyone’s made a supramolecular snub cube, but it is the largest and the first to be made stereoselectively. The researchers who made it say it could be used for chiral separations or catalysis.New neutral nitrogen allotropeWhat has six nitrogen atoms and is stable enough to be isolated and analyzed? Hexanitrogen, the first neutral nitrogen allotrope ever characterized besides N2 (Nature 2025, DOI: 10.1038/s41586-025-09032-9). Researchers created the molecule at room temperature via a gas-phase reaction with silver azide and trapped it under supercold conditions. The energetic cost of breaking the central bond is high enough that the molecule doesn’t immediately blow apart into N2 and N3, enabling researchers to study it spectroscopically.Perplexing molecular knotsTalk about twisted science! This year, chemists reached new heights of knottiness with “perplexanes,” entangled molecules with fiendishly complex topology (J. Am. Chem. Soc. 2025, DOI: 10.1021/jacs.5c04268). Using a zirconium reagent, researchers guided flexible alkyne-tipped arms through interconnected molecular loops and then removed the metal to tie off the knots. They created two types of perplexanes, one with twofold symmetry and one with a trefoil structure. Now they’re working on making even more.Spectacular sea sponge synthesisFeaturing 10 stereocenters and two seven-membered aromatic tropolone rings, (–)-gukulenin A offered chemists a meaty synthetic challenge. They overcame that challenge this year with the first total synthesis of the molecule, which was discovered