A crystalline sponge reveals structures of large 'beyond rule of 5' molecules

Drug discovery has traditionally followed the "rule of 5," which identifies chemical properties generally associated with good absorption of orally administered drugs, including a molecular weight below 500 daltons (Da). However, some pharmaceutical compounds fall outside these guidelines. Known as beyond rule of 5 (bRo5) molecules, these compounds can have larger, more complex structures while still exhibiting strong therapeutic activity and favorable pharmacological properties. Their size and structural complexity, however, make it difficult to characterize them using conventional methods, particularly when very small quantities are available.