Minor and major groove binders interact with DNA through hydrogen bonds and van der Waals interactions. COSAN has C-H groups, which can form hydrogen bonds with N and O H-bond acceptors in DNA bases in minor and major grooves. However, these hydrogen bonds are much weaker than classical hydrogen bonds. Additionally, B-H groups in COSAN can participate in dihydrogen bonds with proton donors, such as the N-H groups of DNA bases. Dihydrogen bonds are also weaker than classical hydrogen bonds, and DNA grooves have fewer partners for dihydrogen bonding than for classical hydrogen bonding: the minor groove has only one N-H group (guanine), whereas the major groove has two N-H groups (adenine and cytosine) available for dihydrogen bonding.