The structural details of a,w-alkanediols and a,w-alkanediamines which are characterized by H bonding and hydrophobic interactions. These systems represent a balance between structural simplicity and interaction complexity, which makes the study of interference between interactions a feasible exercise. The anal. of the crystal structures of diols and diamines revealed the interplay between 2 important intermol. interactions that are possible in these amphiphilic compds., namely, H bonding and hydrophobic interactions. While H bonding and hydrophobic interactions operate in consonance in even members, and therefore culminate in dense packing, they run into geometrical conflicts in odd members, leading to looser packing. Accordingly, the odd members of the diol and diamine series have relatively lower densities and m.ps. than the even members.