The crystal structures of tetrabutyl- and tetrapentylammionium bromide (C4H9)(4)N+Br-, and (C5H11)(4)N+Br- complexes with rac-1,1 '-bi-2-naphthol (C20H14O2); TBAB/BNP and TPAB/BNP, respectively, have been solved by X-ray diffraction techniques. The molecules of TBAB/BNP and TPAB/BNP are held in their aggregates by strong hydrogen bond (O-H horizontal ellipsis Br) and weak hydrogen bonds; C-H horizontal ellipsis O, C-H horizontal ellipsis Br, and C-H horizontal ellipsis pi. The packing structures are different from each other, as well as those observed in tetrabutylammonium bromide with planar aromatic molecules. The tetrabutylammonium cation exhibits conformational and orientational disorder in TBAB/BNP complex, while in TPAB/BNP the alkyl chains of the tetrapentylammonium cation adopt biradial conformation in which there are two sets of paired chains. The tetrapentylammonium cations in TPAB/BNP completely entrap the BNP molecules in a manner that is attributed to the effect of increase in chain length as well as influence of biradial conformation in the tetrapentylammonium cation. However, in TBAB/BNP the naphthol planes of BNP form a void and sandwiches the tetrabutylammonium cation. The patterns of hydrogen bonding network as well as conformation of the tetra-n-akylammonium cations contribute to the formation of the shape of the voids that entrap either BNP or tetrabutylammonium cation. The molecular conformation of the tetra-n-alkylammonium bromides does affect the packing fashion of the nonplanar-shaped BNP molecule and vice versa.