First-principle modeling is used to identify the most likely conformations of two molecular modules A(EG)(3,6) and A(EG)(3,6)CH(2)A (A = CONH, EG = (CH2)(2)O), which in self-assembled monolayers form, respectively, one-and two-layered networks of hydrogen-bonded amides (HBAs). The molecular bond lengths and angles within HBA chains, which are formed within (root 3 x root 3) R30 degrees hexagonal arrays of identical modules, were calculated by exploiting the DFT/BP86/6-31G method. The results from our first-principle conformation analysis highlight an integrated picture of hydrogen bonding in related families of assemblies containing one and two amide groups per molecule, e.g., in HS-(CH2)(n)A(EG)(m)H and HS-(CH2)(n)A(EG)(m)CH(2)A-(CH2)(l)H SAMs on gold. (C) 2013 Elsevier B.V. All rights reserved.