Structure prediction based on hydrophobic to hydrophilic volume ratios in small molecule amphiphilic organic crystals

The structure type for the crystal of 4,4′-bis-(2-hydroxy-ethoxyl)- biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic to hydrophilic volume of 1, this model predicts the crystal structure to be of lamellar or bicontinuous type, which has been confirmed by the X-ray single-crystal structure analysis (C₂₀H₂₆O₆, monoclinic, P2₁/c, a = 16.084(1), b = 6.0103(4), c = 9.6410(7) Å, β = 103.014(2)°, V = 908.1(1) ų, Z = 2, D_c = 1.325 g/cm³, F(000)=388, μ = 0.097 mm ^-1, MoKα radiation, λ = 0.71073 Å, R = 0.0382 and wR = 0.0882 with I > 2σ(I) for 7121 reflections collected, 1852 unique reflections and 170 parameters). As predicted, the hydrophobic and hydrophilic portions of 1 form in the lamellae. The same interfacial model is applied to other amphilphilic small molecule organic systems for structural type prediction.