Crystalline structure of PEO-resorcinol and PEO-methylresorcinol complexes

The molecular structure of the polyethylene oxide (PEO) molecular complexes with resorcinol (RES) and 2-methylresorcinol (two allotropic forms alpha-2MR and beta-BMR) have been solved and refined by an X-ray diffraction technique (the "whole-pattern method"). The space group is Pna2(1) for RES (a = 10.54 Angstrom, b = 10.18 Angstrom, c = 9.89 Angstrom), Pbca for beta-BMR (a = 11.07 Angstrom, b = 18.60 Angstrom, c = 10.74 Angstrom), and P2(1/a), unique axis c, for alpha-2MR (a = 16.24 Angstrom, b = 10.57 Angstrom, c = 18.79 Angstrom, gamma = 89.2 degrees). Although for RES no direct chain-to-chain interactions are established in the molecular packing, for 2MR, the layered organization of chains and small molecules is present with chain-to-chain contact. Moreover, although hydrogen bonds are clearly established in the case of RES and beta-BMR, alpha-2MR should be regarded as a simple intercalated complex, in agreement with a previous solid state NMR and IR investigation.