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-2 MR and beta-BMR) have been solved and refined by an X-ray diffraction techn ique (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), u nique 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-ch ain interactions are established in the molecular packing, for 2MR, the lay ered organization of chains and small molecules is present with chain-to-ch ain contact. Moreover, although hydrogen bonds are clearly established in t he case of RES and beta-BMR, alpha-2MR should be regarded as a simple inter calated complex, in agreement with a previous solid state NMR and IR invest igation.