Polymorphs, Solvates, Polymorphs of Solvate and Cs+–π Interactions of Fluorine-Substituted bis-Phenols

We present here polymorphs and solvates of two isomeric bis-phenols namely 4-[(2-fluorophenyl)­(4-hydroxy-3,5-dimethyl phenyl)­methyl]-2,6 dimethylphenol (bis-phenol 1) and 2-[(2-fluorophenyl)­(2-hydroxy-3,5-dimethylphenyl)­methyl]-4, 6 dimethylphenol (bis-phenol 2), and some of their interconversions. Two polymorphs of bis-phenol 1 with different crystal densities were observed. The polymorph 1a (orthorhombic, Pbca) self-assembles through O–H···O and C–H···F–C interactions and has voids of pore volume of 326 Å3 running along the crystallographic a axis, whereas the polymorph 1b (monoclinic, P21/c) that self-assembles via C–H···F–C and C–H···π interactions is without voids. The polymorph 1a or dimethylformamide solvate 1c transforms to polymorph 1b on heating. The crystal packing of the unsolvated bis-phenol 2 is devoid of C–H···F–C interactions. We obtain two dimethylsulfoxide (dmso) solvates of bis-phenol 2 with different stoichiometry, 2b (1:0.5) and 2c (1:1). The solvate 2c is formed at high temperature from bis-phenol 2 in dmso. The solvate 2b has the dimeric subunits of the parent bis-phenols in its packing pattern, whereas the solvate 2c has repeated units which are constituted by dmso-bridged bis-phenol molecules. The two polymorphs of dioxane solvate (2d and 2e) of bis-phenol 2 are distinguishable. The main difference between the structure 2d and 2e is that the latter contains C–H···F–C interactions, whereas the former does not have C–H···F–C interactions. Structure of the polymeric cesium salt of 2 has η2 and η4-types of Cs+–π interactions.