Investigations of new potential photo-acid generators: crystal structures of 2-[(E)-2-phenylethenyl]phenol (orthorhombic polymorph) and (2E)-3-(2-bromophenyl)-2-phenylprop-2-enoic acid

The title compounds, C14H12O, (I), and C15H11BrO2, (II), were prepared and characterized as part of our studies of potential new photo-acid generators. In (I), which crystallizes in the orthorhombic space group Pca2(1), compared to P2(1)/n for the previously known monoclinic polymorph [Cornella & Martin (2013). Org. Lett. 15, 6298-6301], the dihedral angle between the aromatic rings is 4.35 (6)degrees and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), molecules are linked by O-H center dot center dot center dot pi interactions involving both the major and minor -OH disorder components, generating [001] chains as part of the herringbone packing motif. The asymmetric unit of (II) contains two molecules with similar conformations (weighted r.m.s. overlay fit = 0.183 angstrom). In the crystal of (II), both molecules form carboxylate inversion dimers linked by pairs of O-H center dot center dot center dot O hydrogen bonds, generating R-2(2)(8) loops in each case. The dimers are linked by pairs of C-H center dot center dot center dot O hydrogen bonds to form [010] chains.