Abstract
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 ortho-rhom-bic space group Pca21, compared to P21/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)° and the OH group is disordered over two sites in a 0.795 (3):0.205 (3) ratio. In the crystal of (I), mol-ecules are linked by O-H⋯π inter-actions 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 mol-ecules with similar conformations (weighted r.m.s. overlay fit = 0.183 Å). In the crystal of (II), both mol-ecules form carboxyl-ate inversion dimers linked by pairs of O-H⋯O hydrogen bonds, generating R 2 (2)(8) loops in each case. The dimers are linked by pairs of C-H⋯O hydrogen bonds to form [010] chains.
Highlights
In the crystal of (I), molecules are linked by O—H interactions involving both the major and minor –OH disorder components, generating [001]
This acid subsequently catalyses the degradation of the tert-butylcarboxylate groups of a polymer film in a thermal development step, releasing carboxylic acid groups and isobutene
Scheme 1 shows how substituted trans-stilbenes might act as photo-acid generators via sequential photochemical trans–cis isomerization and ringclosing reactions
Summary
The major disordered component for the OH group is shown (the minor component is attached to C14). As part of these studies, the syntheses and crystal structures of the title substituted stilbenes, (I) and (II), are described [compound (II) could be described as a cinnamic acid derivative: the photochemical reactions of this family of compounds were reported by Schmidt (1971)]. In the monoclinic polymorph of (I) (Cornella & Martin, 2013), the asymmetric unit consists of a half-molecule, which is completed by crystallographic inversion symmetry and the aromatic rings are exactly coplanar: the OH group is statistically disordered by symmetry and the corresponding C—C—O—H torsion angle for the monoclinic phase is 175.
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