Topochemical studies. XIV. Structures of 3,3'-dibromotruxinic acid water–acetic acid (0.5/0.25) solvate and 3,3'-dichlorotruxinic acid water–acetic acid (0.5/0.25) solvate

Polymorphic Phase Transformation in the 3-Bromo-trans-cinnamic Acid System

“…Indeed, these reactions in crystals of trans-cinnamic acids are prototypical examples of solid state reactions that conform to the topochemical principle (8, 20}26). On this basis, for the phase of 3-BrCA, the distance between the C"C bonds of adjacent molecules and their relative orientations are appropriate for a topochemical [2#2] photodimerization reaction (27). For the phase, the distance between adjacent C"C bonds is longer than that normally found for photoreactive trans-cinnamic acid crystals, and a photodimerization reaction is not expected to occur in this case.…”

Topochemical studies. XIII. Structures of 3-bromocinnamic acid and 3-chlorocinnamic acid

“…The next shortest contacts are found between the C(7) atoms and thus also between the C(8) atoms which are related by the translation along the shortest axis [3.9879 (3) /~ for (1); 3.909(1)A for (2)]. Photodimerization occurred between these double bonds in both crystals (Kanao, Kashino & Haisa, 1990). The structure of 4-chlorotrans-cinnamic acid, which is similar to (2), has been reported (Glusker, Zacharias & Carrell, 1975).…”

Effects of Aromatic Substitution on the Photodimerization Kinetics of β-trans Cinnamic Acid Derivatives Studied with 13C Solid-State NMR

“…NMR theoretical calculations were performed using the CASTEP software package . In the simulations, the atom positions were taken from the X-ray crystal structures for ortho and meta cinnamic acid as well as for meta bromo truxinic acid . For para bromo cinnamic acid, the crystal structure was solved within this work (see above) and used for the simulations.…”