Photostable modification of 2,5-distyrylpyrazine

Structural understanding of solid-state photodimerization reactions of cinnamic amide derivatives in terms of reaction cavities – color developer for thermosensitive paper

“…25,[29][30][31][32][33][34] There are some examples in which the reaction cavity concept has been the key to explaining the photoreactivity of a crystal structure possessing potentially reactive double bonds, i.e., a separation distance less than 4.2 Å, but for which photodimerization did not proceed on photoirradiation. [35][36][37][38][39] In the present work, the volumes and shapes of the reaction cavities in the crystal structures of 1, 2, and 3 were calculated using the cavity program. 40 The calculated reaction cavities for the whole molecules of 1, 2, and 3 in their crystal structures are shown in the Fig.…”

p-Phenylenediacrylic acid dimethyl ester (pPDAMe), a photopolymerizable crystal

“…p-PDAMe is photopolymerized in the crystalline state to give a linear polymer containing a cyclobutane ring in the main chain; its reduced viscosity is often as high as 3 m 3 kg -1 (Suzuki, Suzuki, Nakanishi & Hasegawa, 1969). The crystal structure analysis of p-PDAMe was undertaken as part of the crystallographic studies on such four-centre-type photopolymerization (Nakanishi, Ueno & Sasada, 1976). p-PDAMe was synthesized according to Suzuki et al (1969).…”

4-(2-Carboxyvinyl)-α-cyanocinnamic acid dimethyl ester, a photooligomerizable crystal

“…The molecules are piled up infinitely along the shortest crystal axis (c axis) to form a parallel plane-toplane stack which is quite different from that of photopolymerizable crystals; in the latter crystals, molecules are stacked along a ~7 A axis, displaced by half a molecule in the direction of the molecular long axis, to form a characteristic plane-to-plane stack (Nakanishi, Ueno & Sasada, 1978). The length of the c axis is just the shortest intermolecular distance between reactive double bonds and is close to those found in photopolymerizable crystals (3.94 A on average), rather than to those in photostable crystals (4-187 and 4.369 A) (Nakanishi, Ueno & Sasada, 1976b). The second shortest distance longer than 5 ,~ is found between molecules in different stacks (related by the a glide) (Table 2).…”