Engineering organic crystals so as to control the photoreactivity of the reactants and the crystallinity of the products

Single-crystal-to-single-crystal [2 + 2] photodimerizations: from discovery to design

“…The SCSC nature of the reaction has been subsequently confirmed by dynamic X-ray measurements [46], Raman phonon spectroscopy [47], and, more recently, AFM observations [17]. Three derivatives of the cyclic ketone, out of five reported photoactive derivatives, were also found to exhibit SCSC reactivity [28, 48,49]. The in situ observation of the reaction of the parent ketone using dynamic X-ray diffraction (Fig.…”

“…The light provided a suitably slow rate of conversion such that single crystals of the photoproduct formed without disintegration of the reacting crystal. The resulting crystals exhibited a much larger difference in unit cell parameters compared to crystals of the parent ketone, the maximum change being 6.5% [48]. Crystals of the derivative cracked after partial conversion, which was attributed to increased reactivity of the solid [44].…”

Monitoring structural transformations in crystals. 5. A topotactic [2 + 2]-photodimerization reaction

“…The topotactic reaction of (1) was discovered by Jones et al (1980). Compound (1) and the product of its photoreaction were studied by Theocharis et al (1981) and .…”

5-Benzylidene-2-(p-chlorobenzyl)cyclopentanone – a photodimerizable crystal

“…In a study of the growth of crystallographically oriented product in the topochemical dimerization of 2-benzyl-5-benzylidenecyclopentanone (BBCP) derivatives , we have observed that solid-state photoreactivity may be controlled by varying both the nature and position of substitution within the molecule. Thus, whilst 2-benzyl-5-(p-methylbenzylidene)cyclopentanone and its chloro analogue (BpCIBCP) are photostable, 5-benzylidene-2-(p-methylbenzyl)cyclopentanone and its chloro analogue (pC1BBCP) are photoreactive (Jones, Nakanishi, Theocharis & Thomas, 1980). The present study was undertaken as part of an investigation of the effect on crystal packing of varying the nature and position of substitution.…”

“…Whilst the solid-state photodimerization of 2-benzyl-5-benzylidenecyclopentanone (BCCP) and 2-benzyl-5-(p-bromobenzylidene)cyclopentanone (BpBrBCP) proceed smoothly to yield highly perfect single crystals of product , 2-benzyl-6-benzylidenecyclohexanone (BBCH) has been reported to yield an amorphous photoproduct (Forward & Whiting, 1969). As part of a detailed study (Jones, Nakanishi, Theocharis & Thomas, 1980) of the topochemical and topotactic reactivity of BBCP, BBCH and their derivatives we have determined the crystal structure of BBCH.…”