posted on 2015-08-28, 00:00authored byMihiri
S. Weerasinghe, Steven T. Karlson, Yuhua Lu, Kraig A. Wheeler
We
report the single-crystal-to-single-crystal (SCSC) photodimerization
of a sulfonamide isocoumarin. When recrystallized, this material forms
centrosymmetrically related supramolecular dimers that assemble via
the complementary features of molecular shape and carboxyl···carboxyl
contacts. This prescribed motif persists despite the presence of two-part
whole-molecule disorder. Each disorder component is involved in a
unique set of hydrogen-bonding interactions, N–H···OC
versus N–H···OS, that propagate along
the [111] and [110] directions of the crystal, respectively. Despite
the observed disorder, the overall recognition profile of this supramolecular
dimer remained intact, effectively promoting coplanar head-to-tail
alignment with a separation of 3.4–4.1 Å between the neighboring
CC groups. UV illumination studies using the tail-irradiation
technique produced a single photodimer product in quantitative yield
via a SCSC transformation.