Understanding Charge-Transfer Interaction Mode in Cocrystals and Solvates of 1‑Phenyl-3-(pyren-1-yl) Prop-2-en-1-one and TCNQ

Three binary charge-transfer cocrystals
(I, II, and III) and ten cocrystal
solvates (IV­(1)–IV­(10)) were prepared in different
solvents,
involving 1-phenyl-3-(pyren-1-yl) prop-2-en-1-one (PPPO) as electron
donor (D) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as electron
acceptor (A). X-ray diffraction data, vibrational spectroscopy, thermal
behaviors, and diffuse reflectance absorption spectroscopy were exploited
to investigate their structures. The different charge-transfer interaction
mode and molar ratio between donor and acceptor in these crystals
can be affected by the change of solvents. In addition, PPPO and TCNQ
can selectively accommodate aromatic solvents relative to other solvents
except methanol to form an isostructural microporous framework with
solvent residing in the channels. These results demonstrate that these
crystals can have potential applications in purification and separation
of aromatic hydrocarbons.