Reversible Multicolor Photochromism of Dihydroazulene Crystals

Ieva Liepuoniute, Patrick Commins, Durga Prasad Karothu, Stefan Schramm, Hideyuki Hara, Pance Naumov*

Research output: Contribution to journalArticlepeer-review


The photochemical conversion of 1,8a-dihydroazulene-1,1-dicarbonitrile (DHA) to vinylheptafulvene (VHF) is a positive T-type photoswitch that is well understood in solution, but has not been explored in the solid state. Upon excitation with UV light, DHA is converted into VHF in the solid state, with a distinct color change from yellow to deep-red, and retention of crystallinity. The structure of the ring-opened product was assigned to syn-VHF using variable-temperature infrared spectroscopy, and determined by X-ray photodiffraction in a crystal enriched with the product by two-photon excitation. A radical pathway becomes an observable photoreaction channel at low temperatures, and includes a strongly colored, short-lived diradical intermediate.

Original languageEnglish (US)
Pages (from-to)373—378
Number of pages6
JournalChemistry - A European Journal
Issue number1
StatePublished - Nov 2 2018


  • crystallography
  • dihydroazulene
  • photochromism
  • solid state
  • vinylheptafulvene

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry


Dive into the research topics of 'Reversible Multicolor Photochromism of Dihydroazulene Crystals'. Together they form a unique fingerprint.

Cite this