Extraordinary anisotropic thermal expansion in photosalient crystals

Khushboo Yadava, Gianpiero Gallo, Sebastian Bette, Caroline Evania Mulijanto, Durga Prasad Karothu, In Hyeok Park, Raghavender Medishetty, Pance Naumov, Robert E. Dinnebier, Jagadese J. Vittal

Research output: Contribution to journalArticlepeer-review


Although a plethora of metal complexes have been characterized, those having multifunctional properties are very rare. This article reports three isotypical complexes, namely [Cu(benzoate)L 2], where L = 4-styryl pyridine (4spy) (1), 2′-fluoro-4-styryl pyridine (2F-4spy) (2) and 3′-fluoro-4-styryl pyridine (3F-4spy) (3), which show photosalient behavior (photoinduced crystal mobility) while they undergo [2+2] cyclo addition. These crystals also exhibit anisotropic thermal expansion when heated from room temperature to 200°C. The overall thermal expansion of the crystals is impressive, with the largest volumetric thermal expansion coefficients for 1, 2 and 3 of 241.8, 233.1 and 285.7 × 10-6 K-1, respectively, values that are comparable to only a handful of other reported materials known to undergo colossal thermal expansion. As a result of the expansion, their single crystals occasionally move by rolling. Altogether, these materials exhibit unusual and hitherto untapped solid-state properties.

Original languageEnglish (US)
Pages (from-to)83-89
Number of pages7
Issue numberPt 1
StatePublished - Jan 1 2020


  • [2+2] cyclo additions
  • crystal engineering
  • mechanochemistry
  • metal complexes
  • molecular crystals
  • organic solid-state reactions
  • photosalient effects
  • properties of solids
  • solid-state reactions
  • thermal expansion

ASJC Scopus subject areas

  • General Chemistry
  • Biochemistry
  • General Materials Science
  • Condensed Matter Physics


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