Design, synthesis, structural and nonlinear optical properties of photochromic crystals: Toward reversible molecular switches

Michel Sliwa, Sylvie Létard, Isabelle Malfant, Martine Nierlich, Pascal G. Lacroix, Tsuyoshi Asahi, Hiroshi Masuhara, Pei Yu*, Keitaro Nakatani

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

191 Scopus citations

Abstract

Two new anil molecules exhibiting photochromism in the crystalline state, N-(4-hydroxy)-salicylidene-amino-4-(methylbenzoate) (2) and N-(3,5-di-tert- butylsalicylidene)-4-aminopyridine (3), are obtained. Upon irradiation in the UV, the yellow crystals change color to red, owing to enol-keto intramolecular tautomerism. The red color disappears, when crystals are left in the dark or irradiated with visible light. 3 has the most stable keto form among all anil-type photochromic compounds (τ = 460 days at room temperature). Both exhibit nonlinear optical (NLO) properties and show powder second harmonic generation (SHG) of respectively 10 and 3 times vs urea. X-ray diffraction shows acentric structures where molecules line up "head-to-tail" through hydrogen bonds for 2 (space group Pc), or form a chiral helix 3 (space group P32). Evidence of reversible structural change is given for 3, and we demonstrate the functionality of this crystal as an NLO switching material, as SHG can be photomodulated by about 30%.

Original languageEnglish
Pages (from-to)4727-4735
Number of pages9
JournalChemistry of Materials
Volume17
Issue number18
DOIs
StatePublished - 6 Sep 2005

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