Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• electron-withdrawing cyano groups than when they are electron-donating methoxy groups. Keywords: aromatic stabilization energy; diarylethene; ruthenium(I) catalysed Huisgen cyclization; terarylene; thermally reversible photochromism; Introduction Diarylethenes are one of the most widely investigated

• among the photochromic families [1][2][3]. They are known to show thermally irreversible photochromism. However, some of them are thermally reversible [4]: (1) when the aromatic stabilization energy of the aromatic rings is large [5]; (2) when the substituent groups on the ring-closing carbon atoms are

• related families of diarylethenes, are largely thermally reversible [10][12] although some are irreversible when the aromatic stabilization energy of the aromatic rings is small [11]. Their syntheses are usually carried out by the sequential construction of the central aromatic ring at the final stage [10