Alkyl substituent-dependent systematic change in cold crystallization of azo molecules

Akinori Honda, Yukie Hibi, Kazuma Matsumoto, Masato Kawai, Kazuo Miyamura

Research output: Contribution to journalArticlepeer-review


The thermal behavior of alkyl-derivatized 1-(2,4-dimethylphenylazo)-4-naphthol and 1-(2,4-dimethylphenylazo)-2-naphthol (2,4-DM-4-Cn and 2,4-DM-2-Cn, respectively) was investigated. The change in the position of the alkyl substituent led to a variation in the thermal behavior, including the cold crystallization, which is a heat-storing phenomenon. In addition, a comprehensive study of the alkyl chain length revealed that 2,4-DM-4-Cn had better crystallinity and exhibited cold crystallization with short alkyl chains. The π-π, C-H⋯N, and C-H⋯π interactions stabilized the crystal structure of 2,4-DM-4-Cn. On the other hand, the polymorphism of 2,4-DM-2-Cn inhibited the formation of a uniform crystalline phase during cooling, which led to poor crystallinity. The only difference between the compounds, the position of the substituent, resulted in a clear variation in the cold crystallization and heat storage properties.

Original languageEnglish
Pages (from-to)7229-7236
Number of pages8
JournalRSC Advances
Issue number12
Publication statusPublished - 2 Mar 2022


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