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

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 pi-pi, C-HMIDLINE HORIZONTAL ELLIPSISN, and C-HMIDLINE HORIZONTAL ELLIPSIS pi 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.

Automated summary

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 cold crystallization. The study also revealed that the alkyl chain length affected the crystallinity, with better crystallinity observed with shorter alkyl chains. Additionally, the crystal structure of 2,4-DM-4-Cn was stabilized by pi-pi, C-H...pi interactions, while polymorphism hindered the formation of a uniform crystalline phase for 2,4-DM-2-Cn.