Syntheses, structural characterization, and DPPH radical scavenging activity of cocrystals of caffeine with 1- and 2-naphthoxyacetic acids

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• 作者：G.S. Suresh Kumar^a ; P.G. Seethalakshmi^b ; D. Sumathi^a ; N. Bhuvanesh^c ; S. Kumaresan^a ; ^{skumarmsu@yahoo.com}
• 关键词：X-ray crystallography ; Caffeine ; Naphthoxyacetic acid ; Cocrystal ; Density functional theory ; DPPH radical scavenging activity
• 刊名：Journal of Molecular Structure
• 出版年：2013
• 出版时间：13 March, 2013
• 年：2013
• 卷：1035
• 期：Complete
• 页码：476-482
• 全文大小：1109 K

文摘

Caffeine:1-naphthoxyacetic acid [(caf)(1-naa)] and caffeine:2-naphthoxyacetic acid [(caf)(2-naa)] cocrystals have been synthesized and single crystals were grown by slow evaporation technique. The structures of the grown crystals were elucidated using single crystal X-ray diffraction analysis. Both the cocrystals belong to the monoclinic crystallographic system with space group P21/c, Z = 4, and ¦Á = ¦Ã = 90¡ã, whereas ¦Â = 111.4244(18)¡ã for [(caf)(1-naa)] and ¦Â = 109.281(6)¡ã for [(caf)(2-naa)]. The crystal packing is predominantly stabilized by hydrogen bonding and ¦Ð-¦Ð stacking interactions. The presence of unionized -COOH functional group in both the cocrystals was identified by FTIR spectral analysis. Thermal behavior and stability of both the cocrystals were studied by TGA/DTA analyses. Solvent-free formation of these cocrystals was confirmed by powder X-ray diffraction analyses. The theoretical energy of cocrystals showed that the formers have higher energy than cocrystals 1 and 2. DPPH radical scavenging activity of cocrystals 1 and 2 is slightly greater than the formers.