Three iodocuprate hybrids symmetrically modulated by positional isomers and the chiral conformation of N-benzyl-methylpyridinium

• Published in: RSC advances 2016, Vol.6 (58), p.53566-53572
• Main Authors: Hao, Pengfei, Qiao, Yanrong, Yu, Tanlai, Shen, Junju, Liu, Fang, Fu, Yunlong
• Format: Article
• Language: English
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/C6RA08692F

Three iodocuprates, [ N -Bz-2-MePy] 2 [Cu 5 I 7 ] ( 1 ), [ N -Bz-3-MePy] 2 [Cu 5 I 7 ] ( 2 ), and [ N -Bz-4-MePy][Cu 4 I 5 ] ( 3 ) ( N -Bz-2-MePy + = N -benzyl-2-methylpyridinium, N -Bz-3-MePy + = N -benzyl-3-methylpyridinium, N -Bz-4-MePy + = N -benzyl-4-methylpyridinium) were synthesized and structurally characterized, using benzylated methylpyridinium as a potential conformationally chiral structure-directing agent (SDA). The N -Bz-2-MePy + cations in 1 are featured in coexisting chiral and achiral conformations, forming a left-handed helical supramolecular chain, while N -Bz-3-MePy + cations in 2 take on two pairs of mirror-image conformations, aggregating into a racemic supramolecular (10,3)-b net. Comparatively, N -Bz-4-MePy + cations in 3 possess a couple of mirror-image conformations, forming a supramolecular (6,3) net through π–π and C–H⋯π interactions. Accordingly, 1 and 2 crystallize as conglomerate and racemate packing states, respectively, and 3 possesses no chiral features, which shows a regular directing effect of the positional variation of a methyl group on the construction of iodocuprate frameworks. Furthermore, compounds 2 and 3 exhibit interesting low temperature reversible thermochromism.