Switching the Conformation of 3,2':6',3″-tpy Domains in 4'-(4--Alkyloxyphenyl)-3,2':6',3″-Terpyridines.

The preparation and characterization of 4'-(4--octyloxyphenyl)-3,2':6',3″-terpyridine () and 4'-(4--nonyloxyphenyl)-3,2':6',3″-terpyridine () are reported. The single crystal structures of 4'-(4--hexyloxyphenyl)-3,2':6',3″-terpyridine (), 4'-(4--heptyloxyphenyl)-3,2':6',3″-terpyridine (), and compounds and have been determined. The conformation of the 3,2':6',3″-tpy unit is , in and , but switches to , in and . This is associated with significant changes in the packing interactions with a more dominant role for van der Waals interactions between adjacent -alkyloxy chains and C-H... π interactions in and . The solid-state structures of and with the -hexyloxy and -heptyloxy chains feature interwoven sheets of supramolecular assemblies of molecules, with pairs of -alkyloxy chains threaded through cavities in an adjacent sheet.