Phase-separated hydrogen-bonded chloride ion–water–oxonium ion sheets and protonated 4′-(4-bromophenyl)-2,2′:6′,2″-terpyridine stacks, and condensation products of 2-acetylpyridine and benzaldehydes revisited

Synthesis of Terpyridines: Simple Reactions—What Could Possibly Go Wrong?

“…In addition to the parent compound (Ar = Ar 1 = C 6 H 5 ) [39,40,41,42,43,44,45,46], a large number of derivatives with carbocyclic Ar and Ar 1 substituents have been obtained from reactions of substituted benzaldehydes and acetophenones [34,41,43,46,47,48,49,50,51,52,53]. Of most relevance to the chemistry reported in this manuscript, are compounds with heterocyclic substituents and, to date, examples with thiophen-2-yl [34,41,54,55,56], furan-2-yl [54,57], benzofuran-2-yl [33], benzofuran-3-yl [33], benzothiophen-2-yl [33], benzothiophen-3-yl [33], pyridin-2-yl [33,35,45,58,59,60,61,62,63,64,65,66] pyridin-3-yl [33,45,56] and pyridin-4-yl [16,20,33,45,56,67] groups have been reported. Cave and Raston have commented that reactions of 4-acetylpyridine with 4-alkoxybenzaldehydes in solution only yield the 3:2 products rather than the desired 4,2′:6′,4″-terpyridines [16,20].…”