Hydrogen bonded assemblies of 1,8-naphthyridine derivatives: discrete or polymeric structures in the solid state

Crystal structures of the dioxane hemisolvates of N-(7-bromo-methyl-1,8-naphthyridin-2-yl)acetamide and bis-[N-(7-di-bromo-methyl-1,8-naphthyridin-2-yl)acetamide]

The syntheses and crystal structures of N-(7-bromo-methyl-1,8-naphthyridin-2-yl)acetamide dioxane hemisolvate, C11H10BrN3O·0.5C4H8O2, (I), and bis-[N-(7-di-bromo-methyl-1,8-naphthyridin-2-yl)acetamide] dioxane hemisolvate, 2C11H9Br2N3O·0.5C4H8O2, (II), are described. The mol-ecules adopt a conformation with the N-H hydrogen pointing towards the lone electron pair of the adjacent naphthyridine N atom. The crystals of (I) are stabilized by a three-dimensional supra-molecular network comprising N-H⋯N, C-H⋯N and C-H⋯O hydrogen bonds, as well as C-Br⋯π halogen bonds. The crystals of compound (II) are stabilized by a three-dimensional supra-molecular network comprising N-H⋯N, C-H⋯N and C-H⋯O hydrogen bonds, as well as C-H⋯π contacts and C-Br⋯π halogen bonds. The structure of the substituent attached in the 7-position of the naphthyridine skeleton has a fundamental influence on the pattern of inter-molecular noncovalent bonding. While the Br atom of (I) participates in weak C-Br⋯Oguest and C-Br⋯π contacts, the Br atoms of compound (II) are involved in host-host inter-actions via C-Br⋯O=C, C-Br⋯N and C-Br⋯π bonding.

Selective sensing of Al3+ by naphthyridine coupled rhodamine chemosensors

Naphthyridine-based rhodamine chemosensors 1 and 2 are designed and synthesized for selective sensing of Al³⁺ ion.