Revealing Molecular Self-assembly And Geometry Of Non-covalent Halogen Bonding By Solid-state Nmr Spectroscopy

摘要

We report a new spectroscopic fingerprint of intermolecular contacts in halogen bond-driven self-assembling aggregates and a precise determination of intermolecular N...I distances in microcrystalline samples.rnNon-covalent halogen bonding plays an important role in crystal engineering. Molecules bearing halogen atoms (Cl, ;Br, I) can act as electron density acceptors that are able to form complexes with Lewis bases containing donor atoms such as nitrogen, oxygen or sulfur. These non-covalent interactions have a strength that is comparable to hydrogen bonds. They can be strong enough to control the aggregation of organic molecules in solids, liquids and gases. The directionality of halogen bonds contributes to determine the relative orientation of molecules in solids, thus permitting the tailored design of novel materials. Interesting examples of N...I halogen bonding have been identified in supramolecular chemistry, in various solid-state reactions, in cation receptors and in functional materials such as liquid crystals and molecular-imprinted polymers. Recently it has also been recognized that halogen bonds can play a central role in ligand binding and molecular folding of macromolecules such as proteins and DNA.