Supramolecular Architectures of Polyoxometalate Hybrids Originating from Halogen and Hydrogen‐Bonding Interactions

Abstract

In this paper, we explored the possibility of building halogen bonds between polyoxometalate anions by synthesizing a series of polyoxometalate clusters covalently linked to different halogen atoms. Among these samples, the polyoxometalate hybrids containing bromide and iodine atoms exhibited both halogen and hydrogen bonding interactions between the hybrid anions, leading to novel 3D framework assemblies.

Keggin-Type Anions as Halogen Bond Acceptors

“…The halogen bonding proclivities of oxometalate (OM) and polyoxometalate (POM) anions have particularly been investigated only in a handful of studies. This is rather surprising given the interest the polyoxometalates have generally drawn over the past five decades due to not only their structural versatility but also numerous (both potential and actual) applications in catalysis, − molecular electronics, , and medicine. − One way of introducing halogen bonding functionality into a POM system that has been investigated is functionalization of the POM core with a covalently bonded halogenated substituent. − An alternative approach includes using halogenated counterions as halogen bond donors. − Counterions are generally protonated nitrogen bases (pyridine and aniline derivatives) that interact with POM anions by both hydrogen and halogen bonds. In some cases, hydrogen can be replaced by silver ions that coordinate both POM oxygen and the nitrogen of the (halogenated) base molecule, leading to a functionalized heteronuclear POM species. , Alternatively, as demonstrated by Mizuno and co-workers, coordinated species involving halogens can also be used as a potential halogen bond donating macrocations , sometimes resulting in porous ionic materials .…”