Genesis of Complex Polyiodide Networks: Insights on the Blue Box/I−/I2 Ternary System

Abstract

The Stoddart’s blue box (BB) (cyclobis(paraquat-p-phenylene))/iodide binary system was recently demonstrated to give rise to porous three-dimensional networks which can hardly be classified as common XOF-type materials (X = M, C, S, i.e., metal, covalent, or supramolecular organic frameworks), leading to the definition of permutable organized frameworks (POFs). The ternary BB/iodide/iodine system was reported to generate pentaiodide-based structures constituted by the most complex interlocked polyiodides so far isolated (up to an infinite supramolecular pseudopolyrotaxane with a poly[3]catenane axle). The missing link, i.e., the XRD structure of the BB/triiodide complex, is herein reported: structural similarities and novel Raman evidence, opening perspectives in the genesis of solid-state BB-based complex polyiodide networks from solution.

Stabilisation of Exotic Tribromide (Br3−) Anions via Supramolecular Interaction with a Tosylated Macrocyclic Pyridinophane. A Serendipitous Case

“…We will start the discussion from 1 featuring Br 3 − interactions with a benzene (tosyl) and a pyridine ring. Our recent studies with iodides and Stoddart's blue box [44][45][46] For s-triazines, the fitting example of a Br 3 − complex from the literature will help confirm this observation [52]. The structure of the analogous BrIBr − complex will further prove our point [52].…”

“…As shown in Figure 11, for the most convenient (only 1 4 of BB and a single Ianion in the asymmetric unit) (ACN) 2 @(BB)I 4 crystal structure [45], both the BB and I − fingerprint plots show two markedly different regions belonging to I•••H contacts and to anion-π interactions. These features remain unmodified, beyond the intrinsic specificity of each crystal structure and the complications involved in having more than one unique anion in the asymmetric unit, for BB/I − crystal structures (5 structures [45] region seems to be blurred and poorly defined, with differences among the two anions. Yet, as we will show, this is due to the simultaneous presence of two different Br3 -anion interacting with two different aromatic rings (the more the interactions of the same type, the more complicated their fingerprint plot image).…”

“…structures [45]), BB/I3 − structure (1 structure [46]) and BB/I5 − structures (2 structures [44]) fingerprint plots are available in the original studies.…”

“…Given our attention to the topic of anion-π interactions and the interest for novel methodologies that may help us disentangle the individual contribution of different supramolecular forces within a crystal packing, like Hirshfeld surface analysis, we ended up examining a certain number of fingerprint plots of anion complexes [44][45][46]. As we discuss the peculiarities of the (H 2 L-Ts)(Br 3 ) 1.5 (NO 3 ) 0.5 crystal structure under this viewpoint, we cannot help but notice that typical fingerprint plot features exist whenever an anion-π interaction is formed.…”

“…BB and I − fingerprint plot in (ACN) 2 @(BB)I 4 crystal structure (CSD refcode: HUDVOU[45]). Ligand and anion are interacting both via CH•••I contacts (green) and anion-π interactions (red).…”