Silver‐Mediated Formation of a Cofacial Porphyrin Dimer with the Ability to Intercalate Aromatic Molecules

Abstract

Guests welcome: Complex formation between AgI ions and a Zn‐porphyrin ligand (L) possessing four 2,2′‐bipyridyl groups produced a dimeric complex [Ag4L2]4+, wherein the interplane distance between the Zn‐porphyrin groups was ideal for intercalation of aromatic molecules through π–π interactions. The cofacial dimer [Ag4L2]4+ serves as an excellent receptor for π‐electron‐deficient guests.

Maximizing Coordination Capsule–Guest Polar Interactions in Apolar Solvents Reveals Significant Binding

“…With the quinone series (G 1 -G 5 ), increasing the number of fused aromatic rings results in as ignificant increase in K a . In addition to quinones, 1 4+ also binds other guests with suitably disposed H-bond acceptor groups (e.g.G [6][7][8]. [16] These energetic contributions are likely ar esult of additional edge-to-face interactions (CH-p H-bonds, [9a] see below), which is consistent with the significant shielding of H e observed by 1 HNMR spectroscopy following host-guest complexation.…”

Selective Endo and Exo Binding of Mono‐ and Ditopic Ligands to a Rhomboidal Diporphyrin Prism

“…Thed ifferent modes of binding of 3,3'-bipy and 4,4'-bipy to prism 1 contrast strongly.T he binding of 3,3'-bipy is unusual in the context of 3D porphyrin-based host-guest complexes since both covalent and non-covalent diporphyrin cages reported previously show as trong preference for aligned porphyrin faces with minimal lateral displacement, [10,16,18] which precludes the binding of lower-symmetry guests,s uch as 3,3'-bipy,i nf avor of more symmetric guests (for example,4,4'-bipy).…”

“…[10,16,18] Complete transformation of prism 1 into as impler dinuclear complex occurred upon treatment with 2,2'-bipy.Studies to expand the generality of this heteroleptic self-assembly methodology towards the formation of cages with different multitopic pyridylimine and phosphine ligands are currently underway. This heteroleptic approach provides access to an unusual slipped-cofacial porphyrin-porphyrin geometry, which resulted in dual endo and exo binding modes in response to 3,3'-bipy and 4,4'-bipy,c ontrary to the binding preferences of other porphyrin-based hosts.…”

“…Ligands A and B were chosen to generate heteroleptic Cu I N 2 P 2 centers: A does not form an Cu I 4 A 2 homoleptic sandwich due to steric clash between the meso-phenyl groups, [10] and the steric bulk of the phenyl groups of B causes self-assembly to stop at the formation of ad inuclear [{(MeCN) 2 Cu I } 2 B 2 ]c omplex, even in the presence of excess B. [5c,e,9a] Theh exagonal ring described by the Cu À Pa nd P À P vectors in [{ (2,2'-bipy) moieties adopts ac yclohexane-chair conformation owing to the tetrahedral geometries of the Cu I centers.T his chair conformation was expected to cause slanting of the edges of the prism, generating ar homboidal cross-section.…”

Bright Fluorescence and Host–Guest Sensing with a Nanoscale M4L6 Tetrahedron Accessed by Self‐Assembly of Zinc–Imine Chelate Vertices and Perylene Bisimide Edges

“…Changes in the PBI absorption upon guest encapsulation suggest that electronrich C and P guests favor interacting with the electron poor PBI walls of the cage over homo-aggregation. Emission quenching of T by C and P is observed upon encapsulation, thus laying the foundation for developing host-guest fluorescence sensors [7] and supramolecular photosystems. UV/Vis spectra of the same T·C 2 and T·P 3 solutions diluted to 110 À6 mol l À1 exhibit complete recovery of the initial T absorption intensity indicating dissociation of the host-guest complex.…”