Multifunctional Tricarbazolo Triazolophane Macrocycles: One‐Pot Preparation, Anion Binding, and Hierarchical Self‐Organization of Multilayers

Abstract

Programming the synthesis and self-assembly of molecules is a compelling strategy for the bottom-up fabrication of ordered materials. To this end, shape-persistent macrocycles were designed with alternating carbazoles and triazoles to program a one-pot synthesis and to bind large anions. The macrocycles bind anions that were once considered too weak to be coordinated, such as PF6 (-) , with surprisingly high affinities (β2 =10(11) M(-2) in 80:20 chloroform/methanol) and positive cooperativity, α=(4 K2 /K1 )=1200. We also discovered that the macrocycles assemble into ultrathin films of hierarchically ordered tubes on graphite surfaces. The remarkable surface-templated self-assembly properties, as was observed by using scanning tunneling microscopy, are attributed to the complementary pairing of alternating triazoles and carbazoles inscribed into both the co-facial and edge-sharing seams that exist between shape-persistent macrocycles. The multilayer assembly is also consistent with the high degree of molecular self-association observed in solution, with self-association constants of K=300 000 M(-1) (chloroform/methanol 80:20). Scanning tunneling microscopy data also showed that surface assemblies readily sequester iodide anions from solution, modulating their assembly. This multifunctional macrocycle provides a foundation for materials composed of hierarchically organized and nanotubular self-assemblies.

The Chaotropic Effect as an Assembly Motif in Chemistry

“…[10] Thea ctual affinities of POMs with CDs have been studied in detail by Cadot and co-workers [12,22] as well as others. [25] Thechaotropic effect also accounts for the recently reported binding of chaotropic anions to biotinuril, [98] bambusuril, [45,46,97,145] hemicucurbituril, [146] at ricarbazolo triazolophane (not studied in water), [147] and the so-called octaacid (see Figure 3f or structures). [82,83,[148][149][150][151] Thes tudied chaotropic anions included not only those in Table 1but also N 3 À ,C NO À ,S eCN À ,I O 4 À ,R eO 4 À ,a nd SbF 6 À .N oteworthy, the thermodynamic fingerprint (enthalpically driven processes with an egative entropic contribution) is identical in all cases,r egardless of which type of superchaotropic anion and which macrocycle are being used.…”

A macrocyclic oligofuran: synthesis, solid state structure and electronic properties

“…45 We also note a pronounced tendency of the macrocycle to form multilayers at the liquid-solid interface, in line with its aggregation in solution. 46 Fig. 5c shows the multilayer, with molecules missing from the upper layer giving the appearance of holes in which a lower contrast molecule (of the lower layer) can still be identied.…”

Cooperatively Interlocked [2+1]‐Type π‐System–Anion Complexes

“…[3,4] In the case of 2a-2f,t he terminal aryl moieties connecting with the core partt hrough the sp moieties induce the effective interactions throught heir twisting orientations (Figure 3b). [14] The observed cooperativity can also be correlated to the interacting properties in the multiple binding sites of guest anions. In this case, two binding sites were supposed to be present in Cl À ,a so bservedi nt he formation of the [2+ +1]-type complexes.T herefore, we studied the interactions between the NH/CH groups and Cl À in the [2+ +1]-and [1+ +1]-type complexes of 2a-2f.I nterestingly,t he DE 4 values are comparable with the DE 2 values (Figure 4a nd Ta ble 2), indicating that the first and second bindings of Cl À are energetically almost equivalent.…”