Ion-Pair Oligomerization of Chromogenic Triangulenium Cations with Cyanostar-Modified Anions That Controls Emission in Hierarchical Materials

Abstract

The hierarchical assembly of colored cationic molecules with receptor-modified counteranions can be used to control optical properties in materials. However, our knowledge of when the optical properties emerge in the hierarchical organization and the variety of cation-anion salts that are available to create these materials is limited. In this work, we extend the salts from small halides to large inorganic anions and determine how the structure coevolves with the emission properties using solution assemblies. We study the chromogenic trioxatriangulenium (TOTA) cation and its coassembly with cyanostar (CS) macrocycles selected to modify tetrafluoroborate (BF) counteranions through formation of 2:1 sandwich complexes. In the solid state, the TOTA cation stacks in an alternating manner with the sandwich complexes producing new red-shifted emission and absorption bands. Critical to assigning the structural origin of the new optical features across the four levels of organization (1° → 4°) is the selection of specific solvents to produce and characterize different assemblies present in the hierarchical structure. A key species is the electrostatically stabilized ion pair between the TOTA cation and sandwich complex. The red-shifted features only emerge when the ion pairs oligomerize together into larger (TOTA·[CSBF]) assemblies. New electronic states emerge as a result of multiple copies of the TOTA making π-contact with cyanostar-anion complexes. Our findings and the ease with which the materials can be prepared as crystals and films by mixing the salt with a receptor provide a strong platform for the de novo design of new optical materials.

Host–Host Interactions Control Self‐assembly and Switching of Triple and Double Decker Stacks of Tricarbazole Macrocycles Co‐assembled with anti‐Electrostatic Bisulfate Dimers

“…Diastereomers are also seen with protons H a , H b , and H c . The observation of diastereomeric peaks has been seen previously in 2:2 complexes of hydroxyanions with cyanostar . Within such complexes the position of one cyanostar macrocycle relative to the other was fixed in place as a result of the steric gearing between the macrocycle's bulky substituents.…”

High‐Fidelity Multistate Switching with Anion–Anion and Acid–Anion Dimers of Organophosphates in Cyanostar Complexes

“…The 1 H NMR peak positions of the complex are consistent with a π‐stacked pair of cyanostars ,. Specifically, diastereomeric pairs of cyanostars give rise to a 61:39 ratio between major ( meso , MP ) and minor ( chiral , MM and PP ) isomers as defined by pairing of cyanostars with either M or P bowl chirality .…”

The supramolecular assemblies based on heteroatom-containing triangulenes

“…19a). 58 A four-step assembly mechanism was identified by NMR as well as UV/vis absorption and emission spectroscopy: binding of the anion to 19, formation of an ion-paired salt, 1D columnar pp-stacking and, eventually, crystallization (Fig. 19b).…”