First decade of π-electronic ion-pairing assemblies

Abstract

The prologue and progress of π-electronic ion-pairing assemblies, including synthesis of π-electronic ions, preparation of ion pairs, fabrication of assemblies as crystals, gels and liquid crystals and their characteristic properties, are summarized.

Dipyrrolyldiketone PtII Complexes: Ion‐Pairing π‐Electronic Systems with Various Anion‐Binding Modes

“…In dipyrrolyldiketone BF 2 complexes, the inversion of the two pyrrole rings is required for anion binding because their stable conformations are not suitable for anion binding (Figure 1b). [2,3] Thus, the stability of the four conformations of 2 a-c in regard to the orientations of the pyrrole rings were examined by DFT calculations. [12] Similar to BF 2 complexes, the pyrrole-non-inverted structures were the most stable; the dipoles of pyrrole and core six-membered rings were oriented opposite to each other.…”

“…As π-electronic anion-responsive molecules, the BF 2 complexes of 1,3-dipyrrol-2-yl-1,3-propanediones (dipyrrolyldiketones) (e. g., 1 a-c, Figure 1a) form anion complexes and ionpairing assemblies when combined with cations (Figure 1b). [2][3][4][5] A variety of anion complexes (pseudo π-electronic anions) have been prepared by modifying the receptor pyrrole moieties. The tetrahedral boron unit in these anion complexes interferes with their effective stacking with the countercations and themselves.…”

Nitro-Substituted Dipyrrolyldiketone BF2 Complexes as Electronic-State-Adjustable Anion-Responsive π-Electronic Systems

“…It is also noteworthy that nitroarenes behave as electrophilic coupling partners for Suzuki–Miyaura coupling [ 14 ]. As the platforms for NO 2 substitution, dipyrrolyldiketone BF 2 complexes (e.g., 1a , b , Scheme 1 ) have been examined as anion-responsive π-electronic molecules [ 15 , 16 , 17 , 18 , 19 ], which formed anion complexes and ion-pairing assemblies in combination with cations [ 20 , 21 ]. Pyrrole β-substituents of 1b enable the facile and selective introduction of substituents at the α-positions, resulting in the synthesis of various derivatives [ 18 , 19 ].…”

Supramolecular Assemblies of Dipyrrolyldiketone CuII Complexes

“…In particular, π-electronic molecules with planar geometries may afford stacking assemblies, which are suitable for the generation of electrically conductive materials. Ion-pairing assemblies based on π-electronic ions form a variety of ordered states that act as dimension-controlled assemblies, such as crystals, liquid crystals, and supramolecular gels [ 2 , 3 ]. The preparation of π-electronic anions, which can serve as components of ion-pairing assemblies, is more difficult than that of π-electronic cations due to the lower stability of electron-rich species.…”