Ionic Mixed Interactions in Macromolecules

Abstract

Purely ionic interactions in natural and synthetic macromolecules involve the mutual interaction of fixed charges and their interaction with mobile ions. Such charge-dependent interactions lead to well-documented effects, including chain expansion of polyelectrolytes, globularization of polyampholytes, distributions of mobile ions according to charge screening, or ion condensation models. A variety of structural features, functions, and applications of these systems is amplified by the superimposition of charge-independent effects associated with the occurrence of less polar or hydrophobic groups, special salts, surfactants, or complementary protein assemblies. For instance, ionic and hydrophobic attractive interactions stabilize pearls (or rings)-on-a-string conformations, possibly a model for the formation of the chromatin assembly. The attractive interactions due to hydrophobic fatty acid groups attached to polysaccharides promote the formation of vesicles that entrap and slowly release water-soluble drugs. Intra- and intermolecular associations based on ion-pairing mixed interactions also control the formation of host-guest compounds, protein conformation, and the assembly of layered polyelectrolytes. Metallo-supramolecular polymers and networks are formed due to the coordination of multivalent cations with bi- and trifunctional organic ligands. The association of lithium salts to polymers in the absence of water allows the formation of highly efficient energy sources. It also allows the identification of the ionic species that control charge-independent contributions to Hofmeister effects. This critical review presents a synthetic classification of systems displaying ionic mixed interactions, and a discussion of underlying molecular mechanisms.

Conjugated Polycyanines: A New Class of Materials with Large Third‐Order Optical Nonlinearities

“…In this regard, the fully conjugated polycyanines presented here could provide new structural mechanisms to address these issues in addition to potentially extending delocalization pathways beyond one cyanine unit. There are several unique structural merits of this material design such as, good optical properties of polycyanines can be readily achieved for device applications, in addition, polycyanines can be used as a polyelectrolyte to organize extended ionic structures or modulate aggregations through various self‐assembly processes based on electrostatic interactions . Indeed, both PC1 and PC2 (Scheme ) do not show any asymmetric electronic transition peaks in the film absorption spectra relative to their monomeric cyanines C1 and C2 .…”

Ionic Liquid Crystals: Versatile Materials

“…Intra-and intermolecular associations based on ion-pairing control, for instance, the formation of host−guest systems, protein conformations, and the assembly of layered polyelectrolytes. 306 Ionically cross-linked supramolecular networks were developed as well. 307 Electrostatic interactions are isotropic forces, which means that they are not directional and predictable in the same manner as hydrogen bonds or metal−ligand bonds.…”

Inspection of Thermodynamic Behaviors in Binary Mixtures of a Double Chain Ionic Liquid Crystal with a Thermotropic Liquid Crystal

“…With a proper choice of self-assembled ionic components and practical ILCs with fascinating optical, electrical, magnetic, thermal, structural, or mechanical properties, functional ILCs might be designed. − The involvement of charges in ILCs has a strong impact on these compounds such as mesophase behavior, and strong noncovalent interactions are strict electrostatic (Columbic) interactions between ions . The intra- and intermolecular interaction of ILCs were formed based on ion-pair control, for example, the structure of host–guest systems, protein conformation, and assembly of layered polyelectrolytes . A supramolecular network made from ionically cross-linked segments was also evolved .…”

“…2 The intra-and intermolecular interaction of ILCs were formed based on ion-pair control, for example, the structure of host− guest systems, protein conformation, and assembly of layered polyelectrolytes. 28 A supramolecular network made from ionically cross-linked segments was also evolved. 29 Electrostatic interactions are isotropic forces, which means that they are not directional and predictable in the same manner as hydrogen bonds or metal−ligand bonds.…”