1,1'-[1,4-Phenylenebis(methylene)]bis(4,4'-bipyridinium) Bis(hexafluorophosphate)

The compound "1,1'-[1,4-Phenylenebis(methylene)]bis(4,4'-bipyridinium) Bis(hexafluorophosphate)" represents a class of molecules known as viologens, which are characterized by their bipyridinium units. Viologens have garnered significant attention due to their unique electrochemical properties, which make them suitable for a variety of applications, including electrochromic devices, molecular binding, and supramolecular chemistry. The papers provided offer insights into the synthesis, characterization, and applications of viologen derivatives in different fields.

The first paper discusses a novel phenylene viologen functionalized bis(terpyridine) molecule, synthesized through a Zincke reaction, which exhibits strong absorption and fluorescence across a wide UV and visible wavelength range1. This molecule, when complexed with metal ions such as Fe and Ru, can self-assemble into metallo-supramolecular polymers. These polymers display electrochromic properties, changing color in response to redox reactions during cyclic voltammetry scanning. The π-conjugation among the bis(terpyridine)s and the phenylene viologen subunits allows for electronic and chemical connectivity, which is crucial for their electrochromic behavior1.

The second paper explores the molecular binding behaviors of a water-soluble crown ether with bispyridinium-based guests, including methyl viologen (MV(2+))2. The study uses techniques such as (1)H NMR spectroscopy, crystallography, and microcalorimetry to investigate the complexation behavior in aqueous solutions and the solid state. The results show that the binding process is structure-dependent, with MV(2+) threading through the cavity of the crown ether, leading to a significant enthalpy change, while another guest molecule associates with the sulfonate groups of the crown ether, driven by an entropy change2.

The electrochromic properties of the phenylene viologen functionalized bis(terpyridine) make it suitable for applications in electrochromic devices. The ability to reversibly change color by applying voltage has been demonstrated in a simple liquid electrochromic device, suggesting potential use in smart windows, displays, and other color-switching technologies1.

In the field of supramolecular chemistry, the molecular binding study of the crown ether with bispyridinium guests highlights the potential for designing selective host-guest systems. Such systems could be used for sensing applications, where the structure-dependent binding process could allow for the detection of specific molecules based on their charge distribution and size2.