Metallosupramolecular Polyelectrolytes Self-Assembled from Various Pyridine Ring-Substituted Bisterpyridines and Metal Ions:  Photophysical, Electrochemical, and Electrochromic Properties

Abstract

This work presents several metallosupramolecular coordination polyelectrolytes (MEPEs) self-assembled from rigid, pi-conjugated, pyridine ring functionalized bisterpyridines and metal ions. The MEPEs are water-soluble and display different colors spanning the entire visible regions. Optical, electrochemical, and electrochromic properties of the obtained MEPEs are presented. The results show that the properties are profoundly affected by the nature of the substituents at the peripheral pyridine rings. Namely, MEPEs assembled from the electron-rich OMe group modified ligands exhibit high switching reversibility and stability and show a lower switching potential than the unsubstituted and electron-deficient Br-substituted analogues. The response times can be tuned either by the design of the ligands or by the choice of the metal ions to cover a broad time scale from under 1 s to several minutes. The optical memory is enhanced from 30 s to longer than 15 min as a comparison of unsubstituted and substituted MEPEs shows. Thus, the significantly enhanced stability and the ease of tuning the properties render this type of supramolecular assembly attractive as electrochromic materials for applications in a large variety of areas. Most importantly, we presented the structure-property relationships of MEPEs, which lays the groundwork for further design of new bisterpyridine-based metallosupramolecular functional materials.

Fluorescent Fe(II) metallo-supramolecular polymers: metal-ion-directed self-assembly of new bisterpyridines containing triethylene glycol chains

“…We have designed and synthesized a new TPY ligand (L1) containing a TEG chain at the ortho-position of the peripheral pyridine ring of 6-bromo-4¢-(4-bromo-phenyl)-[2,2¢;6¢,2¢¢] terpyridine (1) 14 in good chemical yield by means of chemoselective nucleophilic substitution (Scheme 1). 15 Only one peripheral pyridine ring of TPY was substituted to prevent steric crowding in the coordination sphere.…”

“…These results are in good agreement with previously reported results. 14 In addition, the introduction of substituted TEG chain into BTPY ligands does not have a significant effect on the band gap of their corresponding MEPEs.…”

“…After 2 min, the hexane was removed and dried under vacuum, followed by the addition of dry tetrahydrofuran (30 ml). A solution of TEG monomethyl ether (3) (0.30 g, 1.82 mmol) in dry tetrahydrofuran (10 ml) was added and the solution was refluxed for 1 h. The solution of 6-bromo-4¢-(4-bromo-phenyl)-[2,2¢;6¢,2¢¢] terpyridine (1) 14 (0.75 g, 1.62 mmol) in dry tetrahydrofuran (100 ml) was added slowly. The reaction mixture was refluxed and the course of the reaction was monitored by thin-layer chromatography.…”

Anion Effects to Electrochromic Properties of Ru-based Metallo-supramolecular Polymers

“…[1][2][3] As a new type of EC materials, we have investigated metallo-supramolecular polymers, which are synthesized by the 1:1 complexation of metal ions (Fe, Cu, Ru et al ) and ditopic ligands such as bis(terpyridine)s and bis(phenanthroline)s. [4][5][6][7][8][9][10][11] The polymers have a specific color based on the metal-to-ligand charge transfer (MLCT) absorption. We have revealed that the appearance/disappearance of the MLCT absorption can be reversibly controlled by the electrochemical redox of the metal ions in the polymer.…”

Synthesis of Metallo-Supramolecular Polymers with Bis-NNN-Tridentate Ligand for Electrochromic Devices

“…We synthesized metallo-supramolecular polymers including various metal ions such as Fe(II), Ru(II), Co(II), Cu(I), Ni(II) and Eu(III) by the complexation with bis(terpyridine)s, tris(terpyridine) or bis(phenanthroline)s [6][7][8][9][10][11][12][13][14][15][16][17][18]. The obtained polymers shows electrochromism [6][7][8][9][10][11], non-volatile memory [12], ion conductivity [13,14], vapoluminescence [15], electrochemical switching of emission [16] and DNA binding and cytotoxicity to cancer cells [17,18]. In addition to the unique properties, another advantage of the polymers is the uniform film formation property by spin-or spray-coating, because the solid-state polymers are amorphous unlike small metal complexes.…”