Synthesis and Characterization of New Self-Assembled Metallo-Polymers Containing Electron-Withdrawing and Electron-Donating Bis(terpyridine) Zinc(II) Moieties

Abstract

A series of rigid π-conjugated bis(terpyridines) (M1−M7) bearing electron-acceptor spacer units in 4′-position was synthesized in moderate to high yields by Pd0-catalyzed Sonogashira cross-coupling reactions. The compounds were fully characterized by NMR spectroscopy, MALDI−TOF mass spectrometry, elemental analysis and their photophysical properties were discussed in detail. These new bis(terpyridines) were applied for the self-assembly reaction with ZnII ions to form metallo-homo polymers (P1−P7). Broadened NMR signals and UV−vis titration experiments confirmed the successful polymerization. The electro-optical properties of the materials were investigated in detail. Band gaps up to 2.08 eV and bright blue to orange photoluminescence with quantum yields of 18 to 66% were observed strongly depending on the nature of the π-conjugated bis(terpyridine) system. In combination with electron-donor ditopic terpyridine ligands (MD1 and MD2), two ZnII random copolymers (R1 and R2) were synthesized. These materials were investigated by UV−vis absorption and photoluminescence experiments in dilute solution and in the solid state, prepared by spin-coating from DMF solutions. Thereby, random copolymer R2 featured an energy transfer from the donor to the acceptor part in dilute solution.

π‐Conjugated Donor and Donor–Acceptor Metallo‐Polymers

“…Compounds 1 and 2 were prepared following previously published protocols. [30,31] Details on the synthesis of the polymers, the instrumentation and device preparation are given in the Supporting Information.…”

“…This energy band gap was strongly influenced by the nature of the p-conjugated spacer unit. [21,31] Considering this, the photophysical properties of such Zn II containing metallo-polymers can be tuned via the electro-optical properties of the chromophore. The ruthenium(II) polymers showed, beside two reversible reduction peaks around À1.38 and À1.60 eV, one oxidation wave at 0.89 eV, corresponding to the Ru II /Ru III couple and, thus, representing the HOMO of the polymer.…”

Spectral characterizations and photophysical properties of one-step synthesized blue fluorescent 4′-aryl substituted 2,2′:6′,2′′-terpyridine for OLEDs application

“…Nevertheless, there are a few reports of the application of terpyridine and its derivatives as efficient and stable organic fluorescent blue emitters [30,31]. Hence, it is very necessary to study and understand thermal stability, photophysical properties and electro activity of the aryl substituted terpyridine material to fabricate the efficient blue fluorescent OLEDs.…”

Synthesis and properties of Zn2+/Cd2+-directed self-assembled metallo-supramolecular polymers based on 1,4-diketo-pyrrolo[3,4-c]pyrrole (DPP) derivatives

“…[25][26][27] Among the best studied complexes, Ru(II)(bpy) 3 (bpy ¼ 2,2 0 -bipyridine) is the most popular. [36][37][38][39][40][41][42][43] Würthner reported zinc(II)-directed polymerization of highly uorescent perylene bisimide dye connected to bis(terpyridyl) and their optical properties. [31][32][33][34][35] Many supramolecular polymers containing terpyridine-based complexes were reported presently.…”

“…[36][37][38][39][40][41][42][43] Würthner reported zinc(II)-directed polymerization of highly uorescent perylene bisimide dye connected to bis(terpyridyl) and their optical properties. 42 We reported a series of supramolecular polymers prepared via cadmium(II) ion directed self-assembled polymerization of bis(2,2 0 :6 0 ,2 00 -terpyridine)-based ligand monomers where oligouorenes was introduced as spacers and electronrich triphenylamine was introduced into the backbone of the supramolecular polymers in order to further tune the emission color. 41 Schubert introduced electron-rich units and electron-withdraw units into bis(terpyridine) building block as the spacers to form metallo-supramolecular polymers.…”