Poly(pyridinium salt)s with organic counterions derived from an aromatic diamine containing tetraoxyethylene units exhibiting amphotropic liquid‐crystalline and photoluminescence properties

Abstract

Several poly(pyridinium salt)s containing various organic counterions and tetraoxyethylene units in their backbones were synthesized by either ring-transmutation polymerization reaction of 4,4'-(1,4-phenylene)-bis(2,6-diphenylpyrylium tosylate) with bis(2-(2-(4-aminophenoxy)ethoxy)ethyl) ether on heating in dimethyl sulfoxide or metathesis reaction of the tosylate polymer with the corresponding lithium or sodium salts in acetonitrile. Their chemical structures were determined by 1 H-NMR and 13 C-NMR spectroscopy, and elemental analyses. Their number-average molecular weights and polydispersity indices were in the range of 34,000-52,000 and 1.14-1.38, respectively, as determined by gel permeation chromatography. They were characterized both for their thermotropic and lyotropic liquid-crystalline properties by using differential scanning calorimetry and polarizing optical microscopy. As these polymers exhibited liquid-crystalline phase both in the melt and in solutions, they are classified as an amphotropic class of ionic polymers. Their light-emitting properties in a large number of organic solvents that ranged from nonpolar to polar solvents and in films cast from methanol and acetonitrile were also studied by using spectrofluorometry.

Thermotropic Liquid-Crystalline and Light-Emitting Properties of Poly(pyridinium) Salts Containing Various Diamine Connectors and Hydrophilic Macrocounterions

“…Their number-average molecular weight ( M n ) values were 27,571, 41,000 and 41,263 g/mol and PDI values were 1.49, 1.40 and 1.14, respectively. Given the nature of polymerization, their PDI values are rather narrow that are consistent with the results of other poly(pyridinium salt)s [27,28,29,30,31,32,33,34,35,36,37,38,39,40]. It is quite reasonable to assume that all of polymers II-1 – II-5 have respectable molecular weights to assess their solution, thermal, optical and properties without concern with regard to the effect of molecular weights on these properties.…”

“…The synthetic route for the preparation of water-soluble poly(pyridinium salt)s II-1 – II-5 , from the tosylated precursors I-1 – I-5 , is depicted in Scheme 1. As reported elsewhere [27,32,35], precursory polymers I-1 – I-5 were synthesized through a ring-transmutation polymerization reaction with the bis(pyrylium) salt, M , and various diamines, H 2 N- R -NH 2 , in DMSO. Water generated during the reaction was removed by azeotropic distillation to enhance the polymerization reaction.…”

“…The monomer 4,4′-(1,4-phenylene)bis(2,6-diphenylpyrylium)ditosylate, M , was synthesized according to the reported procedure [27]. Bis(2-(2-(4-aminophenoxy)ethoxy)ethyl) ether was synthesized according to the reported procedures [35,44]. Common organic solvents were purchased from commercial vendors (Sigma Aldrich (Milwaukee, MI, USA), Alfa Aesar (Ward Hill, MA, USA), Acros Organics (Morris, NJ, USA), and TCI America (Portland, OR, USA) and used without further purification.…”

“…Among the numerous examples of ionic polymers found in literature, a class of particularly promising main-chain cationic polymers are the poly(pyridinium) salts. In particular, the synthesis of poly(pyridinium) salts with two N -aryl pyridinium salts separated by 1,4-phenylene connectors has been recently developed and studied by Harris et al [25,26] and Bhowmik et al [27,28,29,30,31,32,33,34,35,36,37,38,39,40], respectively. Their preparation involves the ring-transmutation reaction of bispyrylium salts with aromatic, heterocyclic or aliphatic diamines in dimethyl sulfoxide (DMSO) at elevated temperatures.…”

Synthesis of new 3,3′‐(1,4‐phenylene)bis(1,5‐diones) derivatives

“…3,3′‐(1,4‐Phenylene)bis(1,5‐diones) as versatile synthetic intermediates are important in the synthesis of photoluminescence [1–3], biosensors [4], and photochromism materials [5–8]. Li and Tian [9] synthesized hexatriene compounds provided by the 1,2‐dithienylethene structure, which showed significant photochromic property.…”