Disubstituted Polyacetylenes Containing Photopolymerizable Vinyl Groups and Polar Ester Functionality:  Polymer Synthesis, Aggregation-Enhanced Emission, and Fluorescent Pattern Formation

Abstract

Diphenylacetylene monomers functionalized with vinyl and ester groups (1 and 2) were synthesized. The monomers were polymerized by WCl 6 -Ph 4 Sn into their corresponding polymers (P1 and P2) with the (meth)-acrylic functionality remained intact, as verified by the structural analysis of the polymers using spectroscopic methods. The polymers are soluble in common organic solvents and form films of good quality when their solutions are spin-coated. The solutions of the polymers emit green light upon photoexcitation. Their emission spectra shift to longer wavelengths and narrow in widths when the solution concentrations are increased, presumably due to the formation of the intramolecular excimers. When the polymer chains are aggregated, their emission efficiencies are increased (Φ F up to ∼88%), showing a unique phenomenon of aggregation-enhanced emission. The (meth)acrylic groups bestow photosensitivity on the polymers, whose photo-cross-linking enables ready fabrication of highly fluorescent photoresist patterns.

Synthesis and Functionality of Substituted Polyacetylenes

“…Therefore, it is expected that 66 and 67 shown in Chart 1.9 might show an aggregation-induced emission enhancement (AIEE) effect, since the polymers themselves are already emissive in solution. As anticipated, 66 and 67 are AIEE active, in which the emission intensities are progressively increased with the increasing water fraction in the THF/water mixture (Figure 1.7) [54,55]. Spectral profile of 66 remains unchanged [54], while the emission spectrum of 67 gradually redshifts [55].…”

“…According to the ''n = 3 rule'' shown in Chart 1.10, molecules with phenyl rings spatially separated by three carbon atoms (e.g., 1,3-diphenylpropane and PS) [56,57] can form intramolecular excimers that emit in the redder spectral regions, in comparison to their ''monomer'' emissions [54,55]. Both the poly(diphenylacetylene) and poly(1-phenyl-1-alkyne) derivatives follow this ''n = 3 rule.''…”

Synthesis of Optically Active Poly(diphenylacetylene)s Using Polymer Reactions and an Evaluation of Their Chiral Recognition Abilities as Chiral Stationary Phases for HPLC

“…The direct polymerization of diphenylacetylene monomers bearing polar functional groups, such as carboxyl and amide groups, hardly proceeds because the group 5 transition metals used for polymerization of disubstituted acetylenes are intolerant to such polar functional groups [37,38]. With this in mind, the carboxyl groups of the diphenylacetylene monomer (1) were protected as the corresponding n-heptyl esters prior to being polymerized in toluene with WCl 6 -Ph 4 Sn at 100 • C. Notably, these conditions have been reported to be effective for the polymerization of diphenylacetylenes bearing ester groups [32,39]. It was also envisaged that the long alkyl (n-heptyl) chains of the ester groups would enhance the solubility of the resulting polymer in toluene.…”

“…Molecules 2016, 21, 1487 3 of 14 bearing ester groups [32,39]. It was also envisaged that the long alkyl (n-heptyl) chains of the ester groups would enhance the solubility of the resulting polymer in toluene.…”

Chiral Recognition Ability of an Optically Active Poly(diphenylacetylene) as a Chiral Stationary Phase for HPLC

“…11,19 The molecular weight (M n ) of poly-1 was estimated to be 1.2 © 10 4 (M w /M n = 1.6) as determined by size exclusion chromatography (SEC) with polystyrene standards using tetrahydrofuran (THF) as the eluent. The polymer was converted to poly-2 by alkaline hydrolysis of the ester groups.…”