Copolymerization of N -(prop-1-yne-3-yl)-4-(piperidine-1-yl)-1,8-naphthalimide with Arylacetylenes into Fluorescent Polyacetylene-Type Conjugated Polymers

Abstract

N -(prop-1-yne-3-yl)-4-(piperidine-1-yl)-1,8-naphthalimide (PNPr), i.e., the monomer with a terminal ethynyl group and 1,8-naphthalimide fl uorophore, has been successfully copolymerized with a series of monoethynylarenes into well-soluble high-molecular-weight ( M w up to 210 000) linear polyacetylene-type copolymers containing from 14 to 51 mol% units derived from PNPr. The copolymerization of PNPr with bifunctional 4,4′-diethynylbiphenyl provides polyacetylene-type micro/mesoporous fl uorescent network containing 8 mol% PNPr units and exhibiting the Brunauer-Emmett-Teller surface of ≈1000 m 2 g −1 . The copolymerizations (catalyzed with acetylacetonato(norborna-2,5-diene)rhodium complex, [Rh(nbd)acac]) proceed smoothly despite the fact that the homopolymerization of PNPr fails. The fl uorescence of PNPr (emission at ≈ 510 nm) has been retained after the incorporation of PNPr into the copolymers. The fl uorescence of the copolymers can be induced by a direct excitation of PNPr units or via an energy transfer mechanism. In the latter case, the comonomeric units with aromatic hydrocarbon fl uorophores (e.g., of the biphenyl-type) emitting at 380-400 nm (after irradiation with 300 nm UV radiation) serve as energy donors for fl uorescent PNPr acceptors. The difference between the wavelengths of the primary absorbed radiation and the fi nally emitted radiation is 210 nm.

Unexpectedly Facile Rh(I) Catalyzed Polymerization of Ethynylbenzaldehyde Type Monomers: Synthesis of Polyacetylenes Bearing Reactive and Easy Transformable Pendant Carbaldehyde Groups

“…Evidently, the polymerizations of I to IV proceeded via transformation of the terminal ethynyl groups of the monomers into poly acetylene chains while the carbaldehyde groups remained preserved as the substituents on phenyl rings of the polymers (Scheme 1). The dominant signals in the region from 115 to 150 ppm in 13 C CP/MAS NMR spectra of polymers can be thus ascribed to sp 2 carbons of aromatic rings and polyacetylene main chains. 13 C CP/MAS NMR spectrum of poly(IV), moreover, contained a signal at 90 ppm, ascribable to carbons of internal ethynyl groups: evidently only terminal and not internal ethynyl group was transformed in the polymerization of IV in accord with a common feature of Rh-catalyzed polymerization of monomers comprising both terminal and internal ethynyl groups in one mole cule.…”

“…The dominant signals in the region from 115 to 150 ppm in 13 C CP/MAS NMR spectra of polymers can be thus ascribed to sp 2 carbons of aromatic rings and polyacetylene main chains. 13 C CP/MAS NMR spectrum of poly(IV), moreover, contained a signal at 90 ppm, ascribable to carbons of internal ethynyl groups: evidently only terminal and not internal ethynyl group was transformed in the polymerization of IV in accord with a common feature of Rh-catalyzed polymerization of monomers comprising both terminal and internal ethynyl groups in one mole cule. [30,31] Figure 1 (4 of 7) 1600792 polymers prepared with Rh-catalysts, [32,33] most probably, also the insoluble poly(II), poly(III), and poly(IV) were endowed with a similarly high microstructure uniformity.…”

“…For the polymerization of arylacetylenes (2 of 7) 1600792 with terminal ethynyl groups, the Rh(I) complexes (operating in insertion mode) have been predominantly used because they were found very effective, highly tolerant to the many heteroatoms in functional groups, and leading to polymers with high stereoregularity. [7,8] Pendant functional groups of polyacetylenes may serve as a tool for introducing or tuning the properties of these polymers, e.g., the conductivity, [9] photoconductivity, [10] specific interaction with molecules or ions, [11,12] luminescence, [13] helical conformation, [14] and side-chain liquid crystalline character. [15] Reactive pendant functional groups of polyacetylenes can be moreover chemically modified using various postpolymerization reactions under formation of linear [16,17] or cross-linked [18,19] polymers of modified qualities.…”

“…Pendant functional groups of polyacetylenes may serve as a tool for introducing or tuning the properties of these polymers, e.g., the conductivity, photoconductivity, specific interaction with molecules or ions, luminescence, helical conformation, and side‐chain liquid crystalline character . Reactive pendant functional groups of polyacetylenes can be moreover chemically modified using various postpolymerization reactions under formation of linear or cross‐linked polymers of modified qualities.…”

“…A)13 C CP/MAS NMR spectra of parent poly[(ethynylarene)carbaldehyde]s fromTable 1: poly(I), poly(II), poly(III), and poly(IV), and B) 1 H NMR spectra in CD 2 Cl 2 of parent poly(I) and polyacetylenes modified with p-toluidine: poly(I)T, poly(II)T, and poly(III)T.(6 of 7) 1600792Macromol. Rapid Commun.…”