Green‐emitting poly[(1,3‐phenylenevinylene)‐alt‐ (1,4‐phenylenevinylene)]s: Effect of the substitution patterns on the optical properties

Green‐emitting substituted poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)]s ( 6 ) were synthesized via the Wittig–Horner reaction. The polymers were yellow resins with molecular weights of 10,600. The ultraviolet–visible (UV–vis) absorption of 6 (λ_max = 332 or 415 nm) was about 30 nm redshifted from that of poly[(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(1,4‐phenylenevinylene)] ( 2 ) but was only 5 nm redshifted with respect to that of poly[(1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)] ( 1 ). A comparison of the optical properties of 1 , 2 , and 6 showed that substitution on m‐ or p‐phenylene could slightly affect their energy gap and luminescence efficiency, thereby fine‐tuning the optical properties of the poly[(m‐phenylene vinylene)‐alt‐(p‐phenylene vinylene)] materials. The vibronic structures were assigned with the aid of low‐temperature UV–vis and fluorescence spectroscopy. Light‐emitting‐diode devices with 6 produced a green electroluminescence output (emission λ_max ～ 533 nm) with an external quantum efficiency of 0.32%. Substitution at m‐phenylene appeared to be effective in perturbing the charge‐injection process in LED devices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1820–1829, 2004     

Synthesis and luminescence of yellow/orange‐emitting poly[tris(2,5‐dihexyloxy‐1,4‐phenylenevinylene)‐ alt‐(1,3‐phenylenevinylene)]s

Soluble yellow/orange‐emitting poly[tris(2,5‐dihexyloxy‐1,4‐phenylenevinylene)‐alt‐(1,3‐phenylenevinylene)] derivatives ( 6 ) were synthesized and characterized. These polymers contained oligo(p‐phenylene vinylene) chromophores of equal conjugation length, which were jointed via a common m‐phenylene unit. An optical comparison of 6 and its model compound ( 8 ) at room temperature and low temperatures revealed the similarity in their absorption and fluorescence band structures. The vibronic band structure of 6 was assigned with the aid of the spectroscopic data for 8 at the low temperatures. 6 was electroluminescent and had an emission maximum wavelength at approximately 565 nm. With the device indium tin oxide/PEDOT/ 6 /Ca configuration, the polymer exhibited an external quantum efficiency as high as 0.25%. Simple substitution on m‐phenylene of 6 raised the electroluminescence output by a factor of about 10. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5853–5862, 2004     

Coordination of nickel and copper dithiolate to 2,2′‐bipyridine‐based π‐conjugated polymers

π‐Conjugated polymers (Poly1–Poly3) containing a 2,2′‐bipyridine (bpy) unit were subjected to coordination to nickel and copper dithiolate for the purpose of manipulating the photophysical properties. The absorption maximum peak of Poly1 [maximum wavelength (λ_max) = 446 nm] redshifted by 36 nm upon the coordination of bpy to NiCl₂, which produced Poly1–NiCl₂. A further bathochromic shift was observed in the spectrum of Poly1–mntNi [mntNi = (maleonitrile dithiolate)nickel; λ_max = 499 nm] bearing the dithiolate ligand, which stemmed from the extension of the conjugated system over the nickel dithiolate moiety through the bpy unit. An increase in the [Ni]/[bpy] ratio in Poly1–mntNi rendered the original maximum peak at 446 nm smaller and the lower energy charge‐transfer peak at 499 nm larger; the isosbestic points remained at 380 and 475 nm. The green fluorescence (λ_max = 504 nm) emitted from Poly1 markedly diminished upon the coordination of nickel dithiolate because of the effective energy transfer. The absorption maximum peak of Poly1–mntNi in chloroform at 499 nm blueshifted to 471 nm when the volume ratio of the chloroform/N,N‐dimethylformamide solvent reached 10:90. The coordination of nickel dithiolate to Poly2 and Poly3 also brought about redshifts of the absorption maximum peaks of as much as 55 and 61 nm, respectively. The absorption maximum peak of Poly1–(phenyldithiolate)nickel(pdtNi) (λ_max = 474 nm) redshifted by 28 nm in comparison with that of Poly1, whereas the magnitude of the shift of Poly1–bis(thiophenoxide)nickel(btpNi) bearing two thiophenoxide ligands was 20 nm. Poly1–mntCu with a tetrahedral copper center was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2631–2639, 2004     

Synthesis and surfactochromicity of 1,4‐diketopyrrolo[3,4‐c]pyrrole(DPP)‐based anionic conjugated polyelectrolytes

Two novel anionic conjugated copolyelectrolytes PSDPPPV and PSDPPPE were synthesized via Heck/Sonogashira coupling reactions and characterized by FT‐IR, ¹H NMR, UV‐vis, and PL spectroscopy. The two polymers are respectively constituted of 2,5‐diethoxy‐1,4‐phenyleneethynylene (DPV) and 2,5‐diethoxy‐1,4‐phenyleneethynylene (DPE) with 1,4‐diketo‐2,5‐bis(4‐sulfonylbutyl)‐3,6‐diphenylpyrrolo[3,4‐c]pyrrole (SDPP) which is a novel water soluble diketopyrrolopyrrole derivative. PSDPPPV and PSDPPPE show broad absorption band in visible region and they exhibit strong fluorescence quenching in aqueous solution. The fluorescence of their aqueous solutions can be enhanced in the presence of cationic surfactant or polymer nonionic surfactant. Fluorescence enhancement by introduction of polyvinylpyrrolidone (PVP) shows linear response. This result provides a controllable method to increase fluorescence intensity of dipyrrolopyrrole‐based conjugate polyelectrolytes in aqueous phase. The optical properties suggested that PSDPPPV and PSDPPPE which are negatively charged conjugated polymers can assemble with positively charged photovoltaic materials to form ionic photoactive layer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 739–751     

Poly[(2‐alkoxy‐5‐methyl‐1,3‐phenylene vinylene)‐alt‐(phenylene vinylene)] derivatives with different contents of cis‐ and trans‐olefins: The effect of the olefin bond geometry and conjugation length on luminescence

Poly[(2‐alkyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(1,3‐phenylenevinylene)]s ( 8 ) and poly[(2‐alkyloxy‐5‐methyl‐1,3‐phenylenevinylene)‐alt‐(1,4‐phenylenevinylene)]s ( 10 ) were synthesized by the Wittig reaction to provide materials containing 45–62% cis‐vinylene bonds. The optical characteristics of 8 and 10 were compared with those of their respective isomers, 3 and 4 , the cis‐vinylene contents of which were significantly lower (9–16%). Although a greater fraction of cis‐CH?CH linkages caused the absorption maximum (λ_max) of 8 and 10 to be slightly blueshifted (by ～3–6 nm) from that of 3 and 4 , the impact of the vinylene bond geometry appeared to be negligible on their fluorescence spectra. The fluorescence quantum efficiencies of 8 and 10 were estimated to be approximately 0.25 and 0.72, respectively. Both 8 (λ_max ≈ 445 or 462 nm) and 10 (λ_max ≈ 480 or 506 nm) were electroluminescent, showing effective color tuning by the controlled insertion of m‐phenylene moieties. The external electroluminescence quantum efficiencies were determined to be 4.26 × 10^?3% for 8 and 0.63% for 10 . The cis/trans‐vinylene bond ratio had a great impact on the electroluminescence device performance of 8 but a much smaller impact on the performance of 10 . © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 303–316, 2004     

Synthesis of conjugated polymers with azobenzene moieties in the main chain

Poly(phenylenevinylene)‐based conjugated polymers with azobenzene groups in the main chains were prepared by the Pd‐catalyzed coupling polymerization of divinylarenes with dihaloarenes. The Pd‐catalyzed coupling polymerization of 4,4′‐divinylazobenzene with dihaloarenes such as 1,3‐dibromobenzene, 1,4‐dibromo‐2,5‐dihexylbenzene, 4,4′‐dibromoazobenzene, and 4,4′‐diiodoazobenzene resulted in polymers with poor solubility. In contrast, soluble polymers containing azobenzene moieties in the main chains were attainable from divinylbenzenes with 4,4′‐dihaloazobenzenes if either or both of the monomers possessed hexyl groups on the aromatic rings. The number‐average molecular weight of the polymer exceeded 10,000 under optimized conditions, and the polymer showed a remarkably redshifted absorption in the visible region (456 nm). ¹H NMR and IR spectra supported that the polymers having only trans‐geometry for the double bonds. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1057–1063, 2000     

Synthesis and optical properties of novel blue‐light‐emitting poly(p‐phenylene vinylene) derivatives with pendant oxadiazole or cyano groups

Two novel poly(p‐phenylene vinylene) polymers, which carried side substituents with cyano groups or 1,3,4‐oxadiazole, were synthesized by Heck coupling. They consisted of alternating conjugated segments and nonconjugated aliphatic spacers. The polymers had moderate molecular weights, were amorphous, and dissolved readily in tetrahydrofuran and halogenated organic solvents. They were stable up to approximately 340 °C in N₂ and 290 °C in air, and the anaerobic char yield was around 60% at 800 °C. The polymer with cyano side groups emitted blue light in solutions and thin films with identical photoluminescence (PL) maximum at 450 nm; this supported the idea that chain interactions were hindered even in the solid state. The PL maximum of this polymer in thin films was blueshifted upon annealing at 120 °C, indicating a thermochromic effect as a result of conformational changes in the polymer backbone. The polymer containing side substituents with oxadiazole rings emitted blue light in solutions with a PL maximum at 474 nm and blue‐greenish light in thin films with a PL maximum at 511 nm. The PL quantum yields of the polymers in tetrahydrofuran were 0.13–0.24. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1768–1778, 2004     

Synthesis and properties of conjugated polymers containing 3,9‐ and 2,9‐linked carbazole units in the main chain

Novel conjugated polymers containing 3,9‐ or 2,9‐linked carbazole units in the main chain were synthesized by the polycondensation of ethynyl‐ and iodo‐substituted 9‐arylenecarbazolylene monomers, and their optical and electrical properties were studied. Polymers with weight‐average molecular weights of 3400–12,000 were obtained in 76–99% yields by the Sonogashira coupling polycondensation in piperidine or tetrahydrofuran (THF)/piperidine at 30 °C for 48 h. All the 3,9‐linked polymers absorbed light around 300 nm. The para‐phenylene‐linked polymer also absorbed light around 350 nm, while meta‐phenylene‐linked one did not. The 3,9‐linked polymers absorbed light at a wavelength longer than the 2,9‐linked one. The polymers emitted blue fluorescence with high quantum yields (0.21–0.78) upon excitation at the absorption maxima. The polymers were oxidized around 0.6 V, and reduced around 0.5 V. Poly( 1 ) showed the dark conductivity of 3.7 × 10^?11 S/cm (10³ V/cm). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3506–3517, 2009     

Alternating π‐conjugated block copolymers with precise block length

A Sonogashira polycondensation reaction has been used to synthesize copolymers consisting of alternating oligo(p‐phenyleneethynylene) with a precise block length as an electron‐rich component and 1,4‐bis(2‐phenylene‐2‐cyanovinylene)benzene or 2,6‐bis(2‐pyridinylene‐ethynylene)pyridine as an electron‐poor component. The copolymers differ in the length of the phenyleneethynylene block (trimer or pentamer) and the content of the electron‐poor component. The length of the phenyleneethynylene block has no influence on the maximum wavelength. The electron‐poor cyano‐block component lowers the optical band‐gap energy of the copolymers. The value is equivalent to that of poly(cyano‐phenylenevinylene) (CN‐PPV) (2.3–2.4 eV). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3574–3587, 2005     

Synthesis and double doping behavior of a poly(p‐phenylenevinylene)s bearing conjugated side chains

A poly(p‐phenylenevinylene) derivative bearing conjugated side chains (polyCPV) was synthesized by Migita‐Kosugi‐Stille type coupling polycondensation reaction. This polymer contains phenylenevinylene units in both the main chain and the side chains. UV–vis absorption and fluorescence emission spectroscopies revealed a well‐developed π‐conjugation of the polyCPV. The absorption band of the polymer was extended to long wavelengths. A fluorescent emission maximum of polyCPV is located at considerably longer wavelengths than that of the conjugated side chain monomer. Electron spin resonance measurements of polyCPV confirmed generation of charge species in both the main chain and the side chains via iodine doping. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and optical properties of light‐emitting π‐conjugated polymers containing biphenyl and dithienosilole

Copolymers containing oligo(phenylene vinylene) (2.5), fluorene, and 4,4‐dihexyldithienosilole (DTS) units were synthesized and characterized. The π‐conjugated monomers were joined with the palladium(0)‐catalyzed Suzuki–Miyaura coupling reaction, thus forming either biphenyl– or phenyl–thiophene linkages. These polymers were photoluminescent, with the fluorescent quantum efficiency between 54 and 63% and with λ_max for fluorescence at ～448 nm in tetrahydrofuran. The presence of 5% DTS in the copolymers had little influence on the optical absorption and emission wavelengths. Double‐layer light‐emitting‐diode devices using these polymers as emissive layers had low turn‐on voltages (3.5–4 V) and moderate external quantum efficiencies (0.14–0.30%). The results show that DTS plays a positive role in improving the charge‐injection characteristics of poly(phenylene vinylene) materials. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2048–2058     

Novel two‐dimensional donor–acceptor conjugated polymers containing quinoxaline units: Synthesis,characterization, and photovoltaic properties

Novel two‐dimensional donor–acceptor (D–A) structured conjugated polymers, P1–P4, were designed and synthesized by introducing electron‐deficient quinoxaline as core and electron‐rich alkoxyl‐phenylenevinylene in side chains and p‐phenylenevinylene, triphenylamine, or thiophene in main chain. Benefited from the D–A structures, the polymers possess low bandgaps of 1.75 eV, 1.86 eV, 1.59 eV, and 1.58 eV for P1, P2, P3, and P4, respectively, and show broad absorption band in the visible region: the shorter wavelength absorption peak at ～400 nm ascribed to the conjugated side chains and the longer wavelength absorption peak between 500 nm and 750 nm belonging to the absorption of the conjugated main chains. Especially, the absorption band of P4 film covers the whole visible range from 300 nm to 784 nm. The power conversion efficiencies of the polymer solar cells based on P1–P4 as donor and PCBM as acceptor are 0.029%, 0.14%, 0.46%, and 0.57%, respectively, under the illumination of AM 1.5, 100 mW/cm². The polymers with the low bandgap and broad absorption band are promising photovoltaic materials. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4038–4049, 2008     

Synthesis and characterization of fluorescent poly[fluorene‐co‐phenylene‐1‐(di‐2‐pyridylamine)] copolymer and its Ru(II) complex

2,2′‐dipyridylamine substituted poly(fluorene‐co‐phenylene) copolymers with different concentrations of dipyridylamine have been synthesized by Suzuki polycondensation. These polymers were found to be soluble in organic solvents such as tetrahydrofuran, chloroform, and dimethylformamide. The photoluminescence of the copolymer was slightly blueshifted as the concentration of dipridylamine was increased. The introduction of dipyridylamine and the ruthenium complex into the polymer significantly improved the photoluminescence efficiency. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4838–4846, 2004     

Poly(perylene‐alt‐phenyleneethynylene)s with multiple pendant ester groups in various lengths: Synthesis,photophysics and selective hydrolysis

Five fluorescence polymers with poly(perylene‐alt‐phenyleneethynylene)s (PPPEs) backbone and multiple side chains containing ester‐groups were synthesized via Sonogashira coupling reaction. These polymers were soluble in common organic solvents to form red‐orange solution. The polymer powders had dark red color. The absorption/emission spectra of these polymers were similar, with absorption bands between 300 and 600 nm and an emission peak between 520 and 700 nm. Furthermore, the ester groups of the side chains were partially or completely hydrolyzed, resulting in the fluorescence PPPEs with tunable density of carboxylic acid functional groups on the polymer chains as interaction/reaction sites for further applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1880–1886     

Facile synthesis of ortho‐Phenylene‐based conjugated polymers through transformation of cross‐conjugated poly(2,3‐diaryl[2]dendralene)s and their optical properties

We studied the facile synthesis of ortho‐phenylene‐based conjugated polymers through transformation of cross‐conjugated polymers having [2]dendralene moiety, poly(2,3‐diaryl[2]dendralene)s ( P1 s), and demonstrated the sequential synthesis of (Z)‐alkene‐ and ortho‐arylene‐containing conjugated polymers from P1 s. P1 s were transformed into cyclohexa‐1,4‐diene‐containing conjugated polymers ( P2 s) through a Diels–Alder reaction. Aromatization of the cyclohexa‐1,4‐diene skeleton was achieved by using 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone to give the ortho‐phenylene‐containing conjugated polymers ( P3 s). The ultraviolet–visible and fluorescence spectra of the cross‐conjugated polymers P1 s, and the conjugated polymers P2 s and P3 s indicated that the π–π interactions between the arylene moieties in P2 s were stronger than those in P1 s and P3 s. The synthetic method for P2 s and P3 s offers an effective synthesis of various types of (Z)‐alkene‐ and ortho‐arylene‐containing conjugated polymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 827–832     

Synthesis and characterization of novel π‐conjugated polymers with phosphole ring derivatives

Novel π‐conjugated polymers ( 8 – 10 ) were prepared by the palladium‐catalyzed Sonogashira coupling reaction of three kinds of phosphole‐ring‐containing monomers with 2,5‐dihexyloxyl‐1,4‐diethynylbenzene. The obtained polymers ( 8 – 10 ) were regioregulated with the 2,5‐substituted phosphole ring in the polymer main chain and characterized with ¹H, ¹³C, and ³¹P NMR and FTIR. Polymers 8 – 10 were found to have an extended π‐conjugated system according to the results of UV–vis absorption spectra. In the fluorescence emission spectra of 8 – 10 , moderate emission peaks were observed in the visible blue‐to‐green region. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2867–2875, 2007     

Synthesis and characterization of new sulfone‐derivatized phenylenevinylene‐based conjugated copolymers with evolving energy levels and gaps

A new series of stable, processable, and chain end functionalizable sulfone‐derivatized phenylenevinylene‐based conjugated polymers (SFPVs) containing different donor type comonomers have been synthesized and characterized. The polymer main chains are consisted of a sulfone‐phenylene electron accepting unit coupled with an electron donating unit which is derived from one of the dialdehyde comonomers based on benzene, thiophene, and pyrrole (with or without alkoxy side chains). The optical energy gaps (E_g) of the new polymers (in solvent) are in a range of 1.9–2.3 eV, with the lowest energy gap obtained from the polymer containing pyrrole as the donor unit. By using a combination of strong donor unit (such as pyrrole) and a relatively weak but stable acceptor unit (sulfone‐substituted benzene), E_g of the conjugated polymers can be tailored to below 2 eV, while the vinylene bonds on the polymer main chain are still chemically stable to survive strong basic conditions as compared with the S,S‐dioxo‐thiophene‐based PTV polymers developed earlier for potential supra‐molecular block copolymer systems. The lowest energy gap P(Pyrrole‐SFPV) exhibited 10 times better photoelectric power conversion efficiency than P(TV‐SFPV). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis,optical properties,and electroluminescence of conjugated poly(p‐phenylenevinylene) derivatives containing 1,3,4‐oxadiazole and pyridine rings in the main chain

Three new poly(p‐phenylenevinylene) derivatives—PO, POD, and POP—with oxadiazole and pyridine rings along the main chain were synthesized via Heck coupling. The polymers were amorphous and dissolved readily in common organic solvents. They showed relatively low glass‐transition temperatures (up to 42 °C) and satisfactory thermal stability. Solutions of the polymers emitted blue‐greenish light with photoluminescence (PL) emission maxima around 460 nm and PL quantum yields of 0.28–0.49. Thin films of the polymers displayed PL emission maxima at 461–521 nm, and their tendency to form aggregates was significantly influenced by the chemical structure. Light‐emitting diodes with polymers PO and POP, with an indium tin oxide/poly(ethylenedioxythiophene) (PEDOT)/polymer/Ca configuration, emitted yellow and green light, respectively, and this could be attributed to excimer emission. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3212–3223, 2004     

Synthesis of π‐conjugated oligomer that can form metallo polymers

An oligo(p‐phenylene vinylene) that contains terpyridine ligands has been synthesized. Upon addition of metal ions, a π‐conjugated metallo polymer is formed in which the well‐defined character of oligomers and the material properties of polymers are combined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4020–4023, 2002     

Photophysical properties of σ–π‐conjugated alternating oligothienylene–oligosilylene polymers

UV‐visible absorption and fluorescence properties of three series of σ–π‐conjugated polymers (copolymers of alternative oligothienylene and oligosilylene units) have been studied in dioxane solution. The energies of the absorption maximum, fluorescence maximum, and the 0–0 transition are found to be linearly dependent on the reciprocal of the number of thiophene rings in the repeating unit of the polymer chain, but almost independent of the silicon atom number. The σ–π‐conjugation in the polymers results in red shift in the absorption and fluorescence maxima, higher fluorescence quantum yields, and longer fluorescence lifetimes of the polymers, with respect to their corresponding analogous α‐oligothiophenes. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1873–1880, 1999