On the structure, crystallinity, and paramagnetism of polyphenylacetylene

Ehrlich, P.; Kern, R. J.; Pierron, E. D.; Provder, Theodore

doi:10.1002/pol.1967.110051004

Cited by 39 publications

(16 citation statements)

References 13 publications

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“…As a matter of fact, the cis-trans isomerization of acetylenic polymers is just the order-disorder transition pointed out in crystalline PPA by Ehrlich et al [19][20][21][22] Similar cis-trans transitions have been reported for poly-cr-ethynylnaphthalene,36 poly-P-ethynylnaphthalene,ll poly-N-ethynyl~arbazole,~~ and poly-3-ethyny1phenanthrene.I The paramagnetic centers of cis structures of these polymers behave as shown by Ehrlich in the case of crystalline PPA, i.e., they exhibit a maximum at the temperature of cis-trans is~rnerization.~~…”

Section: Thermal Isomerization Of Structures a And Bmentioning

confidence: 60%

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Polymerization of acetylenic derivatives. XXX. Isomers of polyphenylacetylene

Simionescu¹,

Percéc²,

Dumitrescu³

1977

J. Polym. Sci. Polym. Chem. Ed.

391

288

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SynopsisCis-transoidal (orange, soluble, and of low crystallinity) and cis-cisoidal (red, insoluble, and highly crystalline) polyphenylacetylenes (PPA) were prepared by Ziegler-Natta catalysts and trans-cisoidal (yellow, soluble, and amorphous) polyphenylacetylenes were prepared by using phosphine complexes, T i c 4 and by thermal initiation. The cis-transoidal and cis-cisoidal structures isomerize thermally in the solid state above 100°C. In solution the cis-transoidal structure isomerizes above 80°C. The polymers obtained by thermal isomerization are soluble, amorphous, and have a trans-cisoidal structure. At temperatures higher than 120°C the cis-trans isomerization is accompanied by cyclization and by scission of the polymer chain. A method was developed for determination of cis content of cis-transoidal and cis-cisoidal polyphenylacetylenes.

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Section: Thermal Isomerization Of Structures a And Bmentioning

confidence: 60%

“…Ehrlich et al [19][20][21][22] pointed out that the insoluble crystalline PPA synthesized by Kern14 is characterized by an order-disorder transition at about 120OC. The structure of the polymer and the nature of this order-disorder transition was not elucidated.…”

Section: Introductionmentioning

confidence: 99%

Polymerization of acetylenic derivatives. XXX. Isomers of polyphenylacetylene

Simionescu¹,

Percéc²,

Dumitrescu³

1977

J. Polym. Sci. Polym. Chem. Ed.

391

288

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“…From the point of view of magnetic behavior, the discontinuous character of the polyenic chains' conjugation generates structural defects whose unpaired ir bonds can explain the appearance of paramagnetic signals (13)(14)(15)(16)(17)(18)(19).…”

Section: Resultsmentioning

confidence: 99%

On the Polymerization of Acetylenic Derivatives. XXIV. Some Structural Peculiarities of Poly(α-ethynylnaphthalene)

Simionescu

Dumitrescu

Percéc

1976

Polym J

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ABSTRACT:The present paper deals with the study of conjugated chains of a trans-cisoidal poly(a-ethynylnaphthalene), (a-EN), obtained by bulk polymerization of a-EN with (PPha)2· NiBr2. Based on the results obtained from electronic spectra and electrical conductivity measurements, using the fractions with molecular weight between 3732 and 528, a polymer structure built up from interrupted conjugated blocks is proposed. It is assumed that this interruption of the electronic conjugation system has structural reasons i.e., it is given by the rotation of parts of the polymer chain around some C-C single bonds, thus hindering the complete overlapping of certain rr orbitals. These conjugated blocks have 3-4 conjugated or partial conjugated monomeric units. This structure could explain the low values of electrical conductivity as well as the paramagnetic centers of polyacetylenes with aromatic substituents.KEY WORDS a-Ethynylnaphthalene / Trans-Cisoidal / Conjugated Block / Electrical Conductivity / Electronic Spectra / Paramagnetic Center / Partial Conjugation / Taking into account the effective interaction energy (for Little's four-carbon unit) calculated 1 for ethynylnaphthalene (-2.1 eV), and using a value included among the energy values required by Little for a macromolecular superconductor; we proposed to study the structures and properties of poly(a-ethynylnaphthalene) 3 " 4 and poly (,8-ethynylnaphthalene). 5 First of all, the question arises if it is possible for a head-to-head (or tail-to-tail) structure for poly(ethynylnaphthalene) to obey the structure conditions required by Little's theory. The reduced probability to get such a structure by the polymerization of aromatic acetylenes 6 does not justify the unsatisfactory electrical properties of the polymers, since the value of the effective interaction energy, calculated for the two-carbon unit, is 0.252 e V. 1 This value is also included within the limits required by Little's theory for an organic superconductor.However, the electrical properties of the semiconducting3·4 and superconducting polymers 7 • 8 synthesized did not fulfill our hopes. EXPERIMENTAL Materialsa-Ethynylnaphthalene (a-EN), was synthesised by Leroy's method 9 from a-acetylnaphthalene (a-AN) by chlorination and subsequent dehydrochlorination. Characteristic of the IR spectrum of a-EN are the 2190 cm-1 (llcaac) and 3380 cm-1 (liaac-H) bands (Figure 1). The NMR spectrum of a-EN exhibits at 3.35 ppm the resonance of ethynylic proton and at 7. 05-7.80 and 8.15-8.40 ppm the peaks of aromatic protons (Figure 2). NiBr2· (PPh3)2 was synthesized by Venanzi's method. 10 Poly(a-ethynylnaphthalene) was obtained by bulk polymerization of a-EN with 5-% NiBr2-(PPh3)s at 140°C and was purified by reprecipitation four times from benzene by the addition of methanol. 4 The IR spectrum of poly(a-ethynylnaphthalene) synthesized by this method is characteristic of a trans-configuration (Figure 1). The IR spectrum of a cisconfiguration presents the cis C-H out-of-plane deformation at 700 cm-1 • 4 According ...

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“…AUerdings steigt fur die 3 Fraktionen des Polymeren I (Fraktion 1; Fraktion 2 ; DMF unloslicher Anteil) mit zunehmendem Molekulargewicht -geschlossen aus dem Loslichkeitsverhalten -die elektrische Leitfahigkeit an. Eine Erklarung fur die niedrigere elektrische Leitfahigkeit des Polymeren I gegenuber dem Oligomeren VI ist offenbar im Festkorperbau zu suchen (siehe dazu auch[17][18][19][20][21][22][23][24]). Wahrend die Oligomeren in kristalliner Form vorliegen, besitzen die Proben des Polymeren I neben geordneten Bereichen (mit Kristalliten der GroSe von etwa 70 A bei der in Dimethylformamid unloslichen Fraktion) auch amorphe Anteile.…”

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Über polyenarylene und polyenheteroarylene. 1. Mitt.: Poly‐[thienylen‐(2.5)‐äthenamer] und einige seiner oligomeren. Synthesen, spektrales verhalten und elektrische leitfähigkeit

1970

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ZUSAMMENFASSUNG:Bei der WITTIG-Reaktion von 2.5-Bis-(triphenylphosphoniomethyl)-thiophen-dichlorid mit Thiophen-2.5-dialdehyd wurde Poly-[thienylen-(2.5)-athenamer] mit endstandigen Aldehydgruppen erhalten. Durch Reaktion mit 2-(Tripheny1phosphoniomethyl)-thiophenchlorid laBt sich ein Teil der Aldehydgruppen in Thieny1-(2)-vinyLGruppen iiberfuhren.Zum Vergleich wurden -ebenfalls rnit Hilfe der WITTIG-Reaktion -Oligomere der allge- (2)-; -R-= Thienylen-(2.5)-] mit n = 1, 2, 3,4, 6 hergestellt. Die Struktur der untersuchten Verbindungen wurde durch UV-Spektren, sichtbare Spektren, IR-Spektren und Massenspektren bestatigt. Zur weiteren Charakterisierung wurden Rontgenuntersuchungen herangezogen. Die Oligomeren sowie das Polymere wurden auf ihre elektrische Leitfahigkeit hin untersucht. SUMMARY:Poly[thienylene-(2.5)-ethenamer] was prepared from 2.5-bis(triphenylphosphoniomethy1)thiophene dichloride and thiophene-(2.5)-dicarbaldehyde via the WITTIG reaction. This polymer has terminal aldehyde groups, which can be reacted partly with 2-(triphenylphosphoniomethy1)thiophene chloride to give terminal thienyl-(2)-vinyl groups. For comparison, there were synthesized via the WITTIG reaction oligomers of the general formula R-(-CH=CH-R-)D-H [-R = thienyl-(2)-; -R-= thienylene-(2.5)-] with n = 1, 2. 3, 4, 6. The structure of the oligomers and the polymer was confirmed by their UV,

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On the structure, crystallinity, and paramagnetism of polyphenylacetylene

Cited by 39 publications

References 13 publications

Polymerization of acetylenic derivatives. XXX. Isomers of polyphenylacetylene

Polymerization of acetylenic derivatives. XXX. Isomers of polyphenylacetylene

On the Polymerization of Acetylenic Derivatives. XXIV. Some Structural Peculiarities of Poly(α-ethynylnaphthalene)

Über polyenarylene und polyenheteroarylene. 1. Mitt.: Poly‐[thienylen‐(2.5)‐äthenamer] und einige seiner oligomeren. Synthesen, spektrales verhalten und elektrische leitfähigkeit

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