Copolymers of phenylacetylene and para‐nitrophenylacetylene with nonlinear optical properties: Further insight on the conformational structure

Abstract

Copolymers of phenylacetylene (PA) and para‐nitrophenylacetylene (pNPA), named poly(PA‐co‐pNPA), were obtained in different PA/pNPA ratios and different reaction conditions with Rh(I) catalysts. The structure of the copolymers was investigated with IR, laser Raman, 1H NMR, electron spin resonance (ESR), and diffuse reflective ultraviolet–visible (DRUV) light spectroscopies. The pristine polymers had a cis–transoidal structure as the predominant conformation with some trans sequences. Detailed ESR studies supported by computer simulation and conformation analysis have suggested that the trans sequences were due to pNPA sequences and that the cis‐CC bond sequences of pNPA were associated with a stabilized cis radical formed by four to five of pNPA monomers. This particular stabilization was probably the reason for the higher reactivity of pNPA as compared with PA. These cis sequences were preferentially cleaved to generate π radicals. The compression and, to a minor extent, thermal treatment of poly(PA‐co‐pNPA) samples induced a cis‐to‐trans isomerization, leading to a trans–transoidal form with a planar zigzag structure and with a conjugation length up to n = 24 repeat units, determined by DRUV and Raman experiments. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2365–2376, 2004

Self-assembled nanoparticles of functional copolymers for photonic applications

“…One of the advantages of using functional monomers, such as PA, can be envisaged in the formation of conjugated fragments in the polymeric backbone, which impart bioactivity [23], nonlinear optics [24] and sensor [25,26] properties to the resulting materials, thus opening new advanced perspectives in photonics and sensing applications. However, although the emulsion polymerization allows to control the particle size by means of different reaction environmental parameters, the size distribution of these particles, is quite broad [17,18].…”

Poly[(para‐halogenated)phenylacetylene]s Prepared with a [Rh(norbornadiene)Cl]2 Catalyst: Syntheses and Structure Elucidation

“…The insolubility of PpClPA and PpIPA may be due to strong aggregation between the polymer chains having such polar groups as is also the case of poly[(pnitrophenyl)acetylene]. [25,26,34] We deduce that the insolubility is not caused by formation of a pseudohexagonal crystalline structure called a columnar of the resulting Scheme 1. Syntheses of PpXPAs and its isomerization.…”

“…On the other hand, such aggregation force is not so strong in the cases of PpBrPA and PpFPA so that these polymers are soluble in organic solvents, though it should be noted that in general the usual fluorinated organic compound has high solubility. Previously we have reported [25] that the PpNO 2 PA polymer is completely insoluble in ordinary organic solvents. However, the copolymer between the pNO 2 PA monomer and PA is completely soluble when the monomer ratio of PA was increased.…”

“…In our previous reports we have shown that polymerization of phenylacetylenes bearing o-alkoxy, [18][19][20] p-alkoxy, [20][21][22][23] p-(N,N-dimethylamino), [24] and p-nitro [21,25,26] groups as the side chain in the phenyl ring can be performed stereoregularly to produce the corresponding polymers having the predominant cis form using [Rh(nbd)Cl] 2 , (nbd ¼ norbornadiene) catalyst in the presence of triethylamine (TEA) or alcohol as the polymerization solvent under near room temperature. Further cis-to-trans isomerization of the resulting polymers was found to be induced when pressure was subjected to the polymers at ca.…”

Durch definierte Rhodiumkomplexe vermittelte Polymerisationen

“…Eine Reihe von kommerziell erhältlichen Rh‐Komplexen ist angewendet worden, typischerweise in Kombination mit einer Base wie Triethylamin (NEt 3 ) oder N , N ‐4‐Dimethylaminopyridin (DMAP). Abbildung zeigt die Strukturen der zwei am häufigsten für die Synthese von Phenylacetylen‐basierten (Co)polymeren verwendeten Rh‐Spezies, 1 und 2 , die auch als Vorstufen für andere Rh‐Komplexe fungieren . Sowohl 1 als auch 2 sind Beispiele von Halogen‐verbrückten zweikernigen Rh‐Komplexen mit stabilisierenden Dienliganden – bizyklischem 2,5‐Norbornadien (nbd) in 1 und 1,5‐Cyclooctadien (cod) in 2 .…”