Organometallic nonlinear optical polymers. 2. Synthesis of main-chain organometallic polymers and a structural study of ferrocene NLO-phores
A detailed structural analysis of several ferrocene-based nonlinear optical (NLO)-phores was done by X-ray diffraction. Structures were reported for ( eta super(5)-C sub(5)H sub(5))( eta super(5)-C sub(5)H sub(4)CH = C(CN)(R))Fe (1a, R = CO sub(2)Et; 1b, R = CN; 1c, R = 4-pyridyl; 1d, R = 4-bromophe...
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Veröffentlicht in: | Macromolecules 1992-10, Vol.25 (22), p.6050-6054 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | A detailed structural analysis of several ferrocene-based nonlinear optical (NLO)-phores was done by X-ray diffraction. Structures were reported for ( eta super(5)-C sub(5)H sub(5))( eta super(5)-C sub(5)H sub(4)CH = C(CN)(R))Fe (1a, R = CO sub(2)Et; 1b, R = CN; 1c, R = 4-pyridyl; 1d, R = 4-bromophenyl). The study illustrated that electron-withdrawing groups favor and control the planarity of the pi -system. Through selective functionalization of the cyclopentadienyl rings of ferrocene, new monomers, namely, ( eta super(5)-C sub(5)H sub(4)CH sub(2)O(CH sub(2)) sub(n)OH)( eta super(5)-C sub(5)H sub(4)CH = C(CN)CO sub(2)-Et)Fe (5) and ( eta super(5)-C sub(5)H sub(4)CH sub(2)O(CH sub(2)) sub(n)O sub(2)CCH sub(2) CN)( eta super(5)-C sub(5)H sub(4)CHO)Fe (6, n = 6; 8, n = 1), were prepared in the study. Monomer 5 was suitable for Lewis acid catalyzed transesterification/polymerization using Ti(OC sub(4)H sub(9)) sub(4), and 6 and 8 were appropriate for a Knoevenagel polycondensation. The transesterification polymerization resulted in formation of an intractable polymeric material of unknown structure. The homopolymerization of 6 by the Knoevenagel technique afforded the desired polymer 9a, albeit in low molecular weight (M sub(n) = approx.6800). The polymer was characterized by gel permeation chromatography and spectroscopic data. A major byproduct in the polymerization was the macrocyclic lactone 10a produced from an intramolecular Knoevenagel condensation. The lactone structure was confirmed by single-crystal X-ray diffraction. |
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ISSN: | 0024-9297 1520-5835 |
DOI: | 10.1021/ma00048a030 |