Ferrocene and Azulene - a Promising Combination for NLO Materials

Rudolf Herrmann*, Gabriele Wagner and Cordt Zollfrank

Institut für Organische Chemie und Biochemie der Technischen Universität München, Lichtenbergstr.4,
D - 85747 Garching (Germany)

Dedicated to Prof. Peter L. Pauson on the occasion of his 70th birthday

Materials exhibiting non-linear optical (NLO) properties are of great interest for the development of optical devices. They generally contain a donor - acceptor combination connected by a conjugated bridge. Since both ferrocene (donor) and azulene (donor: five-membered ring, acceptor: seven-membered ring) derivatives are known to exhibit NLO properties to some degree [1 - 8], we became interested in the potential of molecules containing both groups.



Optical Properties of New Compounds

While amine 4 and the alcohols 6 and 7 have optical properties similar to a superposition of that of the starting materials, cation 3 (connecting ferrocene and azulene with the five-membered ring) exhibits a much stronger band at 691 nm (epsilon = 4190), demonstrating the delocalization of the positive charge. The alkenes 8 and 9, obtained as a 9:1 mixture, contain ferrocene, azulene (connected with the seven-membered ring), and an additional substituent at the double bond. The UV spectrum of 8a (R = H) shows absorptions in the visible region (396 nm, epsilon = 8720) not present in the parent compounds (UV/VIS spectra of cation 3 and alkene 8a in acetone), and a solvatochromic effect of the lowest energy band (502 nm in acetone, 482 nm in hexane).

Calculations of Second Order Hyperpolarizabilities (beta)

For discussion, here is the e-mail-link: R.Herrmann, TU München
Research group of Priv.Doz. Dr. Rudolf Herrmann, May 25th 1995

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