Structure−Property Dependence of the First Hyperpolarisabilities of Organometallic Merocyanines Based on the μ-Vinylcarbynediiron Acceptor and Ferrocene Donor

Abstract

In order to investigate the structure−property relationship of nonlinear optical materials, a series of organometallic chromophores were synthesised utilising the [Fe 2 (η-C 5 H 5 ) 2 (CO) 2 (µ-CO)(µ-C−)] + electron-accepting moiety and the ferrocenyl group, Fc, as the electron donor. The π-linker between these two termini was systematically modified and the mutual electronic communication between them was determined using IR, NMR, and electronic absorption spectroscopy. An X-ray structure determination of [Fe 2 (η-C 5 H 5 ) 2 (CO) 2 (µ-CO)(µ-C−CH=CH−CH=C(Cl)−Fc)][BF 4 ] confirmed the strong electronic interaction between the donor and the acceptor with reduced π-bridge bond-length alternation. The nonlinear optical properties of these complexes were examined using the hyper Rayleigh scattering technique. The experimental first hyperpolarisabilities are some of the highest obtained for ferrocenyl chromophores and, significantly, no enhancement

Ferrocene: An unrivaled electroactive building block for the design of push-pull dyes with near-infrared and infrared absorptions

“…With aim at examining the influence of the π-conjugated spacer, a series of 10 merocyanine salts were designed and obtained with yields ranging from 49% for M26 until 72% for M22 (See Fig. 39) [161] (see Fig. 40).…”

Quadratic nonlinear optical properties of novel pyridinium salts

“…This is a very unusual observation because the ICT bands of donor-acceptor polyene chromophores almost always red-shift upon chain extension, and this trend applies regardless of whether terminal purely organic groups or metal centres are present. [47][48][49][50][51] As far as we are aware, the only previously reported donor-acceptor polyenes in which the ICT bands blue-shift with chain extension are compounds containing tetrathiafulvalenyl (TTF) donor groups and various strong electron acceptors including 2,2-dicyanovinyl and 4-methylidene-1,3-diethyl-2-thiobarbituric acid. 52 The cyclic voltammetric data in Table 4 show that the Ru III/II E 1/2 values decrease by ca 50 mV on moving from n = 0 to 1, indicating that the Ru centres become more electron rich due to the mildly electron donating influence of the 4-vinyl groups.…”

Ferrocenyl D–π–A conjugated polyenes with 3-dicyanomethylidene-1-indanone and 1,3-bis(dicyanomethylidene)indane acceptor groups: Synthesis, linear and second-order nonlinear optical properties and electrochemistry

“…''Push-pull'' compounds containing ferrocenyl (Fc) donor group bound to a conjugated polyenic chain capped by an acceptor moiety A, (Fc-p-A), have attracted considerable interest as second-order nonlinear optical (NLO) chromophores [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. They display large first hyperpolarizabilities (b), and some of them second harmonic generation (SHG) ability in the solid state.…”