Cellulose-Based Polymers with Long-Chain Pendant Ferrocene Derivatives as Organometallic Chromophores
作者:Fan Zhang、Volkmar Vill、Jürgen Heck
DOI:10.1021/om0343216
日期:2004.8.1
Selective transmetalation reactions via 1,1'-distannylated ferrocene enables the synthesis of the new ferrocenyl chromophore [Fe(eta(5)-C5H4-CH2OH)(eta(5)-C5H4-CH=CH-C7H7)] (6). Coupling reactions of complex 6 with corresponding alkyl halides reveal the sandwich compounds [Fe(eta(5)-C5H4-CH2OCH3)(eta(5)-C5H4-CH=CH-C7H7)] (7), [Feeta(5)-C5H4-CH2O(CH2)(6)Br}(eta(5)-C5H4-CH=CH-C7H7)] (8), [Feeta(5)-C5H4-CH2O(CH2)(6)OTHP}(eta(5)-C5H4-CH=CH-C7H7)] (9) (THP = tetrahydropyranyl), and [Feeta(5)-C5H4-CH2O(CH2)(6)I}(eta(5)-C5H4-CH=CH-C7H7)] (10), which are potential precursors for dipolar donor-acceptor complexes, providing nonlinear optical properties. The synthesis of the THP derivative 9 was intended as a precursor for the hydroxy-terminated compound [Feeta(5)-C5H4-CH2O(CH2)(6)OH}(eta(5)-C5H4-CH=CH-C7H7)] (11), which would be a suitable starting material for a coupling reaction with modified cellulose. However, an acid-catalyzed cleavage of the THP group of 9 in ethanol solution resulted in the formation of [Fe(eta(5)-C5H4-CH2OCH2CH3)(eta(5)-C5H4-CH=CH-C7H7)] (12) instead of 11. The fixation of ferrocenyl chromophores to 2,3-di-O-methyl cellulose was successful by using the ferrocenyl derivative 10, which reveals 2,3-di-O-methyl-6-O-partially[Feeta(5)-C5H4-CH2O(CH2)(6)}(eta(5)-C5H4-CH=CH-C7H7)] cellulose (18) with different DS [0.1 (18a), 0.2 (18b), 0.3 (18c), 0.5 (18d), 0.6(18e)], depending on the reaction conditions. 1.8a-e were characterized by H-1 NMR, H-1-C-13 correlation spectroscopy, UV/vis spectra, and cyclic voltammetry (18c). Polarization microscopy observations of the cellulose derivative 18c demonstrate its thermotropic and lyotropic liquid crystallinities. Reaction of 12 with [Cp*Ru(CH3CN)(3)]PF6 forms the dipolar monohydro sesquifulvalene complex [Fe(eta(5)-C5H4-CH2OC2H5)eta(5) -C5H4-CH= CH-(eta(6)-C7H7)}RuCp*]PF6 (13), indicating that the ferrocenyl derivatives 7-10 can in principle be transformed to dinuclear, dipolar, monocationic, monohydro sesquifulvalene complexes and opens the feasibility of introducing dinuclear and dipolar sesquifulvalene units as pendant units of a cellulose backbone, which have potential nonlinear optical properties.