Hydrophilic and water-soluble poly(ferrocenylsilanes)

The synthesis of a series of navel hydrophilic and water-soluble neutral and cationic high molecular weight poly(ferrocenylsilanes) is reported. The dichlorosilyl-bridged [1]ferrocenophane Fe(eta-C5H4)(2)SiCl2 (3) was reacted with various polyether alcohols in the presence of Et3N as an HCl acceptor to afford the monomers Fe(eta-C5H4)(2)Si(OR)(2) (4: R = CH2CH2OCH3; 5: R = CH2CH2OCH2CH2OCH3). Using ambient temperature transition-metal catalyzed ring-opening polymerization of these monomers, hydrophilic poly(ferrocenylsilanes) were obtained. Transition-metal catalyzed ring-opening polymerization of the silicon-bridged [1]ferrocenophane Fe(eta-C5H4)(2)SiMeCl (8) afforded the corresponding polymer [Fe(eta-C5H4)(2)SiMeCl](n) (9). Replacement of the chlorine substituents of 9 Tvas achieved using (a) poly(ethylene glycol) methyl ether, M-n = 350, in the presence of Et3N to afford the poly(ferrocenylsilane) [Fe(eta-C5H4)(2)SiMe(OCH2CH2)(x)OCH3](n). (x similar to 8: 10a: M-n similar to 56 000; 10b: M-n similar to 189 000) and (b) N,N-dimethylethanolamine to afford [Fe(eta-C5H4)(2)SiMe(OCH2CH2NMe2)](n), (II) Quaternization of polymer II with Mel or HCl afforded the polyelectrolytes [Fe(eta-C5H4)(2)SiMe(OCH2CH2NMe3I)], (12) and [Fe(eta-C5H4)(2)SiMe(OCH2CH2NMe2HCl)](n) (13). Poly(ferrocene) 10b dissolved in water to give a clear solution whereas 10a, 12, and 13 afford slightly cloudy solutions. Lower critical solution temperatures (LCST) for 10a and 10b were determined to be 38 and 46 degrees C, respectively. Investigations by dynamic Light scattering and centrifugation experiments indicated the presence of aggregates. In the case of 12 the larger aggregates could be partially broken up using mild ultrasonication but re-form over time. Clear solutions of the polymers 10a, 12, and 13 in water can be easily prepared by microfiltration techniques.