Hydrophilic and water-soluble poly(ferrocenylsilanes)

The synthesis of a series of navel hydrophilic and water-soluble neutral an d cationic high molecular weight poly(ferrocenylsilanes) is reported. The d ichlorosilyl-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 r ing-opening polymerization of these monomers, hydrophilic poly(ferrocenylsi lanes) were obtained. Transition-metal catalyzed ring-opening polymerizatio n of the silicon-bridged [1]ferrocenophane Fe(eta-C5H4)(2)SiMeCl (8) afford ed the corresponding polymer [Fe(eta-C5H4)(2)SiMeCl](n) (9). Replacement of the chlorine substituents of 9 Tvas achieved using (a) poly(ethylene glyco l) methyl ether, M-n = 350, in the presence of Et3N to afford the poly(ferr ocenylsilane) [Fe(eta-C5H4)(2)SiMe(OCH2CH2)(x)OCH3](n). (x similar to 8: 10 a: M-n similar to 56 000; 10b: M-n similar to 189 000) and (b) N,N-dimethyl ethanolamine to afford [Fe(eta-C5H4)(2)SiMe(OCH2CH2NMe2)](n), (II) Quaterni zation 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 w hereas 10a, 12, and 13 afford slightly cloudy solutions. Lower critical sol ution temperatures (LCST) for 10a and 10b were determined to be 38 and 46 d egrees C, respectively. Investigations by dynamic Light scattering and cent rifugation experiments indicated the presence of aggregates. In the case of 12 the larger aggregates could be partially broken up using mild ultrasoni cation but re-form over time. Clear solutions of the polymers 10a, 12, and 13 in water can be easily prepared by microfiltration techniques.