Nonlinear optical properties, ferrocene polymers

More recently, a soluble polymer (32) was prepared via reaction of l,l -ferrocenedimethanol with 4,4 -biphenyltetraamine in the presence of [RuCl2(P(C6115)3)3] (70). Approximately 20% of the iron centers were foimd to be in the Fe(III) state as a result of oxidation by ruthenium complexes formed during the polycondensation reaction. Wright and co-workers have reported the synthesis of ferrocene-based polymers possessing nonlinear optical properties (33) (71-73). These polymers were formed by polycondensation of a difunctionabzed ferrocene monomer (71). 

Sidechain ferrocene-based polymers possessing nonlinear optical properties have been described by Wright and coworkers as shown in Scheme The copolymerization of 5 mol% of the ferrocenyl functionalized monomer 28 with methyl methacrylate 29 resulted in an organometallic polymer (30) displaying second-harmonic-generation activity. The Tg and T values of this organometallic polymer were 120 and 225°C, respectively, which are similar to those of poly(methyl methacrylate). 

Ferrocene polymers with nonlinear optical properties were also prepared via Knoevenagel polycondensation reactions. " Scheme 32 shows the reaction of monomer 123 with 124 to give the accordion polymer 125 with values ranging from 9100 to 26,600." A mixture of A and Z isomers was initially obtained however, an isomerically enriched polymer (98% E isomer) could be isolated through selective precipitation. 

Ferrocenyl-based polymers are established as useful materials for the modification of electrodes, as electrochemical biosensors, and as nonlinear optical systems. The redox behavior of ferrocene can be tuned by substituent effects and novel properties can result for example, permethylation of the cyclopentadienyl rings lowers the oxidation potential, and the chaige transfer salt of decamethylfer-rocene with tetracyanocthylene, [FeCpJ]" (TCNE], is a ferromagnet below = 4.8 K, and electrode surfaces modified with a pentamethylferrocene derivative have been used as sensors for cytochrome c These diverse properties have provided an added impetus to studies on ferrocene dendrimers. 

There have also been many studies of the polymerization kinetics of organoiron monomers these have shown that such polymerizations often do not follow the same rate laws as organic monomers. Ferrocene-substituted polymethacrylates possessing nonlinear optical (NLO) properties were reported by Wright and coworkers." The copolymerization of the ferrocenyl-fimctionalized monomer (5mol%) 14 with methyl methacrylate 15 yielded the organometaUic polymer 16, as shown in scheme 4." This polymer displayed second-harmonic-generation activity and possessed... 

---