Alkyne Metathesis Graft Polymerization: Synthesis of Poly(ferricinium)-Based Silica Supports for Anion-Exchange Chromatography of Oligonucleotides

2-[3-(Ethynyl)phenyl]ethenyl]-1‘,2,2‘,3,3‘,4,4‘,5-octamethylferrocene ( 2 ) was prepared via Wittig- and chloro-Wittig-type reactions. 2 reacts with the well-defined Schrock-initiator Mo( N -2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)(OCMe(CF 3 ) 2 ) 2 via α-addition. The resulting class VI polymerization system allows the living polymerization of 2 up to a degree of polymerization of 150. Mesoporous and nonporous silica (Nucleosil 300-5 and Micra, respectively) with different specific surface area (100 and 2 m 2 /g, respectively) were surface-derivatized with norborn-2-en-5-yltrichlorosilane, leading to an average surface functionalization of 230 and 50 μmol norbornene/g, respectively. Monomer 2, ethynylferrocene ( 1 ), and 2-[4-(ethynyl)phenyl]ethenyl]-1‘,2,2‘,3,3‘,4,4‘,5-octamethylferrocene) ( 3 ) were surface-grafted onto these silica supports via alkyne metathesis polymerization using Mo( N -2,6-Me 2 C 6 H 3 )(CHCMe 2 Ph)(OCMe(CF 3 ) 2 ) 2 . Typical amounts of grafted monomer were in the range 50−5 μmol/g. The resulting poly(ferrocene)-grafted supports were subsequently oxidized with iodine to the corresponding poly(ferricinium)-grafted supports and successfully used for anion-exchange chromatography of oligonucleotides (dT) 12 −(dT) 18 .