Synthesis of benzaldehyde-grafted polysilane: A highly stable and selective “turn-on” fluorescent sensor for cytosine

Abstract A higly stable fluorescent probe for the selective detection of cytosine is reported. The probe is based on a polyhydrosilane copolymer, onto which pendant 2-{4-[(4-formylphenoxy)methyl]phenyl}ethyl moieties were grafted. The appendage of these moieties to poly[methyl(H)-diphenyl]silane was accomplished in two steps, namely hydrosilylation of a polysilane having reactive Si-H functions with 4-(chloromethyl)styrene, and subsequent Williamson ether formation through the reaction of the chloromethyl-substituted intermediate with 4-hydroxybenzaldehyde. The grafting of the benzaldehyde-terminated fragments renders the novel polysilane soluble in lower alcohols. Analysis of the optical properties of the grafted copolymer in solution showed that these are similar to those of the parent polyhydrosilane, but the intensity of the emission–absorption processes is strongly enhanced. The novel polymer selectively detects cytosine through fluorescence amplification, an optical property that could be exploited for the design of a “turn-on” fluorescent sensor capable to recognize subtle changes in DNA structures.