Silica guanidine-functionalised

Fig. 8.8. A comparison of capacity factors from HPLC studies of guanidine-functionalised silica xerogels imprinted (dark bars) and non-imprinted (hatched bars) with PPA template, measured at pH 6 and pH 8.

Fig. 8.10. PPA interacting with a guanidine-functionalised silica surface encounters different scenarios at low and high pH. At low pH the surface silanols are protonated and the guanidines are free to interact with PPA, whereas at high pH the surface becomes anionically charged and inhibits binding.

Two approaches have been employed to prepare supported guanidines - a ringopening of the glycidyl-functionalised silica by 1,5,9-triazabicyclodecane (TBD)[15], and the nucleophilic displacement of a chloro substituent again by TBD [16]... 

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