ISSN:
0894-3230
Keywords:
molecular recognition
;
non-aqueous titration
;
hydrogen bonding
;
proton transfer
;
pKa shifts
;
acid-base catalysis
;
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Whenever hydrogen bonding is involved in molecular recognition, the possibility of a proton transfer from the donor to the acceptor arises. In most cases the pKa of the donor is far enough above the pKa of the conjugate acid of the acceptor for it to be clear that no proton transfer will occur. However, as the difference between the donor and acceptor pKas decreases, it can become difficult to predict whether a proton transfer will occur. Since most hydrogen bond-driven molecular recognition is studied in low dielectric solvents, non-aqueous titrations can be used to measure the pKas and therefore predict proton transfers. In this paper three studies which involved non-aqueous titrations are summarized. The first deals with distinguishing simple proton transfer from host-guest complex formation. The second involves measuring pKa shifts upon host-guest complex formation. The last is a study of the catalysis of a phosphoryl transfer. In all three scenarios the non-aqueous titration method gave results which would have been difficult to obtain by other means, and which proved crucial for a complete understanding of the molecular recognition process. © 1997 John Wiley & Sons, Ltd.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
