Coupling of mechanical and chemical energy: Proton affinity as a function of external force

Small action, large effect: The proton affinity has been defined as a function of an external mechanical force and its applicability as a chemical concept is explored (see scheme). It is shown that forces in the sub-nN to nN range change the proton afinity of small model molecules by values ranging from kT up to several 10 kJ mol-1, which suggests that these affinity changes are chemically significant.