  We combine infrared spectroscopy, nano-indentation measurements, and \emph{ab
initio} simulations to study the evolution of structural, elastic, thermal, and
electronic responses of the metal organic framework MOF-74-Zn when loaded with
H$_2$, CO$_2$, CH$_4$, and H$_2$O. We find that the molecular adsorption in
this MOF triggers remarkable responses in all of these properties of the host
material, with specific signatures for each of the guest molecules. With this
comprehensive study we are able to clarify and correlate the underlying
mechanisms regulating these responses with changes of the physical and chemical
environment. Our findings suggest that metal organic framework materials in
general, and MOF-74-Zn in particular, can be very promising materials for novel
transducers and sensor applications, including highly selective small-molecule
detection in gas mixtures.
