OH-stretching red shifts in bulky hydrogen-bonded alcohols: jet spectroscopy and modeling

The available database for OH-stretching bands of jet-cooled aliphatic alcohol dimers is extended to systems including 1-adamantanol and 2-adamantanol, using a heated pulsed nozzle coupled to an FTIR spectrometer. This database is used to simplify and parametrize the standard Wang et al. AMBER/parm99.dat force field for the prediction of hydrogen-bond-induced red shifts, as it avoids complications due to mode coupling and cooperativity. Apart from subtle chiral recognition effects, the performance of the simple model in describing steric, electronic, and conformational influences on the red shifts is remarkable, as exemplified by predictions for mixed-alcohol dimers. The resulting semiempirical approach can complement quantum chemical calculations, in particular for larger systems, although the good performance is rather specific to red shift predictions.