Laboratory Observation of the Rotational Spectrum of a C4 Sugar, 1,4-Anhydroerythritol

The free jet millimeter wave spectra of 1,4-anhydroerythritol (a C4 anhydrosugar) and of three deuterated isotopologues have been recorded in the frequency region 59.6-78.3 GHz. Rotational transitions have been assigned only for the lowest in energy conformer (according to DFT calculations). Its structure is characterized by a distorted ring and two O-H∙∙∙O hydrogen bonds involving the two alcoholic groups and the ring oxygen. Since C2 sugars have already been observed, and C3 sugars have been extensively searched – with controversial results - in the interstellar medium, we believe that 1,4-anhydroerythritol – a C4 sugar - to be of interest for astrochemical observation of larger sugar molecules. Accurate rest frequencies are provided for the radio-astronomical search.