Partial deuterium substitution as a tool for identification of the most stable conformer of a polyatomic molecule. A case of the 2,5-bis(2-benzoxazolyl)-1,4-dimethoxybenzene in supersonic jet

► The most stable structure of BBDB was proposed on the basis of calculations. ► LIF spectra of BBDB and deuterated BBDB in supersonic jet support the structure. ► Presence of different isotopologues is manifested by multiplet structure of LIF spectrum.