Synthesis and properties of C13-substituted retinals

Several analogues of all-trans-retinal were synthesised, containing, instead of CH3-group at C13, the following substituents: H, C2H]3, C2H5, iso-C3H7, C4H9, C6H5 or alpha-C10H8. The compounds synthesised on coupling with bacterioopsin gave artificial chromoproteins, which retained the ability to participate in the cycle of photochemical transformations and H+-transport.