Motor on dating
This molecular set-up is related to the Feringa motor system consisting of a sterically overcrowded double bond in combination with carbon-based stereogenic centres Motor 1 was synthesized in three steps starting from known, easily accessible precursors (Fig. Because of its instability and high tendency to dimerize, benzothiophenone 3 was used in the next synthetic step in crude form.
Commercially available 4,7-dimethoxy-1-indanone (4) was methylated twice in the 2-position using sodium hydride and methyl iodide to give indanone 5.
Our new molecular motor is based on the hemithioindigo (HTI) chromophore that can be operated exclusively by visible light in both switching directions.Most light-powered molecular motors require damaging ultraviolet light to perform their task, which is a major drawback for biological or smart materials applications.At present, only a few motor systems are available that undergo unidirectional 360° rotation using visible light, but the speed of their motion is slow, which again impedes applications in (heat) sensitive environments95% unidirectionality and at a very fast rate (1 k Hz at 20 °C).To confine light-induced rotations around the central double bond to one direction and exclude unwanted back-movements, we implemented additional stereochemical elements to the HTI framework: the sulfur atom was oxidized to the corresponding sulfoxide, introducing a sulfur-based stereocentre (R- or S-configuration), and sterical crowding at the ring-fused stilbene fragment led to helical twisting (P- or M-helicity) around the central double bond.Combined with its Z and E isomeric forms, motor 1 can thus assume four different diastereomeric structures for each configuration of the stereogenic sulfur centre, for example, Z-(S)-(P), Z-(S)-(M), E-(S)-(M) and E-(S)-(P), which can be distinguished by conventional spectroscopic methods. 39) was converted into the corresponding acid chloride, which subsequently underwent cyclization via intramolecular Friedel–Crafts acylation to give benzothiophenone 3.