A non-rotatory isomerization path in ethene derivatives? Investigation of a stilbenophane and protonated azobenzenophanes (“pseudo-stilbenophanes”)Dedicated to Professor F. Dörr on the occasion of his 80th birthday.Electronic supplementary information (ESI) available: Synthesis of stilbenophane and protonated azobenzenophanes. See http://www.rsc.org/suppdata/cp/b1/b111483m/

A stilbenophane and protonated azobenzenophanes (“pseudo-stilbenes”) with four –CH2–S–CH2– bridges in all meta-positions were synthesized. The spectroscopic and photochemical properties were investigated: excited dimer absorption spectra and for the stilbenophane also emission spectra were observed. Photochemical reactions could be identified as the [2+2] photocycloaddition for the stilbenophane; the nature of the photoproducts in the case of pseudo-stilbenes could not be established. Photo-isomerizations could not be observed which gives a negative answer to the title question.