Structure and photoconductive behavior of (E-) and (Z-)-1-cyano-1-carbethoxymethylene acenaphthen-2-one taken by stereoselective synthesis

The stereoselective synthesis of the two geometric isomers (E-) and (Z-) of 1-cyano-1-carbethoxymethylene acenaphthen-2-one, was achieved via two different, simple, pure and low cost Knovenagel condensation reactions. The chemical structure of the as-prepared isomers was identified by 1H NMR technique, IR spectroscopy, elemental analysis and X-ray diffraction. Photoconductivity measurements of both the isomers isolated and formulated as thin films on titanium substrates were performed by a solution deposition technique in a photoelectrochemical cell (PEC) under different illumination conditions. The photocurrents observed might be attributed to the structure of the substances prepared which favors the development of an extended π-conjugated system. However, the Z-isomer presents higher photoconductivity compared with that of the E-isomer. So, it could be supposed that the lower photoresponse characterizing the E-isomer is due to an observed development of a non-traditional intramolecular hydrogen bond leading to the formation of an additional six-membered ring.The Z-diastereomer, belonging to the group of small-molecule semiconductors, may be useful in devices as organic thin film transistors, on/off sensors, etc.