Star-shaped conjugated compounds forming nematic discotic systems

Star-shaped compounds, having a benzene () or a 1,3,5-triazine () core and stilbenoid arms were prepared. Hexyloxy chains, attached in the middle of the arms, provide nematic discotic phases ND, which are unusual for such systems. The position of the sidechains prevents the micro-segregation, which is valid for star-shaped discs of columnar phases. The stilbenoid character of and guarantees a high light sensitivity. Apart from the statistical CC bond formation by irradiation in solution or in the LC phases, a topochemically controlled chemo-, regio- and stereoselective photocyclodimerization → was found in the crystalline state. The structure determination of is based on different two-dimensional NMR techniques (COSY, NOESY, HMQC, HMBC).