New biforked mesogen series

Four new series of biforked mesogens derived from 3,4-dialkoxybenzoic acids or 3,4-dialkoxybenzaldehydes have been prepared and studied. These derivatives exhibit an interesting polymorphism in which both columnar and lamellar mesophases exist in the same series and in some cases in the same compound. The short chain derivatives exhibit a nematic and/or a smectic C phase but those with long chains display the hexagonal, rectangular or oblique columnar phases. In some of them, a centred cubic phase is found.