Dimesogenic compounds consisting of a cholesteryl moiety and an aromatic mesogen interconnected through a central pentamethylene spacer

New non-symmetric dimesogens consisting of a cholesteryl moiety and an arom atic mesogenic unit interconnected through a pentamethylene spacer have bee n prepared. The aromatic units consist of two phenyl rings linked by carbox y, oxycarbonyl, ethylene, ethynylene, azo or Schiff's base groups. The meso morphic and transitional properties have been investigated by using optical microscopy, differential scanning calorimetry, helical pitch measurements, and electric held and miscibility studies. The structures of the mesophase s have been studied using X-ray diffraction. Several kinds of smectic packi ngs are observed depending on the nature of the linking group and an attemp t to understand the origin of the different phase structures at a molecular level is made.