Fluorophobic Effect Generates a Systematic Approach to the Synthesis of the Simplest Class of Rodlike Liquid Crystals Containing a Single Benzene Unit

4-Substituted n-5,5,6,6,7,7,8,8,9,9,10,10,10-tridecafluorododecan-1-yloxybenzenes, n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan-1- yloxybenzenes, and2-methyl-4-substituted n-5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan-1- yloxybenzenes were synthesized and characterized by a combination of techniques consisting of differential scanning calorimetry (DSC), thermal optical polarized microscopy, and small-and wide-angle X-ray diffraction. Thermotropic S_A and S_C LC phases are exhibited by compounds with NO₂, CN, CO₂CH₃, CH₂OH, CO₂H, and COCH3 substituents in the 4-position of the benzene ring. The thermal stability of the LC phase of these compounds increases with the increase of the length of the perfluorinated segment of their alkoxy group. A ratio of the perhydrogenated [(CH₂)_m]/perfluorinated [F(CF₂)n] segment lengths of m/n < 1 favors the formation of LC phases when n + m = 10 and 12. Additional substitution in the 2-position of the benzene ring with a methyl group decreases the thermal stability of the LC phase. The S_A phase of these compounds has a bilayered structure in which the perfluorinated segments are interdigitated. These compounds represent the simplest class of rodlike liquid crystals containing a single benzene unit which exhibit classic calamitic phases. The experiments reported in this paper demonstrate a simple and convenient method for the synthesis of liquid crystals containing a single benzene unit via the fluorophobic effect.