SYNTHESIS AND CHARACTERIZATION OF LIQUID-CRYSTALS CONTAINING A NONACTIVATED ',3'-TRIMETHYLSPIRO[2H-1-BENZOPYRAN-2,2'-INDOLINE] GROUP

Two series of mesogens derived from the non-activated spiropyran dyes 6-hydroxy-1',3',3'-trimethylspiro [2H-1-benzopyran-2,2'-indoline] (ser ies 1) and 6-(4-hydroxyphenyl)-1',3',3'-trimethylspiro [2H-1-benzopyra n-2,2'-indoline] (series 2) have been synthesized. Analysis by differe ntial scanning calorimetry, polarizing microscopy and X-ray diffractio n showed that compounds in series 1 form monotropic nematic and SmA ph ases, while compounds in series 2 form only a monotropic nematic phase . One compound in series 1, rimethylspiro-[2H-1-benzopyran-2,2'-indoli ne)-6-yl 4'-octyloxybiphenyl-4-carboxylate (1b), was also shown to for m a monotropic SmC phase between 71 and 60 degrees C.