Cholesteric liquid crystal glass platinum acetylides

To prepare cholesteric liquid crystalline nonlinear optical materials with ability to be vitrified on cooling and form long time stability cholesteric glasses at room temperature, a series of platinum acetylide complexes modified with cholesterol has been synthesized. The materials synthesized have the formula trans -Pt( PR 3 )(cholesterol (3 or 4)-ethynyl benzoate)(1-ethynyl-4- X -benzene), where R = Et , Bu or Oct and X = H , F , OCH 3 and CN . A cholesteric liquid crystal phase was observed in the complexes R = Et , and X = F , OCH 3 and CN but not in any of the other complexes. When X = CN , a cholesteric glass was observed at room temperature which remained stable up to 130 o C, then converted to a mixed crystalline/cholesteric phase and completely melted to an isotropic phase at 230 o C. When X = F or OCH 3 the complexes were crystalline at room temperature with conversion to the cholesteric phase upon heating to 190 and 230 o C, respectively. In the series X = CN , OCH 3 and F , the cholesteric pitch was determined to be 1.7, 3.4 and 9.0 µ , respectively.