The dynamic control of liquid films through light driven molecular motors is a highly attractive way to generate responsive materials.1 We herein describe the behavior of two series of molecular motors when used as in a nematic liquid crystal. Major interest lies in drawing a conclusion with regards to the correlation of structure and electronic properties with respect to the helical twisting power (HTP) observed for each motor. First a series of molecular motors (1  -4  ) with varying substituent in the bridge head position has been synthesized and studied. Previous studies2 revealed a significant change in the folding angle of the lower half which could influence the HTP. In a second series various3 electron donating and withdrawing substituents are introduced (5  -9  ) and the impact on the HTP was studied. Understanding such a correlation of structural and electronic properties dopant to the HTP would allow for a better design of dopants for future applications. Previous studies in our lab revealed that changing the structure of a molecular motor can have significant effects on the HTP.4,51. R. Eelkema, M. M. Pollard, J. Vicario, N. Katsonis, B. Serrano Ramon, C. W. M. Bastiaansen, D. J. Broer, B. L. Feringa, Nature 2006 , 440, 163.2. M. M. Pollard, P. V. Wesenhagen, D. Pijper, B. L. Feringa, Org. Biomol. Chem. 2008 , 6, 1605-1612.3. A. Cnossen, J. C. M. Kistemaker, T. Kojima, B. L. Feringa, J. Org. Chem. 2014 , 79, 927-935.4. R. Eelkema, M. M. Pollard, N. Katsonis, J. Vicario, D. J. Broer, B. L. Feringa, J. Am. Chem. Soc. 2006 , 128, 14397�14407.5. R. A. van Delden, N. Koumura, N. Harada, B. L. Feringa PNAS 2002 , 99, 4945-9.

Substituent effect on helical twisting power of molecular motors in liquid crystals

248th National Meeting (2014)

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