(83e) Computational Chemistry Design of Liquid Crystal-Based Chemoresponsive Systems with Increased Water Tolerance

Authors: 
Szilvási, T., University of Wisconsin-Madison
Yu, H., University of Wisconsin-Madison
Rai, P., Kent State University
Twieg, R., Kent State University
Abbott, N. L., University of Wisconsin-Madison
Mavrikakis, M., University of Wisconsin-Madison
Nematic liquid crystals are prone to anchor to surfaces that can alter their overall orientation in the bulk liquid phase. This orientation change can be exploited to detect analytes which can replace liquid crystal molecules bound to the surface and thus it can force liquid crystals to restore their original orientation in the bulk.1 Dimethyl-methylphosphonate (DMMP), a common precursor of nerve gases, is an important analyte which has been proved to replace liquid crystals.2,3 To make one step further towards developing a sensor that can be used in practical applications it is important to exclude false positive signals arising from ubiquitous molecules such as water. Previously, we have developed theoretical models, based on quantum mechanics, to simulate the orientational transition of nematic liquid crystals4,5 which provide the basis to describe the effect water in these complex environments. We have also developed an integrated theoretical and experimental approach where computational models are validated against well-defined experimental data and new predictions are tested experimentally.4,5

In this presentation, we present computational models to simulate the effect of humidity on potential liquid crystal-based chemical sensors. Using experimental data, we validate descriptors that can indicate the sensitivity of liquid crystal-based systems towards high relative humidity. Based on our models, we have identified new previously unknown liquid crystal molecules that can have higher water tolerance than traditional liquid crystal molecule 4-cyano-4’-pentylbiphenyl (5CB). Motivated by our calculations, we have successfully synthesized the predicted molecules and tested their chemo-responsiveness in humid environment. Our experimental results have confirmed our theoretical predictions about increased water tolerance while the detection of DMMP is still possible. These results indicate the importance of close collaboration between theory and experiments to facilitate the progress in complex liquid crystal material design for chemoresponsive applications.

1. Shah, R. R.; Abbott, N. L., Science, 2001, 293, 1296.

2. Yang, K. L.; Cadwell, K.; Abbott, N. L., Journal of Physical Chemistry B, 2004, 108, 20180.

3. Hunter, J.T.; Abbott, N.L., Applied Materials and Interfaces, 2013, 6, 2362.

4. Roling L. T.; Scaranto, J.; Herron, J. A.; Yu, H.; Choi, S.; Abbott, N. L.; Mavrikakis, M., Nature Communication, 2016, 7, 13338.

5. Szilvási, T.; Roling, L. T.; Yu, H.; Rai, P.; Choi, S.; Twieg, R. J.; Mavrikakis, M.; Abbott, N. L., Chemistry of Materials, 2017, accepted.