Dynamic Control of Self-Organized Assemblies using Near Infrared and Visible Light Activated Azo-BF2 Switches
Abstract
The objective of this effort is to design and synthesize chiral dopants that can effectively and efficiently control the optical properties of liquid crystals. This effort will examine the fundamental factors controlling the photophysical properties of visible and NIR light-activated BF2-azo switches to design chiral dopants that can efficiently and effectively control the optical properties of liquid crystals. Structure/property relationships of the BF2-azo switches will be determined based on the size, shape, and electronic properties of the main sub-components of the molecule (aryl group in the stator and quinolinyl ring in the rotor; iftime permits, replacement of the cyano group will be studied). These sub-groups will be modified with different functional groups including electron doting and withdrawing groups. Isomerization properties of the target molecules will be studied using lH NMR and UV/V is spectroscopies. Changes in medium and its impact on switching properties will also be investigated. Switchable chiral dopants will be designed by varying the number of chiral groups, structurally rigid switches, and biphenyl arms. Chiral groups include cholesterol, chiral amine, and isosorbide. The properties of the switches in solution will be studied using the same techniques as above as well as circular dichroism. The ability of the chiral dopants to induce chirality in nematic liquid crystals will be studied using polarized optical microscopy. Changes in the selective reflection spectra due to switching and the ability of dopants to tune the reflection colors will be investigated. Helical twisting power studies will be carried out to determine the ability of the chiral dopants to impart a helical twist on liquid crystal hosts. Experimental studies will be complemented by DFT calculations (how dopant structure effects helical twisting power).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 12, 2017
- Source ID
- W911NF1510587
Entities
People
- Ivan Aprahamian
Organizations
- Army Contracting Command
- Dartmouth College
- United States Army