Chiral azobenzene dopants with increased delta helical twisting power
A chiral azobenzene dopant with helical twisting power has a structure represented by the following formula (I): wherein Z and Z′ are independently selected from the group consisting of naphthalene and phenanthrene; when Z or Z′ is naphthalene, the naphthalene optionally has R 3 at the 6 position and R 4 at the 6′ position; when Z or Z′ is phenanthrene, the phenanthrene optionally has R 3 at the 7 position and R 4 at the 7′ position; R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of an alkyl group having 1 to 20 carbons, an alkoxy group having 1 to 20 carbons, an aryl group having 6 to 20 carbons, and an aryloxy group having 6 to 20 carbons; and on any R 1 , R 2 , R 3 , and R 4 , on any CH 2 a CH 3 is optionally attached by replacing a hydrogen on a CH 2 .
1. A chiral azobenzene dopant with helical twisting power, the chiral dopant having a structure represented by the following formula (I):
wherein Z and Z′ are independently selected from the group consisting of naphthalene and phenanthrene;
when Z or Z′ is naphthalene, the naphthalene optionally has R 3 at the 6 position and R 4 at the 6′ position;
when Z or Z′ is phenanthrene, the phenanthrene optionally has R 3 at the 7 position and R 4 at the 7′ position;
R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of an alkyl group having 1 to 20 carbons, an alkoxy group having 1 to 20 carbons, an aryl group having 6 to 20 carbons, and an aryloxy group having 6 to 20 carbons; and
on any one or more R 1 , R 2 , R 3 , and R 4 , a CH 3 is optionally attached by replacing a hydrogen of a CH 2 .
2. The chiral azobenzene dopant of claim 1 , wherein the chiral dopant has a structure of formula (Ia):
3. The chiral azobenzene dopant of claim 2 , having the following structure:
4. The chiral azobenzene dopant of claim 2 , having the following structure:
5. The chiral azobenzene dopant of claim 2 , having the following structure:
6. The chiral azobenzene dopant of claim 2 , having the following structure:
7. The chiral azobenzene dopant of claim 2 , having the following structure:
8. The chiral azobenzene dopant of claim 1 , wherein the chiral dopant has a structure of formula (Ib)
9. The chiral azobenzene dopant of claim 1 , wherein the chiral dopant has a structure of formula (Ic):
10. The chiral azobenzene dopant of claim 9 , having the following formula:
11. A liquid crystal layer comprising a liquid crystal material and the chiral azobenzene dopant of claim 1 .
12. The liquid crystal layer of claim 11 , wherein the liquid crystal material is reversibly adjustable between transparent and opaque by irradiation.
13. The liquid crystal layer of claim 11 , wherein the irradiation is with a visible light and an ultraviolet light, respectively.