Photochromism optical rotation

When azobenzenes are attached to polypeptides, photochromic reactions of azobenzenes can induce the change in helical properties of the polypeptides, which may be detected by CD spectrum as well as optical rotation. For 4-phenylazophen-ylamine-condensed poly(y-glutamic acid) A-9 containing up to 80 mol% of 4-phenylazophenylamide side chain, UV irradiation in organic solvents, such as... 

Chiroptical molecular switches (photochromic compounds among them dihetarylethenes, fulgides, and spiropyrans permitting undestructive read-out of information using change of optical rotation 00CRV1789. 

Optical rotation changes accompanied by the photochromic reaction are a promising alternative for nondestructive readout. To enhance the readout signal intensity, two conditions must be satisfied ... 

The photochromic compounds should exhibit significantly contrasting optical rotating strengths between the two states. 

Diarylethenes are one of the most promising photochromic materials for such purposes as molecular optical memories and switches, because of their excellent thermal stability and fatigue-resistant nature [51]. A chiral dithienylethene has the potential for non-destructive readout by detecting optical rotation at wavelengths longer than its own absorption band. However, it is not a simple task to achieve appreciable stereoselectivity in solution-phase photocyclization of dithienylethenes, even for those with chiral substituents [52-54]. In this regard, a... 

In special cases of optically active photochromes the change in molecular form is accompanied by a change in specific rotation. Singh (170) noted that as (l-naphthylamino)camphor (0.726 g. in 100 cc. chloroform) turned from colorless to green with a 6-min. exposure to sunlight, the specific rotation changed from 126° to 186.6°. Reversal of the system required days. 

The specific rotation values of 11E and its UV pss at the sodium D-line (589 nm [a]D) in toluene were -572° and -186°, respectively hence markedly different. This phenomenon was reproduced in PMMA films. Because irradiation at the sodium D-line wavelength does not induce photochromic reactions, measurement of optical... 

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