Synthesis and chiroptical properties of optically active poly(N‐propargylamide) bearing photoisomerizable azobenzene moieties

Abstract

A chiral azobenzene-containing N-propargylamide monomer, that is, (R)-2-(4-phenylazophenoxy)-n-prop-2-ynyl-propionamide, was prepared and polymerized in the presence of a rhodium catalyst to yield an optically active polyacetylene. The 1 H NMR analysis of the polymer indicated a predominant cis structure of the backbone (cis concentration ¼ 80%); and the chiroptical property studies showed an enhanced optical rotatory power and a strong Cotton effect, indicating the formation of a secondary helical conformation. A reversible optical modulation of chiroptical properties of the polymer due to the reversible photoisomerization of the azobenzene was observed. V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6047-6054, 2006

Synthesis of novel helical poly(N-propargylamides) containing azobenzene pendant groups and effects of substitution groups on azobenzene on the stability of helix

“…5(C)). The same phenomenon was also found in most reported poly (N-propargylamides) carrying azobenzene moieties, which did not exhibit intense CD signals in DMF as well [30][31][32]. The azobenzene moieties in Poly(V 3 ) and those reported polymers did not contain bulky substituents.…”

“…Many polymers bearing azobenzene chromophores have been explored extensively because of the unique optical properties [25][26][27][28][29]. Recently, some helical poly(N-propargylamides) containing azobenzene moieties have been synthesized, and the reversible transformation of higher order structures triggered by azobenzene isomerization were studied [6,[30][31][32]. Sanda and coworkers synthesized the helical poly(N-propargylamides) bearing designed azobenzene moieties.…”

“…The reversible transformation of helical side chains upon photoirradiation was observed, while their main chains still kept the helical structures upon the UV irradiation [30]. Zhou and coworkers investigated the effect of the photoisomerization of azobenzene groups on the chiroptical properties of polymers [32]. However, the helical conformations of most poly(Npropargylamides) containing azobenzene moieties were still affected by the external stimulus, such as polar solvents and temperature.…”

A Rigid, Chiral, Dendronized Polymer with a Thermally Stable, Right‐Handed Helical Conformation

“…[1] They have been prepared either by achiral polymerization of optically active monomers such as acetylenes, [2] isocyanates, [3] and silanes, [4] or by helix-senseselective polymerization of achiral monomers (carbodiA C H T U N G T R E N N U N G im-A C H T U N G T R E N N U N G ides [5] and methacrylates [6] ) and chiral monomers (isocyanides [7] and methacrylamides [8] ). The former helical polymers are dynamic in solution, and right-handed helices can change into left-handed ones and vice versa under certain conditions, while the helical conformations of the latter are more persistent.…”

Preparation of New Optically Active Polyamides Containing a L-Phenylalanine, Phthalimide Side-Chain via the Diisocyanate Route by Microwave Energy: Comparison With Conventional Heating

“…In polymer chemistry, the advantage of microwave-assisted reaction progress has also become a common field of investigation. Microwave energy is being studied as a technique to process resins, such as epoxides, polyesters, polyurethanes and, more recently, polyamides, due to the advantages of shorter processing time, improved energy consumption, and the potential for lower processing temperature and better product uniformity [1][2][3][4]. These reactions are very fast and completed within a short period of time.…”