Synthesis, chiroptical properties and photoresponsive behaviour of optically active poly[(S)-4-(2-methacryloyloxypropanoyloxy)azobenzene]

Synthesis and chiroptical properties of optically active photochromic methacrylic polymers bearing in the side chain the (S)-3-hydroxypyrrolidinyl group conjugated with thetrans-azoaromatic chromophore

“…However, it is reasonable to attribute this enhancement mainly to a larger presence of ordered chiral conformations in solution. It is also worth noting that the optical activity at the sodium D line exhibited by poly[(S)-MAP] in CHCl 3 solution is noticeably higher than those previously found for poly(MOSI) 4 and poly(MLO), 2 indicative of an important role played by the pyrrolidine moiety in this system. As expected, the optical rotation at 589 nm of poly[(S)-MAP-N] could not be measured, due to the elevated light absorbance of the conjugated chromophore.…”

“…19 The tacticity of poly[(S)-MAP] has been evaluated from the 13 C-NMR signals of methyl group, which displays two resonances located at 19.9 and 17.4 ppm, assigned to mr and rr heterotactic and syndiotactic triads, respectively. 20 The probability of formation of a meso dyad m (P m ) can be calculated from the ratio of peak areas (mr/rr), which corresponds to 2P m (1-P m )/(1-P m ), 2 i.e., to the ratio between the probabilities of formation of mr and rr triads. A value of 0.26 is thus found for P m .…”

“…Upon trans-cis photoisomerization, the exciton splitting progressively disappeared, finally giving rise to a single band that was attributed to incapability by cis-azobenzene chromophores to give exciton coupling through dipole-dipole interactions between the aromatic rings. By contrast, the CD properties of the homopolymer of trans-(S)-4-(2-methacryloyloxypro-panoyloxy) azobenzene [poly(MLO)] were indicative of a lower conformational homogeneity as compared to poly(MLA); this behavior was interpreted 2 as due to the absence in the former derivative of secondary amide groups favoring the establishment of interand intramolecular hydrogen bonds with consequent stabilization to a larger extent of dissymmetric conformations along the macromolecular chain.…”

Synthesis and chiroptical properties of optically active photochromic polymers with side-chainL-lactic residues connected totrans-azobenzene moieties bearing a reactive formyl electron-withdrawing group

“…It appeared therefore interesting to extend the above investigation to analogous polymeric derivatives bearing the optically active group linked to the trans-4-hydroxyazobenzene moiety [poly(MLO)], as well as to azobenzene chromophores possessing an electron-withdrawing group in the 49 position, in order to increase, through an internal charge transfer process, the extent of aromatic conjugation and hence the polarizability of the system, useful to produce materials potentially suitable for revers-ible optical storage, chemical photoreceptors and in general to non-linear optical applications 2) . Synthesis, chiroptical properties and photoresponsive behaviour of poly-(MLO) and its structural low molecular weight model compound have already been reported 3) . In the present paper we describe the synthesis and characterization of trans-poly[(S)-4-(2-methacryloyloxypropanoyloxy)-49-formylazobenzene] [poly(MLO-F)], which has been envisaged as a precursor of the corresponding derivatives bearing in the 49 position of the azobenzene moiety the electron-withdrawing (b-cyano-bmethylsulfonyl)vinyl group, in turn obtainable by reaction of the 49-formyl group with (methylsulfonyl)acetonitrile 4) .…”

Photo-polymers Containing (S)-Phenylalanine and Stilbene Pendants: Synthesis and Properties of Ionic Polyacrylates

“…Despite their structural diversity, such polymers are biocompatible and biodegradable, relatively nontoxic and easily metabolized by living tissues, making them useful for multiple applications that involve drug controlled-delivery agents, chiral recognition stationary phases, asymmetric catalysts, metal-ion absorbents, affinity-based separators and optobioelectronic devices [12][13][14].…”