Poly optical rotation

A unique chiral phosphine-phosphate ligand has been applied for hydrofor-mylation reaction of alkenes. In the case of 170 this ligand can be applied for obtaining poly(propylene-aZt-Co) with the highest molar optical rotation and with the highest molecular weight ([ ]d4 = + 40°, Mw = 104400, MJMn = 1.6) [284]. 

However, there will be a possibility of obtaining an optically active polymer when the polymerization proceeds by forming a tight helix of polymer chian and the helix is sufficiently stable in solution (26). This concept was first demonstrated with poly(tert-butyl isocyanide) [ = - ( ) ] (27). In this case, the polymer was resolved into two fractions of positive and negative optical rotations. This is not a vinyl polymer. The results of the copolymerization of (j3)-MBMA and TrMA prompted us to investigate the possibility of forming an optically active homopolymer of TrMA. 

All derived from poly(TrMA) were almost fully isotactic and showed almost no optical rotation. 

With heating from 5 to 45°C, thermal changes in conformation in the major /3-casein are observed by spectral methods (Garnier 1966). From measurements of the optical density at 286 nm and of the specific optical rotation at 436 nm, a rapidly reversible endothermic transition (AH 30 kcal/mole) with a half-transition temperature of 23-24°C is observed. The optical rotatory dispersion data suggest a decrease in the poly-L-proline II structure (12 to 5%) and a slight increase in a-helix (11 to 16%) with increasing temperature. This transition probably occurs prior to association, since it is rapid, and the carboxyacyl derivative of the monomer, which does not polymerize with increasing temperature, also demonstrates the optical rotatory disperson thermal transition. 

A poly[ 3-Asp(a-OiBu)]n (50) was prepared by Yuki et al.[32] by the polycondensation of the [3-4-nitrophenyl ester of a-isobutyl-L-aspartate [HCl H-Asp((3-ONp)-u-OiBu] (49) (Scheme 15). Some of the data recorded for the optical rotations of these polymers (and the monomer after hydrolysis of samples of the polymer) suggests that some racemization may have taken place during polymerization although the authors believe this not to be the case. For example, the addition of HOBt to the polymerization reaction appeared to result in an increased yield of 80% but the [a]D value dropped from approximately -15 in most cases to —7 under these conditions. Co-polymerization of HBr H-Asp((3-ONp)-a-OiBu and (3-Ala ((3-HGIy) under the same conditions yielded a co-polymer with a composition of 53 mol% 13-Ala and 47 mol% Asp(a-OiBu). 

To avoid any complications caused by the intermolecular association, Goodman (78) reinvestigated the optical rotation of the peptides in dimethyl formamide, since in this medium the specific rotation is independent of concentration. From the latter study it was concluded that at 25° C the spontaneous helix formation of poly-y-methyl-L-glutamate in dimethyl formamide is occurring at the critical range of 7—9 units. Extension of these studies (73 b, 79) led to a better understanding of temperature and solvent effects upon the helix-coil transition of oligomeric polypeptides. 

In spite of the above relationships between absolute structure of the monomer and sign of the rotatory power of the polymer, which are consistent with what has been found in poly-a-olefins, the relationships between optical rotation and structure in poly-vinyl-ethers are much more complicated than in the paraffins. 

However, as the optical rotation dispersion curves between 250 and 589 m/t of some poly-acrylic and poly-methacrylic esters seem to be anomalous1 relationship between optical activity and conformation in... 

The optical rotatory dispersion of poly-(+)-l-methyl-benzyl-methacry ate has been measured between 320 and 230 raft. The optical activity for polymer and model has values of the same sign and of the same order of magnitude, but the isotactic polymer seems to have a larger [M] than the syndiotactic and the atactic polymers [K. J. Liu, J. S. Lignowski, R. Ullman ACS Polymer Preprints, 6, 904 (1965)]. Optically active N-methyl-N-methylbenzyl-acrylamide and N-(n-propyl)-N-methylbenzyl-acrylamide have been polymerized by Kaiser and Schulz and the optical rotation dispersion between 589 raft and 365 raft has been... 

Section II, 4a. Optical activity and O.K.D. of (+)-tartaric acid salts of poly-2-vinyl pyridine having different stereoregularity have been determined the optical rotation between 578 m/r and 365 mfi of the salt of atactic poly-2-vinyl-pyridine is lower than that of the salt of the isotactic poly-vinyl-pyridine [R. C. Schulz and J. Schwaab Makromol. Chem. 85, 297 (1965)]. 

The order of decreasing capacity for reducing the optical rotation of poly-L-proline is181,216 ... 

In 1991, Newkome and Lin 121 reported a series of acid terminated poly(ether amido) dendrimers (e.g., 3, 4), generated from the tetraacid core (1) and sequential use of the amino acid building block 2 (Scheme 7.1). These acid-terminated dendrimers were readily transformed 131 into the related polytryptophane analogues (5-7) by treatment with tryptophane methylester hydrochloride employing a common peptide coupling procedure (DCC 1-HBT in DMF). 141 The resultant chiral cascade series was examined via ORD/CD and the preliminary data indicate a linear relationship between optical rotation and the number of surface tryptophane moieties. 

When the most common spiropyran SP-4 was mixed in poly(y-benzylglutamate) to prepare a film, a reversible change in optical rotation was observed upon 365 nm light irradiation and visible light irradiation [49], The largest Aa before and after UV irradiation at sodium D-line (589 nm) was 1.225° for 4 mol% concentration. It was supposed that the change might have arisen from the chiral interaction between the chiral polypeptide environment and the colored merocyanine. Indeed, an induced CD was observed. 

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... 

Conformations of the polymers were studied by CD and optical rotation measurements. Poly-L-lysine is known to exist in disordered, helical and -conformation, depending on the temperature, pH of the system and the solvent used. The side chain of the polymer has a significant effect on the backbone conformation. At neutral pH, poly-L-lysine exists in a random coil structure while at pH above 10, the e-amino group becomes a neutral form and the polymer undergoes transition to a helical structure. In order to elucidate the effect of base substituents on the conformation of poly-L-lysine, CD spectra of the copolymer were measured. 

Another important factor for the polymer conformation is the solvent effect. As the usual solvents for the copolymers in question are DMSO and DMF, which have absorption in the UV region, CD spectral measurements are impossible. However, the optical rotation measurements and analyses using the Moffitt-Yang equation give the Moffitt parameter bo for the copolymers (Table 21). Hie parameter is known to be related to the helix content of poly-(a-amino acids). The b0 value of polycarboben-... 

Hudson s rules of isorotation are used for the determination of the configuration at the anomeric centers in oligo- and poly-saccharides and Korytnyk has discussed some extensions of these rules. Reeves has demonstrated that studies of the optical rotation in cuprammonia solution can give valuable information on the types of linkages and also on the conformation of sugar residues in a polysaccharide. Bourne and coworkers have shown that some o- and /S-D-glycosidic linkages display characteristic absorptions in the infrared at 844 and 891 cm, respectively. 

Optically active poly[(isosorbide-co-bisphenol A) carbonate)], (11), was also prepared and consisted of 90% isosorbide and 10% bisphenol A with diphenyl carbonate and had an optical rotation of 140° with excellent scratch resistance. 

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