Chiroptical properties of 6-0-.alpha.-(1-naphthylmethyl)-2,3-di-0-pentylcellulose

Abstract

A novel specifically substituted polymer, 6-0-a-(l-naphthylmethyl)-2,3-di-0-pentylcelIulose ((MeNp)(Pe)C), has been synthesized and characterized. This cellulose derivative forms a chiral nematic thermotropic liquid crystalline phase that exhibits a reflection band in the visible region of the spectrum. The naphthyl chromophores attached to the cellulose backbone exhibit chiroptical activity in both dilute solution and the liquid crystalline phase. The sign and magnitude of the observed circular dichroism were found to differ in the isotropic and chiral nematic phases. Dilute-solution circular dichroism studies indicate that the naphthyl chromophores may be arranged in a helical arrangement along the cellulose backbone.

Spectroscopic studies of the conformational properties of naphthoyl chitosan in dilute solutions

“…The contributions of the C2, C3, and C5 chiral centers to the induced CD have been confirmed to be very small 17–19. Therefore, CD signals observed in substituted polysaccharides are generally assumed to be induced from a chromophore absorbance under the asymmetric interaction of the helical main chain 20–23. As far as naphthoyl chitosan is concerned, the observed transition moments are separated from the nearest chiral center by more than three bonds and are able to adopt many configurations with respect to the chiral center because of the rotation of the joining bonds.…”

New approaches to advanced polymers by selective cellulose functionalization

“…A problem of high actuality with polymer solutions in general is the formation of liquid crystalline (LC) phases, i. e., lyotropic or thermotropic mesophases, in relation to polymer primary structure and concentration, solvent composition and temperature, and the characterization of these mesophases predominantly by optical and rheological techniques [39,40,97,981. In connection with cellulose, the relevance of liquid crystalline phases in thread formation by spinning processes is still an open question, widely discussed at present regarding cellulose dissolved in amine oxides or cellulose acetate solutions in various solvent systems.…”

Cellulosic Liquid Crystals

“…Both thermotropic and lyotropic systems exhibit cholesteric phases with a righthanded helicoidal supermolecular structure, [82] Trialkyl ester of (tri-0-carboxymethyl) cellulose (CMC) [83] Oligocellulose derivatives [84, 31 tri-0-(2-methoxyethoxy)ethyl cellulose, 6-0-a-( l-methylnaphthalene)-2,3-0-pentyl cellulose [68] tri-0-heptyl cellulose (DP = 11) right-+ left-handed right-handed, biphasic right-handed banded texture leading to cellulose and exhibit excellent ORD and CD spectra (Fig. 23) [Eq.…”