ASSOCIATION OF CHLOROPHYLL WITH AMIDES ON PLASTICIZED POLYETHYLENE PARTICLES—I. N, N‐DIMETH YLM YRISTAMIDE*

Abstract

Abstract— Model systems have been prepared in which chlorophyll a (Chl a) and N.N‐dimethylmyristamide (DMMA) are adsorbed together in various ratios to particles of polyethylene swollen with undecane. The adsorption is performed by equilibrating the particles with methanol‐water solutions of increasing water content. Absorption spectra of the coated particles in viscous suspenions show sharp well‐marked bands over much of the composition range examined. With the aid of second derivative spectra. the red absorption band has been resolved into three components. at 661.5. 674 and 680 nm. Fluoresccnce spectra have also been resolved into their principal components with some assistance from comparison with spectra of Chl in undecane solution containing DMMA. At room temperature (295 K) the resolvable components are of monomeric Chl at 670 nm. and of associated species at 681 and 725 nm. Fluorescence at 77 Kis of similar intensity but is distributed differently. in favor of longer‐wave components. Corresponding to the 295 K components are emission bands at 675, 683–5 and 735 nm. Othcr components appear under certain conditions: at 695–700 nm when the Chl and DMMA conccntrations are both high, and at 705 nm whcn the ratio of DMMA to Chl is low. If DMMA is absent or at low concentration, much of the Chl exists as an aggregated form absorbing near 741 nm and fluorescing weakly near 760 nm at 77 K. Adsorption isotherms indicate some degree of cooperativity in the binding of Chl and DMMA to the particles. The photoreduction of p‐dinitrobenzene by hvdrazobenzene. scnsitized by these particles, has been demonstrated