ROOM-TEMPERATURE PHOSPHORESCENCE OF AMORPHOUS METAL-COMPLEXES OF ALIPHATIC CARBOXYLIC-ACIDS WITH BASIC-AMINO-ACIDS

Luminescent materials have been prepared from aqueous gels of metal sa lts of dicarboxylic and some monocarboxylic acids with the basic amino acid lysine and its related amino acids ornithine and diaminopimelic acid. The development of an amorphous structure is required for room-t emperature phosphorescence in the solid and is dependent on various fa ctors including stoichiometry, metal type, and the size of the organic acid. Studies with commercial grades of lysine prepared from various sources and magnesium oxide or zinc oxide as the metal oxide indicate that linear aliphatic dicarboxylic acids of three to six carbons in le ngth produce maximal emission. For a given chain length the photolumin escence intensity decreases with cation radius according to Li > Na > K for alkali metals and Mg > Ca > Sr > Ba for alkaline-earth metals. D evelopment of intense fluorescence and phosphorescence emission correl ates to noncrystalline structures, and based on the given method of pr eparation, phosphorescence was not obtained with crystalline products. The simple and rapid preparation of this new biological glass provide s a matrix for the further investigation of the photophysics of organi c compounds of biological interest and their interactions with differe nt molecular environments,