Interactions of Phosphors in Glucose Glasses for Solid-Matrix Phosphorescence

Abstract

Quenching of the room-temperature solid-matrix phosphorescence (SMP), near-infrared spectrometry, differential scanning calorimetry, and a polarity probe were used to study interactions of heterocyclic aromatic amines in glucose glasses prepared using crystalline glucose and a glucose melt. A near-infrared spectrometry method was developed to determine the wt % moisture in the glucose glasses. The wt % moisture of the glucose glasses was then related to phosphorescence intensities and lifetime ratios of the heterocyclic aromatic amines. A modified form of the Stern–Volmer equation was used to describe the changes in phosphorescence intensity and lifetime ratios. In other experiments, the glass transition temperatures of the glucose glasses were determined using differential scanning calorimetry. The glass transition temperatures were then correlated to the SMP of the heterocyclic aromatic amines in the glucose glasses. Lastly, the micro-environmental polarities of the glucose glasses were studied using a polarity probe. From these results a model was developed that described the effects of several parameters on the glucose glass matrices. For example, water was able to diffuse through channels in the glucose glasses and cause dynamic quenching of the phosphorescence. Also, the hydrogen bonding network in the glucose glasses was disrupted by water. This resulted in matrix quenching of the phosphorescence signals.