Mechanisms of excited-state structuring in the Diamond™ Nucleic Acid Dye molecule induced by enhanced local charge distribution in rigid matrices

We demonstrate that by modulating the medium's viscosity and employing rigid matrices, the dynamics of excited states in complex molecular systems can be effectively controlled. Furthermore, we show that restricting the intramolecular degrees of freedom of nucleic acid dyes significantly alters their emission parameters, enabling precise control over the fluorescence efficiency of Diamond™ Nucleic Acid Dye (DD). Our results indicate that the DD dye aggregates only in specific environments and that matrix viscosity significantly affects fluorescence intensity. Moreover, we point out that for a reliable spectroscopic analysis, it is necessary to account for the dye's local charge distribution. These hypotheses were experimentally validated using both steady-state and time-resolved methodologies, including analyses of fluorescence intensity decay profiles and anisotropy parameters. The experimental observations are further supported by numerical calculations developed on the Rhodamine 6G molecule (R6G) used as a reference xanthene model to describe the proposed physical processes in rigid systems.