Development of Red Dye Based Optical Filters for Blocking Harmful Ultraviolet Radiation.

Far-ultraviolet radiation poses significant health and environmental risks, so developing effective attenuation methods is essential. This study explores the potential of red dyes as optical filter materials which can block harmful far-ultraviolet radiation while allowing visible light to pass through. A series of red dyes including congo red, methyl red, neutral red, phenol red, and carminic acid were subjected to detailed spectroscopic analysis to evaluate their absorption capabilities in the far-ultraviolet range. Dyes with extended π-conjugation and azo groups, such as congo red and methyl red, showed strong absorption below 250 nm. Additionally, the presence of electron withdrawing groups and disrupted conjugation was found to enhance far-ultraviolet attenuation through hypsochromic shifts. Fluorescence analysis revealed excimer formation, which results from π-π stacking interactions. These results suggest that red dyes hold promise as effective components in optical filters for far-ultraviolet protection applications.