Synthesis of a Novel Fluorescent Optical pH Sensor

ABSTRACT: In today’s high technological applications organic materials were widely employed in many sensing architectures. Plenty of ongoing research shows the importance and necessity of smart organic compounds with profound optical, photophysical, and electrochemical properties to apply in the industry. Perylene dyes are well known dyes with unique optical properties in conjunction with outstanding stabilities and are widely applied in many photonic applications. Benzopurpurin 4B is a purpurin derivative known as a textile dye has a pH sensing ability. The combination of these two interesting materials led to an excellent fluorescent optical pH sensor with great characteristics. Here in, we report the design, synthesis and characterization of a novel fluorescent optical pH sensing perylene derivative (Di-N-(4-hydroxyphenyl)-3,4,9,10-perylenetetracarboxy monoimide chrmophores containing benzopurpurin-4B) based on a perylene monoimide, N-(4-Hydroxyphenyl)-3, 4, 9, 10-perylene tetracarboxylic-3, 4-anhydride-9, 10-imide (OH-PMI), and benzopurpurin 4B. The synthesized compound was well characterized by FTIR, Mass, Elemental, UV-vis, Emission, DSC, and TGA techniques. BP-OHPDI has shown interesting pH sensing property in addition to the high thermal stability. It has shown mostly two colors at day light; violet in acidic solutions (pH=1–3) and pink-violet in organic solvents with a gradual increase in pH (up to 9). On the other hand, in sulfuric acid (pH=0) the color of the solution is dark blue. Under UV light at 365 nm, except in acidic solutions the color was mostly fluorescent yellow and fluorescent greenish-yellow. Interestingly, in acidic solutions under 365 nm, the color was intense orange. On the other hand, in sulfuric acid intense red color was observed. Keywords: Perylene, benzopurpurine 4B, pH sensor, plasma stain. ……………………………………………………………………………………………………………………………………………………………………………………………………………………