Selective Fluorescent Sensing of Adenine Via the Emissive Enhancement of a Simple Cobalt Porphyrin

Porphyrins absorb strongly in the visible region and are also excellent fluorophores that emit in the visible region that make them excellent candidates for fluorescence sensing and in vivo imaging. This work describes the fluorescence determination of adenine using cobalt complex of a simple porphyrin. Tetraphenylporphyrin (TPP) and tetraphenylpophyrinatocobalt(II) (CoTPP) were synthesized and characterised. TPP on metallation with cobalt resulted in the red shift of fluorescence emission in the region 652 nm and 716 nm and showed an enhancement in the emission peaks with the addition of the nucleobase, adenine. CoTPP is found to be an efficient fluorescent sensor for adenine in DMF solvent. The fluorescence enhancement is due to the formation of the ground state complex formation between adenine and CoTPP, which is supported by experimental evidences from UV- visible spectra, time resolved fluorescence life time measurements etc. The detection limit of adenine was found to be 4.2 μM using the CoTPP fluorescent probe. The proposed sensor is found to be highly selective for adenine in presence of other nitrogen bases like guanine, cytosine, uracil, thymine, alanine, histidine etc. in 1:1 concentration.