Emission based sensing of phosphate ions and ATP via a newly synthesized Cu(II) chelated tetra N-phenyl carbazole porphyrin derivative

Abstract

In this work spectral properties and sensor characteristics of a newly synthesized porphyrin derivative were investigated by absorption, excitation and emission spectroscopy. We also treated this molecule as a metal-ion chelation based fluorescent probe and investigated its response for PO₄³⁻ and hydrolyzed adenosine triphosphate. Tetra-N-phenyl-carbazole-porphyrin derivative (TN-PCP) equipped with four symmetrical carbazole units via phenyl linkages exhibited high quantum yield in DMSO (Ф=0.55.1). We reported effect of the Cu (II) and Ag (I) ions on the fluorescence of the TN-PCP considering general sensor parameters including calibration studies, selectivity and LOD values. Metal chelation by Cu (II) and Ag (I) quenched the fluorescence of the probe with I₀/I₁₀₀ ratios of 20.1 and 2.5, respectively. Considering the higher magnitude and effectiveness of the Cu(II)-induced quenching, we tested some analytes that could restore the emission of Cu[TN-PCP], thereby signaling the analytes including chelating anions. Among them, phosphate ion exhibited an exceptional and selective response towards the Cu[ TN-PCP] complex at pH 12.0 in a buffered solution. We measured 14.0 and 2.0-fold increase in emission intensity of the dye at 360 and 687 nm, upon phosphate binding, respectively. Additionally, we reported a very promising and selective response for the ATP molecule (I₀/I₁₀₀ = 50.0) for a concentration range; 1.8*10⁻⁴ M −1.7*10⁻² M, at 420 nm, which can easily determine the ATP levels in bacteria, yeast, mammalian cells, muscle cells and even in intercellular spaces. The LOD value of the probe was found to be 2.1*10⁻⁵ M for the ATP molecule. We have also demonstrated that the proposed probe can be used as an emission-based sensor capable of exhibiting good detection limits for these two metal cations.