Novel Aza-BODIPY based turn on selective and sensitive probe for on-site visual detection of bivalent copper ions

Abstract

3-Ethoxy-N,N-diethylaniline substituted aza-BODIPY dye (7) was designed and synthesized that could recognize Cu (II) ions through sequential binding interactions. The visible changes in the absorption and enhancement in fluorescence intensity with the addition of Cu (II) ions makes this dye as a selective and sensitive probe for on-site visual detection and analysis. The presence of 3-ethoxy-N,N-diethylaniline group at the peripheral positions shifted its absorption to the near-infrared region, ca. 640–890 nm of the electromagnetic spectrum. This dye showed a gradual shift in the absorption maximum towards red with the increase in polarity of the medium. The triplet excited state properties of this dye suggest that it shows negligible singlet oxygen generation efficiency. The dye possesses excellent photostability, low fluorescence quantum yields, sharp absorption bands in the near-infrared region (NIR) and exhibits selective interactions with Cu(II) ions. The limit of detection was found to be as low as 350 nm and selectivity was not interfered by other metal ions and anions, thereby demonstrating its use as a novel probe for the detection and analysis of copper ions through visual absorption changes and ‘turn on’ fluorescence intensity.