A rhodamine based dye for sensing of Group 13 metal ions

Search for a new reagent for the detection of a particular group members is of significant importance to the researchers of analytical and inorganic chemistry. We report here a rhodamine based compound, L1, for the colorimetric as well as fluorometric sensing of Group 13 cations in 10 mM HEPES buffer in (1:9, v/v) water:ethanol (pH = 7.4). L1 has been obtained from the condensation between rhodamine 6G hydrazide and 4-(4-fluorobenzyloxy)benzaldehyde and characterized by standard methods. Colorless L1 becomes pink in the presence of Al³⁺, Ga³⁺, In³⁺ and Tl³⁺ ions. Its absorbance increases at ∼530 nm considerably with these cations. L1 is nonfluorescent. However, it exhibits strong fluorescence enhancement at about 555 nm in the presence of Al³⁺, Ga³⁺, In³⁺ and Tl³⁺.Other metal ions fail to alter any significant change in abosrbance and fluorescence. Opening of spirocyclic ring of L1 occurs with the Group 13 cations followed by the strong complex formation to display its color change and fluorescence increment. Lifetime and quantum yield of L1 increase appreciably with the cations. Limit of detection values of the probe are in order of 10^-8 M indicating high sensitivity towards these cations. It has been utilized to sense these cations using river water. Thus, it may be concluded that L1 is effective to sense Group 13 metal ions.