Sequential Recognition of Bisulfate and Acetate by a Ruthenium(II) Complex: Experimental and Theoretical Studies

Abstract

AbstractNew complex [RuLCl2(PPh3)] (L=N,N‐bis(2‐hydroxy‐5‐nitrobenzaldehyde)‐2,2’‐diaminodiethylamine) was prepared and characterized analytically and was employed as a luminescent chemosensor for the detection of anions. The results show that [RuLCl2(PPh3)] can detect HSO4− and AcO− selectively and in sequential order in H2O‐CH3CN (8 : 2, v/v) at pH 7.0. The spectral binding, titration, and interference analyses reveal that the addition of HSO4− to [RuLCl2(PPh3)] results in an intense fluorescence emission (IF/I0=6.55). This shows that HSO4− interacts suitably with the complex to switch ON the fluorescence which could be explained by inhibition of a PET mechanism as the above addition forms [RuLCl(HSO4)(PPh3)] in the excited state. Selectivity interaction of complex [RuLCl2(PPh3)] with HSO4− results in the formation of [RuLCl(HSO4)(PPh3)] in water but the system exhibits negligible change in its emission except for AcO−, which enhances fluorescence intensity. For the addition of AcO− to [RuLCl2(PPh3)], the system [RuLCl(AcO)(PPh3)] is formed, however, the adding of HSO4− to [RuLCl(AcO)(PPh3)] does not show any change in the intensity, suggesting that there exists a logic gate function for the addition of HSO4− followed by AcO− to [RuLCl2(PPh3)]. This finding is interesting because [RuLCl2(PPh3)] can act as a fast selective chemosensor for the sequential detection of HSO4− and AcO−.