Highly selective and sensitive fluorescence reporter for toxic Hg(II) ion by a synthetic symmetrical azine derivative

A symmetrical azine derivative, N,N′-Bis(imidazo[1,2-a]pyridine-2-ylmethylene hydrazine (sensor L) has been synthesized and its fluorescence sensing potential towards metal ions has been demonstrated using simple fluorometric technique. The sensor shows high fluorescence selectivity and high sensitivity towards Hg2+ ion in aqueous-methanol media. Only Hg2+ ion is found to effectively enhance fluorescence quantum yield of the nearly non-fluorescent sensor. The sensor can effectively distinguish Hg2+ from Cd2+ or Zn2+ ion within the same group via different mechanistic pathway i.e. chelation enhanced fluorescence (CHEF) effect for Hg2+ ion and charge transfer (CT) mechanism for Cd2+ or Zn2+ ion. Experimental spectral properties have been correlated with theoretical calculation based on Density Functional Theory method.