Effective fluorescent chemosensors for the detection of Zn2+ metal ion

Benzimidazole derivatives synthesized from three components assembling condensation reaction behaves as a selective fluorescent sensor for Zn2+ metal ion. These benzimidazole derivatives were characterized by 1H, 13C NMR, mass and elemental analysis. XRD analysis was carried out for 1-(4-methylbenzyl)-2-p-tolyl-1H-benzo[d]imidazole. The increase in the fluorescence enhancement can be explained on the basis of photo induced electron transfer (PET) mechanism. The blockage of the photoinduced electron transfer process from benzimidazole ring to aryl fluorophore induced by Zn2+ co-ordination induced emission enhancement.

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► Photo induced electron transfer (PET) mechanism plays main role.
► FT-IR spectra confirm the binding of ligand with Zn2+ metal ion.
► In the case of Pb2+, Fe2+, Co2+, Ni2+, Ca2+ and Hg2+ metal ions the fluorescence enhancement is very low.
► Crystalline benzimidazole derivatives (5) are triclinic crystal.