Synthesis of Novel Dibenzo‐18‐crown‐6‐ ether‐Functionalized Benzimidazoles and its Applications in Colorimetric Recognition to Hg 2+ and as Antifungal Agents

New crown ether‐functionalized benzimidazoles was designed and synthesized via formylation of dibenzo‐18‐crown‐6 followed by condensation with different o‐phenylene diamines. The complexation properties of crown ether‐functionalized benzimidazoles with various metals (K + , Ca 2+ , Ba 2+ , Co 2+ , Hg 2+ ) were examined using UV–vis spectroscopy. Hg 2+ showed a well‐defined peculiar absorption maximum at 366 nm exclusively. All these newly synthesized compounds were screened for antifungal activity against Aspergillus niger and Aspergillus oryzae , respectively.