Amino acids based on 2,4,5-triarylimidazoles: synthesis and evaluation as new chemosensors for ion recognition

Abstract

2,4,5-Triaryl-imidazoles have found application in medicinal chemistry due to their interesting photophysical properties (high fluorescence quantum yields and large Stokes shift's), for example as ligands for Pt(II) complexes, as probes of DNA structure or new therapeutic agents due to their capacity to bind or interact with DNA. Recently we reported the synthesis of several 2,4,5-tri(heteroaryl)imidazoles which could be used in diverse optical applications (e.g. nonlinear optics, fluorimetric chemosensors, OLEDs and DNA intercalators). Metallic cations can be complexed through N, O and S donor atoms in amino acids, at the main and side chains, and in aromatic heterocycles, whereas anion coordination, based on hydrogen bonding and electrostatic interactions, can arise from amino acid side and main chain OH and NH groups, or from NH groups in heterocycles. Therefore, the insertion of suitable heterocyclic systems at the side chain of natural amino acids can add extra functionality to the amino acid. We now report the synthesis and photophysical characterization of novel 2,4,5-triarylimidazolyl-alanines and the interaction study with biologically important ions such as F-, OH-, Cu2+, Fe3+ and Hg2+, through spectrophotometric and spectrofluorimetric titrations.