HPLC Characterization Method of A Chemosensing Ensemble for Histidine

Chemosensing ensemble, a fertile area, is elucidating the nature and dynamics of small molecules, such as amino acids, binding to DNA. In particular, the design of site conformation-specific probes, selective cleaving agents for mapping and fingerprinting, and the potential in drug design drive this work. Traditionally, work has focused on small interactive binders with extended π system heterocycles having high imidazolate and sometimes carboxylate affinity. A major difficulty of this chemosensor design has been the lack of a clear understanding of the receptor-guest interactions that play a critical role in performance when these are characterized by HPLC method. Covalent systems provide means of attaching amino acids that bind tightly enough to the metal complex-receptors. In this work, the two Cu¹¹ centers of the dimetalic complex of the bis-p-xylylBISDIEN was synthesized as a designed receptor for the recognition of histidine. This provides selective recognition of the ambidentate imidazole residue of histidine prepositioned at the right dictance within BISDIEN ligand. The characterization method reported in this paper is simple in its preparatory and determinative stages. While significant fluorescence quenching observed from the molecule upon binding with two Cu¹¹ to the imidazole residue of histidine caused a very low fluorescence emission detected from HPLC characterization, a high specific of nonfluorescent products were observed by the optimized chromatographic gradient elution coupled with a UV-DAD detector measured at 338 nm and an Hypersil ODS column were utilized for analysis. It has been demonstrated that the peak areas were proportional to the concentrations of our receptor, [L·6HBr-Cu₂¹¹], after the optimum gradient conditions were performed. Linearity of the calibration curve was also very good (r² = 0.984). Minimum concentrations of histidine detection at 0.5 mM of reduced and nonreduced receptors were 1µM and 0.5 µM, respectively with the specific retention time 1.93 min.

Keywords: HPLC method, Chemosensing ensemble, Histidine, Transition metal complex, Imidazole group.

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