engleski

Novel adamantane-dipyrromethanes and their anion binding properties

In the scope of our research on the synthesis of the macrocyclic compounds capable of selective recognitions of different guest molecules (1), we turned our attention to preparation of anion sensors. Anions play key roles in wide range of chemical and biological processes and it is of great importance to design suitable molecular receptors that can recognize and bind anions. A significant number of molecules wich are used as anion sensors are composed of pyrroles which can serve sa binding subunit due to presence of acidic NH proton to which anion can be attached by the hydrogen bonds. Since it was shown that the presence of two NH protons is enough to accomplish binding of an anion with sufficient binding constants (2), we choose to investigate the applicability of dipyrromethanes as anion binding agents. Herein we report the synthesis of four new adamantane-dipyrromethane derivatives (AdD) 1-4, as well as investigation of their anion binding properties. It was anticipated that incorporation of the bulky adamantane would hinder rotational mobility of the pyrrole moietes in the AdD resulting in the increase of the stability of the complexes with anion, as compared to the dipyrromethane bearing aromatic phenyl subdtituent in the meso position (5-phenyldipyrromethane). Moreover, adamantane derivatives are characterized by lipophilicity which may provide the potentional applicability of the AdD molecules as anion extracting agents. In this study we also present the result s of the binding with 5 anions: F-, Cl-, Br-, HSO4- and H2PO4-. Stability constants for the complexes with F- anion are much larger then for the other anions.

Adamantane-dipyrromethanes; aninon binding; 1H-NMR titrations

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