ISSN-1996-918X Pak. J. Anal. Environ. Chem. Vol. 8, No. 1 & 2, (2007) Computational Evaluation of N,N-Dimethylaminophenyl Methyl Ether and Crown Ether for Metal Selective Sensor Development Margarita Dunina-Barkovskaya 1 , D. Max Roundhill 2 , Shahabuddin Memon *3 , M. I. Bhanger 3 and Mustafa Yilmaz 4 1 Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, TX 79409-1061 USA 2 Present address at Chem. Consulting, 13325 Black Canyon Drive, Austin, TX 78729-7481 USA 3 National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro-76080, Pakistan 4 Department of Chemistry, Seluk University, Konya-42031, Turkey -------------------------------------------------------------------------------------------------------------------------------------------- Abstract The present computational study describes some representative contributions in metal selective sensor development. During the course of study, charge densities have been calculated for a series of dimethylamino methyl ether and crown ether metal complexes. For the dimethylamino methyl ether metal complexes the charges on ether oxygen and amine nitrogen have been calculated for both the free dimethylamino methyl ether and its metal complex. Similar calculations have been carried out for crown ether metal complexes and dimethylamino crown ether metal complexes. The metal ions have been chosen because they cover a wide range of charge densities as well as having strategic significance. Therefore, their extraction, separation, purification and analytical determination are of continuing importance. However, for the crown ether metal complexes the charge on the metal ion and, for the dimethylamino crown ether metal complexes, as well as the charge on metal ion and on the dimethylamino nitrogen in the complex are calculated. The change in charge on the dimethylamino nitrogen after complexation of the ether oxygen(s) is presented and discussed with respect to the combination of a crown receptor and an alkylamine reporter being an effective system for the design of a chemosensor. Keywords: calixarene, N,N-dimethylaminophenyl methyl ether, crown ether, metal complex, cation charge, chemosensor. ------------------------------------------------------------------------------------------------------------------------------- Introduction Computational approaches have been successfully used as a powerful tool to obtain valuable insight into the reactivity and mechanism of several synthetic reactions of high interest. Chemosensors for metal ions have both receptor and reporter combinations that act in a complementary manner [1-4]. The receptor functions to bind the analyte, and the reporter signals this binding event. In order for selectivity to be achieved, the receptor must have specific binding properties, and the reporter must effectively communicate with the receptor. One strategy to achieve this complementary goal is to design a receptor-reporter combination that is in a coupled electronic conjugation via a -system. However, such a chemosensor system 1 has been found to be selective for calcium(II) over other metal ions. This chemosensor has a calixcrown receptor and a conjugated azo system as the reporter. The function of this chemosensor can be explained on the basis of charge effects whereby the calixcrown complexed metal ion induces a charge in the electronic structure of the reporter 2, resulting in a change in its charge density distribution and its electronic spectrum [5]. If such an explanation is valid, complexation of metal ions having different sizes and charges should lead to different charges at the metal center and any heteroatoms that are present on the complexant. Such a model should have generality, and not be limited to calixcrowns. Both simple ethers and crown ether *Correspondence Author E-mail: shahabuddinmemon@yahoo.com