From Molecular Design to Supramolecular Design:  Synthesis and Size-Selective Coordination Chemistry of 1,2-Bis(2'-pyrazineethynyl) Benzene


The synthesis and coordination chemistry of 1,2-bis(2‘-pyrazineethynyl)benzene are presented. With four Lewis base sites, the ligand may adopt a conformation in which two nitrogen atoms face inward and two nitrogens face out. In this conformation, it may complex transition metal cations either "internally" or "externally". An "internal" 1:1 complex is formed with silver(I) nitrate, while the larger dicopper(II) tetraacetate moiety does not fit in the internal cavity and is thus externally coordinated by two separate ligands as a 2:2 coordination complex. When mixed with 1 equiv each of silver(I) cation and copper(II) acetate the ligand selectively complexes the cations and a coordination complex with two "internally coordinated" silver(I) cations and an "externally coordinated" dimeric copper(II) acetate moiety is obtained. Self-assembly with 1 equiv of silver(I) nitrate and 2 equiv of copper(II) acetate results in the formation of a mixed-metal coordination polymer with alternating silver and copper centers. In the presence of an excess of silver(I) cations, an infinite one-dimensional coordination polymer is formed with one "internal" and one "external" silver(I) cation.


Chemistry and Biochemistry

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conformation, organic compounds, anions, ligands, cations

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Journal Title

Crystal growth & design