Date of Award
Bachelor of Science
Marina A. Petrukhina
Metal wires are a linear arrangement of metal centers that conduct electrical current. Linear polynuclear metal clusters are of great importance for the design of metal-rich nanomaterials and the development of theories describing metal-metal bonds. Theoretical work on metal strings is valuable in understanding their properties and discovering their potential applications as molecular wires. Linear metal atom chains can be ligand supported or unsupported. The anions of polypyridylamines have been used extensively to support linear metal chains. However, due to challenges involving the synthesis of these ligands, the longest metal chain reported contains nine metal atoms. Examples of unsupported extended copper chains emphasize the crucial role of cuprophilic interactions in supporting these strings. Also based on CuCu contacts are the infinite helical arrangements of carboxylate bridged copper(I) ions in Cu(I) pivalate and Cu(I) 3,5-bis(trifluoromethyl)benzoate. Among carboxylates, the 2,4,6-triisopropylbenzoate ligand is known to be sufficiently bulky to prevent self-association of dinuclear paddlewheel units. Therefore, it was selected in this work to bridge copper(I) centers and favor CuCu over CuO interactions. The result was the copper(I) 2,4,6-triisopropylbenzoate compound with a remarkable structure which was not known before for this class of compounds: an infinite linear arrangement of copper(I) ions bridged by the carboxylate ligand. We were successful in isolating two polymorphs of this new extended chain of copper atoms: a “linear” wire and a “zigzag” chain held together by cuprophilic interactions. This allowed us for the first time to study the structure-photoluminescence correlations for two polymorphs of the same chain of metal atoms. Solution crystallization from o-dichlorobenzene resulted in the fragmentation of the infinite string to a nonluminescent dicopper(I) complex. This study has revealed remarkable structural variations that can be found for carboxylate complexes having the same bridging ligand and the same empirical formula. The consideration of photoluminescent behavior for the structurally diverse copper(I) 2,4,6-triisopropylbenzoate products revealed that emission wavelengths and intensities depend not only on the overall structural type, but show great sensitivity to the subtle differences in spatial distribution of Cu(I) atoms.
Dubceac, Cristina, "Cu(I) Wires: Structural Polymorphism and Photoluminescence" (2011). Chemistry. 2.