Date of Award

1-1-2011

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Chemistry

Content Description

1 online resource (xvii, 201 pages) : illustrations (some color)

Dissertation/Thesis Chair

Marina A Petrukhina

Committee Members

Evgeny V Dikarev, Eric Block, Paul J Toscano, Igor K Lednev

Keywords

carboxylates, copper(I), photoluminescence, X-ray diffraction, Copper compounds, Photoluminescence

Subject Categories

Chemistry

Abstract

Polynuclear copper(I) carboxylates exhibiting rich luminescent properties and a remarkable structural diversity have been the main focus of this investigation. In spite of the well-developed methods of copper(I) carboxylates synthesis, only a handful of complexes have been crystallographically characterized prior to our work. Notably, they all demonstrate different structural arrangements in the solid state. This dissertation describes the work that has been carried out towards the synthesis of new copper(I) carboxylates, the study of their molecular and solid-state structures, and their solid-state photoluminescent (PL) properties. In this work, we have prepared a series of new copper(I) carboxylates of the general formula [Cun(O2CR)n] (n = 2, 4, 6, and ∞) with a variety of bridging carboxylate ligands. To avoid problems of disproportionation, hydrolysis, and oxidation of copper(I) carboxylates in solution, we used the micro-scale gas phase deposition technique for crystal growth in a solvent-free environment. On several occasions, the solution-phase approaches of crystal growth were also successfully applied. This allowed us to significantly expand the number of new copper(I) carboxylates isolated in the form of bulk single crystalline materials. The newly prepared copper(I) compounds have been investigated by X-ray diffraction methods to reveal novel structural types and to add new members to the known types. The influence of electrophilic substituents of several aliphatic and aromatic bridging carboxylates on the resulting solid-state structures has been carefully examined. An unprecedented example for the reversible [Cu4] ↔ [Cu6] core interconversion was revealed after different crystal growth conditions have been tested and successfully yielded variable crystalline products for a given metal-ligand combination. Furthermore, the use of single X-ray diffraction allowed us to detect a temperature-induced reversible single-crystal-to-single-crystal phase transition. All prior structurally confirmed copper(I) carboxylate complexes created an illusion that a specific structure is related to a particular carboxylate ligand. In this work, we confirmed the existence of several structural possibilities for a given carboxylate group. For example, the structures of known copper(I) carboxylates can be additionally varied by changes in the preparation or crystallization conditions. Overall, while copper(II) carboxylate chemistry is dominated by a dimetal paddlewheel structural type, the copper(I) carboxylate class of compounds exhibits a unique structural diversity ranging from discrete to infinite motifs based on mono-, di-, tetra-, or hexanuclear copper(I) cluster cores. Moreover, multiple intermolecular interactions of the types Cu***Cu, Cu***O, and Cu***π between the clusters are responsible for variable solid-state packing arrangements. The implications of structural variations on photoluminescent properties of new copper(I) carboxylates have been also investigated. The controlled on/off switch of axial copper-oxygen interactions on the structural outcome and the resulting photoluminescent behavior was also studied. Importantly, the experimental results accumulated in this work clearly illustrate the crucial role of both the copper(I) core structure and the solid-state interactions on the resulting photoluminescent behavior. The importance of correlating the measured PL properties with the solid-state structures of products is revealed in this work.

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