Molecules, Clusters, and Solid State Compounds with Lanthanide-Chalcogen Bonds

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This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Professor John G. Brennan at Rutgers University to synthesize, characterize, and interconvert molecules, clusters, and solid-state compounds containing lanthanide (Ln) metals and the heavier chalcogens (E2-, EE2-, EPh-; E = S, Se, and Te). A number of new ligand systems will be used, including the ionic fluorides and more covalent hydrides, nitrides, and phosphides, as well as some increasingly complicated heteroligand and heterometallic systems. A long-term goal is to understand the relationships between the chemical bonding and physical properties of molecular, cluster, and solid state Ln systems. This will be accomplished by studying how lanthanide cluster properties vary as a function of cluster size. A second goal is to understand the chemistry and physical properties of increasingly complicated cluster systems in order to rationally design clusters with desired properties. The variety of ligands affords the opportunity to systematically balance charge, vary solubility, control air sensitivity, and influence Ln- Ln distances in cluster frameworks. Molecules and clusters with Ln-E bonds exhibit extraordinary near infra-red emission characteristics with the feasibility of using these compounds as amplifiers in polymer based optical fibers. Some of the proposed clusters are ideal candidates for doping Ln into polymer-based optical fibers, because they have properties that are a blend of the characteristics of solid-state Ln materials (high Ln concentrations, high quantum efficiencies) and those of molecular compounds (solubility in organic solvents, optical transparency). A select series of molecular Ln(ER)3 compounds are also proposed. Compounds with highly electropositive tellurium based anions have been chosen because they will provide fundamental information regarding the nature of the Ln-E bond. Fluorinated R groups (i.e. SeC6F5) are introduced to form soluble and highly emissive molecules. Chelating ligands (i.e. 2-Se-NC5H4) are expected to give volatile Ln(ER)3 compounds that deliver Ln2E3 thin films in chemical vapor deposition processes. The proposed molecules and clusters are members of the most efficient class of near-IR emitting Ln compounds reported to date, which is vital to the development of organic-polymer based optical fibers. Graduate students will be exposed to a technically demanding, multidisciplinary research experience with clearly defined industrial applications and will be involved in chemistry events at local high schools. Undergraduates are also consistently active in the laboratory, and most of these students continue on to graduate school or jobs in local industries.