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theses

This dissertation covers the synthesis and characterization of three unique classes of lanthanide materials produced exclusively by the addition of sodium azide (NaN3) into solution based lanthanide reactions. The products were achieved through transmetallation and redox reactions between rare earth chalcogenolate reagents (Lnx(EPh)y), NaN3 and elemental chalcogenides (E = O, S, Se, Te). The products displayed atypical structural and physical properties including; unique coordination geometries, high nuclearities, tunable detonation/deflagration, strong NIR emissions, and unexpected magnetic ordering behaviors. The introduction of NaN3, Na2O, Cd, elemental Se and Te into Ln (EPh)2 and Ln(EPh)3 pyridine (py) solutions led to the production of (py) 2Na2(EPh)2 and 5 structurally distinct azide encapsulated rare earth clusters; (Py)10Sm6O2(N3)16Na2, (py)8Ln6O2(N3)12(SePh)2, (py)10Ln6O2(Se2) 2(N3)10 (Ln=Er, Ho), and (py)16Sm8Se(O2)Na2(Te2)6(N3)8. Each system was encapsulated by a variety of azide bridging moieties, while exhibiting a [Ln]/[N3] dependent correlation with detonation and deflagration temperatures. ! The inclusion of NaN3 in Ln(SePh)3 pyridine solutions with elemental Se, led to the discovery of the (py)16Ln17NaSe18(SePh)16; (Ln= Ce, Pr, and Nd). Emission studies of the Nd17 analogue, revealed a 35% quantum efficiency for the 4F3/2 - 4I11/2 transition (1070 nm emission), and a near solid state emission intensity for the 4F3/2 → 4I15/2 transition (1822 nm emission). The novel Eu(EPh)4Na2•2DME; (E=S,Se), specimens were synthesized by the combination of Eu(EPh)2 with NaN3 in dimethoxyethane (DME). The europium coordination sphere was solvent free and resembles the coordinations of europium monochalcogenides (EuE). Comparative structural analysis and magnetic susceptibility studies of the Eu3+ product, ((py)6Eu2(μ4-S2)2(OC6F5)2) revealed paramagnetic ordering at low temperature for Eu(EPh)4Na2•2DME; (E=S,Se), while ferrimagnetic ordering was found for ((py)6Eu2(μ4-S2)2(OC6F5)2). All materials exhibited antiferromagnetic ordering above 50 K, while a Curie temperature of 18.0 K was determined for ((py)6Eu2(μ2-S2)2-(OC6F5)2).

ETD_4562

Ph.D.

Includes bibliographical references

Includes vita

by Brian Freeman Moore

http://hdl.rutgers.edu/1782.1/rucore10001600001.ETD.000068918

doi:10.7282/T3QC023K

ETD doctoral

The author owns the copyright to this work.