Date of Award
Master of Science in Chemical Sciences (MSCB)
Michael Stollenz, PhD
Daniela Tapu, PhD
Thomas Leeper, PhD
Five novel bis(difluoroboryl)-bis(amidinates) L1-5(BF2)2 were synthesized in yields of 12−33%. Ethylene-linked bis(difluoroboryl)-bis(amidinates) represent an unprecedented class of new bifunctional fluorophores that have the potential to serve as air stable indicators and sensors for applications in medicine, materials science, and supramolecular chemistry.
The syntheses of the precursor bis(amidines) L1-5H2 were carried out through a proven three-step method of by treating 2 equivalents of pivoloyl chloride with ethylene diamine in CH2Cl2 to yield a bis(amide) as a colorless powder in 76% yield. The bis(amide) was subsequently reacted with 2 equivalents of PCl5 in CH2Cl2 to give the corresponding bis(imidoylchloride) as a yellow oil in 86% yield. Subsequent aminolysis with 2-aminopyridine, 4-methyl-2-aminopyridine, 6-methyl-2-aminopyridine, 4,6-dimethyl-2-aminopyridine, and 2-aminoquinoline yielded the polydentate bis(amidines) as colorless solids (61−71%).
L1-5H2 were stirred in toluene at room temperature with 2 equivalents of BF3∙OEt2 in the presence of excess trimethylamine to form L1-5(BF2)2 as colorless solids in 12−33% yields. Compounds L1-4(BF2)2 were characterized by NMR, IR, and UV-Vis spectroscopy as well as mass spectrometry and elemental analysis. For all four diboron-bis(amidinate) complexes, the molecular structures are presented. The photoluminescent properties of L1-4(BF2)2 were investigated by their excitation, and emission spectra, as well as quantum yield determinations and the photostability tests both in solution (THF) and in the solid-state.
Calderon-Diaz, Alvaro, "BIFUNCTIONAL BF2 COMPLEXES OF POLYDENTATE BIS(AMIDINATES): SYNTHESIS, STRUCTURES, AND PHOTOLUMINESCENCE PROPERTIES" (2021). Master of Science in Chemical Sciences Theses. 43.
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