Dissertation Defense: Amanda Ley

Candidate Name: Amanda Ley

Major: Chemistry

Thesis Advisor: K. Travis Holman, Ph.D.

Title: Heterogenization of Metallocyclopentadienyl Precatalysts through Ligand Functionalization for Incorporation into Metal-Organometallic Frameworks

Heterogenization of metallocyclopentadienyl ([CpxMII]+, M = Ru, Fe) precatalysts is explored through introduction to Metal-Organic Frameworks (MOFs) using [CpxMII]+-functionalized organic ligands. Such precatalytic moieties are known to be photoactivated by ultraviolet irradiation to give well-known and versatile catalytically-active species that aid in a variety of organic transformations including carbon-carbon bond formation. Different methods of introducing these precatalysts to MOFs is investigated.

Firstly, synthesis of [Cp*MII]+-functionalized linear aryl dicarboxylates (Cp* = 1,2,3,4,5-pentamethylcyclopentadienyl anion, M = RuII) via direct facial metalation is reported, with particular focus given to functionalization of extended aryl dicarboxylate 1,4-biphenyldicarboxylic acid (H2BPDC). Additionally, the zwitterionic [(Cp*Ru)2BPDC] ligand is substituted into known polymers of 4,4’-bipyridine (bpy) and geometric differences that result from ligand substitution in the resulting polymers is discussed. Facial metalation of 4,4’’-terphenyldicarboxylic acid (H2TPDC) is also attempted, though control over product formation is limited.

Secondly, synthesis and incorporation of facially-metalated functionalized ligand
[(CpM)(TPA)]- (Cp = cyclopentadienyl anion, M = FeII, RuII, TPA = terephthalate) into MIL-101
(MIII(μ3-O)(RCO2)6(L)3]X), a MOF with high native porosity, is investigated. [(CpM)(TPA)]- is
introduced to framework synthesis in mixed-ligand fashion along with unfunctionalized
NH2TPA2- (NH2TPA) = aminoterephthalate) to give a variety of permanently porous metal-organometallic frameworks (MOMFs) with incorporation of functionalized ligand ranging from 1% to 33%. [(CpM)(TPA)]- incorporation and its effect on framework porosity is discussed in terms of internal surface area and total internal pore volume, and the effect of framework geometry on incorporation and porosity is also explored. Attempts at photoactivation of a resulting framework demonstrate framework stability under ultraviolet irradiation, though evidence of generation of any desired catalytic species is not seen.

Finally, synthesis of a terphenyldicarboxylate ligand bearing a covalently-tethered precatalytic metallocyclopentadienyl ruthenium moiety is achieved through reaction of a pendant-arm bearing [Cp*OHRu(benzene)]+ moiety with a substituted terphenyldicarboxylic acid. Three analogues of the ligand are also synthesized and characterized and their behavior under UV irradiation studied. The functionalized ligand is successfully incorporated into two known MOFs, and the behavior of the resulting frameworks under ultraviolet irradiation studied. Evidence for successful photogeneration of the desired catalytic species is discussed.

Friday, July 5, 2019 at 10:00am to 12:00pm

Regents Hall, 221

Event Type

Academic Events, Dissertation Defense

Departments

Georgetown College, Chemistry, Graduate School of Arts & Sciences

Cost

Free

Open to the public and the press?

Yes

Event Contact Name

Muhammad Itani

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