Using Carbonyl Vibrational Probes to Characterize Changes to the Local Environment With Two-Dimensional Infrared Spectroscopy / Phoebe Gilman Askelson.

Format:

Book

Thesis/Dissertation

Author/Creator:

Askelson, Phoebe Gilman, author.

Contributor:

University of Pennsylvania. Chemistry, degree granting institution.

Language:

English

Subjects (All):

Physical chemistry.

Chemistry.

Organic chemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Local Subjects:

Physical chemistry.

Chemistry.

Organic chemistry.

Chemistry--Penn dissertations.

Penn dissertations--Chemistry.

Physical Description:

1 online resource (277 pages)

Distribution:

Ann Arbor : ProQuest Dissertations & Theses, 2023

Contained In:

Dissertations Abstracts International 85-08B.

Place of Publication:

[Philadelphia, Pennsylvania] : University of Pennsylvania, 2022.

Language Note:

English

Summary:

In natural systems, such as enzymes and photosynthetic light harvesting complexes, the properties of bound substrates and cofactors are tuned through various noncovalent interactions with the local environment. Understanding fundamentally how these interactions affect target molecules could lead to development of rational design principles to enhance reactivity, specificity, or yield in chemical systems. In this work, I've studied how carbonyl reporter vibrations respond to changes in the local environment, using two-dimensional infrared (2DIR) spectroscopy.Combining 2DIR spectroscopy and spectral modeling, I characterized changes to the energetics of the cofactor phylloquinone (PhQ). I found that hydrogen bonding to a single PhQ carbonyl unit decouples the carbonyl normal modes into local modes, and leads to the red-shift of the hydrogen bonded carbonyl. This work determines how hydrogen bonding presents in the 2DIR spectra of PhQ, and demonstrates the potential to use PhQ as a probe of local hydrogen bonding in protein environments.I also investigated how changing the local environment impacts the energetics and dynamics of a bridging [CpFe(CO)2]2 dimer complex. Focusing on the terminal carbonyl regions, I found that encapsulation in a nanocage host does not impact the population transfer timescale between carbonyl vibrations despite decreasing the vibrational lifetime. This is likely due to stronger coupling to low-frequency modes through the nanocage. Furthermore, by simultaneously probing the bridging carbonyl modes and the terminal carbonyl modes of [CpFe(CO)2]2 in solution, I found that population transfer between the bridging and terminal modes does not exhibit strong solvent dependence, likely due to their large energy gap.Finally, I studied how stabilization of a formyl intermediate [Ru(bpy)2(CO)(CHO)]+ by addition of Lewis acid salts, affected the energetics and kinetics of the carbonyl mode. Formation of a Lewis acid-base adduct, where the cations interact with the formyl group to form a carbene-like state, lead to a blue-shift in the frequencies of the carbonyl vibrational mode and a subtle increase in its vibrational lifetime, without altering its anharmonicity.Through these projects, I have focused on characterizing how changes in the local environment can impact the properties of molecules that are important for solar energy conversion and catalysis.

Notes:

Source: Dissertations Abstracts International, Volume: 85-08, Section: B.

Advisors: Anna, Jessica M.; Committee members: Lester, Marsha I.; Subotnik, Joseph; Yodh, Arjun.

Department: Chemistry.

Ph.D. University of Pennsylvania 2023.

Local Notes:

School code: 0175

ISBN:

9798381510096

Access Restriction:

Restricted for use by site license.