Award Date

12-15-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry and Biochemistry

First Committee Member

Clemens Heske

Second Committee Member

Balakrishnan Naduvalath

Third Committee Member

Jared Bruce

Fourth Committee Member

Helen Wing

Number of Pages

129

Abstract

Metal–organic frameworks (MOFs) are highly porous, three-dimensional networks composed of coordinated metal clusters and organic ligand subunits. While tens of thousands of MOFs have been synthesized, the Ti(IV)-based MOF MIL-125 has garnered scientific interest due to the observed changes to its optical and photocatalytic properties upon chemical modification. For example, upon UV irradiation in the presence of an alcohol, MIL-125 undergoes a photochromic color change to a photodoped state that has been associated with the storage of charge in the form of Ti(III) sites. Another example is exemplified by the amine group functionalization of the 1,4-benzenedicarboxylate (BDC) linker of MIL-125 to produce MIL-125-NH2, which results in a ~1 eV reduction of its experimental optical gap. These observations suggest that the exhibited properties of MIL-125 can be tailored to specific values. To date, the effect of the photodoping process and the amine functionalization on the electronic structure of MIL-125 is not thoroughly understood outside of bulk-sensitive techniques and theoretical modeling. In order to establish a basis for fine-tuning the properties of these MOF systems, it is imperative to supplement the existing studies with techniques that directly probe their electronic structures.

In this thesis, the electronic structures of MIL-125 and its photodoped and aminefunctionalized derivatives are characterized using a combination of synchrotron-based soft x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES), and resonant inelastic soft x-ray scattering (RIXS) using the map approach. The HOMOLUMO separations derived from the RIXS maps collected at the carbon and titanium atoms were compared to the optical gaps and the theoretically derived gaps found in the literature.

Keywords

MIL-125; MIL-125-NH2; MOFs; RIXS; soft x-ray spectroscopy; XES

Disciplines

Chemistry | Physical Chemistry | Physical Sciences and Mathematics

File Format

PDF

File Size

10200 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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