Abstract: Organic semiconductors, derived from π-conjugated polymers and molecules, enable the development of deformable, stretchable and flexible electronics due to  their tunable redox, optical, electronic and mechanical properties. However, an informed understanding of how multi-scale morphological characteristics of the polymeric and molecular semiconductors influence bulk properties that contribute to electronic and optical performance, especially under operational thermal and mechanical stresses, remains incomplete. 

This lack of understanding poses a challenge to scalability and commercialization of organic electronics. This dissertation develops and deploys computational modeling approaches, particularly atomistic molecular dynamics (MD) simulations, to investigate the multiscale morphological behavior of these synthetic semiconducting materials in the context of thermomechanical stability.

Herein, electron-donating π-conjugated polymers and electron-accepting molecules — systems that are used in combination to develop bulk heterojunction (BHJ) organic semiconductors — are modeled as their neat phases and as blends to elucidate expectations regarding their thermomechanical behavior as they traverse operational thermal and mechanical processes. 

By systematically modeling these organic semiconductors over time and length scales that approach experiments, this dissertation fits into the larger quest for how local (or long-range) molecular morphology, beginning from molecular structural compositions, dictate thermomechanical behavior, thus providing valuable design and processing principles in the bid for electronically efficient, mechanically robust and manufacture-scale organic electronics.

Abstract: Organic semiconductors, derived from π-conjugated polymers and molecules, enable the development of deformable, stretchable and flexible electronics due to  their tunable redox, optical, electronic and mechanical properties. However, an informed understanding of how multi-scale morphological characteristics of the polymeric and molecular semiconductors influence bulk properties that contribute to electronic and optical performance, especially under operational thermal and mechanical stresses, remains incomplete. 

This lack of understanding poses a challenge to scalability and commercialization of organic electronics. This dissertation develops and deploys computational modeling approaches, particularly atomistic molecular dynamics (MD) simulations, to investigate the multiscale morphological behavior of these synthetic semiconducting materials in the context of thermomechanical stability.

Herein, electron-donating π-conjugated polymers and electron-accepting molecules — systems that are used in combination to develop bulk heterojunction (BHJ) organic semiconductors — are modeled as their neat phases and as blends to elucidate expectations regarding their thermomechanical behavior as they traverse operational thermal and mechanical processes. 

By systematically modeling these organic semiconductors over time and length scales that approach experiments, this dissertation fits into the larger quest for how local (or long-range) molecular morphology, beginning from molecular structural compositions, dictate thermomechanical behavior, thus providing valuable design and processing principles in the bid for electronically efficient, mechanically robust and manufacture-scale organic electronics.

Abstract: Graphitic materials possess unique properties due to the unique combination of layered crystalline structure and carbon’s low atomic weight. High performance carbon fiber is one such example, displaying exceptional strength-to-weight ratios, stiffness and thermal and chemical resistance. These properties render high performance carbon fiber a critical structural reinforcement material in the manufacture of composites across industries, including automotive and aerospace applications. Balancing fiber performance with precursor and processing costs, however, remains a challenge. As alternative carbonaceous feedstocks are explored, coal has gained interest for use in graphitic products as a relatively abundant and low-cost source of aromatic carbon.

This work broadly covers the process of using coal for high performance carbon fiber. First, coal extracts are obtained through direct coal liquefaction in petroleum-derived fluid catalytic cracking decant oil. The efficacy of the process and the suitability of the coal extract as a precursor to graphitic products is assessed through comprehensive solubility testing, chemical and thermal characterization and polarized optical microscopy. The thermal conversion of coal extracts to mesophase pitch is then examined, and process development, optimization and methods for real-time reaction progress monitoring are described. Additionally, a general framework for understanding the isotropic-mesophase phase transition from a colloidal perspective is proposed. 

The production of high performance carbon fiber from a coal extract-derived mesophase pitch is then successfully demonstrated, and mesophase pitch properties impacting melt-spinning stability are discussed. Finally, coal contribution to carbon fiber was quantitatively determined via stable carbon isotope analysis. The investigations detailed in this work provide in-depth understanding of co-processing coal and decant oil system via direct coal liquefaction, the impact of processing steps on chemical and material properties, mesophase pitch processability and carbon fiber performance.

Abstract: Graphitic materials possess unique properties due to the unique combination of layered crystalline structure and carbon’s low atomic weight. High performance carbon fiber is one such example, displaying exceptional strength-to-weight ratios, stiffness and thermal and chemical resistance. These properties render high performance carbon fiber a critical structural reinforcement material in the manufacture of composites across industries, including automotive and aerospace applications. Balancing fiber performance with precursor and processing costs, however, remains a challenge. As alternative carbonaceous feedstocks are explored, coal has gained interest for use in graphitic products as a relatively abundant and low-cost source of aromatic carbon.

This work broadly covers the process of using coal for high performance carbon fiber. First, coal extracts are obtained through direct coal liquefaction in petroleum-derived fluid catalytic cracking decant oil. The efficacy of the process and the suitability of the coal extract as a precursor to graphitic products is assessed through comprehensive solubility testing, chemical and thermal characterization and polarized optical microscopy. The thermal conversion of coal extracts to mesophase pitch is then examined, and process development, optimization and methods for real-time reaction progress monitoring are described. Additionally, a general framework for understanding the isotropic-mesophase phase transition from a colloidal perspective is proposed. 

The production of high performance carbon fiber from a coal extract-derived mesophase pitch is then successfully demonstrated, and mesophase pitch properties impacting melt-spinning stability are discussed. Finally, coal contribution to carbon fiber was quantitatively determined via stable carbon isotope analysis. The investigations detailed in this work provide in-depth understanding of co-processing coal and decant oil system via direct coal liquefaction, the impact of processing steps on chemical and material properties, mesophase pitch processability and carbon fiber performance.

Abstract: Methyltransferases (MTs) are increasingly recognized as promising drug targets in precision medicine due to their essential role in regulating diverse biological processes. Our research is centered on discovering cell-potent and isoform-selective inhibitors for epigenetic targets, including MTs, through innovative strategies. 

In this talk, I will discuss our recent progress in developing selective and potent inhibitors for protein N-terminal methyltransferase 1 (NTMT1), which show significant potential in promoting muscle regeneration. Additionally, I will present our advancements in creating inhibitors for nicotinamide N-methyltransferase (NNMT) and protein arginine methyltransferase 4 (PRMT4), which are being actively investigated for their therapeutic efficacy in cancer treatment.

Noncovalent interactions (NCIs) in π-conjugated organic materials serve as tunable levers that influence molecular structure and intermolecular interactions in the condensed phase and, in turn, impact the electronic, optical and mechanical properties of these materials. NCIs include attractive dispersion, electrostatic and induction interactions as well as repulsive exchange interactions. 

How to design materials with NCI considerations, however, remains an open question across many fields. Here, we seek to provide an atomistic perspective on these interactions through multiscale simulations to aid materials design, processing, and performance optimization. In this study, we investigate NCIs and their effects across various systems and complexity scales. 

First, we explore intramolecular NCIs and their influence on molecular conformation and the resulting electronic and optical properties. We demonstrate how NCI can lead to various preferred molecular conformations that, in turn, modulate the intrinsic molecular properties. Then we turn to  NCIs in multicomponent organic systems to elucidate how intermolecular NCIs influence molecular association, nucleation and growth in the organic condensed phase. Particular emphasis is placed on π-conjugated organic semiconductors, where both backbone-backbone and side-chain-mediated interactions critically influence solid-state packing and crystal growth. 

Collectively, this study demonstrates how NCIs can be strategically leveraged to guide material design and processing to optimize functional materials for organic electronics applications.

Noncovalent interactions (NCIs) in π-conjugated organic materials serve as tunable levers that influence molecular structure and intermolecular interactions in the condensed phase and, in turn, impact the electronic, optical and mechanical properties of these materials. NCIs include attractive dispersion, electrostatic and induction interactions as well as repulsive exchange interactions. 

How to design materials with NCI considerations, however, remains an open question across many fields. Here, we seek to provide an atomistic perspective on these interactions through multiscale simulations to aid materials design, processing, and performance optimization. In this study, we investigate NCIs and their effects across various systems and complexity scales. 

First, we explore intramolecular NCIs and their influence on molecular conformation and the resulting electronic and optical properties. We demonstrate how NCI can lead to various preferred molecular conformations that, in turn, modulate the intrinsic molecular properties. Then we turn to  NCIs in multicomponent organic systems to elucidate how intermolecular NCIs influence molecular association, nucleation and growth in the organic condensed phase. Particular emphasis is placed on π-conjugated organic semiconductors, where both backbone-backbone and side-chain-mediated interactions critically influence solid-state packing and crystal growth. 

Collectively, this study demonstrates how NCIs can be strategically leveraged to guide material design and processing to optimize functional materials for organic electronics applications.

Conjugated polymers have attracted significant attention as active materials in organic electronics, including organic photovoltaics, light-emitting diodes and thin-film transistors. Their appeal lies in the combination of solution processability, tunable electronic properties and mechanical flexibility, which together enable applications not readily achievable with conventional inorganic semiconductors. The widespread adoption of these materials, however, is hindered by their limited long-term stability. Exposure to oxygen, moisture, light and thermal stress can initiate a variety of degradation pathways, leading to structural and electronic changes that compromise device performance. Understanding the molecular level processes underlying such degradation remains a critical challenge for advancing the durability of organic electronic technologies.

Spectroscopic techniques are essential for probing the electronic structure and chemical evolution of conjugated polymers under operational and accelerated aging conditions. Such conventional methods as ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) reveal energy level alignment and chemical bonding, while device-based techniques like deep-level transient spectroscopy (DLTS), impedance spectroscopy and thermally stimulated current (TSC) measurements are used to identify trap or defect states. These approaches, however, often rely on device fabrication and can suffer from interface or contact artifacts. 

In contrast, Constant Final State Yield Spectroscopy (CFSYS) and Variable Energy Ultraviolet Photoelectron Spectroscopy (VE-UPS) offer a highly sensitive, device-free framework for mapping the occupied electronic structure of materials. CFSYS monitors electron emission at a fixed electron kinetic energy while sweeping the photon energy, providing energy references directly tied to the vacuum level and revealing defect state distributions intrinsic to the material. In contrast, VE-UPS varies the photon energy to obtain full UPS spectra at each excitation energy, offering detailed insight into the electronic structure beyond simple HOMO–LUMO transitions. Together, CFSYS and VE-UPS enhance sensitivity to subtle electronic variations and defect states that arise during degradation. 

Applying these complementary techniques to conjugated polymer degradation enables a direct correlation between spectroscopic signatures and performance loss, providing new insight into the molecular origins of instability and guiding the design of more durable conjugated systems for organic electronic applications.

The work encompasses the development, optimization and application of advanced photoemission spectroscopy techniques to probe the electronic structure and stability of organic and hybrid materials. The second chapter focuses on precise calibration and performance optimization of the PHOIBOS hemispherical analyzer, ensuring accurate and reproducible spectroscopic measurements across diverse material systems. The third chapter highlights the design, construction and implementation of the VE-UPS and CFSYS systems, developed to enhance sensitivity to defect states and quantify the change in defect states of doped systems. 

These techniques are applied in the fourth chapter to investigate defect evolution and stability in conjugated polymers under varying electrochemical doping levels, revealing how doping influences degradation and electronic structure. The final chapter extends these methods to Dion-Jacobson tin halide perovskites, demonstrating how variations in spacer cations modulate their structural, energetic, and optical properties. Together, these studies advance both the methodological capabilities and the fundamental understanding of material electronic behavior and stability.

Conjugated polymers have attracted significant attention as active materials in organic electronics, including organic photovoltaics, light-emitting diodes and thin-film transistors. Their appeal lies in the combination of solution processability, tunable electronic properties and mechanical flexibility, which together enable applications not readily achievable with conventional inorganic semiconductors. The widespread adoption of these materials, however, is hindered by their limited long-term stability. Exposure to oxygen, moisture, light and thermal stress can initiate a variety of degradation pathways, leading to structural and electronic changes that compromise device performance. Understanding the molecular level processes underlying such degradation remains a critical challenge for advancing the durability of organic electronic technologies.

Spectroscopic techniques are essential for probing the electronic structure and chemical evolution of conjugated polymers under operational and accelerated aging conditions. Such conventional methods as ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) reveal energy level alignment and chemical bonding, while device-based techniques like deep-level transient spectroscopy (DLTS), impedance spectroscopy and thermally stimulated current (TSC) measurements are used to identify trap or defect states. These approaches, however, often rely on device fabrication and can suffer from interface or contact artifacts. 

In contrast, Constant Final State Yield Spectroscopy (CFSYS) and Variable Energy Ultraviolet Photoelectron Spectroscopy (VE-UPS) offer a highly sensitive, device-free framework for mapping the occupied electronic structure of materials. CFSYS monitors electron emission at a fixed electron kinetic energy while sweeping the photon energy, providing energy references directly tied to the vacuum level and revealing defect state distributions intrinsic to the material. In contrast, VE-UPS varies the photon energy to obtain full UPS spectra at each excitation energy, offering detailed insight into the electronic structure beyond simple HOMO–LUMO transitions. Together, CFSYS and VE-UPS enhance sensitivity to subtle electronic variations and defect states that arise during degradation. 

Applying these complementary techniques to conjugated polymer degradation enables a direct correlation between spectroscopic signatures and performance loss, providing new insight into the molecular origins of instability and guiding the design of more durable conjugated systems for organic electronic applications.

The work encompasses the development, optimization and application of advanced photoemission spectroscopy techniques to probe the electronic structure and stability of organic and hybrid materials. The second chapter focuses on precise calibration and performance optimization of the PHOIBOS hemispherical analyzer, ensuring accurate and reproducible spectroscopic measurements across diverse material systems. The third chapter highlights the design, construction and implementation of the VE-UPS and CFSYS systems, developed to enhance sensitivity to defect states and quantify the change in defect states of doped systems. 

These techniques are applied in the fourth chapter to investigate defect evolution and stability in conjugated polymers under varying electrochemical doping levels, revealing how doping influences degradation and electronic structure. The final chapter extends these methods to Dion-Jacobson tin halide perovskites, demonstrating how variations in spacer cations modulate their structural, energetic, and optical properties. Together, these studies advance both the methodological capabilities and the fundamental understanding of material electronic behavior and stability.

Abstract: The early drug discovery workflow relies heavily on high-throughput experimentation, both in terms of organic synthesis as well as analysis of complex biosamples. The identification of new biological targets through large-scale biospecimen studies, the generation of large sets of drug candidates and their rapid bioactivity screening, as well as the in vitro and cell-based confirmation of hits followed by lead optimization, all rely on high-throughput strategies that  are typically spread out across diverse technologies in specialized facilities. The efficiency of this workflow could benefit from the consolidation of these activities in a single closed-loop platform. Mass spectrometry (MS) is an attractive technique to achieve such consolidation due to the inherent speed of mass analysis; however, this advantage is rarely fully used due to the widespread use of sample purification approaches (e.g. chromatography) before MS. 

Here we describe an automated system that achieves the consolidation of the early drug discovery pipeline by leveraging the advantages of desorption electrospray ionization (DESI), an ambient ionization technique that allows for the rapid and direct analysis of complex samples, both in qualitative and quantitative manner, without any need for workup. This system results from the combination of custom and commercial software, robotics and analytical instrumentation and can achieve throughputs better than 1 Hz using high-density arrays (up to 6,144 samples per array) and 50-nL samples (<5 ng analyte). More significantly, the inherent reaction acceleration phenomenon that occurs in microdroplets, such as those generated intrinsically through the DESI process, allows reaction times to be reduced to just milliseconds, effectively providing an on-the-fly synthetic method that can be coupled with in operando MS analysis or nano-microgram scale product collection for bioactivity assessment. 

The general workflow of this platform involves:

• Automated sample preparation or manipulation using a fluid handling workstation. 
• Generation of microarrays using a pin-tool.
• Automated transfer and analysis of spotted slides using ultrahigh-throughput DESI-MS. 
• Real-time processing of the spectral data. 

This methodology has been extensively demonstrated for the screening of organic reactions for identification of optimal synthesis conditions and the selective late-stage functionalization of complex molecules as well as for label-free quantitative biological assays using purified targets (e.g. enzymes, receptors), cell cultures, microorganisms or tissue biopsies, all with no sample cleanup. Examples of all these capabilities will be provided and framed within the overall context of drug discovery showcasing a new-generation system built within the ASPIRE initiative of the US National Center for Advancing Translational Sciences as well as a historical recount of the development of this technology.

Bio: Nicolás Morato is a research assistant professor at the Purdue Institute for Cancer Research of Purdue University. He is a trained chemist and engineer, and most of his career has been focused on analytical chemistry, in particular mass spectrometry. He completed his undergraduate studies at Universidad de los Andes (Colombia), and later his Ph.D. and a postdoctoral fellowship at Purdue University under the mentorship of Graham Cooks. 

Overall, his research involves the development of strategies for the rapid analysis of complex samples using ambient ionization mass spectrometry. Most of this effort revolves around the development and application of desorption electrospray ionization mass spectrometry (DESI-MS) for high-throughput experimentation in biochemistry, organic synthesis, clinical diagnosis and biomarker discovery with the underlying objective of consolidating this technology as an efficient closed-loop automated platform for early drug discovery. His work in this area has been recognized by several honors including graduate fellowships by Eastman and the ACS Division of Analytical Chemistry as well as the Tomas B. Hirschfeld Scholar Award from FAACS and the Postgraduate Award from IMSF and JMS.