Ph.D. Dissertation Defense - Mostafa Manjahi

About

Doctoral Defense Seminar

Mostafa Manjahi

Ph.D. Candidate

Department of Chemistry

University of North Dakota

Presents:

“Photochemical Construction and Functionalization of Cyclobutane-Based Architectures from Maleimide via Photocyclization and Epoxidation Strategies”

Friday, Nov. 6 at 12:20 p.m.

Abbott Hall Room 138

Bio: Mostafa Manjahi is a Ph.D. candidate in the Department of Chemistry at the University of North Dakota, where he conducts research under the supervision of Dr. Safiya Nisar and Dr. Guodong Du, chair of the Department. His doctoral research uses light-driven [2+2] photocycloaddition to construct rigid cyclobutane frameworks and transform them into functional monomers, including bisphenol A-free epoxy monomers, for sustainable polymers and materials. This work integrates synthetic photochemistry with NMR spectroscopy, single-crystal X-ray diffraction, and computational chemistry. He received his B.S. in Chemistry from King Khalid University, Saudi Arabia, where he graduated first in his class, and his M.S. in Chemistry from Texas A&M University–Kingsville, where his research focused on the acid-free intermolecular hydroarylation of alkynes catalyzed by dicationic palladium (II) and platinum (II) ethylene complexes. He began his career teaching chemistry in secondary schools (high schools) under the Ministry of Education in Saudi Arabia and subsequently served as a lecturer in the Department of Chemistry at King Khalid University, where he taught organic and inorganic chemistry laboratories to undergraduate students in the Colleges of Medicine and Science.

Abstract: Rigid molecular frameworks impart strength and thermal stability to polymers; however, many widely used rigid monomers, most notably bisphenol A in epoxy resins, are petroleum-derived and resistant to degradation. This dissertation investigates the cyclobutane ring, constructed in a single photochemical step, as a versatile rigid building block for sustainable materials. First, catalyst- and photosensitizer-free photodimerization of maleimide afforded cyclobutane bisimides on a gram scale in 85–95% yield, which were subsequently converted into tetraamides. Second, photocycloadditions of maleimide with eight substituted benzenes produced rigid, cage-like bisimides, with the substitution pattern of each arene governing regioisomer formation; single-crystal X-ray diffraction and density functional theory calculations supported the proposed structures and mechanisms. Third, cyclobutane dicarboxylic acids, bisimides, and a diol were transformed into bisphenol A-free epoxy monomers under conditions tailored to the reactivity of each functional group. Short-wavelength UV irradiation cleaved the cyclobutane core of a cinnamate-derived diepoxide while leaving its epoxide groups intact, offering a pathway toward recyclable epoxy materials. Finally, the photocycloaddition of maleimide was extended to cyclic, terminal, and electron-deficient alkenes, broadening the scope of functionalized cyclobutane imides for future monomer design. Collectively, these studies provide efficient, light-driven routes to rigid and partly renewable building blocks for polymers, adhesives, and epoxy resins.