Electrons bound to donors (impurities in a crystal) in the semiconductor zinc oxide (ZnO) are promising candidates for solid-state spin qubits. These qubits may be useful for building quantum memories, which are necessary for establishing long range quantum communication. To actually use these electrons as qubits, we have to understand transitions from the donor-bound exciton state (where there are 2 electrons and a hole bound to the impurity) to the neutral donor state (with just a single bound electron). The width of the distribution of photon wavelengths emitted by this transition (where an electron and hole recombine) is the excitonic linewidth. This linewidth will determine our ability to store quantum information, since entanglement requires close to identical photons. The linewidth can be affected by isotopic randomness in the crystal, an effect which may be pronounced in ZnO due to wide distribution of isotopes in zinc. Studying this effect can tell us if isotopically pure ZnO is required for building quantum memories. This work will present results from theoretical models created in Python and Mathematica simulating the influence of isotopic randomness on the observed linewidths, and will compare these estimates with experimental data. These models simulate particles bound to impurities in isotopically varied crystal environments, determine their wavefunctions and the effect of isotope on their energies, and estimate the resulting linewidth. This theoretical estimate will be compared to experimental data obtained by photoluminescence excitation spectroscopy. The current experimental linewidth, measured by the full width at half maximum (FWHM) is 46 μeV operating at a temperature of 1.53 K. Initial models predict relatively high values, from 25 – 45 μeV FWHM. Results from this model and a more refined model focused on the neutral donor state’s wavefunction will be discussed.

Today, chemical separation processes are a major contributor to the global threat of climate change. Therefore, the development of more energy efficient methods to separate and purify chemical mixtures has become an important field of research. Limitations exist in the current application of metal-organic frameworks (MOFs)- extended, 3D networks formed from metal ions and bridging organic linkers- to fabricate high quality films for gas separation. We were interested in investigating a potential solution to this problem by synthesizing metal–organic cages with well-defined interior cavities and modifiable surface chemistry, which can be engineered to produce materials that bind and store many types of gas molecules. Here, we report a generalizable synthetic route towards lower symmetry cages- an area largely unexplored relative to their symmetrical counterparts- that possess a combination of solution processability, high porosity, and selective gas uptake. To illustrate the robustness of our synthetic route, a series of five metal–organic cages were synthesized and characterized by single crystal X-ray diffraction, gas sorption analysis, MALDI-TOF mass spectrometry, and ¹H NMR digestion experiments. Variable temperature CO₂ gas sorption data show that open binding sites can be generated, and that they remain accessible to molecules even in variants lacking permanent porosity. Our results demonstrate a mixed-ligand platform that supports a wide family of structurally related cages. This opens the door to new types of soft nanoporous materials possessing unique functions and properties, with applications in membrane-based separations, ionic conductivity, and controlled drug release.

Hydrogels are a versatile biomaterial commonly used for tissue engineering and drug delivery. In particular, photodegradable hydrogels have facilitated research breakthroughs in multiple fields, including organ development, disease progression, and blood vessel formation. While these reports have contributed greatly to the literature using in vitro experiments, current photodegradable designs are unable to function inside the human body due to their insensitivity to low energy light. Nearly all photodegradable hydrogels incorporate ortho-nitrobenzyl moieties as photosensitizers, which responds to UV light, a wavelength that does not penetrate complex tissue. In order to expand the applications of these photodegradable hydrogels a new crosslinker is needed that cleaves in response to visible light. I am working to develop a new photodegradable crosslinker based on ruthenium polypyridyl linker complexes, which can be structurally tuned to respond to visible light irradiation, leading to exchange of a ligand with water and rapid hydrogel degradation. We have modified the complexes with a reactive azide handle for site-specific incorporation into hydrogel biomaterials that can be transplanted to or formulated within specific bodily locations. Our preliminary results suggest the Ruthenium polypyridyl complexes degrade in the visible spectrum, and previous experiments have concluded that click chemistry allows for PEG-hydrogel incorporation with azide-modified crosslinkers. In this poster, I will describe the synthesis and characterization of one model Ru-based linker, including its photolysis, stability, and applications of the complex in the development of dynamic biomaterials for drug delivery and cell growth in vivo.

Cellulose is an abundant biopolymer that provides much of the structural support for plant cell walls. Its many desirable properties include high tensile strength, biocompatibility, thermal stability, and high water absorption. Cellulose has considerable potential as a component in polymeric composite materials, which combine polymer matrices with fillers to enhanced their mechanical properties for applications in drug delivery, food engineering, packaging, medical implants, and textiles. Even so, the difficulties of processing and manipulating cellulose at industrial scale have been cost prohibitive due to its high energy, chemical, and water usage. Here, we investigate the potential for simultaneous in situ production and incorporation of cellulose within hydrogels based on a photo-curable derivative of Pluronic® F-127, F127-bisurethane methacrylate (F127-BUM). We utilized a “symbiotic culture of bacteria and yeast” (SCOBY), obtained from a commercially available fermented tea beverage (Kombucha) starter kit, for the hydrogel formulation. We show that within cured F127-BUM hydrogel constructs, a SCOBY is viable and its biomass increases over time when maintained with a sucrose and black tea medium. These results will lead to further investigation into the composition of the SCOBY biomass, as well as physical and mechanical properties of the resulting composite material.