Uniform, independent bifunctionalization of a metal-organic framework material

Master of ScienceDepartment of ChemistryTendai GadzikwaMolecular architecture involves the assembly of molecular building blocks to form supramolecular structures and the decoration of their interiors. The evolution and gathering of molecular building blocks into supramolecular constructs include examples such as co-crystals, micelles, nanoparticles, etc. These cases offer novel and advantageous pathways for research in supramolecular chemistry, however, a class of materials known as metal-organic frameworks (MOFs) materials has emerged as a prime candidate for molecular construction and interior design. MOFs are highly tunable materials because they can be synthesized from a wide range of metals cations and organic linkers. The organic linkers can also be functionalized after the MOF material has been synthesized through a process known as post-synthetic modification (PSM). These materials can be synthesized using two different organic linkers, resulting in a mixed-ligand MOF. If these ligands are modifiable and react independently, the resulting MOF structure will be orthogonally functionalized. Upon PSM we hypothesize that our porous, mixed-ligand MOF will contain homogenous bifunctionality as a blueprint for the construction of a uniformly orthogonally functionalized MOF. The synthesis of the first metal-organic framework, KSU-1, is the first of its kind to be developed at Kansas State University. PSM strategies used in this research show successful functionalization of each organic linker leading to uniform bifunctionality throughout our material. Characterization studies commonly used with MOFs verifies the synthesis and PSM of KSU-1

Inelastic neutron scattering studies of methyl chloride synthesis over alumina

Not only is alumina the most widely used catalyst support material in the world, it is also an important catalyst in its own right. One major chemical process that uses alumina in this respect is the industrial production of methyl chloride. This is a large scale process (650 000 metric tons in 2010 in the United States), and a key feedstock in the production of silicones that are widely used as household sealants. In this Account, we show how, in partnership with conventional spectroscopic and reaction testing methods, inelastic neutron scattering (INS) spectroscopy can provide additional insight into the active sites present on the catalyst, as well as the intermediates present on the catalyst surface.<p></p> INS spectroscopy is a form of vibrational spectroscopy, where the spectral features are dominated by modes involving hydrogen. Because of this, most materials including alumina are largely transparent to neutrons. Advantageously, in this technique, the entire “mid-infrared”, 0–4000 cm<sup>–1</sup>, range is accessible; there is no cut-off at 1400 cm<sup>–1</sup> as in infrared spectroscopy. It is also straightforward to distinguish fundamental modes from overtones and combinations. <p></p> A key parameter in the catalyst’s activity is the surface acidity. In infrared spectroscopy of adsorbed pyridine, the shifts in the ring stretching modes are dependent on the strength of the acid site. However, there is a very limited spectral range available. We discuss how we can observe the low energy ring deformation modes of adsorbed pyridine by INS spectroscopy. These modes can undergo shifts that are as large as those seen with infrared inspectroscopy, potentially enabling finer discrimination between acid sites. <p></p> Surface hydroxyls play a key role in alumina catalysis, but in infrared spectroscopy, the presence of electrical anharmonicity complicates the interpretation of the O–H stretch region. In addition, the deformations lie below the infrared cut-off. Both of these limitations are irrelevant to INS spectroscopy, and all the modes are readily observable. When we add HCl to the catalyst surface, the acid causes changes in the spectra. We can then deduce both that the surface chlorination leads to enhanced Lewis acidity and that the hydroxyl group must be threefold coordinated. <p></p> When we react η-alumina with methanol, the catalyst forms a chemisorbed methoxy species. Infrared spectroscopy clearly shows its presence but also indicates the possible coexistence of a second species. Because of INS spectroscopy’s ability to discriminate between fundamental modes and combinations, we were able to unambiguously show that there is a single intermediate present on the surface of the active catalyst. This work represents a clear example where an understanding of the chemistry at the molecular level can help rationalize improvements in a large scale industrial process with both financial and environmental benefits. <p></p&gt

Symbiotic Reagent Activation: Oppenauer Oxidation of Magnesium Alkoxides by Silylglyoxylates Triggers Second-Stage Aldolization

The treatment of silylglyoxylates with magnesium alkoxides at ambient temperature results in symbiotic Oppenauer oxidation of the alkoxide and Meerwein-Ponndorf-Verley reduction of the silylglyoxylate. The reduced silylglyoxylate undergoes subsequent [1,2]-Brook rearrangement and aldol reaction with the carbonyl oxidation product. The magnesium alkoxide may be accessed via deprotonation of primary or secondary alcohols with EtMgBr, via addition of Grignard reagents to aldehydes, or via CuI-catalyzed alkylation of epoxides. For aliphatic primary alkoxides, moderate levels of anti diastereoselection are observed. A crossover experiment reveals that dissociation of the nascent aldehyde from the magnesium center is faster than [1,2]-Brook rearrangement and aldolization

A Novel Interdisciplinary Course in Gerontechnology for Disseminating Computational Thinking

While specialized knowledge and skills are the hallmark of modern society, the size and complexity of contemporary problems often require cooperative effort to analyze and solve. Therefore, experiences with skills, methodologies, and tools for effective interdisciplinary collaboration and structured problem solving are vital for preparing students for future academic and professional success. Meanwhile, computational systems have permeated much of modern professional and personal life, making computational thinking an essential skill for members of modern society. However, formal training in these techniques is primarily limited to students within computer science, mathematics, management of information systems, and engineering. At Iowa State University, we have designed and offered an experimental course to develop undergraduate students’ abilities for interdisciplinary teamwork and to disseminate computational thinking skills to a broader range of students. This novel course was jointly designed and instructed by faculty from the Computer Science Department, Gerontology Program, and Graphic Design Program to incorporate diverse faculty expertise and pedagogical approaches. Students were required to interview real users to identify real-life problems, gather requirements, and assess candidate solutions, which necessitated communication both within the group and with technologically-disinclined users. In-class presentations and wiki-based project websites provided regular practice at disseminating domain expertise to larger interdisciplinary audiences. Workshops, group-based mentoring, peer learning, and guided discovery allowed non-CS majors to learn much more about computer programs and tools, and grading criteria held students individually accountable within their disciplines but also emphasized group collaboration

Study of fuel cells using storable rocket propellants Final report, 18 Aug. 1965 - 23 Jun. 1969

Operating fuel cells on gaseous nitrogen tetroxide and aerozine 5

Self-Consistent Synthesis of the Squalene Synthase Inhibitor Zaragozic Acid C via Controlled Oligomerization

Despite the prevalence of repeating subunits in chiral natural products, stereocontrolled oligomerization is a largely unexplored strategy for construction of carbon skeletal frameworks. This report describes the use of silyl glyoxylates as dipolar glycolic acid synthons in a controlled oligomerization reaction for the efficient construction of the squalene synthase inhibitor zaragozic acid C. This new methodology allows rapid, stereocontrolled formation of the carbon skeleton with a desirable protecting group scheme while minimizing functional group repair and oxidation state manipulations

Was the Scanner Calibration Slide used for its intended purpose?

In the article, Scanner calibration revisited, BMC Bioinformatics 2010, 11:361, Dr. Pozhitkov used the Scanner Calibration Slide, a key product of Full Moon BioSystems to generate data in his study of microarray scanner PMT response and proposed a mathematic model for PMT response [1]. In the end, the author concluded that "Full Moon BioSystems calibration slides are inadequate for performing calibration," and recommended "against using these slides." We found these conclusions are seriously flawed and misleading, and his recommendation against using the Scanner Calibration Slide was not properly supported

Reading handwritten digits: a ZIP code recognition system

A neural network algorithm-based system that reads handwritten ZIP codes appearing on real US mail is described. The system uses a recognition-based segmenter, that is a hybrid of connected-components analysis (CCA), vertical cuts, and a neural network recognizer. Connected components that are single digits are handled by CCA. CCs that are combined or dissected digits are handled by the vertical-cut segmenter. The four main stages of processing are preprocessing, in which noise is removed and the digits are deslanted, CCA segmentation and recognition, vertical-cut-point estimation and segmentation, and directly lookup. The system was trained and tested on approximately 10000 images, five- and nine-digit ZIP code fields taken from real mail