OLED outcoupling efficiency is limited by several factors, one major factor is the limitation caused by internal reflection of light with the interface between organic layers including the anode and glass substrate. Here, we approach this problem by adding a fairly exotic material to the OLED setup, which strongly scatters light. We expect the scattering to weaken total internal reflection and increase outcoupling efficiency. Through measurements, we compare the out coupling efficiency of the control OLEDs and the OLEDs with the scattering layer. Finally, we analyze the potential for increased outcoupling efficiency and, later, industrial application. After analysis we find a 1-2% increase in efficiency without accounting for error.

One challenge in the development of ferroelectric liquid crystal (LC) display materials^1,2 is the presence of defects attributed to smectic layer contraction on cooling from the smectic A phase to the smectic C phase during alignment. Though some materials exist which do not exhibit such defects (DeVries materials), an understanding of which structural features favor such properties is not yet available. Our group has discovered several LC mesogens containing sulfur-based moieties that do not possess these problematic defects. In this study, our goal is to synthesize several structural variants of a LC family containing a thieno[3,2-b]thiophene ring (1) within the LC core to determine how structural changes impact mesogenic behavior. Preliminary studies by another group member targeted some thieno[3,2-b]thiophene-based LCs, though in only low yields.² In this project, we hope to synthesize several of these LC targets in sufficient yields for evaluation of their mesogenic behavior.

The synthesis of these compounds uses a new approach for 2-alkoxythiophene synthesis recently developed in our laboratories (Scheme 1).² Thienone 6 was prepared in four steps from commercial materials. Mitsunobu etherification using 1-octanol yields compound 7. Compound 7 is deprotonated with LDA and treated with N-formylpiperidine followed by hydrolysis to give the aldehyde 8, which reacts with ethyl mercaptoacetate (9) in the presence of base to produce the thieno[3,2-b]thiophene ester 10. The final targeted mesogens 13 (Scheme 2) will be prepared via saponification of 10 to the carboxylic acid 11 followed by esterification with a variety of chiral and achiral 4-alkoxyphenols 12.

References:

(1) Beekman, J.; Neyts, K.; Vanbrabant, P. J. M. Opt. Eng. 2011, 50, 081202-081217

(2) (a) Tietz, J. I., M.S. Thesis, Kent State University, Kent, OH, 2012. (b) Tietz, J.I.; Seed, A.J.;

Sampson, P. Org. Lett. 2012, 14, 5058-5061.

Nitroxyl (HNO) is a biologically relevant small molecule with considerable clinical promise for the treatment of heart failure. However, studies of the chemistry and biology of nitroxyl are hampered by its short lifetime in aqueous solution. To aid in biological and chemical studies, various nitroxyl donors (molecules that degrade to release HNO) have been synthesized. Our group’s focus is on the synthesis of nitroxyl donors that rapidly release HNO under physiological conditions through photoactivation of a pendent 3-hydroxy-2-naphthyl methyl (3,2-HNM) group. First generation 3,2-HNM-based HNO donor 1 released HNO upon photoactivation, but competition was also observed from a redox side reaction. In this study, we are probing the impact of a methyl substituent at C* (2) on these competing processes. Difficulty in the synthesis of key alkoxylamine intermediate 3 has led to studies of variant Mitsunobu reactions that might be suitable for the efficient synthesis of 3. Ongoing studies involve use of various N-hydroxyphthalimide nucleophiles and applying differnet protecting groups (PG) in the key Mitsunobu step. This poster will present progress made to date on the Mitsunobu step leading to 3 and its elaboration to the final target 2.

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Graphene is a material that promises much technologic advancement, from more efficient solar cells to higher capacity batteries. Currently the use of graphene is limited due to the difficulty of obtaining large pure sheets. Graphene oxide is similar to graphene except oxygen-containing functional groups are attached to the carbon lattice. Graphene oxide is easier to synthesize than graphene; however, the functional groups reduce the electrical conductivity of the material. If these groups could be partially or fully removed from graphene oxide the material would have properties closer to those of graphene. This process of removing oxygen groups is known as reduction and the final product is aptly called reduced graphene oxide. We aim at investigating if radiation from an electron beam accelerator could reduce graphene oxide. Samples of pre-prepared graphene oxide solution (from Graphene Supermarket Inc. USA) were deposited on glass slides partially coated in Indium tin oxide. After being dried, the samples were irradiated in the dose interval from 100 kGy to 1.6 MGy, using an electron beam accelerator at energies 80 keV and 120 keV. The samples were tested using Fourier transform infrared spectroscopy to determine any structural changes induced by the radiation, paying special attention to the absorbance peaks corresponding to carboxyl (-COOH) and alcohol (-OH) functional groups as well as the sp² hybridized Carbon-Carbon bond. Four-probe resistivity measurements were later performed to determine the sheet resistance of the samples and characterize the conductivity changes caused by the radiation.

While liquid crystals (LCs) possess diverse structures, they are often oversimplified as requiring a “hard” ring/core component and a “soft” acyclic/tail component as well as some sufficient degree of spacial anisotropy (rods/calamitic or disks/discotic). Small molecule rod-like calamitic LCs without tails are well known but small molecule disc-like LCs without tails are extremely rare. The technical goal of this project is to design, prepare and characterize simple aromatic molecules with no tails that display discotic/columnar behavior. Such materials are potentially important as organic semiconductor materials.

We have prepared triphenylene compounds with careful control of fluorination and other substitution. These molecules were prepared using a series of organometallic C-C bond forming reactions and a final photochemical photocyclodehydrofluorination (PCDHF) reaction; specifically developed for the controlled preparation of selectively fluorinated polynuclear aromatics. New materials have been routinely characterized by standard chemical/physical techniques (NMR, GC-MS, DSC, POM). A subset of materials identified as potentially discotic are subjected to further additional characterization methods (TOF, XRD).

This approach has led to the discovery of a growing class of tail-free triphenylene discotic materials. We are in the process of systematically modifying the structure of the triphenylenes (varying the number, identity and location of small substituents) in order to understand the underlying molecular features required to deliver discotic behavior in the absence of soft segments. As we continue to identify the specific molecular and intermolecular contributions involved we can then selectively turn them on and off to deliver a well-controlled set of phase transitions including columnar phases.

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Antibiotic resistant bacteria strains have come into focus in recent years; these bacteria are unable to be treated by normal antibiotics and have resulted in an increase in the number of mortalities by infectious diseases for the first time in decades. The antibiotic properties of gallium have been studied in recent years. Bacterial cells require iron to function; gallium, which has very similar ionic size and charge, travels through the body by the same mechanisms (i. e. siderophores) and is delivered to the cell by the same uptake pathways. Gallium attacks the cell by a “Trojan horse” method: it takes the place of iron in the metabolic pathway of the cell, but since it does not possess iron’s redox properties, gallium cannot do iron’s job, and the cell is forced to undergo apoptosis (programmed self-death). Gallium has also been shown to penetrate biofilms, self-produced matrices created by bacteria to protect themselves. Gallium was utilized in therapy as Ganite®, a gallium nitrate solution; however, 12.5% of patients had renal failure because gallium precipitated as gallium hydroxide and prevented proper kidney function. Our plan is to utilize gallium cysteinate nanoparticles to kill antibiotic-resistant strains of bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa that will not cause aggregation and kidney death. In addition, properties of a copper-bound gallium cysteinate nanoparticle in these therapies will be explored.

https://docs.google.com/document/d/1pXGvprxPTlu5zuM2orvPikc2Bp-KNvub9O_…

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