In this talk, I will present an update on the current status of our ability to design and discover new materials, and discuss their relevance to providing chemically controlled synthetic pathways and understanding the high efficiency of photovoltaic properties of methyl ammonium metal halides. Specific examples will be chosen from our recent work including the successful synthesis and crystal growth of: (i) a Mott insulator exhibiting photoconductivity properties and (ii) a methyl ammonium mixed-metal bromide and its dynamic disorder driving the structural packing.

Chemically controlled design and discovery of new materials

The synthesis of nanoparticle delivery systems for biomedical applications has grown over the last decade. Efforts to manipulate size, biocompatibility, and cargo loading of these materials have demonstrated some synthetic control over these variables. Lung adenocarcinoma cells are of interest for targeted delivery of aerosol-based nanomaterial systems, including electron dense (Au) and tunable fluorescent (CdE, E = S, Se, Te) nanoparticles. For these reasons, a series of core/shell nanoparticles were synthesized to examine the impact of different silica-based architectures with Au and CdTe quantum dots on A549 lung cells. Stöber and mesoporous silica shells were added to metal cores and samples were dispersed in PBS buffer solution. A comparison of the cytotoxicity of the cores and respective core-shell particles were made at 24 and 48-hour intervals. A discussion on nanoparticle syntheses, characterization, and cytotoxicity results will be presented.

Synthesis of core/shell nanoparticles and their impact on cytotoxicity of A549 lung cells

Growing environmental and economic concerns as well as the uncertainty that accompanies finite petrochemical resources caused an increase in recent years in research and development of bio-based, renewable polymer materials. To replace petroleum-derived materials, bio-based polymers are directly produced, or, their monomers are derived from renewable sources and later polymerized. In order to determine if lignin, a highly abundant and renewable resource, could serve as a basis for bio-based conductive polymers, fractions of Kraft lignin and lignin-derived monomers were functionalized and subsequently polymerized with multi-functional thiol monomers. Powdered Kraft lignin was fractionated and characterized before imparted with allyl functionalities and used in a thiol-ene polymerization. Lignin-derived monomer vanillyl alcohol (4-(hydroxymethyl)-2-methoxyphenol) was also functionalized and UV-polymerized to yield thin, flexible polymers. Sheet resistivities of the polymers were determined according to a four-point probe method by applying a current to the thin film polymers and measuring the resulting voltage. This study adds to the list of synthesis methods of lignin-based polymers and provides insight on how to design structurally and thermally desirable bio-based polymers for battery applications.

Bio-based thiol-ene polymers for use in battery applications: Synthesis and properties

The utilization of wood-derived building blocks (xylochemicals) to replace fossil-based precursors is an attractive research subject of modern polymer science.The continuing development of new bio-based feedstocks opens opportunities to increase the resource base from which chemical and materials engineers can draw to meet specific polymer property requirements. Recently, significant efforts have transpired to obtain bio-based polymers and copolymers with enhanced thermomechanical properties for a wide variety of applications.In continuing these efforts, we have prepared and examined novel linear polyesters and polycarbonates derived from xylochemicals. Bio-based bisphenolic analogues were synthesized via electrophilic aromatic condensations of lignin-based building blocks. These bisphenolics were subsequently polymerized with multiple diacid chlorides/diacids to prepare a series of polyesters with varied and well-defined thermomechanical properties. Additionally, the same monomers were used for the synthesis of polycarbonates. These novel thermoplastics were characterized to assess their structure-property relationships and compared to industrial, fossil-based “equivalents”. The results of our study illustrate that these new polymers are valid alternatives to petroleum-based materials currently employed in the plastics industry.

Preparation and characterization of bio-based polyesters and polycarbonates derived from xylochemicals

Many types of coatings are used to protect the oil and gas pipelines from erosion and corrosion, which could lead to catastrophic failure. Electroless coatings, which is an autocatalytic process, are widely used in different industries for their unique combination of properties such as wear resistance, corrosion resistance, and higher hardness. Recently, Incorporation of nanoparticles in the matrix of electroless coatings to improve the properties of electroless and to obtain high performance composite coatings has been developed. Among these particles, carbon nitride (C3N4) with high hardness and excellent thermal and chemical stability. Herein, we report the deposition of Ni-P/C3N4 nanocomposite coatings on API X120 steel through a Ni-P electroless bath containing ultrasonically dispersed carbon nitride nanoparticles. The surface morphology, composition and structural properties of coatings were studied by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction techniques. The effect of heat treatment on the micro-hardness and surface roughness was evaluated by Vickers microhardness tester and the Atomic force microscopy (AFM). The electrochemical impedance spectroscopy and potentiodynamic polarization methods were utilized to investigate the corrosion resistance of the NiP and NiP-C3N4 nanocomposite coatings in 3.5 wt% NaCl solution before and after the heat treatment of the coatings at 400 oC for one hour. The results indicated that the carbon nitride is distributed uniformly in the NiP-C3N4 composite coatings, as shown in enclosed Figure. The NiP-C3N4 composite coating exhibit higher micro hardness after heat treatment and superior corrosion resistance lasted for 30 days. The higher hardness and superior corrosion resistance of the new nanocomposite makes it durable and a suitable candidate to be used in the oil and gas industries applications.

Novel electroless plated Ni-P-C3N4 nanocomposite coating with outstanding performance

Rational, data-driven materials discovery has the potential to make research and development efforts far faster and cheaper. In such a paradigm, computer models trained to find patterns in massive chemical datasets would rapidly scan compositions and systematically identify attractive candidates.  Here, we present several examples of our work on developing machine learning (ML) methods capable of creating predictive models using a diverse range of materials data. As input training data, we demonstrate ML on both large computational datasets of DFT calculations, as implemented in the Open Quantum Materials Database (oqmd.org), and also experimental databases of materials properties.  We construct ML models using a large and chemically diverse list of attributes, which we demonstrate can be used as an effective tool to automatically learn intuitive design rules, predict diverse properties of crystalline and amorphous materials, such as formation energy, specific volume, band gap energy, and glass-forming ability, and accelerate combinatorial searches.

Using machine-learning to create predictive material property models

Inhibition of ketohexokinase (KHK, fructokinase) leads to decrease in fructose metabolism and may provide a new treatment option for non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH). A scalable route was developed to access bulk quantities of the [3.1.0] amino acid fragment used in the synthesis of Pfizer’s ketohexokinase (KHK) inhibitor. The route utilized an advanced amino-alcohol intermediate and homologation chemistry to furnish the final [3.1.0] amino ester monomer in 93% yield in 4 steps as an isolable solid without chromatography. This route was used to deliver 100 g of the monomer in house and an additional 700 g at a vendor. The resultant material was utilized to synthesize &gt;450 g of final API.

Synthesis of the [3.1.0] amino acid fragment of a ketohexokinase inhibitor for the treatment of NAFLD/NASH

Ketohexokinase (KHK) inhibition has shown potential as a treatment for non-alcoholic steatohepatitis (NASH) and non-alcohol fatty liver disease (NAFLD). As the KHKi program at Pfizer narrowed in on lead matter for clinical development, multiple compounds were profiled in parallel and a robust plan was created to both allow time for data generation and for optimization of the synthesis of multiple leads for large scale without having to adjust timelines. Strategic planning to enable bulk delivery of multiple compounds along with the necessity for crisp decision making to balance long-term optimization with short term delivery goals allowed the team to position for efficient access to the clinical candidate. The triaging of lead matter and the synthesis of key compounds will be presented including the enablement of key monomers: 2-methyl azetidine and [3.1.0] amino ester which were used to access &gt;300 g of the clinical candidate to support pre-clinical efficacy and safety studies.

Optimization of the chemical matter and synthesis leading to a ketohexokinase inhibitor clinical candidate

One important characteristic of benzoxazine resin (BA-a) is its ability to alloy with various species of resins or polymers. In this research, we have demonstrated an ability of benzoxazine resin to alloy with epoxy and urethane resins to form polymers with shape memory properties. The dual function of benzoxazine resin to act as curing agent of epoxy resin and as a stable or rigid network segment for shape memory epoxy (SMEs) significantly simplifies a formulation of shape memory epoxy systems. The presence of the polybenzoxazine in SMEs was found to significantly enhance their recovery stress values. Moreover, with an addition of suitable amount of reinforcement e.g. silicon carbide whisker (SiCw), recovery stress of the resulting shape memory composites in flexural mode as high as 11.2 MPa can be achieved compared to the value of 3.4 MPa of the neat SMEs. Furthermore, the alloys of benzoxazine resin with urethane elastomers were found to provide relatively broad glass transition temperature with multiple-shape memory effects. High values of shape fixity i.e. 70%-96% for the first temporary shape and 83%-99% for the second temporary shape and high shape recovery of 88%-96% for the first temporary shape and 97%-99% for the original shape were also achieved.

Shape memory polymers based on polybenzoxazine alloys and composites enhancement of recovery stress and thermal properties

Increasing polymer-based materials of several engineering polymers, including industrial equipment, self-lubricating materials, automotive, and aerospace require knowledge of their tribological properties – different from much better understood tribological properties of metals and ceramics. Polybenzoxazines are a relatively novel class of thermosetting phenolic resin that is recently attracting much attention both industrially and academically as they possess various advantageous characteristics that overcome the limitations of conventional phenolic and epoxy resins. Therefore, the purpose of the present work is to investigate tribological properties, i.e., friction coefficient and wear resistance, and thermal property of polybenzoxazine composites filled with various sizes of synthetic graphite (SG) particles in a range of 32-150 μm. The tribological results showed that the incorporation of the various SG particle sizes was an effective way to enhance the tribological properties of the composites. A noticeable increase of the friction coefficient and the wear resistance of the composites was achieved with the increase of the SG particle size. A 106 µm SG causes an increment of the friction coefficient from 0.29 to 0.41. In term of the thermal property, it was found that glass transition temperature (Tg) of the composites was in a temperature range of 197oC to 209oC and the highest Tg belonged to the composite filled with 75 µm SG. Therefore, among all synthetic graphite particle sizes, the polybenzoxazine composites filled with 75-106 μm synthetic graphite appear to be the suitable candidate for friction materials due to their relative high friction coefficient and glass transition temperature.

Tribological and thermal properties of friction composites based on polybenzoxazine

A multicolor Organic Chemistry laboratory experiment involving synthesis of a single dye is the highlight of this experiment. This experiment is one of the most discussed labs among undergraduate students at Plymouth State University. In first laboratory period, students synthesize a solvatochromic dye by nucleophilic attack of a carbanion on an aldehyde carbonyl group. This is a great way to introduce carbonyl chemistry and synthesis to students. During the reflux period, the dipole moments of seven solvents are calculated using Spartan computational program. The dye is recrystallized and yield is calculated. Following week, students prepare brightly colored solutions of dye using the same seven solvents. Each solvent displays amazingly different colors due to stabilization or destabilization of ground and excited states. Complimentary colors of each solution are identified using simple color wheel. Using UV-Visible spectroscopy, wavelength of maximum absorption (λmax) are determined. Students discover the relation between dipole moment and λmax. Additional spectroscopic techniques are used for structure determination.This visually stimulating experiment proved effective for triggering students’ curiosity about solvation and colors in the laboratory.

Thought-provoking colorful sophomore organic chemistry laboratory experiment

Atom economy is a useful concept and metric that can help inform sustainability-related discussions of chemical transformations. Applied at the stoichiometric level, it provides fundamental information about the inherent mass efficiency of a given reaction. As a novel concept published by Trost in 1991, atom economy has helped chemists think about their synthetic routes in a way that seeks to incorporate all of the reactants into the desired product, so that reactions are designed to be inherently mass efficient. Over the last few decades, it can be argued that the conversation on chemical reaction mass efficiency has expanded from atom economy to the circular economy, and the perspective expanded from the molecular level to the level of the global economy. In industrial processes, consideration of recycle loops and by-product utilization are important, and each can help reduce the environmental impact of a chemical process. Life Cycle Assessment (LCA) and life cycle thinking help to better understand the impact of a chemical process across the life cycle of the intended products. And recently, there has been tremendous focus on helping society move from a linear economy to a circular economy, where materials are maintained in their most valuable states for maximum time, and ultimately converted back into useful materials at end of life. In this talk, we will share perspective on the Atom Economy principle, and discuss the nano to macro thinking that is applied today when evaluating chemical transformations and chemical products. We will provide examples of how the concepts of LCA, waste utilization, and circular economy can help to assess the sustainability attributes of chemical technology. Taken together with atom economy, these concepts can help us better understand where a given reaction, process, and technology fits within a sustainable society.

Principle 2. From atom economy to circular economy

A novel class of carbon-based nanorods that reversibly adsorb water at low humidity and spontaneously expel the adsorbed water at high relative humidity will be presented. Similar to porous materials such as carbons, silica gels and metal-organic frameworks, these nanorods may have application for water management in catalysis, dehumidification and heating, or ventilation and air conditioning (HVAC). The nanorods are synthesized by the catalytic decomposition of a switchable ionic liquid (SWIL) comprising of carbon disulphide, hexanol and DBU over iron (III) chloride. The mechanism for the growth of the nanorods, the effects of temperature, different transition metals, and amidinium alkylxanthate ionic liquid precursors (different alcohols and amines) on the nanomaterial formation, and its water adsorption/expulsion behavior will be discussed. In-situ microscopy and NMR studies will be presented to show the process of water adsorption/expulsion phenomenon.

Carbon nanorods for water expulsion at high humidity

This experiment presents a great way to introduce synthesis, spectroscopy, solvatochromism, and computational chemistry as a wet lab/dry lab combination in sophomore Organic Chemistry laboratory. The experiment involves base catalyzed synthesis of merocyanine dye, recrystallization and structural determination using spectroscopic methods. Seven solvents of varying polarity are used to study the effect of solvent polarity on merocyanine dye. Students make visual observations of color changes as well as study the effect using UV-Vis spectroscopy. Spartan computational program is used to compute dipole moments of the same solvents. Students learn and apply both theoretical and practical data collected from this experiment to explain the effect of solvent polarity on solvatochromic dye. Literature survey, critical thinking, data analysis, report writing and group work skills are developed during this experiment. UV-Visible and visual analysis of solutions helps visual learners and student engagement.

Synthesis and analysis of merocyanine dye: A wet/dry lab approach in undergraduate organic chemistry laboratory

This experiment sets out to create shock absorbing polysaccharide hydrogels with mechanical properties that could be changed in the presence of light. To form gels with polysaccharides the transition metal ions, Fe3+, Fe2+, Ni2+, Cu2+, Zn2+, and Co2+ were used as coordination complexes. Solutions of various concentrations of the polysaccharides Alginate and Chitosan were soaked in solutions of each ion and their mechanical properties were measured. The gels were then exposed to 405nm light and their UV-Vis spectra were measured as well as their mechanical properties again. The results of the experiment indicated Co2+ exhibited the best potential for ideal shock absorbing hydrogel behavior. It also indicated the ability to be reduced by light after being oxidized to Co3+.

Mechanical and photochemical properties of polysaccharide-based, metal-coordinated hydrogels

During the past years the presence of pharmaceuticals in the environment has attracted the attention of the scientific community as well as raised public concern, as they could pose a serious risk to the environment. The presence of pharmaceutical active compounds (PhACs) in the natural aquatic environment reinforces the fact that conventional activated sludge (CAS) technologies for wastewater treatment do not remove these compounds efficiently. In recent years, an increasing number of publications have been reporting the efficiency of alternative wastewater treatment technologies able to eliminate pharmaceuticals from wastewater in a more efficient matter. Among all the new technologies studied, membrane bioreactors (MBRs) and fungal bioreactors (FBRs) are currently at different stage of implementation: MBR technology has become an accepted alternative to CAS technology for municipal wastewater treatment, not only with regard to PhACs removal but also regarding the overall effluent water quality, whereas fungal treatment has shown its efficiency in removing recalcitrant and toxic PhACs at laboratory scale, but its implementation in full-scale WWTPs is still under consideration. In this work, removal efficiencies of PhACs in MBRs, followed by nanofiltration or reverse osmosis, i.e., the so-called integrated membrane systems, and in FBRs are evaluated, paying special attention to the removal of transformation products (TPs) of the target contaminants. These TPs are not only present in raw wastewater but also generated during water treatment, both in MBRs and FBRs and can also contribute to ecotoxicological impact of wastewater effluents in the receiving waters.

Challenges and solutions for the removal of pharmaceuticals from wastewater: The use of fungal treatment and integrated membrane systems

Proton activity on oxide surface is paid considerable attention not only from the view point of basic science but also the applications to catalysts and electrolytes. To reveal the intrinsic protonic activity, hydration reactions on oxide surfaces are studied by ab initio molecular dynamic (AIMD) simulations. In these studies, it is concluded that surface acidity is governed by deprotonation reactions of chemisorbed H2O molecules on metal ions (M-OH2 → M-OH− + H+, pKa1) and polydentate hydroxyl groups formed on oxide ions (&gt;OH+→ &gt;O + H+ pKa0). Here, pH at point of zero charge condition (pHPZC), an indicator of surface acidity based on the experiment, is determined as an average of acid constants, pHPZC= 1/2(pKa1+pKa0). Therefore, since catalytic activity is not governed by pHPZC but by the strength of acidity or basicity of reaction sites, pKas of hydroxyl groups on the surface are also estimated in several AIMD simulations. However, the effect of acid-base molecules on surface acidity has not been studied yet. In catalytic reactions such as methanol synthesis, intermediate species on the surface like carbonates and formates could be reduced by proton and electron migrations. Therefore, the efficiency of these processes is highly related to the acid-base property on the surface. Here, we report AIMD simulations for hydration reactions on carbonate, formate, and methanol adsorbed surfaces to study the effect of acid and base modification on oxide surface. To obtain these surfaces, a few ps AIMD simulations for CO2, HCOOH, and CH3OH adsorption on bare cubic ZrO2 (110) surface are performed. After the adsorption, all organic molecules stably exist on each surface throughout several-ps hydration reactions by introducing H2O molecules. Bond overlap population analysis shows that carbonates and formates are inert to the acid-base reactions, whereas methoxy groups tend to form strong hydrogen bonds with surrounding H2O molecules. In addition, the bond length and strength of Zr-OH2 and Zr-OH− are constant regardless of organic molecule adsorption, which suggests pKa1 is maintained constant. On the other hand, thermodynamic discussion suggests that the basicity of surface oxide ions, pKa0, decreases as the coverage of organic molecules increases, which results in pHPZC reduction. Finally, according to these results, the relation between acid-base property of molecules and the change in acidity on the surface is discussed in terms of surface equilibrium.

Ab initio molecular dynamic study about effect of acid-base molecule adsorption on acidity on ZrO2 surface

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.