Co-Principle Investigators involved in this Thrust: Tatiana Timofeeva, Michael Petronis (NMHU); Chris Hammel, Ezekiel Johnston-Halperin (OSU)

Based on our previous experience in crystal engineering we plan on using the framework of the present project to broaden the search for new two- and multicomponent charge transfer materials with potential applications as OFETs. We also plan to conduct further searches for two- and multicomponent organic nonlinear optical materials. Our plans include developing the pathway from modeling of prospective materials, including theoretical evaluation of their potential properties, to synthesis and overall characterization of these materials that will include their structural studies and measurements of their physical characteristics.

Important aspect of our studies will include crystal growth of engineered materials and their structural characterization. Single crystals are the materials in which fundamental properties of charge transfer compounds will be studied. Although crystallization of charge transfer adducts (co-crystals) has been reported many times, there are no established procedures for obtaining crystals with different stoichiometry or different polymorphs, so further investigation is needed. We will use different solvents as well as mixtures of solvents, variable temperature conditions, and different ratio of components in a systematic search for families of compounds with multiple polymorphs and different stoichiometry. At first new phases will be identified by comparison of melting points of the starting materials with the melting point of the product. The relative simplicity of these procedures and the straightforward results in this portion of the project will be used for attraction and initial training of new undergraduate students who have just joint PREM project.

Crystal growth will be followed by X-ray diffraction studies of single crystalline samples. All X-ray diffraction data will be collected using a Bruker APEX II CCD single-crystal instrument equipped with a low-temperature (100K) system. To improve the precision of these experiments we plan to collect all data at low temperature. For samples that demonstrate polymorphism we plan to carry out multi-temperature experiments to follow possible phase transitions and molecular disorder. All samples will be characterized by differential scanning calorimetry (DSC) and analysis (TGA) for additional testing of possible phase transitions (polymorphism) and thermal stability of the obtained adducts.

Magnetic charge transfer complexes have been known for several decades. We plan to carry out magnetic evaluation of all charge transfer materials synthesized at NMHU. The facilities at NMHU's paleomagnetism laboratory allows for a spectrum of magnetic experiments at both low temperature and high temperature for natural and synthetic materials.

Co-Principle Investigators involved in this Thrust: Tatiana Timofeeva, Michael Petronis, Qiang Wei, Jennifer Lindline (NMHU); Chris Hammel, Ezekiel Johnston-Halperin (OSU)

This thrust is focused on the creation of two types of materials, metal-organic frameworks (MOFs) and metal-organic aerogels (MOA). We plan to reveal how their design and specific reaction conditions will help to achieve the desired structures and properties of these materials. We plan to concentrate our attention on MOFs for applications in gas adsorption/separation and different sensors. The NMHU team has gained significant expertise in metal-organic frameworks during our previous PREM project.

Current research on MOFs with magnetic properties has shown that these materials have an enormous potential for many diverse applications. Combining both their magnetic properties and their enormous surface areas, magnetic MOFs (MMOFs) have successfully demonstrated their use in such applications such as drug delivery systems, chemical separation and detection, catalysis, and even as materials for enhanced magnetic refrigeration. For the most part MMOFs will be synthesized by incorporating magnetic nanoparticles into the channels of the MOFs to grant the MOFs their magnetic properties.

Metal-organic aerogels are another area that we plan to develop in this project. Similar to MOFs, MOAs are composed of metal ions or clusters with organic ligands through coordination interactions. However, as in the form of aerogel, MOAs are amorphous and do not possess 3D crystalline structures. Atomic pair distribution function (PDF) analysis of synchrotron XRPD data of the aerogel samples reveals a locally similar coordination environment around metal clusters in MOAs as MOFs, and suggested a hierarchical architecture of aerogel structure.

Co-Principle Investigators involved in this Thrust: Jiao Chen, Gil Gallegos (NMHU); Roland Kawakami, Jessica Winter (OSU)

The main objective of this study is to develop an ensemble of metallic nanoparticle-modified graphene metamaterials and then study their photonic, electrical and magnetic properties for applications in various photonic and metatronic devices.

Graphene, containing a monolayer of sp2 hybridized carbon atoms, is a one-atom-thick material. It has attracted tremendous interests due to its excellent electronic, thermal, mechanical and optical properties. It was reported that graphene-metal nanocomposites have enhanced mechanical strength more than that of pure graphene. However, it is still not well-understood how the deposition and the types of metallic nanoparticles on graphene affect the resulting properties. Therefore, a systematic study will be performed in this research. Two noble metallic nanoparticles, gold and silver, will be used due to their strong surface plasmon resonance phenomenon and ability to concentrate light into the deep subwavelength scale.

Noble metals (Au and Ag) will be used as plasmonic modulators, which can be accomplished through manipulation of the surface (topography) of the metamaterial. Both random growth and structured control (EBL) of the ST will be explored using computational methods, scanned probe microscope (SPM) and electron microscopes. The synergistic coupling of laboratory work and computational efforts will lead to the development of a quantitative framework for the design of functional photonic devices. This thrust will use synthetic techniques to vary the density, size and composition of metal nanoparticles on the graphene substrate to effectively change the response of the material to a range of light wavelength excitation (infrared through visible spectrum) and measure the SP resonant frequency response to this range of input excitation (tuning of the device to specific light wavelength input via nanoparticle density manipulation). Ultimately, the precise behavior of the synthesized metamaterial will be gleaned from both experimental and computational results.