DIRECT SELF-ASSEMBLY OF MULTI-LAYERED SUPRAMOLECULAR ARCHITECTURES
Department of Chemistry, University of South Florida, Tampa FL 33620, USA
Self-assembly as one of the main organizing principles of biological systems is also a widely applied strategy in supramolecular chemistry as the driving forces for the assembly of artificial structures from simple building blocks. Among the diverse fields of supramolecular chemistry, coordination-driven self-assembly offers a 'bottom-up' approach to mimic nature's activities and constructs various 2D and 3D metallo-supramolecules based on the highly directional and predictable feature of coordination. Up to date, the design of metallo-supramolecules has matured beyond the proof of principles and is ready to face more challenges with respect to the complexity of assembled architectures rather than relatively simple polygons and polyhedrons. With the goal of increasing the complexity of metallo-supramolecules, we designed and assembled a series of concentric, multi-layered architectures using multi-topic ligand. Using terpyridine-based building blocks, 2D macrocycles with concentric geometry were constructed; with multi-topic pyridine ligands, 3D sphere-in-spheres were assembled with increasing complexity and stability. Through further understanding of the design and self-assembly of supramolecular structures, our research is poised to advance the design, research and development of new synthetic materials with molecular level precision and high physical performance.
CORE AND SHELL SIZE DEPENDENCES ON STRAIN IN CORE@SHELL PRUSSIAN BLUE ANALOGUE (PBA) NANOPARTICLES AND THE EFFECT ON PHOTOMAGNETISM
John M. Cain1, Caue Favero Ferreira1, Ashley C. Felts1, Steven A. LoCicero1, Jiamin Liang1, Mark W. Meisel2,3, Daniel R. Talham1
¹Department of Chemistry, University of Florida, Gainesville FL 32611-7200, USA
²Department of Physics, University of Florida, Gainesville FL 32611-7200, USA
³National High Magnetic Field Laboratory, E. Paul Dirac Dr, Tallahassee FL, USA
RbxCo[Fe(CN)6]y@KaNi[Cr(CN)6]b core@shell heterostructures have been shown to exhibit a photoinduced decrease in magnetization that persists up to the Tc = 70 K of the KNiCr-PBA component, which is not photoactive as a single-phase material. A magnetomechanical eﬀect can explain how the strain in the shell evolves from thermal and photoinduced changes in the volume of the core. Moreover, a simple model has been used to estimate the depth of the strained region of the shell, but only one size of core (347±35 nm) has been studied. Since the strain depth in the shell is expected to be dependent on the size of the core, three distinct RbCoFe-PBA core sizes were synthesized, and on each, three diﬀerent KNiCr-PBA shell thicknesses were grown. The magnetization of each core-shell combination was measured before and after irradiation with white light. Our results suggest the strain depth, as expected, increases from ≈ 50 nm in heterostructures with a core size of 328±29 nm to more than 90 nm in heterostructures with a core size of 575±113 nm. The data from the smallest core size also shows features indicating the model may be too simple.
Design and synthesis of Pt(II) precursors for focused electron beam induced deposition
Hang Lu1, Julie A. Spencer2, Yung-Chien Wu, D. Howard Fairbrother2 and Lisa McElwee-White1
1. University of Florida
2. Johns Hopkins University
Pt(II) precursors have been designed specifically for focused electron beam induced deposition (FEBID) and synthesized for mechanistic study of electron-induced reactions under ultrahigh vacuum (UHV) surface science conditions. In situ X-ray photoelectron spectroscopy, mass spectrometry and Auger electron spectroscopy were used to demonstrate electron-induced loss of ligands from cis-Pt(CO)2Cl2, providing a pathway to Pt deposits by FEBID. The results from cis-Pt(CO)2Cl2 were used to inform the design of additional FEBID precursors, which will be discussed.
AEROSOL ASSISTED CHEMICAL VAPOR DEPOSITION OF WS2 FROM A SINGLE SOURCE PRECURSOR
Nathaniel E. Richey, Lisa McElwee-White
Department of Chemistry, University of Florida, Gainesville FL 32611-7200, USA
Aerosol assisted chemical vapor deposition (AACVD) is a technique which allows the use of nonvolatile compounds for the deposition of metallic and semiconductor thin films. The sulfur-rich complex WS(S2)(S2CNEt2)2 has been used in AACVD as a single source precursor for the deposition of WS2. The thermal properties of WS(S2)(S2CNEt2)2 have been investigated using thermogravimetric analysis and gaseous byproducts were determined through mass spectrometry. WS2 was successfully deposited at temperatures between 350-500 °C. Synthesis, thermal decomposition, and deposition from WS(S2)(S2CNEt2)2 will be discussed.
HIGHLY DISPERSIBLE CORE-SHELL Ag@TiO2 NANOPARTICLES FOR NON-PHOTOCHEMICAL DEGRADATION OF METHYL PARATHION
Somayeh Talebzadeh Farooji,1 Clémence Queffélec,2 Florian Forato,2 Bruno Bujoli,2 Scott A. Trammell,3 and D. Andrew Knight
1Chemistry Department, Florida Institute of Technology, Melbourne, FL 32901
2Université de Nantes, Laboratoire CEISAM, UMR CNRS 6230, Nantes, France.
3Center for Bio/Molecular Science and Engineering, Naval Research Laboratory, Washington, DC 20375
Highly water-dispersible core-shell Ag@TiO2 nanoparticles were prepared and were shown to be catalytically active for the rapid degradation of the organothiophosphate pesticide methyl parathion (MeP). Formation of degradation product, p-nitrophenolate was monitored at pH=8 using UV-Vis spectroscopy, and 31P NMR spectroscopy confirmed that hydrolysis is the predominant pathway for substrate breakdown under non-photocatalytic conditions. We have demonstrated that the unique combination of TiO2 with silver nanoparticles is required for catalytic hydrolysis with good recyclability. This work represents the first example of MeP degradation using TiO2 doped with AgNP under mild and ambient conditions. The analysis of catalytic data and a proposed dark mechanism for MeP hydrolysis using core-shell Ag@TiO2 will be presented.
Can we leverage equilibrium thermodynamics to unlock new well-defined polymeric materials?
Dr. Goutam Palui, William Neary, Stefan Brits, Michele Bohlmann, Aaron Kendrick, and Prof. Justin G. Kennemur
Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306
Recent success in low ring strain cycloalkenes towards ring opening metathesis polymerization (ROMP) has been achieved. Once considered a negative attribute towards obtaining well-defined materials at high conversions, we have shown that a strategic approach towards leveraging the thermodynamics of this equilibrium polymerization can afford polymers with living-like conditions and at high yields. Synthetic aspects, characterization, and potential utility of these materials will be discussed.