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Wilson EAK, Kumar P, Montjoy DG, Kotov NA. Dispersion of Hydrophilic "Hedgehog" Microparticles in Liquid CO 2 Mixtures. ACS NANO 2022; 16:13942-13948. [PMID: 36036608 DOI: 10.1021/acsnano.2c03058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid and supercritical CO2 are nontoxic and nonflammable reaction media with pressure-variable physical properties. These states of CO2 also have high solubility limits for gas and liquid hydrocarbons, making them good candidates for "green" hydrophobic solvents in sustainable chemical technologies. However, the dispersion of hydrophilic colloidal nanoscale and microscale particles in CO2 is challenging due to the tendency of polar particles to aggregate in nonpolar media, limiting their available surface area and catalytic efficiencies. Here we show that native hydrophilic semiconductor particles can be effectively dispersed in a liquid CO2 mixture with acetonitrile (ACN) without additional chemical or mechanical dispersion techniques. Using surface corrugation as a method to prevent aggregation, we find that geometrically complex particles with a halo of stiff nanoscale spikes disperse and remain suspended longer in liquid CO2 than those without or with less prominent nanoscale corrugation. For the particles of this size and liquid CO2 mixtures, individual particle mass remains a prominent factor determining particle sedimentation rate even in the absence of aggregation. Particle dispersion and structural stability are confirmed using a combination of UV-vis spectroscopy, finite-difference time-domain modeling, and electron microscopy. The necessity of the cosolvent (ACN) indicates that particle behavior in liquid CO2 is vastly different than in traditional liquid-phase solvents and highlights the need for future studies to understand the wetting behavior of hydrophilic particles in high-pressure nonpolar environments.
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Affiliation(s)
- Elizabeth A K Wilson
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Prashant Kumar
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Douglas G Montjoy
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Nicholas A Kotov
- Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Materials Science, University of Michigan, Ann Arbor, Michigan 48109, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
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Darzinezhad K, Amini MM, Janghouri M, Mohajerani E, Fathollahi MR, Jamshidi Z, Janiak C. Introducing Bluish-Green Light-Emitting Diodes (OLEDs) and Tuning Their Color Intensity by Uranium Complexes: Synthesis, Characterization, and Photoluminescence Studies of 8-Hydroxyquinoline Complexes of Uranium. Inorg Chem 2020; 59:17028-17037. [PMID: 33232608 DOI: 10.1021/acs.inorgchem.0c02242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To improve our understanding of the chemistry of actinide complexes and to spur their development in the field of actinide markers, two new uranium complexes were synthesized using 8-hydroxyquinoline and 5,7-dichloro-8-hydroxyquinoline. The prepared complexes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, ultraviolet-visible spectroscopy, elemental analysis, and single-crystal X-ray diffraction. The impact of the electron-withdrawing group of the ligand on the photoluminescence spectra of the complexes in solution and in the solid state was scrutinized. The bandgap of the complexes was calculated using the density functional theory (DFT) method to investigate the effects of the electron-withdrawing groups on energy levels. The synthesized uranium complexes demonstrated appropriate levels of the lowest unoccupied molecular orbital energy, leading to favorable dye stability. The prepared uranium complexes showed blue fluorescent emission, and the sample with the most intense fluorescence was used to construct bluish-green organic light-emitting diodes using simple solution processing fabrication methods. Absorbance spectra, emission spectra, DFT-calculated energy levels, and comparisons of the fabricated organic light-emitting diodes indicated that the electron-withdrawing group was a key factor in photoluminescence behavior.
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Affiliation(s)
| | - Mostafa M Amini
- Department of Chemistry, Shahid Beheshti University, Tehran 1983963113, Iran
| | - Mohammad Janghouri
- Faculty of Industrial Technologies, Urmia University of Technology, Band Road, Urmia 5716693187, Iran
| | - Ezeddin Mohajerani
- Laser and Plasma Research Institute, Shahid Beheshti University, Tehran 1983963113, Iran
| | | | - Zahra Jamshidi
- Chemistry Department, Sharif University of Technology, Tehran 11155-9516, Iran
| | - Christoph Janiak
- Institut für Anorganische Chemie und Strukturchemie Heinrich-Heine Universität, D-40204 Düsseldorf, Germany
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