24 results on '"Youn Jue Bae"'
Search Results
2. Tunable interaction between excitons and hybridized magnons in a layered semiconductor
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Geoffrey M. Diederich, John Cenker, Yafei Ren, Jordan Fonseca, Daniel G. Chica, Youn Jue Bae, Xiaoyang Zhu, Xavier Roy, Ting Cao, Di Xiao, and Xiaodong Xu
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Biomedical Engineering ,General Materials Science ,Bioengineering ,Electrical and Electronic Engineering ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics - Abstract
The interaction between distinct excitations in solids is of both fundamental interest and technological importance. One such interaction is the coupling between an exciton, a Coulomb bound electron-hole pair, and a magnon, a collective spin excitation. The recent emergence of van der Waals magnetic semiconductors
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- 2022
3. Mechanically interlocked pyrene-based photocatalysts
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Amine Garci, Jacob A. Weber, Ryan M. Young, Masoud Kazem-Rostami, Marco Ovalle, Yassine Beldjoudi, Ahmet Atilgan, Youn Jue Bae, Wenqi Liu, Leighton O. Jones, Charlotte L. Stern, George C. Schatz, Omar K. Farha, Michael R. Wasielewski, and J. Fraser Stoddart
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Process Chemistry and Technology ,Bioengineering ,Biochemistry ,Catalysis - Published
- 2022
4. π‐Extended Donor–Acceptor Porphyrins and Metalloporphyrins for Antimicrobial Photodynamic Inactivation
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Tadeusz Lis, Yi Lin Wu, Anzhela Galstyan, Yogesh Kumar Maurya, Youn Jue Bae, Halina Zhylitskaya, Ulrich Dobrindt, Michael R. Wasielewski, and Marcin Stępień
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inorganic chemicals ,Porphyrins ,Metalloporphyrins ,medicine.medical_treatment ,Chemie ,chemistry.chemical_element ,triplet state ,Photodynamic therapy ,Zinc ,010402 general chemistry ,Photochemistry ,Gram-Positive Bacteria ,01 natural sciences ,Catalysis ,singlet oxygen ,Metal ,π-extended porphyrins ,chemistry.chemical_compound ,medicine ,Humans ,Triplet state ,Photosensitizing Agents ,Full Paper ,010405 organic chemistry ,Singlet oxygen ,Organic Chemistry ,Free base ,General Chemistry ,photosensitizers ,Full Papers ,Antimicrobial ,Porphyrins | Hot Paper ,0104 chemical sciences ,Anti-Bacterial Agents ,chemistry ,Photochemotherapy ,visual_art ,visual_art.visual_art_medium ,antimicrobial ,Palladium - Abstract
Free base, zinc and palladium π‐extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in antimicrobial photodynamic therapy (aPDT). Their efficacy, assessed by photophysical and in vitro photobiological studies on Gram‐positive bacteria, was found to depend on metal coordination, showing a dramatic enhancement of photosensitizing activity for the palladium complex., Photo finish it: Antimicrobial photodynamic therapy (aPDT) has been proposed as an alternative approach for the treatment of bacterial infections. Here, free base, zinc and palladium π‐extended porphyrins containing fused naphthalenediamide units were employed as photosensitizers in aPDT, assessed by photophysical and in vitro photobiological studies.
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- 2020
5. Spin Dynamics of Quintet and Triplet States Resulting from Singlet Fission in Oriented Terrylenediimide and Quaterrylenediimide Films
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Michael R. Wasielewski, Hiroki Nagashima, Joseph Strzalka, Qingteng Zhang, Youn Jue Bae, Xingang Zhao, and Matthew D. Kryzaniak
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Materials science ,Spin dynamics ,02 engineering and technology ,Chromophore ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Photoexcitation ,Organic semiconductor ,Condensed Matter::Materials Science ,General Energy ,Chemical physics ,Singlet fission ,Physics::Atomic and Molecular Clusters ,Condensed Matter::Strongly Correlated Electrons ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Singlet fission in organic semiconductors provides an important opportunity to study high-spin states in electronically coupled chromophores. Photoexcitation of oriented, crystalline films of N,N-b...
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- 2020
6. Exciton-Coupled Coherent Magnons in a 2D Semiconductor
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Youn Jue Bae, Jue Wang, Allen Scheie, Junwen Xu, Daniel G. Chica, Geoffrey M. Diederich, John Cenker, Michael E. Ziebel, Yusong Bai, Haowen Ren, Cory R. Dean, Milan Delor, Xiaodong Xu, Xavier Roy, Andrew D. Kent, and Xiaoyang Zhu
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Condensed Matter::Materials Science ,Multidisciplinary ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter::Other ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect - Abstract
Two-dimensional (2D) magnetic semiconductors feature both tightly-bound excitons with large oscillator strength and potentially long-lived coherent magnons due to the presence of bandgap and spatial confinement. While magnons and excitons are energetically mismatched by orders of magnitude, their coupling can lead to efficient optical access to spin information. Here we report strong magnon-exciton coupling in the 2D van der Waals (vdW) antiferromagnetic (AFM) semiconductor CrSBr. Coherent magnons launched by above-gap excitation modulate the interlayer hybridization, which leads to dynamic modulation of excitonic energies. Time-resolved exciton sensing reveals magnons that can coherently travel beyond 7 micrometer, with coherence time above 5 ns. We observe this exciton-coupled coherent magnons in both even and odd number of layers, with and without compensated magnetization, down to the bilayer limit. Given the versatility of vdW heterostructures, these coherent 2D magnons may be basis for optically accessible magnonics and quantum interconnects., 14 pages, 5 figures, 30 pages Supporting Info
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- 2022
7. Temperature Tuning of Coherent Mixing between States Driving Singlet Fission in a Spiro-Fused Terrylenediimide Dimer
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Ryan M. Young, Chenjian Lin, Xingang Zhao, James P. O’Connor, Michael R. Wasielewski, Jonathan D. Schultz, and Youn Jue Bae
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Materials science ,010304 chemical physics ,Absorption spectroscopy ,Dielectric ,Orbital overlap ,010402 general chemistry ,01 natural sciences ,Electron spectroscopy ,Molecular physics ,0104 chemical sciences ,Surfaces, Coatings and Films ,Photoexcitation ,Excited state ,0103 physical sciences ,Singlet fission ,Materials Chemistry ,Singlet state ,Physical and Theoretical Chemistry - Abstract
The excited-state dynamics of a spiro-fused terrylene-3,4:11,12-bis(dicarboximide) (TDI) dimer (sTDI2) in toluene and 2-methyltetrahydrofuran (mTHF) were investigated as a function of temperature using femtosecond- and nanosecond-transient absorption spectroscopy, as well as two-dimensional electronic spectroscopy. The spiro conjugation and the corresponding geometry of this compound guarantee a short intermonomer distance along with a partial orbital overlap between the orthogonal TDI π-electron systems, providing electronic coupling between the TDIs. Photoexcitation of sTDI2 in toluene, a low dielectric solvent, at 295 K, results in the ultrafast formation of a state composed of a coherent mixture of singlet 1(S1S0), multiexciton 1(T1T1), and charge-transfer (CT) electronic characters. This mixed species decays to decorrelated triplet states on the nanosecond timescale, completing the process of intramolecular singlet fission (SF) in sTDI2. Upon decreasing the temperature from 295 to 200 K, the contribution of the 1(T1T1) state to the mixed species decreases concurrently with an increase in the CT state character. We attribute this behavior to the variation in the vibrational energy level alignment between the states comprising the mixture due to changes in the temperature and hence the local dielectric environment. In contrast, photoexcitation of sTDI2 in more polar mTHF at 295 K results in the formation of a mixed singlet and CT state before undergoing symmetry-breaking charge separation, owing to the increased stabilization of the CT state in the medium. However, in glassy mTHF at 85 K, photoexcited sTDI2 exhibits discernible multiexciton character, comparable to that observed in toluene at 200 K, which we rationalize by the similarity of the dielectric constants under these two sets of conditions. These observations of mixed states of varying diabatic contributions over the range of experimental conditions show that the temperature and the static dielectric constant can directly control the composition of the electronically mixed excited state of sTDI2 and thus the fate of the SF process.
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- 2021
8. Combining Intra- and Intermolecular Charge Transfer with Polycationic Cyclophanes To Design 2D Tessellations
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J. Fraser Stoddart, Charlotte L. Stern, Douglas Philp, Yassine Beldjoudi, Michael R. Wasielewski, M. Mustafa Cetin, Matthew D. Krzyaniak, Ommid Anamimoghadam, Youn Jue Bae, Indranil Roy, Ryan M. Young, and Fehaid Alsubaie
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Square tiling ,Superstructure ,Intermolecular force ,Viologen ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Crystallography ,Colloid and Surface Chemistry ,chemistry ,Intramolecular force ,medicine ,Tetrathiafulvalene ,Hexagonal tiling ,medicine.drug ,Cyclophane - Abstract
A series of donor-acceptor (D-A) naphthalene-viologen-based cyclophanes of different shapes, sizes, and symmetries have been synthesized and characterized. Solution optical studies on these cyclophanes reveal the existence of photoinduced intramolecular charge transfer (CT) at 465 nm from naphthalene (D) to viologen (A) units, resulting in a conformational change in the viologen units and the emergence of an emission at 540 nm. The D-A cyclophanes with box-like and hexagon-like shapes offer an opportunity to control the arrangement within 2D layers where D-A interactions direct the superstructures. While a box-like 2,6-disubstituted naphthalene-based tetracationic cyclophane does not form square tiling patterns, a truncated hexagon-like congener self-assembles to form a hexagonal superstructure which, in turn, adopts a hexagonal tiling pattern. Tessellation of the more rigid and highly symmetrical 2,7-disubstituted naphthalene-based cyclophanes leads to the formation of 2D square and honeycomb tiling patterns with the box-like and hexagon-like cyclophanes, respectively. Co-crystallization of the box-like cyclophanes with tetrathiafulvalene (TTF) results in the formation of D-A CT interactions between TTF and viologen units, leading to tubular superstructures. Co-crystallization of the hexagon-like cyclophane with TTF generates well-ordered and uniform tubular superstructures in which the TTF-viologen CT interactions and naphthalene-naphthalene [π···π] interactions propagate with 2D topology. In the solid state, the TTF-cyclophane co-crystals are paramagnetic and display dual intra- and intermolecular CT behavior at ∼470 and ∼1000 nm, respectively, offering multi-responsive materials with potential pathways for electron transport.
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- 2019
9. Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature
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Matthew D. Krzyaniak, Jordan N. Nelson, Richard D. Schaller, Michael R. Wasielewski, Samantha M. Harvey, Youn Jue Bae, Michelle Chen, and Ryan M. Young
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Physics ,Multidisciplinary ,Annihilation ,Absorption spectroscopy ,Spin states ,Dimer ,Molecular physics ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Liquid crystal ,Physical Sciences ,Singlet fission ,Molecule ,Electron paramagnetic resonance - Abstract
Singlet fission (SF) is a photophysical process in which one of two adjacent organic molecules absorbs a single photon, resulting in rapid formation of a correlated triplet pair (T(1)T(1)) state whose spin dynamics influence the successful generation of uncorrelated triplets (T(1)). Femtosecond transient visible and near-infrared absorption spectroscopy of a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI(2)), in which the two TDI molecules are directly linked at one of their imide positions, reveals ultrafast formation of the (T(1)T(1)) state. The spin dynamics of the (T(1)T(1)) state and the processes leading to uncoupled triplets (T(1)) were studied at room temperature for TDI(2) aligned in 4-cyano-4′-pentylbiphenyl (5CB), a nematic liquid crystal. Time-resolved electron paramagnetic resonance spectroscopy shows that the (T(1)T(1)) state has mixed (5)(T(1)T(1)) and (3)(T(1)T(1)) character at room temperature. This mixing is magnetic field dependent, resulting in a maximum triplet yield at ∼200 mT. The accessibility of the (3)(T(1)T(1)) state opens a pathway for triplet–triplet annihilation that produces a single uncorrelated T(1) state. The presence of the (5)(T(1)T(1)) state at room temperature and its relationship with the (1)(T(1)T(1)) and (3)(T(1)T(1)) states emphasize that understanding the relationship among different (T(1)T(1)) spin states is critical for ensuring high-yield T(1) formation from singlet fission.
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- 2019
10. Effect of Electronic Coupling on Electron Transfer Rates from Photoexcited Naphthalenediimide Radical Anion to Re(bpy)(CO)3X
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Nathan T. La Porte, Alessandro Sinopoli, Victor S. Batista, Michael R. Wasielewski, Subhajyoti Chaudhuri, Muhammad Sohail, Youn Jue Bae, and Jose F. Martinez
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Materials science ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Acceptor ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Fin (extended surface) ,Gibbs free energy ,Ion ,Electron transfer rate ,Coupling (electronics) ,Condensed Matter::Materials Science ,Electron transfer ,symbols.namesake ,General Energy ,Chemical physics ,symbols ,sense organs ,Physics::Chemical Physics ,Physical and Theoretical Chemistry ,skin and connective tissue diseases ,0210 nano-technology - Abstract
The electron transfer rate between a donor and an acceptor depends on the free energy change for the reaction as well as differences in structure and electronic coupling between the initial and fin...
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- 2019
11. Singlet fission in core-linked terrylenediimide dimers
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Chenjian Lin, Youn Jue Bae, Michael R. Wasielewski, Samantha M. Harvey, Xingang Zhao, Michelle Chen, Ryan M. Young, Jiawang Zhou, and Richard D. Schaller
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Physics ,010304 chemical physics ,Dimer ,General Physics and Astronomy ,Charge (physics) ,Chromophore ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical physics ,Excited state ,0103 physical sciences ,Singlet fission ,Polar ,Singlet state ,Physical and Theoretical Chemistry ,Triplet state - Abstract
We have studied two regioisomeric terrylenediimide (TDI) dimers in which the 1-positions of two TDIs are linked via 1,3- or 1,4-phenylene spacers, mTDI2 and pTDI, respectively. The nature and the dynamics of the multiexciton state are tuned by altering the through-bond electronic couplings in the ground and excited states and by changing the solvent environment. Our results show that controlling the electronic coupling between the two chromophores by an appropriate choice of linker can result in independent triplet state formation, even though the initial correlated triplet pair state is confined to a dimer. Moreover, even in polar solvents, if the electronic coupling is strong, the correlated triplet pair state is observed prior to symmetry-breaking charge separation. These results point out the close relationship between the singlet, correlated triplet pair, and charge transfer states in molecular dimers.
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- 2020
12. Balancing Charge Transfer and Frenkel Exciton Coupling Leads to Excimer Formation in Molecular Dimers: Implications for Singlet Fission
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Atsuhiro Osuka, George C. Schatz, Gyeongwon Kang, Daiki Shimizu, Michael R. Wasielewski, Jonathan D. Schultz, Jiawang Zhou, and Youn Jue Bae
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Photoexcitation ,Anthracene ,chemistry.chemical_compound ,chemistry ,Exciton ,Singlet fission ,Physics::Atomic and Molecular Clusters ,Molecule ,Charge (physics) ,Physical and Theoretical Chemistry ,Chromophore ,Excimer ,Molecular physics - Abstract
Photoexcitation of molecular chromophore aggregates can form excimer states that play a significant role in photophysical processes such as charge and energy transfer as well as singlet fission. An excimer state is commonly defined as a superposition of Frenkel exciton and charge transfer states. In this work, we investigate the dynamics of excimer formation and decay in π-stacked 9,10-bis(phenylethynyl)anthracene (BPEA) covalent dimers appended to a xanthene spacer, where the electronic coupling between the two BPEA molecules is adjusted by changing their longitudinal molecular slip distances. Using exciton coupling calculations, we quantify the relative contributions of Frenkel excitons and charge transfer states and find that there is an upper and lower threshold of the charge transfer contribution for efficient excimer formation to occur. Knowing these thresholds can aid the design of molecular aggregates that optimize singlet fission.
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- 2020
13. Controlling the structure and photophysics of fluorophore dimers using multiple cucurbit[8]uril clampings
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Daniel Antón-García, Oren A. Scherman, István Szabó, Magdalena Olesińska, Michael R. Wasielewski, Youn Jue Bae, Guanglu Wu, Edina Rosta, Wu, Guanglu [0000-0002-9690-5992], Antón-García, Daniel [0000-0001-5466-2921], Wasielewski, Michael R [0000-0003-2920-5440], Scherman, Oren A [0000-0001-8032-7166], and Apollo - University of Cambridge Repository
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3403 Macromolecular and Materials Chemistry ,Fluorophore ,Materials science ,34 Chemical Sciences ,010405 organic chemistry ,Intermolecular force ,3405 Organic Chemistry ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,3. Good health ,chemistry.chemical_compound ,Chemistry ,chemistry ,Chemical physics ,Excited state ,Bathochromic shift ,Molecule ,Ground state ,Quantum - Abstract
A modular strategy has been employed to develop a new class of fluorescent molecules, which generates discrete, dimeric stacked fluorophores upon complexation with multiple cucurbit[8]uril macrocycles. The multiple constraints result in a “static” complex (remaining as a single entity for more than 30 ms) and facilitate fluorophore coupling in the ground state, showing a significant bathochromic shift in absorption and emission. This modular design is surprisingly applicable and flexible and has been validated through an investigation of nine different fluorophore cores ranging in size, shape, and geometric variation of their clamping modules. All fluorescent dimers evaluated can be photo-excited to atypical excimer-like states with elongated excited lifetimes (up to 37 ns) and substantially high quantum yields (up to 1). This strategy offers a straightforward preparation of discrete fluorophore dimers, providing promising model systems with explicitly stable dimeric structures and tunable photophysical features, which can be utilized to study various intermolecular processes., Dimerisation of a wide range of fluorophores through multiple CB[8] clampings leads to constrained intracomplex motion and distinct photophysical properties.
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- 2019
14. Charge‐Transfer Character in a Covalent Diketopyrrolopyrrole Dimer: Implications for Singlet Fission
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Yi Lin Wu, Michelle Chen, Michael R. Wasielewski, Natalia E. Powers-Riggs, Catherine M. Mauck, and Youn Jue Bae
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Chemistry ,Dimer ,Organic Chemistry ,Intermolecular force ,Stacking ,02 engineering and technology ,Chromophore ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,Analytical Chemistry ,Electron transfer ,chemistry.chemical_compound ,Covalent bond ,Intramolecular force ,Singlet fission ,Physical and Theoretical Chemistry ,0210 nano-technology - Abstract
Diketopyrrolopyrrole (DPP) is a strongly absorbing, photostable chromophore that can undergo singlet fission (SF), a photophysical process that promises to significantly enhance solar‐cell performance. In the solid state, DPP packs in a herringbone arrangement that maximizes intermolecular donor–acceptor interactions, suggesting that charge‐transfer (CT) states play a role in DPP SF. In order to characterize intermolecular DPP CT states in molecular assemblies, we have synthesized a covalent DPP dimer bridged by a xanthene linker, which places two thiophene‐substituted DPPs (TDPPs) in a cofacial arrangement that mimics chromophore π–π stacking in the thin film. After photoexcitation in polar solvents, symmetry‐breaking charge separation forms the fully charge separated TDPP+.–TDPP−. ion‐pair state. In nonpolar solvents, charge separation is incomplete leading to the TDPPδ+–TDPPδ− CT state, which is in pseudoequilibrium with the relaxed S1S0 state observed by transient absorption and emission spectroscopy. This study highlights the importance of intramolecular coupling as well as the importance of entropy to promoting SF in chromophore dimers for which SF is endo‐ or isoergic.
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- 2017
15. Understanding the Bias Introduced in Quantum Dot Blinking Using Change Point Analysis
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Tina X. Ding, Natalie A. Gibson, A. Paul Alivisatos, Stephen R. Leone, and Youn Jue Bae
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Technology ,Truncation ,Bioengineering ,02 engineering and technology ,Physical Chemistry ,01 natural sciences ,Bin ,Engineering ,Optics ,0103 physical sciences ,Nanotechnology ,Statistical physics ,Physical and Theoretical Chemistry ,010306 general physics ,Physics ,business.industry ,Fluorescence intermittency ,Charge (physics) ,021001 nanoscience & nanotechnology ,Critical value ,Thresholding ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Intensity (physics) ,General Energy ,Quantum dot ,Chemical Sciences ,0210 nano-technology ,business - Abstract
© 2016 American Chemical Society. The fluorescence intermittency of single CdSe/CdS quantum dots (QDs) with different shell sizes is studied using the conventional bin and threshold method and the statistically more rigorous method, change point analysis (CPA). The on-state truncation time (τc) is a critical value used to interpret the dynamics of charge trapping in single QDs; however, changing the bin size and threshold in blink traces significantly modifies τc. Herein, we use the CPA method to minimize the bias that binning and thresholding introduces and find that a widely used assumption that there is only one on and one off state is questionable. We observe that 12 out of 17 QDs exhibit more than two intensity levels and find that the τcvalues of individual levels differ from the values obtained when the levels are combined, i.e., when one assumes there is only one on and one off state as in the conventional bin and threshold method. For instance, one QD has τcvalues of 0.5 (0.1) and 2.0 (0.2) s from two different intensity levels, whereas when the levels are combined into only one on state, τcis found to be 7 (1) s. The CPA method is found to be more suitable for studying multilevel emission in QDs than the conventional bin and threshold method.
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- 2016
16. Substituent effects on energetics and crystal morphology modulate singlet fission in 9,10-bis(phenylethynyl)anthracenes
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Yi Lin Wu, Youn Jue Bae, Ryan M. Young, Michael R. Wasielewski, Gyeongwon Kang, Richard P. Van Duyne, Joseph A. Christensen, George C. Schatz, and Jiawang Zhou
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Anthracene ,010304 chemical physics ,Intermolecular force ,Substituent ,General Physics and Astronomy ,Crystal structure ,Chromophore ,010402 general chemistry ,Photochemistry ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Yield (chemistry) ,0103 physical sciences ,Singlet fission ,Physical and Theoretical Chemistry ,Triplet state - Abstract
Singlet fission (SF) converts a singlet exciton into two triplet excitons in two or more electronically coupled organic chromophores, which may then be used to increase solar cell efficiency. Many known SF chromophores are unsuitable for device applications due to chemical instability or low triplet state energies. The results described here show that efficient SF occurs in derivatives of 9,10-bis(phenylethynyl)anthracene (BPEA), which is a highly robust and tunable chromophore. Fluoro and methoxy substituents at the 4- and 4′-positions of the BPEA phenyl groups control the intermolecular packing in the crystal structure, which alters the interchromophore electronic coupling, while also changing the SF energetics. The lowest excited singlet state (S1) energy of 4,4′-difluoro-BPEA is higher than that of BPEA so that the increased thermodynamic favorability of SF results in a (16 ± 2 ps)−1 SF rate and a 180% ± 16% triplet yield, which is about an order of magnitude faster than BPEA with a comparable triplet yield. By contrast, 4-fluoro-4′-methoxy-BPEA and 4,4′-dimethoxy-BPEA have slower SF rates, (90 ± 20 ps)−1 and (120 ± 10 ps)−1, and lower triplet yields, (110 ± 4)% and (168 ± 7)%, respectively, than 4,4′-difluoro-BPEA. These differences are attributed to changes in the crystal structure controlling interchromophore electronic coupling as well as SF energetics in these polycrystalline solids.
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- 2019
17. Competition between Singlet Fission and Spin-Orbit-Induced Intersystem Crossing in Anthanthrene and Anthanthrone Derivatives
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Yi Lin Wu, Maude Desroches, Michael R. Wasielewski, Youn Jue Bae, Matthew D. Krzyaniak, Jean-François Morin, and Marek B. Majewski
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education.field_of_study ,Materials science ,010405 organic chemistry ,Anthanthrene ,Population ,General Chemistry ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Fluorescence ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,Intersystem crossing ,chemistry ,law ,Singlet fission ,Singlet state ,Triplet state ,Electron paramagnetic resonance ,education - Abstract
Singlet and triplet excited‐state dynamics of anthanthrene and anthanthrone derivatives in solution are studied. Triisopropylsilyl‐ (TIPS) or H‐terminated ethynyl groups are used to tune the singlet and triplet energies to enable their potential applications in singlet fission and triplet fusion processes. Time‐resolved optical and electron paramagnetic resonance (EPR) spectroscopies are used to obtain a mechanistic understanding of triplet formation. The anthanthrene derivatives form triplet states efficiently at a rate (ca. 107 s−1) comparable to radiative singlet fluorescence processes with approximately 30 % triplet yields, despite their large S1‐T1 energy gap (>1 eV) and the lack of carbonyl groups. In contrast, anthanthrone has a higher triplet yield (50±10 %) with a faster intersystem crossing rate (2.7urn:x-wiley:21926506:media:cplu201900410:cplu201900410-math-0001 108 s−1) because of the n‐π* character of the S1←S0 transition. Analysis of time‐resolved spin‐polarized EPR spectra of these compounds reveals that the triplet states are primarily generated by the spin‐orbit‐induced intersystem crossing mechanism. However, at high concentrations, the EPR spectrum of the 4,6,10,14‐tetrakis(TIPS‐ethynyl) anthanthrene triplet state shows a significant contribution from a non‐Boltzmann population of the ms=0 spin sublevel, which is characteristic of triplet formation by singlet fission.
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- 2019
18. Varying the Interpentacene Electronic Coupling to Tune Singlet Fission
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Timothy Clark, Johannes Zirzlmeier, Youn Jue Bae, Constantin Hetzer, Michael R. Wasielewski, Ilias Papadopoulos, Matthew D. Krzyaniak, Rik R. Tykwinski, and Dirk M. Guldi
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Coupling ,education.field_of_study ,Chemistry ,Population ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Biochemistry ,Molecular physics ,Catalysis ,0104 chemical sciences ,law.invention ,Colloid and Surface Chemistry ,Superexchange ,law ,Intramolecular force ,Singlet fission ,Ultrafast laser spectroscopy ,Electron paramagnetic resonance ,education ,Quantum - Abstract
We have designed and used four different spacers, denoted A-D, to connect two pentacenes and to probe the impact of intramolecular forces on the modulation of pentacene-pentacene interactions and, in turn, on the key steps in singlet fission (SF), that is, the 1(S1S0)-to-1(T1T1) as well as 1(T1T1)-to-5(T1T1) transitions by means of transient absorption and electron paramagnetic resonance measurements. In terms of the 1(S1S0)-to-1(T1T1) transition, a superexchange mechanism, that is, coupling to a higher-lying CT state to generate a virtual intermediate, enables rapid SF in A-D. Sizeable electronic coupling in A and B opens, on one hand, an additional pathway, that is, the population of a real intermediate, and changes, on the other hand, the mechanism to that of hopping. In turn, A and B feature much higher 1(T1T1) quantum yields than C and D, with a maximum value of 162% for A. In terms of the 1(T1T1)-to-5(T1T1) transition, the sizable electronic coupling in A and B is counterproductive, and C and D give rise to higher 5(T1T1)-to-(T1 + T1) quantum yields than A and B, with a maximum value of 85% for D.
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- 2019
19. Transparent Metal–Organic Framework/Polymer Mixed Matrix Membranes as Water Vapor Barriers
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Jeffrey J. Urban, Fen Qiu, Eun Seon Cho, Teresa E. Williams, Daniel T. Sun, Wendy L. Queen, and Youn Jue Bae
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Materials science ,Polymers ,Nanotechnology ,02 engineering and technology ,Substrate (electronics) ,Cyclic olefin copolymer ,010402 general chemistry ,01 natural sciences ,7. Clean energy ,chemistry.chemical_compound ,Organic chemistry ,General Materials Science ,Gas separation ,chemistry.chemical_classification ,Reproducibility of Results ,Water ,Polymer ,Permeation ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,Steam ,Membrane ,chemistry ,Metals ,Metal-organic framework ,0210 nano-technology ,Water vapor - Abstract
Preventing the permeation of reactive molecules into electronic devices or photovoltaic modules is of great importance to ensure their life span and reliability. This work is focused on the formation of highly functioning barrier films based on nanocrystals (NCs) of a water-scavenging metal-organic framework (MOF) and a hydrophobic cyclic olefin copolymer (COC) to overcome the current limitations. Water vapor transmission rates (WVTR) of the films reveal a 10-fold enhancement in the WVTR compared to the substrate while maintaining outstanding transparency over most of the visible and solar spectrum, a necessary condition for integration with optoelectronic devices.
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- 2016
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20. Fully Conjugated [4]Chrysaorene. Redox-Coupled Anion Binding in a Tetraradicaloid Macrocycle
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Yi Lin Wu, Jiawang Zhou, Janusz Gregoliński, Marcin A. Majewski, Marcin Stępień, Michael R. Wasielewski, Hanna Gregolińska, Piotr J. Chmielewski, Alan D. Chien, Youn Jue Bae, and Paul M. Zimmerman
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chemistry.chemical_classification ,010405 organic chemistry ,Chemistry ,Iodide ,General Chemistry ,Conjugated system ,010402 general chemistry ,Photochemistry ,01 natural sciences ,Biochemistry ,Redox ,Catalysis ,0104 chemical sciences ,Adduct ,Dication ,Colloid and Surface Chemistry ,Radical ion ,Chemical stability ,Anion binding - Abstract
[4]Chrysaorene, a fully conjugated carbocyclic coronoid, is shown to be a low-bandgap π-conjugated system with a distinct open-shell character. The system shows good chemical stability and can be oxidized to well-defined radical cation and dication states. The cavity of [4]chrysaorene acts as an anion receptor toward halide ions with a particular selectivity toward iodides (Ka = 207 ± 6 M–1). The interplay between anion binding and redox chemistry is demonstrated using a 1H NMR analysis in solution. In particular, a well-resolved, paramagnetically shifted spectrum of the [4]chrysaorene radical cation is observed, providing evidence for the inner binding of the iodide. The radical cation–iodide adduct can be generated in thin solid films of [4] chrysaorene by simple exposure to diiodine vapor.
- Published
- 2018
21. Singlet Fission in Covalent Terrylenediimide Dimers: Probing the Nature of the Multiexciton State Using Femtosecond Mid-Infrared Spectroscopy
- Author
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Aritra Mandal, Michael R. Wasielewski, Youn Jue Bae, Michelle Chen, Catherine M. Mauck, and Ryan M. Young
- Subjects
Dimer ,Exciton ,Infrared spectroscopy ,02 engineering and technology ,General Chemistry ,Chromophore ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Photochemistry ,01 natural sciences ,Biochemistry ,Catalysis ,0104 chemical sciences ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,chemistry ,Singlet fission ,Femtosecond ,Triplet state ,0210 nano-technology ,Spectroscopy - Abstract
Singlet fission (SF) is a spin-allowed process that involves absorption of a photon by two electronically interacting chromophores to produce a singlet exciton state, 1(S1S0), followed by rapid formation of two triplet excitons if the singlet exciton energy is about twice that of the triplet exciton. The initial formation of the multiexciton correlated triplet pair state, 1(T1T1), is thought to involve the agency of charge transfer (CT) states. The dynamics of these electronic states were studied in a covalent slip-stacked terrylene-3,4:11,12-bis(dicarboximide) (TDI) dimer in which the conformation of two TDI molecules is determined by a xanthene spacer (XanTDI2). Femtosecond mid-infrared (fsIR) spectroscopy shows that the multiexciton 1(T1T1) state has absorptions characteristic of the T1 state in the carbonyl stretch region of the IR spectrum, in addition to IR absorptions specific to the CT state in the C═C stretch region. The simultaneous presence of CT and triplet state features in both high dielectr...
- Published
- 2018
22. Design Principles for Efficient Singlet Fission in Anthracene-based Organic Semiconductors.
- Author
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Youn Jue Bae, Christensen, Joseph A., Kang, Gyeongwon, Malliakas, Christos D., Jiawang Zhou, Nelson, Jordan N., Young, Ryan M., Yi-Lin Wu, Van Duyne, Richard P., Schatz, George C., and Wasielewski, Michael R.
- Published
- 2019
- Full Text
- View/download PDF
23. Importance of Internal Porosity for Glucan Adsorption in Mesoporous Carbon Materials
- Author
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Alexandre Charmot, Alexander Katz, Timothy Click, Po-Wen Chung, Youn Jue Bae, Yuchun Lin, and Jhih-Wei Chu
- Subjects
chemistry.chemical_classification ,Aqueous solution ,Materials science ,Inorganic chemistry ,chemistry.chemical_element ,Surfaces and Interfaces ,Molecular Dynamics Simulation ,Condensed Matter Physics ,Carbon ,Molecular dynamics ,Adsorption ,chemistry ,Etching (microfabrication) ,Electrochemistry ,Carbohydrate Conformation ,Solvents ,General Materials Science ,Mesoporous material ,Porosity ,Glucans ,Spectroscopy ,Glucan - Abstract
To better understand the adsorption of long-chain poly(1 → 4)-β-D-glucans on carbon surfaces as well as interactions responsible for this adsorption, we use a comparative study involving mesoporous carbon-silica composite materials that have been etched to varying degrees and all-atom molecular dynamics simulations. The materials synthesized as part of this etching study consist of an as-synthesized composite material (MCN-MSN), MCN-MSN-0.5 (composite materials consisting of 50% carbon by mass), MCN-MSN-0.3 (composite materials consisting of 70% carbon by mass), and MCN, in which silica etching was conducted using an aqueous ethanolic solution of either NaOH or HF. Data for the adsorption of long-chain glucans to these materials from concentrated aqueous HCl (37 wt %) solution demonstrate a direct relationship between the amount of β-glu adsorption and the magnitude of exposed carbon mesopore surface area, which systematically increases and is also accompanied by an increase in the mesopore size during silica etching. This demonstrates β-glu adsorption as occurring on internal carbon mesopores rather than exclusively on the external carbon surface. These experimental data on adsorption were corroborated by molecular dynamics (MD) simulations of β-glu adsorption to a graphene bilayer separated by a distance of 3.2 nm, chosen to correspond to the carbon mesopore diameter of the experimental system. Simulation results using a variety of β-glu solvent systems demonstrate the rapid adsorption of a β-glu strand on the graphitic carbon surface via axial coupling and are consistent with experimentally observed trends in fast adsorption kinetics. Solvent-mediated effects such as small-scale hydrophobicity and preferential interactions with ions are shown to play important roles in modulating glucan adsorption to carbon surfaces, whereas experimental data on hydrophobically modified silica demonstrate that hydrophobicity in and of itself is insufficient to cause β-glu adsorption from concentrated aqueous HCl solution.
- Published
- 2015
24. Quintet-triplet mixing determines the fate of the multiexciton state produced by singlet fission in a terrylenediimide dimer at room temperature.
- Author
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Chen, Michelle, Krzyaniak, Matthew D., Nelson, Jordan N., Youn Jue Bae, Harvey, Samantha M., Schaller, Richard D., Young, Ryan M., and Wasielewski, Michael R.
- Subjects
SINGLET state (Quantum mechanics) ,ENERGY levels (Quantum mechanics) ,EXCITON theory ,CRYSTAL structure ,FISSION (Asexual reproduction) - Abstract
Singlet fission (SF) is a photophysical process in which one of two adjacent organic molecules absorbs a single photon, resulting in rapid formation of a correlated triplet pair (T
1 T1 ) state whose spin dynamics influence the successful generation of uncorrelated triplets (T1 ). Femtosecond transient visible and near-infrared absorption spectroscopy of a linear terrylene-3,4:11,12-bis(dicarboximide) dimer (TDI2 ), in which the two TDI molecules are directly linked at one of their imide positions, reveals ultrafast formation of the (T1 T1 ) state. The spin dynamics of the (T1 T1 ) state and the processes leading to uncoupled triplets (T1 ) were studied at room temperature for TDI2 aligned in 4-cyano-4'-pentylbiphenyl (5CB), a nematic liquid crystal. Time-resolved electron paramagnetic resonance spectroscopy shows that the (T1 T1 ) state has mixed5 (T1 T1 ) and ³(T1 T1 ) character at room temperature. This mixing is magnetic field dependent, resulting in a maximum triplet yield at ~200 mT. The accessibility of the ³(T1 T1 ) state opens a pathway for triplet-triplet annihilation that produces a single uncorrelated T1 state. The presence of the5 (T1 T1 ) state at room temperature and its relationship with the ¹(T1 T1 ) and 3(T1 T1 ) states emphasize that understanding the relationship among different (T1 T1 ) spin states is critical for ensuring high-yield T1 formation from singlet fission. [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF
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