1
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Zhang B, Du C, Wen X, Zhang L, Duan R, Liu M. Supramolecular Chiral Aggregation of Porphyrin Induced by Photo-Generated Triphenylamines Radical Cations. SMALL METHODS 2024:e2400538. [PMID: 38988148 DOI: 10.1002/smtd.202400538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2024] [Revised: 06/18/2024] [Indexed: 07/12/2024]
Abstract
Here, it is shown that photoirradiation triggered chiral J-aggregates formation of an achiral anionic porphyrin, TPPS (tetrakis(4-sulfonatophenyl) porphyrin), in the presence of chiral triphenylamine (TPA) derivatives. A series of chiral triarylamines linked with aromatic rings is designed through urea or amide bonds. UV-irradiation of self-assembled urea-linked triphenylamine derivatives causes the formation of persistent radical cations in the chlorinated solvents, which subsequently induces the aggregation of TPPS. Transferring chirality of TPA derivatives to achiral TPPS J-aggregates leads to the chiral assemblies with remarkable chiroptical signals. The experimental results demonstrate that, TPA derivatives linked by the urea bond can effectively promote the aggregation of TPPS rather than those with the amide bond although the photo-generated radical cations are both produced. It is suggested that the urea-linked TPA derivatives are more favorable to stable radical cations and thus cause the formation of TPPS chiral J-aggregation. This work may open up an avenue for designing photo-modulated chiral supramolecular assemblies.
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Affiliation(s)
- Bojia Zhang
- Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Cong Du
- Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
- School of Materials Science and Engineering, and Key Lab for Special Functional Materials of Ministry of Education, Henan University, Kaifeng, 475004, P. R. China
| | - Xin Wen
- Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Li Zhang
- Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Ran Duan
- Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Minghua Liu
- Beijing National Laboratory for Molecular Science (BNLMS), CAS Key Laboratory of Colloid, Interface and Chemical Thermodynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, P. R. China
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2
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Zhu Z, Zhang L. The crystal structure of 1-(4-bromophenyl)-3-(2-chlorobenzyl)urea, C 14H 12BrClN 2O. Z KRIST-NEW CRYST ST 2022. [DOI: 10.1515/ncrs-2022-0456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Abstract
C14H12BrClN2O, monoclinic, P21/c (no. 14), a = 13.4072(6) Å, b = 8.6103(5) Å, c = 12.3824(6) Å, β = 100.475(4), V = 1405.60(12) Å3, Z = 4, Rgt
(F) = 0.0499, wRref
(F
2) = 0.1215, T = 173 K.
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Affiliation(s)
- Zhihong Zhu
- School of Food and Drug, Luoyang Polytechnic , 471000 , Luoyang , China
| | - Lilei Zhang
- College of Chemistry and Chemical Engineering, Luoyang Normal University , 471934 , Luoyang , China
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3
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Li D, Yang J, Fang M, Tang BZ, Li Z. Stimulus-responsive room temperature phosphorescence materials with full-color tunability from pure organic amorphous polymers. SCIENCE ADVANCES 2022; 8:eabl8392. [PMID: 35213217 PMCID: PMC8880773 DOI: 10.1126/sciadv.abl8392] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Achieving stimulus-responsive ultralong room temperature phosphorescence (RTP) in organic materials especially with full-color tunable emissions is attractive and important but rarely reported. Here, a strategy was reported to realize stimulus-responsive RTP effect with color-tunable emissions by using water as solvent in the preparation process without any organic solvent through covalent linkage of arylboronic acids with different π conjugations and polymer matrix of polyvinyl alcohol. The yielded polymer films exhibit outstanding RTP performance (2.43 s). Furthermore, an excitation-dependent RTP film was obtained, and the afterglow color changes from blue to green, then to red as the excitation wavelength increases. The RTP property of all the above materials is sensitive to water and heat stimuli, because the rigidity of the system could be broken by water. Last, they were successfully applied in a multilevel information encryption and multicolor paper and ink.
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Affiliation(s)
- Dan Li
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
| | - Jie Yang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
- Corresponding author. (J.Y.); (B.Z.T.); (Z.L.)
| | - Manman Fang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
| | - Ben Zhong Tang
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
- Shenzhen Institute of Molecular Aggregate Science and Engineering, School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen, Guangdong 518172, China
- Corresponding author. (J.Y.); (B.Z.T.); (Z.L.)
| | - Zhen Li
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China
- Tianjin Key Laboratory of Molecular Optoelectronic Sciences, Department of Chemistry, Tianjin University, Tianjin 300072, China
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China
- Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China
- Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
- Corresponding author. (J.Y.); (B.Z.T.); (Z.L.)
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4
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Islam MF, Sindt AJ, Hossain MS, Ayare PJ, Smith MD, Vannucci AK, Garashchuk S, Shimizu LS. Assembled triphenylamine bis-urea macrocycles: exploring photodriven electron transfer from host to guests. Phys Chem Chem Phys 2021; 23:23953-23960. [PMID: 34661219 DOI: 10.1039/d1cp03000k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Absorption of electronic acceptors in the accessible channels of an assembled triphenylamine (TPA) bis-urea macrocycle 1 enabled the study of electron transfer from the walls of the TPA framework to the encapsulated guests. The TPA host is isoskeletal in all host-guest structures analyzed with guests 2,1,3-benzothiadiazole, 2,5-dichlorobenzoquinone and I2 loading in single-crystal-to-single-crystal transformations. Analysis of the crystal structures highlights how the spatial proximity and orientation of the TPA host and the entrapped guests influence their resulting photophysical properties and allow direct comparison of the different donor-acceptor complexes. Diffuse reflectance spectroscopy shows that upon complex formation 1·2,5-dichlorobenzoquinone exhibits a charge transfer (CT) transition. Whereas, the 1·2,1,3-benzothiadiazole complex undergoes a photoinduced electron transfer (PET) upon irradiation with 365 nm LEDs. The CT absorptions were also identified with the aid of time dependent density functional theory (TD-DFT) calculations. Cyclic voltammetry experiments show that 2,1,3-benzothiadiazole undergoes reversible reduction within the host-guest complex. Moreover, the optical band gaps of the host 1·2,5-dichlorobenzoquinone (1.66 eV), and host 1·2,1,3-benzothiadiazole (2.15 eV) complexes are significantly smaller as compared to the free host 1 material (3.19 eV). Overall, understanding this supramolecular electron transfer strategy should pave the way towards designing lower band gap inclusion complexes.
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Affiliation(s)
- Md Faizul Islam
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Ammon J Sindt
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Muhammad Saddam Hossain
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Pooja J Ayare
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Aaron K Vannucci
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Sophya Garashchuk
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
| | - Linda S Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia South Carolina 29208, USA.
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5
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Belh SJ, Ghosh G, Greer A. Surface-Radical Mobility Test by Self-Sorted Recombination: Symmetrical Product upon Recombination (SPR). J Phys Chem B 2021; 125:4212-4220. [PMID: 33856798 DOI: 10.1021/acs.jpcb.1c01099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe here a study of the mobility of the alkoxy radical on a surface by detection of its recombination product. A novel method called symmetrical product recombination (SRP) uses an unsymmetrical peroxide that upon sensitized homolysis recombines to a symmetrical product [R'OOR → R'O•↑ + •OR → ROOR]. This allows for self-sorting of the radical to enhance the recombination path to a symmetrical product, which has been used to deduce surface migratory aptitude. SPR also provides a new opportunity for mechanistic studies of interfacial radicals, including monitoring competition between radical recombination versus surface hydrogen abstraction. This is an approach that might work for other surface-borne radicals on natural and artificial particles.
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Affiliation(s)
- Sarah J Belh
- Department of Chemistry, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York 11210, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Goutam Ghosh
- Department of Chemistry, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York 11210, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
| | - Alexander Greer
- Department of Chemistry, Brooklyn College, 2900 Bedford Avenue, Brooklyn, New York 11210, United States.,Ph.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 Fifth Avenue, New York, New York 10016, United States
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6
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Yang Y, Ying H, Li Z, Wang J, Chen Y, Luo B, Gray DL, Ferguson A, Chen Q, Z Y, Cheng J. Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent. Nat Commun 2021; 12:1572. [PMID: 33692349 PMCID: PMC7947004 DOI: 10.1038/s41467-021-21678-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/13/2021] [Indexed: 11/09/2022] Open
Abstract
Macrocycles are unique molecular structures extensively used in the design of catalysts, therapeutics and supramolecular assemblies. Among all reactions reported to date, systems that can produce macrocycles in high yield under high reaction concentrations are rare. Here we report the use of dynamic hindered urea bond (HUB) for the construction of urea macrocycles with very high efficiency. Mixing of equal molar diisocyanate and hindered diamine leads to formation of macrocycles with discrete structures in nearly quantitative yields under high concentration of reactants. The bulky N-tert-butyl plays key roles to facilitate the formation of macrocycles, providing not only the kinetic control due to the formation of the cyclization-promoting cis C = O/tert-butyl conformation, but also possibly the thermodynamic stabilization of macrocycles with weak association interactions. The bulky N-tert-butyl can be readily removed by acid to eliminate the dynamicity of HUB and stabilize the macrocycle structures.
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Affiliation(s)
- Yingfeng Yang
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Hanze Ying
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Zhixia Li
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jiang Wang
- Department of Chemistry, Rice University, Houston, TX, 77005, USA
| | - Yingying Chen
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Binbin Luo
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Danielle L Gray
- George L. Clark X-Ray Facility & 3M Materials Laboratory, School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Andrew Ferguson
- Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL, 60637, USA
| | - Qian Chen
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Y Z
- Department of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jianjun Cheng
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. .,Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
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7
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Goodlett DW, Sindt AJ, Hossain MS, Merugu R, Smith MD, Garashchuk S, Gudmundsdottir AD, Shimizu LS. From Incident Light to Persistent and Regenerable Radicals of Urea-Assembled Benzophenone Frameworks: A Structural Investigation. J Phys Chem A 2021; 125:1336-1344. [PMID: 33534579 DOI: 10.1021/acs.jpca.0c08953] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Herein we probe the effects of crystalline structure and geometry on benzophenone photophysics, self-quenching, and the regenerable formation of persistent triplet radical pairs at room temperature. Radical pairs are not observed in solution but appear via an emergent pathway within the solid-state assembly. Single crystal X-ray diffraction (SC-XRD) of two sets of constitutional isomers, benzophenone bis-urea macrocycles, and methylene urea-tethered dibenzophenones are compared. Upon irradiation with 365 nm light-emitting diodes (LEDs), each forms photogenerated radicals as monitored by electron paramagnetic resonance (EPR). Once generated, the radicals exhibit half-lives from 2 to 60 days before returning to starting material without degradation. Re-exposure to light regenerates the radicals with similar efficiency. Subtle differences in the structure of the crystalline frameworks modulates the maximum concentration of photogenerated radicals, phosphorescence quantum efficiency (φ), and n-type self-quenching as observed using laser flash photolysis (LFP). These studies along with the electronic structure analysis based on the time-dependent density functional theory (TD-DFT) suggest the microenvironment surrounding benzophenone largely dictates the favorability of self-quenching or radical formation and affords insights into structure/function correlations. Advances in understanding how structure determines the excited state pathway solid-state materials undertake will aid in the design of new radical initiators, components of OLEDs, and NMR polarizing agents.
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Affiliation(s)
- Dustin W Goodlett
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Ammon J Sindt
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Muhammad Saddam Hossain
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Rajkumar Merugu
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Mark D Smith
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sophya Garashchuk
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Anna D Gudmundsdottir
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, United States
| | - Linda S Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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8
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Link BA, Sindt AJ, Shimizu LS, Do TD. Selective host-guest chemistry, self-assembly and conformational preferences of m-xylene macrocycles probed by ion-mobility spectrometry mass spectrometry. Phys Chem Chem Phys 2020; 22:9290-9300. [PMID: 32309846 DOI: 10.1039/c9cp06938k] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We demonstrated ion-mobility spectrometry mass spectrometry (IMS-MS) as a powerful tool for interrogating and preserving selective chemistry including non-covalent and host-guest complexes of m-xylene macrocycles formed in solution. The technique readily revealed the unique favorability of a thiourea-containing macrocycle MXT to Zn2+ to form a dimer complex with the cation in an off-axis sandwich structure having the Zn-S bonds in a tetrahedral coordination environment. Replacing thiourea with urea generates MXU which formed high-order oligomerization with weak binding interactions to neutral DMSO guests detected at every oligomer size. The self-assembly pathway observed for this macrocycle is consistent with the crystalline assembly. Further transformation of urea into squaramide produces MXS, a rare receptor for probing sulfate in solution. Tight complexes were observed for both monomeric and dimeric of MXS in which HSO4- bound stronger than SO42- to the host. The position of HSO4- at the binding cavity is a 180° inversion of the reported crystallographic SO42-. The MXS dimer formed a prism-like shape with HSO4- exhibiting strong contacts with the 8 amine protons of two MXS macrocycles. By eliminating intermolecular interferences, we detected the low energy structures of MXS with collisional cross section (CCS) matching cis-trans and cis-cis squaramides-amines, both were not observed in crystallization trials. The experiments collectively unravel multiple facets of macrocycle chemistry including conformational flexibility, self-assembly and ligand binding; all in one analysis. Our findings illustrate an inexpensive and widely applicable approach to investigate weak but important interactions that define the shape and binding of macrocycles.
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Affiliation(s)
- Benjamin A Link
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, USA.
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9
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Sindt AJ, DeHaven BA, Goodlett DW, Hartel JO, Ayare PJ, Du Y, Smith MD, Mehta AK, Brugh AM, Forbes MDE, Bowers CR, Vannucci AK, Shimizu LS. Guest Inclusion Modulates Concentration and Persistence of Photogenerated Radicals in Assembled Triphenylamine Macrocycles. J Am Chem Soc 2019; 142:502-511. [DOI: 10.1021/jacs.9b11518] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Ammon J. Sindt
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Baillie A. DeHaven
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Dustin W. Goodlett
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Johannes O. Hartel
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Pooja J. Ayare
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Yong Du
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Mark D. Smith
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Anil K. Mehta
- National High Magnetic Field Laboratory and McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, United States
| | - Alexander M. Brugh
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Malcolm D. E. Forbes
- Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, United States
| | - Clifford R. Bowers
- Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Aaron K. Vannucci
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Linda S. Shimizu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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10
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Sindt AJ, DeHaven BA, McEachern DF, Dissanayake DMMM, Smith MD, Vannucci AK, Shimizu LS. UV-irradiation of self-assembled triphenylamines affords persistent and regenerable radicals. Chem Sci 2019; 10:2670-2677. [PMID: 30996983 PMCID: PMC6419929 DOI: 10.1039/c8sc04607g] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 01/09/2019] [Indexed: 11/21/2022] Open
Abstract
UV-irradiation of assembled urea-tethered triphenylamine dimers results in the formation of persistent radicals, whereas radicals generated in solution are reactive and quickly degrade. In the solid-state, high quantities of radicals (approximately 1 in 150 molecules) are formed with a half-life of one week with no significant change in the single crystal X-ray diffraction. Remarkably, after decay, re-irradiation of the solid sample regenerates the radicals to their original concentration. The photophysics upon radical generation are also altered. Both the absorption and emission are significantly quenched without external oxidation likely due to the delocalization of the radicals within the crystals. The factors that influence radical stability and generation are correlated to the rigid supramolecular framework formed by the urea tether of the triphenylamine dimer. Electrochemical evidence demonstrates that these compounds can be oxidized in solution at 1.0 V vs. SCE to generate radical cations, whose EPR spectra were compared with spectra of the solid-state photogenerated radicals. Additionally, these compounds display changes in emission due to solvent effects from fluorescence to phosphorescence. Understanding how solid-state assembly alters the photophysical properties of triphenylamines could lead to further applications of these compounds for magnetic and conductive materials.
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Affiliation(s)
- Ammon J Sindt
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - Baillie A DeHaven
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - David F McEachern
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - D M M Mevan Dissanayake
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - Mark D Smith
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - Aaron K Vannucci
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
| | - Linda S Shimizu
- Department of Chemistry and Biochemistry , University of South Carolina , Columbia , South Carolina 29208 , USA .
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