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Nusser BD, Accardo JV, Zhu L. Luminescence and Stability of 1,4,5-Triaryl-1,2,3-Triazoles. Chemphyschem 2023; 24:e202300209. [PMID: 37395382 DOI: 10.1002/cphc.202300209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/04/2023]
Abstract
The fluorescence, phosphorescence, and photochemical properties of di- and triaryl-substituted-1,2,3-triazoles are reported in this work. The ease of synthesis of regioisomers of substituted triazoles enables a systematic study on the correlation between regiochemistry and excited state properties, which include the solvent dependence of fluorescence, energy gap between singlet and triplet emitters, and propensity to photon-triggered transformations. The triazoles that carry electron (e)-donor and e-acceptor aryl substituents show high fluorescence quantum yields in weakly polar solvents and exhibit solvent-dependent fluorescence. The luminescence properties of these compounds in glass matrices at 77 K are characterized. The thermal and photo-stability, two parameters that are crucial to their potential utilities in optical devices, of these compounds are determined. The position of the e-donor substituent has a significant impact on the fluorescence emission energy and solvent sensitivity, singlet-triplet energy gap, and photochemical reactivity and stability. The experimental observations on the structural correlation with the photophysical and photochemical properties are explained by quantum chemical calculations. This study provides a rationale on the placement of substituent on a donor-acceptor type fluorophore to maneuver a range of photo-related properties.
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Affiliation(s)
- Brandon D Nusser
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-4390, USA
| | - Joseph V Accardo
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-4390, USA
| | - Lei Zhu
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftan Way, Tallahassee, FL 32306-4390, USA
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Zhang V, Accardo JV, Kevlishvili I, Woods EF, Chapman SJ, Eckdahl CT, Stern CL, Kulik HJ, Kalow JA. Tailoring Dynamic Hydrogels by Controlling Associative Exchange Rates. Chem 2023; 9:2298-3317. [PMID: 37790656 PMCID: PMC10545375 DOI: 10.1016/j.chempr.2023.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Dithioalkylidenes are a newly-developed class of conjugate acceptors that undergo thiol exchange via an associative mechanism, enabling decoupling of key material properties for sustainability, biomedical, and sensing applications. Here, we show that the exchange rate is highly sensitive to the structure of the acceptor and tunable over four orders of magnitude in aqueous environments. Cyclic acceptors exchange rapidly, from 0.95 to 15.6 M-1s-1, while acyclic acceptors exchange between 3.77x10-3 and 2.17x10-2 M-1s-1. Computational, spectroscopic, and structural data suggest that cyclic acceptors are more reactive than their acyclic counterparts because of resonance stabilization of the tetrahedral exchange intermediate. We parametrize molecular reactivity with respect to computed descriptors of the electrophilic site and leverage this insight to design a compound with intermediate characteristics. Lastly, we incorporate this dynamic bond into hydrogels and demonstrate that the characteristic stress relaxation time (τ) is directly proportional to molecular kex.
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Affiliation(s)
- Vivian Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
| | - Joseph. V Accardo
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
| | - Ilia Kevlishvili
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, Cambridge, MA, USA
| | - Eliot F. Woods
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
| | - Steven J. Chapman
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
| | | | - Charlotte L. Stern
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
| | - Heather J. Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, 25 Ames Street, Cambridge, MA, USA
| | - Julia A. Kalow
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL, USA
- Lead contact
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Husted KEL, Brown CM, Shieh P, Kevlishvili I, Kristufek SL, Zafar H, Accardo JV, Cooper JC, Klausen RS, Kulik HJ, Moore JS, Sottos NR, Kalow JA, Johnson JA. Remolding and Deconstruction of Industrial Thermosets via Carboxylic Acid-Catalyzed Bifunctional Silyl Ether Exchange. J Am Chem Soc 2023; 145:1916-1923. [PMID: 36637230 DOI: 10.1021/jacs.2c11858] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Convenient strategies for the deconstruction and reprocessing of thermosets could improve the circularity of these materials, but most approaches developed to date do not involve established, high-performance engineering materials. Here, we show that bifunctional silyl ether, i.e., R'O-SiR2-OR'', (BSE)-based comonomers generate covalent adaptable network analogues of the industrial thermoset polydicyclopentadiene (pDCPD) through a novel BSE exchange process facilitated by the low-cost food-safe catalyst octanoic acid. Experimental studies and density functional theory calculations suggest an exchange mechanism involving silyl ester intermediates with formation rates that strongly depend on the Si-R2 substituents. As a result, pDCPD thermosets manufactured with BSE comonomers display temperature- and time-dependent stress relaxation as a function of their substituents. Moreover, bulk remolding of pDCPD thermosets is enabled for the first time. Altogether, this work presents a new approach toward the installation of exchangeable bonds into commercial thermosets and establishes acid-catalyzed BSE exchange as a versatile addition to the toolbox of dynamic covalent chemistry.
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Affiliation(s)
- Keith E L Husted
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Christopher M Brown
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Peyton Shieh
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Ilia Kevlishvili
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Samantha L Kristufek
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Hadiqa Zafar
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Joseph V Accardo
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Julian C Cooper
- Department of Chemistry, University of Illinois at Urbana Champaign, Champaign County, Illinois 61820, United States
| | - Rebekka S Klausen
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21287, United States
| | - Heather J Kulik
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Jeffrey S Moore
- Department of Chemistry, University of Illinois at Urbana Champaign, Champaign County, Illinois 61820, United States.,Department of Materials Science and Engineering, University of Illinois at Urbana Champaign, Champaign County, Illinois 60208, United States
| | - Nancy R Sottos
- Department of Materials Science and Engineering, University of Illinois at Urbana Champaign, Champaign County, Illinois 60208, United States
| | - Julia A Kalow
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Jeremiah A Johnson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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Abstract
Polymer networks built out of dynamic covalent bonds offer the potential to translate the control and tunability of chemical reactions to macroscopic physical properties. Under conditions at which these reactions occur, the topology of covalent adaptable networks (CANs) can rearrange, meaning that they can flow, self-heal, be remolded, and respond to stimuli. Materials with these properties are necessary to fields ranging from sustainability to tissue engineering; thus the conditions and time scale of network rearrangement must be compatible with the intended use. The mechanical properties of CANs are based on the thermodynamics and kinetics of their constituent bonds. Therefore, strategies are needed that connect the molecular and macroscopic worlds. In this Perspective, we analyze structure-reactivity-property relationships for several classes of CANs, illustrating both general design principles and the predictive potential of linear free energy relationships (LFERs) applied to CANs. We discuss opportunities in the field to develop quantitative structure-reactivity-property relationships and open challenges.
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Affiliation(s)
- Vivian Zhang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois60208, United States
| | - Boyeong Kang
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois60208, United States
| | - Joseph V Accardo
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois60208, United States
| | - Julia A Kalow
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois60208, United States
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Accardo JV, Kalow JA. Reversibly tuning hydrogel stiffness through photocontrolled dynamic covalent crosslinks. Chem Sci 2018; 9:5987-5993. [PMID: 30079213 PMCID: PMC6050525 DOI: 10.1039/c8sc02093k] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 06/15/2018] [Indexed: 11/25/2022] Open
Abstract
Controlling the physical properties of soft materials with external stimuli enables researchers to mimic and study dynamic systems. Of particular interest are hydrogels, polymer networks swollen by water with broad applicability to biomedicine. To control hydrogel mechanics with light, researchers have relied on a limited number of photochemical reactions. Here we introduce an approach to reversibly tune hydrogel mechanics with light by manipulating the stability of dynamic covalent crosslinks at the molecular level. The equilibrium between a boronic acid and diol to form a boronic ester can be altered by the configuration of an adjacent azobenzene photoswitch. By irradiating branched polymers bearing azobenzene-boronic acid and diol end groups with two different wavelengths of light, we can stiffen or soften the resulting hydrogel. Alternating irradiation induces reversible mechanical changes. Rheological characterization reveals that the hydrogels are viscoelastic, exhibiting stress relaxation on the order of seconds, and the stiffness is tuned independently of the crossover frequency. We have also demonstrated that this approach can be extended to use visible light for both softening and stiffening. These photocontrolled dynamic covalent crosslinks provide a versatile platform for tunable dynamic materials.
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Affiliation(s)
- Joseph V Accardo
- Department of Chemistry , Northwestern University , 2145 Sheridan Rd. , Evanston , IL 60208 , USA .
| | - Julia A Kalow
- Department of Chemistry , Northwestern University , 2145 Sheridan Rd. , Evanston , IL 60208 , USA .
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Abstract
The structural and optical properties of hydroxyphenyl-substituted-1,2,3-triazole molecules ("click" triazoles) are described. "Click" triazoles are prepared from the copper(I)-catalyzed azide-alkyne cycloaddition reactions. The alkyne-derived C4 substituent of a "click" triazole engages in electronic conjugation more effectively with the triazolyl core than the azide-derived N1 substituent. Furthermore, triazolyl group exerts a stronger electron-withdrawing effect on the N1 than the C4 substituent. Therefore, the placement of an electron-donating group at either C4 or N1 position and the presence or the absence of an intramolecular hydrogen bond (HB) have profound influences on the optical properties of these compounds. The reported "click" triazoles have fluorescence quantum yields in the range of 0.1-0.3 and large apparent Stokes shifts (8000-13 000 cm-1) in all tested solvents. Deprotonation of "click" triazoles with a C4 hydroxyphenyl group increases their Stokes shifts; while the opposite (or quenching) occurs to the triazoles with an N1 hydroxyphenyl substituent. For the triazoles that contain intramolecular HBs, neither experimental nor computational results support a model of excited state intramolecular proton transfer (ESIPT). Rather, the excited state internal (or intramolecular) charge transfer (ICT) mechanism is more suitable to explain the fluorescence properties of the hydroxyphenyl-substituted "click" triazoles; specifically, the large Stokes shifts of these compounds.
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Affiliation(s)
- Quinton J Meisner
- Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way , Tallahassee , Florida 32306-4390 , United States
| | - Joseph V Accardo
- Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way , Tallahassee , Florida 32306-4390 , United States
| | - Guoxiang Hu
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Ronald J Clark
- Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way , Tallahassee , Florida 32306-4390 , United States
| | - De-En Jiang
- Department of Chemistry , University of California , Riverside , California 92521 , United States
| | - Lei Zhu
- Department of Chemistry and Biochemistry , Florida State University , 95 Chieftan Way , Tallahassee , Florida 32306-4390 , United States
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