1
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Martyka M, Jankowska J. New insights into the photocyclization reaction of a popular diarylethene switch: a nonadiabatic molecular dynamics study. Phys Chem Chem Phys 2024; 26:13383-13394. [PMID: 38646878 DOI: 10.1039/d3cp06256b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
Diarylethene (DAE) molecular switches have continued to attract the attention of researchers for over 20 years. Their remarkable photophysical properties endow them with countless applications in photonics and molecular technologies. However, despite extensive experimental and theoretical research, the mechanism of DAE photoswitching is not yet fully rationalized. In this work, we investigate the ring closure dynamics of a popular DAE switch, 1,2-bis(3-methyl-5-phenyl-2 thienyl)perfluorocyclopentene (PT), using nonadiabatic molecular dynamics (NAMD) simulations. Employing the fewest switches surface hopping protocol, along with the semi-empirical multireference ODM2/MRCI-SD method, we investigate possible reaction pathways for this photoprocess, as well as their timescales and resulting photoproducts. Furthermore, using a dynamic configuration-space sampling procedure, we elucidate the role of triplet states in the photocyclization of PT, supporting available experimental data for the closely related DMPT molecule, which indicate an ultrafast intersystem crossing (ISC) transition competing with the singlet-driven photoswitching reaction. Our findings not only corroborate experimental studies on DAE switches, but also provide new mechanistic insights into the potential use in the rational design of DAE switches tailored for specific technological applications.
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Affiliation(s)
- Mikołaj Martyka
- Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, 02-093, Poland.
- Interdisciplinary Doctoral School, University of Warsaw, Dobra 56/66, Warsaw, 00-312, Poland
| | - Joanna Jankowska
- Faculty of Chemistry, University of Warsaw, Pasteura 1, Warsaw, 02-093, Poland.
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2
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Shillito GE, Preston D, Crowley JD, Wagner P, Harris SJ, Gordon KC, Kupfer S. Controlling Excited State Localization in Bichromophoric Photosensitizers via the Bridging Group. Inorg Chem 2024; 63:4947-4956. [PMID: 38437618 PMCID: PMC10951951 DOI: 10.1021/acs.inorgchem.3c04110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 01/18/2024] [Accepted: 01/30/2024] [Indexed: 03/06/2024]
Abstract
A series of photosensitizers comprised of both an inorganic and an organic chromophore are investigated in a joint synthetic, spectroscopic, and theoretical study. This bichromophoric design strategy provides a means by which to significantly increase the excited state lifetime by isolating the excited state away from the metal center following intersystem crossing. A variable bridging group is incorporated between the donor and acceptor units of the organic chromophore, and its influence on the excited state properties is explored. The Franck-Condon (FC) photophysics and subsequent excited state relaxation pathways are investigated with a suite of steady-state and time-resolved spectroscopic techniques in combination with scalar-relativistic quantum chemical calculations. It is demonstrated that the presence of an electronically conducting bridge that facilitates donor-acceptor communication is vital to generate long-lived (32 to 45 μs), charge-separated states with organic character. In contrast, when an insulating 1,2,3-triazole bridge is used, the excited state properties are dominated by the inorganic chromophore, with a notably shorter lifetime of 60 ns. This method of extending the lifetime of a molecular photosensitizer is, therefore, of interest for a range of molecular electronic devices and photophysical applications.
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Affiliation(s)
- Georgina E. Shillito
- Institute
of Physical Chemistry, Friedrich Schiller
University Jena, Helmholtzweg 4, 07743 Jena, Germany
| | - Dan Preston
- Research
School of Chemistry, Australian National
University, Canberra, ACT 2600, Australia
| | - James D. Crowley
- Department
of Chemistry, University of Otago, 362 Leith Street, Dunedin 9016, New Zealand
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - Pawel Wagner
- University
of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia
| | - Samuel J. Harris
- Department
of Chemistry, University of Otago, 362 Leith Street, Dunedin 9016, New Zealand
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - Keith C. Gordon
- Department
of Chemistry, University of Otago, 362 Leith Street, Dunedin 9016, New Zealand
- MacDiarmid
Institute for Advanced Materials and Nanotechnology, Wellington, 6012, New Zealand
| | - Stephan Kupfer
- Institute
of Physical Chemistry, Friedrich Schiller
University Jena, Helmholtzweg 4, 07743 Jena, Germany
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3
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Otolski CJ, Raj AM, Ramamurthy V, Elles CG. Spatial confinement alters the ultrafast photoisomerization dynamics of azobenzenes. Chem Sci 2020; 11:9513-9523. [PMID: 34094217 PMCID: PMC8162038 DOI: 10.1039/d0sc03955a] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ultrafast transient absorption spectroscopy reveals new excited-state dynamics following excitation of trans-azobenzene (t-Az) and several alkyl-substituted t-Az derivatives encapsulated in a water-soluble supramolecular host-guest complex. Encapsulation increases the excited-state lifetimes and alters the yields of the trans → cis photoisomerization reaction compared with solution. Kinetic modeling of the transient spectra for unsubstituted t-Az following nπ* and ππ* excitation reveals steric trapping of excited-state species, as well as an adiabatic excited-state trans → cis isomerization pathway for confined molecules that is not observed in solution. Analysis of the transient spectra following ππ* excitation for a series of 4-alkyl and 4,4'-dialkyl substituted t-Az molecules suggests that additional crowding due to lengthening of the alkyl tails results in deeper trapping of the excited-state species, including distorted trans and cis structures. The variation of the dynamics due to crowding in the confined environment provides new evidence to explain the violation of Kasha's rule for nπ* and ππ* excitation of azobenzenes based on competition between in-plane inversion and out-of-plane rotation channels.
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Affiliation(s)
| | - A Mohan Raj
- Department of Chemistry, University of Miami Coral Gables Florida USA
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4
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Barclay MS, Elles CG, Caricato M. On the Discrepancy between Experimental and Calculated Raman Intensities for Conjugated Phenyl and Thiophene Derivatives. J Phys Chem A 2020; 124:4678-4689. [PMID: 32392419 DOI: 10.1021/acs.jpca.0c00363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Compared with experimental spectra, calculations for conjugated phenyl and thiophene oligomers tend to overestimate the ground state Raman intensities of higher-frequency vibrations (1200-1800 cm-1) relative to the intensities at lower frequencies (<1200 cm-1). The discrepancy was observed in previous benchmarking work that examined the method dependence of the calculated Raman spectra for a series of aromatic molecules. This paper further investigates the nature of the discrepancy by examining the role of anharmonic corrections and the dependence of the calculated Raman spectra on the inter-ring torsion angle for the representative molecules biphenyl (BP), 2-phenylthiophene (PT), and 2,2'-bithiophene (BT). Perturbative anharmonic corrections to the spectra calculated using density functional theory (DFT) provide only slightly better agreement with experiment. On the other hand, calculations at larger torsion angles give up to 30% improvement in the relative Raman intensities compared with the spectra calculated at the optimized geometries. The torsion-angle dependence of the Raman intensities is most pronounced for delocalized C-C and C-S stretching modes, and less pronounced for bending and ring distortion modes that do not involve inter-ring stretching. Higher-level calculations using the coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] method indicate that DFT underestimates the energy barrier for torsion isomerization at small angles, and it overestimates the barriers at large angles, thus predicting minimum geometries at torsion angles that are too small. Therefore, the results suggest that the discrepancy in relative Raman intensities may be related to an overestimation of inter-ring conjugation by DFT, which also tends to favor geometries that are too planar.
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Affiliation(s)
- Matthew S Barclay
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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5
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Sotome H, Une K, Nagasaka T, Kobatake S, Irie M, Miyasaka H. A dominant factor of the cycloreversion reactivity of diarylethene derivatives as revealed by femtosecond time-resolved absorption spectroscopy. J Chem Phys 2020; 152:034301. [PMID: 31968954 DOI: 10.1063/1.5134552] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dynamics of the cycloreversion reaction of a photochromic diarylethene derivative with a small ring-opening reaction yield (∼1%) was investigated by using femtosecond transient absorption spectroscopy. The reaction rate constant and activation barrier on the reaction coordinate were quantitatively analyzed on the basis of the temperature and excitation wavelength dependencies of the reaction yield and excited state dynamics. From the comparison of the present results with those in a more reactive derivative, we concluded that a key factor regulating the overall reaction yield is the branching ratio at the conical intersection where the excited state population is split into the product and the initial reactant. The excitation wavelength dependence of the dynamics indicated that the geometrical relaxation and vibrational cooling proceed in a few picosecond time scale behind the cycloreversion process, and the vibrational excess energy assists the molecule to climb up the energy barrier.
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Affiliation(s)
- Hikaru Sotome
- Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kanako Une
- Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Tatsuhiro Nagasaka
- Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Seiya Kobatake
- Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan
| | - Masahiro Irie
- Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Hiroshi Miyasaka
- Division of Frontier Materials Science and Center for Advanced Interdisciplinary Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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6
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Barclay MS, Elles CG, Caricato M. Benchmark Study of Ground-State Raman Spectra in Conjugated Molecules. J Chem Theory Comput 2019; 16:612-620. [DOI: 10.1021/acs.jctc.9b00960] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew S. Barclay
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G. Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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7
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Barclay MS, Caricato M, Elles CG. Femtosecond Stimulated Raman Scattering from Triplet Electronic States: Experimental and Theoretical Study of Resonance Enhancements. J Phys Chem A 2019; 123:7720-7732. [DOI: 10.1021/acs.jpca.9b05955] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthew S. Barclay
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Marco Caricato
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G. Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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8
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Otolski CJ, Mohan Raj A, Sharma G, Prabhakar R, Ramamurthy V, Elles CG. Ultrafast trans → cis Photoisomerization Dynamics of Alkyl-Substituted Stilbenes in a Supramolecular Capsule. J Phys Chem A 2019; 123:5061-5071. [PMID: 31140802 DOI: 10.1021/acs.jpca.9b03285] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ultrafast spectroscopy reveals the effects of confinement on the excited-state photoisomerization dynamics for a series of alkyl-substituted trans-stilbenes encapsulated in the hydrophobic cavity of an aqueous supramolecular organic host-guest complex. Compared with the solvated compounds, encapsulated trans-stilbenes have broader excited-state absorption spectra, excited-state lifetimes that are 3-4 times longer, and photoisomerization quantum yields that are 1.7-6.5 times lower in the restricted environment. The organic capsule disrupts the equilibrium structure and restricts torsional rotation around the central C═C double bond in the excited state, which is an important motion for the relaxation of trans-stilbene from S1 to S0. The location and identity of alkyl substituents play a significant role in determining the excited-state dynamics and photoisomerization quantum yields by tuning the relative crowding inside the capsule. The results are discussed in terms of distortions of the ground- and excited-state potential energy surfaces, including the topology of the S1-S0 conical intersection.
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Affiliation(s)
- Christopher J Otolski
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
| | - A Mohan Raj
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | - Gaurav Sharma
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | - Rajeev Prabhakar
- Department of Chemistry , University of Miami , Coral Gables , Florida 33146 , United States
| | | | - Christopher G Elles
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
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9
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Quincy TJ, Barclay MS, Caricato M, Elles CG. Probing Dynamics in Higher-Lying Electronic States with Resonance-Enhanced Femtosecond Stimulated Raman Spectroscopy. J Phys Chem A 2018; 122:8308-8319. [PMID: 30256101 DOI: 10.1021/acs.jpca.8b07855] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Femtosecond stimulated Raman scattering (FSRS) measurements typically probe the structural dynamics of a molecule in the first electronically excited state, S1. While these measurements often rely on an electronic resonance condition to increase signal strength or enhance species selectivity, the effects of the resonance condition are usually neglected. However, mode-specific enhancements of the vibrational transitions in an FSRS spectrum contain detailed information about the resonant (upper) electronic state. Analogous to ground-state resonance Raman spectroscopy, the relative intensities of the Raman bands reveal displacements of the upper potential energy surface due to changes in the bonding pattern upon S n ← S1 electronic excitation, and therefore provide a sensitive probe of the ultrafast dynamics in the higher-lying state, S n. Raman gain profiles from the wavelength-dependent FSRS spectrum of the model compound 2,5-diphenylthiophene (DPT) reveal several modes with large displacement in the upper potential energy surface, including strong enhancement of a delocalized C-S-C stretching and ring deformation mode. The experimental results provide a benchmark for comparison with calculated spectra using time-dependent density functional theory (TD-DFT) and equation-of-motion coupled-cluster theory with single and double excitations (EOM-CCSD), where the calculations are based on the time-dependent formalism for resonance Raman spectroscopy. The simulated spectra are obtained from S1-S n transition strengths and the energy gradients of the upper (S n) potential energy surfaces along the S1 normal mode coordinates. The experimental results provide a stringent test of the computational approach, and indicate important limitations based on the level of theory and basis set. This work provides a foundation for making more accurate assignments of resonance-enhanced excited-state Raman spectra, as well as extracting novel information about higher-lying excited states in the transient absorption spectrum of a molecule.
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Affiliation(s)
- Timothy J Quincy
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
| | - Matthew S Barclay
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
| | - Marco Caricato
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
| | - Christopher G Elles
- Department of Chemistry , University of Kansas , Lawrence , Kansas 66045 , United States
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10
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Snyder JA, Bragg AE. Ultrafast Pump-Repump-Probe Photochemical Hole Burning as a Probe of Excited-State Reaction Pathway Branching. J Phys Chem Lett 2018; 9:5847-5854. [PMID: 30226782 DOI: 10.1021/acs.jpclett.8b02489] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We demonstrate pump-repump-probe (PRP) transient hole burning as a spectroscopic tool for differentiating reactive from nonreactive deactivation of excited photochemical reactants observed by transient absorption spectroscopy (TAS). This method utilizes a time-delayed, wavelength-tunable ultrafast pulse to alter the excited reactant population, with the impact of "repumping" quantified through depletions in photoproduct absorption. We apply this approach to characterize dynamics affecting the nonadiabatic photocyclization efficiency to form S0 dihydrotriphenylene (DHT) following 266 nm excitation of ortho-terphenyl (OTP). TAS studies revealed bimodal deactivation of OTP*, but neither relaxation time scale (700 fs and 3.0 ps) could be assigned unambiguously to DHT formation due to overlap of excited-state and product spectra. PRP studies reveal that S1 OTP only cyclizes on the slower of these time scales, with the faster process attributable to nonreactive deactivation. We demonstrate that this method offers greater photochemical insights without assuming models to globally fit spectral transients collected by TAS.
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Affiliation(s)
- Joshua A Snyder
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
| | - Arthur E Bragg
- Department of Chemistry , Johns Hopkins University , 3400 North Charles Street , Baltimore , Maryland 21218 , United States
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11
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Sotome H, Nagasaka T, Une K, Morikawa S, Katayama T, Kobatake S, Irie M, Miyasaka H. Cycloreversion Reaction of a Diarylethene Derivative at Higher Excited States Attained by Two-Color, Two-Photon Femtosecond Pulsed Excitation. J Am Chem Soc 2017; 139:17159-17167. [DOI: 10.1021/jacs.7b09763] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Hikaru Sotome
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Tatsuhiro Nagasaka
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Kanako Une
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Soichiro Morikawa
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Tetsuro Katayama
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
| | - Seiya Kobatake
- Department
of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sumiyoshi,
Osaka 558-8585, Japan
| | - Masahiro Irie
- Department
of Chemistry and Research Center for Smart Molecules, Rikkyo University, 3-34-1
Nishi-Ikebukuro, Toshima-ku, Tokyo 171-8501, Japan
| | - Hiroshi Miyasaka
- Division
of Frontier Materials Science and Center for Advanced Interdisciplinary
Research, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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12
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Barclay MS, Quincy TJ, Williams-Young DB, Caricato M, Elles CG. Accurate Assignments of Excited-State Resonance Raman Spectra: A Benchmark Study Combining Experiment and Theory. J Phys Chem A 2017; 121:7937-7946. [DOI: 10.1021/acs.jpca.7b09467] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew S. Barclay
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Timothy J. Quincy
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | | | - Marco Caricato
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G. Elles
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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13
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Bragg AE, Yu W, Zhou J, Magnanelli T. Ultrafast Raman Spectroscopy as a Probe of Local Structure and Dynamics in Photoexcited Conjugated Materials. J Phys Chem Lett 2016; 7:3990-4000. [PMID: 27681200 DOI: 10.1021/acs.jpclett.6b01060] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An important challenge in the study of conjugated organic materials is to relate the properties of transient states underlying macroscopic material responses directly with intra- and intermolecular structure. We discuss recent efforts using the vibrational sensitivity of time-resolved Raman spectroscopy to interrogate structural properties of transient excited and charge-separated states in conjugated oligomers and polymers in order to relate them to molecular conformations and material microstructures. We focus on recent work with excited-state Raman spectroscopy that provides mode-specific signatures of structural relaxation in oligo- and polythiophenes, examination of structural heterogeneities associated with exciton localization in different structural motifs of amorphous polymers, and interrogation of correlations between microstructure and properties and dynamics of charge-separated states within polymer aggregates. On the basis of these recent efforts, we provide an outlook for further applying this method to elucidate relationships between the structure and properties of transient states and the photoresponses of conjugated materials.
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Affiliation(s)
- Arthur E Bragg
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Wenjian Yu
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Jiawang Zhou
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Timothy Magnanelli
- Department of Chemistry, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States
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14
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Batignani G, Pontecorvo E, Ferrante C, Aschi M, Elles CG, Scopigno T. Visualizing Excited-State Dynamics of a Diaryl Thiophene: Femtosecond Stimulated Raman Scattering as a Probe of Conjugated Molecules. J Phys Chem Lett 2016; 7:2981-8. [PMID: 27428853 DOI: 10.1021/acs.jpclett.6b01137] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Conjugated organic polymers based on substituted thiophene units are versatile building blocks of many photoactive materials, such as photochromic molecular switches or solar energy conversion devices. Unraveling the different processes underlying their photochemistry, such as the evolution on different electronic states and multidimensional structural relaxation, is a challenge critical to defining their function. Using femtosecond stimulated Raman scattering (FSRS) supported by quantum chemical calculations, we visualize the reaction pathway upon photoexcitation of the model compound 2-methyl-5-phenylthiophene. Specifically, we find that the initial wavepacket dynamics of the reaction coordinates occurs within the first ≈1.5 ps, followed by a ≈10 ps thermalization. Subsequent slow opening of the thiophene ring through a cleavage of the carbon-sulfur bond triggers an intersystem crossing to the triplet excited state. Our work demonstrates how a detailed mapping of the excited-state dynamics can be obtained, combining simultaneous structural sensitivity and ultrafast temporal resolution of FSRS with the chemical information provided by time-dependent density functional theory calculations.
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Affiliation(s)
- Giovanni Batignani
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" , Roma I-00185, Italy
- Dipartimento di Scienze Fisiche e Chimiche, Universitá degli Studi dell'Aquila , L'Aquila I-67100, Italy
| | - Emanuele Pontecorvo
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" , Roma I-00185, Italy
| | - Carino Ferrante
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" , Roma I-00185, Italy
| | - Massimiliano Aschi
- Dipartimento di Scienze Fisiche e Chimiche, Universitá degli Studi dell'Aquila , L'Aquila I-67100, Italy
| | - Christopher G Elles
- Department of Chemistry, University of Kansas , Lawrence, Kansas 66045, United States
| | - Tullio Scopigno
- Dipartimento di Fisica, Universitá di Roma "La Sapienza" , Roma I-00185, Italy
- Center for Life Nano Science @Sapienza, Istituto Italiano di Tecnologia , Roma I-00161, Italy
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15
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Yu W, Magnanelli TJ, Zhou J, Bragg AE. Structural Heterogeneity in the Localized Excited States of Poly(3-hexylthiophene). J Phys Chem B 2016; 120:5093-102. [DOI: 10.1021/acs.jpcb.6b04215] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wenjian Yu
- Department
of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
| | - Timothy J. Magnanelli
- Department
of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
| | - Jiawang Zhou
- Department
of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
| | - Arthur E. Bragg
- Department
of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, Maryland 21218, United States
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16
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Zhou J, Guo X, Katz HE, Bragg AE. Molecular Switching via Multiplicity-Exclusive E/Z Photoisomerization Pathways. J Am Chem Soc 2015; 137:10841-50. [PMID: 26258436 DOI: 10.1021/jacs.5b07348] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Mutual exclusivity in the nature of forward and reserve isomerization pathways holds promise for predictably controlling responses of photoswitchable materials according to molecular structure or external stimuli. Herein we have characterized the E/Z photoisomerization mechanisms of the visible-light-triggered switch 1,2-dithienyl-1,2-dicyanoethene (4TCE) in chlorobenzene with ultrafast transient absorption spectroscopy. We observe that switching mechanisms occur exclusively by relaxation through electronic manifolds of different spin multiplicity: trans-to-cis isomerization only occurs via electronic relaxation within the singlet manifold on a time scale of 40 ps; in contrast, cis-to-trans isomerization is not observed above 440 nm, but occurs via two rapid ISC processes into and out of the triplet manifold on time scales of ∼2 ps and 0.4 ns, respectively, when excited at higher energies (e.g., 420 nm). Observation of ultrafast ISC in cis-4TCE is consistent with photoinduced dynamics of related thiophene-based oligomers. Interpretation of the photophysical pathways underlying these isomerization reactions is supported by the observation that cis-to-trans isomerization occurs efficiently via triplet-sensitized energy transfer, whereas trans-to-cis isomerization does not. Quantum-chemical calculations reveal that the T1 potential energy surface is barrierless along the coordinate of the central ethylene dihedral angle (θ) from the cis Franck-Condon region (θ = 175°) to geometries that are within the region of the trans ground-state well; furthermore, the T1 and S1 surfaces cross with a substantial spin-orbital coupling. In total, we demonstrate that E/Z photoswitching of 4TCE operates by multiplicity-exclusive pathways, enabling additional means for tailoring switch performance by manipulating spin-orbit couplings through variations in molecular structure or physical environment.
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Affiliation(s)
- Jiawang Zhou
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Xin Guo
- Department of Materials Science and Engineering, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Howard E Katz
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States.,Department of Materials Science and Engineering, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Arthur E Bragg
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
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17
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Yu W, Donohoo-Vallett PJ, Zhou J, Bragg AE. Ultrafast photo-induced nuclear relaxation of a conformationally disordered conjugated polymer probed with transient absorption and femtosecond stimulated Raman spectroscopies. J Chem Phys 2014; 141:044201. [DOI: 10.1063/1.4890326] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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18
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Pontecorvo E, Ferrante C, Elles CG, Scopigno T. Structural Rearrangement Accompanying the Ultrafast Electrocyclization Reaction of a Photochromic Molecular Switch. J Phys Chem B 2014; 118:6915-21. [DOI: 10.1021/jp5051047] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Emanuele Pontecorvo
- Dipartimento
di Fisica, Università di Roma “Sapienza”, P.le Aldo Moro 2, I-00185 Roma, Italy
| | - Carino Ferrante
- Dipartimento
di Fisica, Università di Roma “Sapienza”, P.le Aldo Moro 2, I-00185 Roma, Italy
| | - Christopher G. Elles
- Department
of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Tullio Scopigno
- Dipartimento
di Fisica, Università di Roma “Sapienza”, P.le Aldo Moro 2, I-00185 Roma, Italy
- Centre
for Life Nano Science IIT@Sapienza, Istituto Italiano di Tecnologia, I-00161 Roma, Italy
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19
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Narayanan Nair M, Hobeika N, Calard F, Malval JP, Aloïse S, Spangenberg A, Simon L, Cranney M, Vonau F, Aubel D, Serein-Spirau F, Lère-Porte JP, Lacour MA, Jarrosson T. One- and two-photon absorption and emission properties of an oligo(phenylenethienylene)s series. Phys Chem Chem Phys 2014; 16:12826-37. [DOI: 10.1039/c2cp44365a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Zheldakov IL, Grinevich O, Mejiritski A, Elles CG, Neckers DC. Transient Spectroscopy of 5,7-diiodo-3-butoxy-6-fluorone (DIBF). Photochem Photobiol 2013. [DOI: 10.1111/php.12190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Igor L. Zheldakov
- Department of Chemistry; University of Kansas; Lawrence KS
- Spectra Group Limited; Inc.; Millbury OH
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21
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Ward CL, Elles CG. Controlling the Excited-State Reaction Dynamics of a Photochromic Molecular Switch with Sequential Two-Photon Excitation. J Phys Chem Lett 2012; 3:2995-3000. [PMID: 26292240 DOI: 10.1021/jz301330z] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Sequential two-photon excitation increases the cycloreversion yield of a diarylethene-type photochromic molecular switch compared with one-photon excitation. This letter shows for the first time that an optimal delay of ∼5 ps between primary and secondary excitation events gives the largest enhancement of the ring-closing reaction. Pump-probe (PP) and pump-repump-probe (PReP) measurements also provide detailed new information about the excited-state dynamics. The initially excited molecule must first cross a barrier on the excited-state potential energy surface before secondary excitation enhances the reaction. The PReP experiments demonstrate that the reaction path of a photochromic molecular switch can be selectively controlled through judicious use of time-delayed femtosecond laser pulses.
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Affiliation(s)
- Cassandra L Ward
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Christopher G Elles
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
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