A Detailed Analysis of Multiple Photoreactions in a Light-Harvesting Molecular Triad with Overlapping Spectra by Utrafast Spectroscopy

Roland, Thomas; Heyer, Elodie; Liu, Li; Ruff, Adrian; Ludwigs, Sabine; Ziessel, Raymond; Haacke, S.

doi:10.1021/jp507474r

Cited by 17 publications

(11 citation statements)

References 64 publications

(83 reference statements)

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“…Understanding the excited state optical properties of small organic molecules is important for many areas of science and technology, including their potential application in molecular optoelectronics. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] As compared to their inorganic analogues, they are relatively easy to synthesize at lower cost and they are gaining further attention because of their potential applications in nano scale physics. [20][21][22][23][24][25][26][27] A wide range of small organic molecules is currently under spectroscopic investigation by many groups.…”

Section: Introductionmentioning

confidence: 99%

“…Understanding the excited state optical properties of small organic molecules is important for many areas of science and technology, including their potential application in molecular optoelectronics. − They are easy to synthesize and they are gaining further attention because of their potential applications in nano scale physics. − The molecular geometry of such systems in both the ground and excited state plays a vital role in controlling their optical properties. Here, we discuss the excitation wavelength dependent, excited-state structural dynamics of bis(phenylethynyl)benzene (BPEB) (see Figure a), a cylindrical π-conjugated system having acetylene linkers that connect the aromatic phenyl rings.…”

Section: Introductionmentioning

confidence: 99%

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Understanding Ultrafast Dynamics of Conformation Specific Photo-Excitation: A Femtosecond Transient Absorption and Ultrafast Raman Loss Study

et al. 2017

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Excited state ultrafast conformational reorganization is recognized as an important phenomenon that facilitates light-induced functions of many molecular systems. This report describes the femtosecond and picosecond conformational relaxation dynamics of middle-ring and terminal ring twisted conformers of the acetylene π-conjugated system bis(phenylethynyl)benzene, a model system for molecular wires. Through excitation wavelength dependent, femtosecond-transient absorption measurements, we found that the middle-ring and terminal ring twisted conformers relax at femtosecond (400-600 fs) and picosecond (20-24 ps) time scales, respectively. Actinic pumping into the red flank of the absorption spectrum leads to excitation of primarily planar conformers, and results in very different excited state dynamics. In addition, ultrafast Raman loss spectroscopic studies revealed the vibrational mode dependent relaxation dynamics for different excitation wavelengths. To corroborate our experimental findings, DFT and time-dependent DFT calculations were carried out. The Franck-Condon simulation indicated that the vibronic structure observed in the electronic absorption and the fluorescence spectra are due to progressions and combinations of several vibrational modes corresponding to the phenyl ring and the acetylenic groups. Furthermore, the middle ring torsional rotation matches the room-temperature electronic absorption, in stark contrast to the terminal ring torsional rotation. Finally, we show that the middle-ring twisted conformer undergoes femtosecond torsional planarization dynamic, whereas the terminal rings relax on a few tens of picosecond time scale.

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Section: Introductionmentioning

confidence: 99%

“…Understanding the excited state optical properties of small organic molecules is important for many areas of science and technology, including their potential application in molecular optoelectronics. − They are easy to synthesize and they are gaining further attention because of their potential applications in nano scale physics. − The molecular geometry of such systems in both the ground and excited state plays a vital role in controlling their optical properties. Here, we discuss the excitation wavelength dependent, excited-state structural dynamics of bis(phenylethynyl)benzene (BPEB) (see Figure a), a cylindrical π-conjugated system having acetylene linkers that connect the aromatic phenyl rings.…”

Section: Introductionmentioning

confidence: 99%

Understanding Ultrafast Dynamics of Conformation Specific Photo-Excitation: A Femtosecond Transient Absorption and Ultrafast Raman Loss Study

et al. 2017

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“…This is because the spacer unit is also redox active and could promote through-bond charge transfer by way of superexchange interactions. 29 It is also important to stress that earlier work 30 has described such light-induced charge transfer in somewhat related molecular architectures.…”

Section: Charge Transfer Involving the Terminal Exbod Unitmentioning

confidence: 95%

“…It seems likely that this reaction is responsible for the incomplete match between excitation and absorption spectra. In principle, the occurrence of intramolecular charge transfer can be scrutinised 30 by pumpprobe transient absorption spectroscopy but it is essentially impossible to isolate a suitable excitation wavelength in the case of PEN. This is because of the strong spectral overlap between BODIPY and ExBOD in the region around 500 nm, together with the difficulty to generate certain excitation wavelengths.…”

Section: Electronic Energy Transfer Along the Molecular Axismentioning

confidence: 99%

A bifurcated molecular pentad capable of sequential electronic energy transfer and intramolecular charge transfer

Harriman

Stachelek

Sutter

et al. 2015

Phys. Chem. Chem. Phys.

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An extended molecular array, comprising three distinct types of chromophores and two additional redox-active subunits, that harvests photons over most of the visible spectral range has been synthesized and characterised. The array exhibits a rich variety of electrochemical waves when examined by cyclic voltammetry but assignment can be made on the basis of control compounds and molecular orbital calculations. Stepwise electronic energy transfer occurs along the molecular axis, corresponding to a gradient of excitation energies, to populate the lowest-energy excited state of the ultimate acceptor. The latter species, which absorbs and emits in the far-red region, enters into light-induced charge transfer with a terminal amine group. The array is relatively stable under illumination with white light but degrades slowly via a series of well-defined steps, the first of which is autocatalytic. One of the main attributes of this system is the capability to harvest an unusually high fraction of sunlight while providing protection against exposure to UV light.

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“…Recent results using ultrafast spectroscopy have revealed that electron transfer from the TPA to the DPPTh and BODIPY occurs within 52 ps. 37 Interestingly, when increasing the solvent polarity from toluene to THF, no significant bathochromic shift linked with a charge transfer process was observed on the BODIPY absorption. This observation could suggest that the charge transfer process would be more pronounced between the triphenylamine and the DPP module.…”

Section: The Journal Of Organic Chemistrymentioning

confidence: 95%

Step-by-Step Synthesis of Multimodule Assemblies Engineered from BODIPY, DPP, and Triphenylamine Moieties

Heyer

Ziessel

2015

J. Org. Chem.

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In the present account we describe unsymmetrical triads constructed from extended borondipyrromethene (BODIPY) dyes, diketopyrrolopyrrole (DPP) dyes, and electron donor fragments based on triarylamine. The assemblages are such that each module maintains its individual optical and redox properties. The use of phenyl-alkyne-phenyl or phenyl-alkyne-thienyl spacer units is favorable for weak electronic interaction between the modules. The step-by-step linking of each module using palladium-catalyzed cross-coupling reactions provides both mono- and disubstituted derivatives, the latter obtained by passing in particular through a pivotal monosubstituted DPP building block with a reactive bromo substituent. Thus, grafting of a second dye occurs in a controlled manner, providing the target triads in good yields. This protocol allows also the synthesis of key intermediates and dyads, which appear useful for the understanding of the electrochemical and spectroscopic properties. All the dyes exhibit redox and optical properties suitable for cascade energy transfer and photoinduced electron transfer processes in appropriate solvents.

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A Detailed Analysis of Multiple Photoreactions in a Light-Harvesting Molecular Triad with Overlapping Spectra by Utrafast Spectroscopy

Cited by 17 publications

References 64 publications

Understanding Ultrafast Dynamics of Conformation Specific Photo-Excitation: A Femtosecond Transient Absorption and Ultrafast Raman Loss Study

Understanding Ultrafast Dynamics of Conformation Specific Photo-Excitation: A Femtosecond Transient Absorption and Ultrafast Raman Loss Study

A bifurcated molecular pentad capable of sequential electronic energy transfer and intramolecular charge transfer

Step-by-Step Synthesis of Multimodule Assemblies Engineered from BODIPY, DPP, and Triphenylamine Moieties

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