Charge on the move: how electron-transfer dynamics depend on molecular conformation

Benniston, Andrew C.; Harriman, Anthony

doi:10.1039/b503169a

Cited by 175 publications

(164 citation statements)

References 49 publications

(100 reference statements)

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“…We derived a very specific expression for the conformational dependence of the electronic coupling for OPE bridges. [38] This expression is nearly the same as the one expected from consideration of overlap between two mutually rotating p-orbitals, which has previously been reported for TEET, [43,45] and is given in Equation (11).…”

Section: Discussionsupporting

confidence: 54%

Temperature Dependence of Electronic Coupling through Oligo‐p‐phenyleneethynylene Bridges

Eng¹,

Mårtensson²,

Albinsson³

2008

Chemistry A European J

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A series of donor-bridge-acceptor (D-B-A) systems with varying donor-acceptor distances has been studied with respect to the temperature dependence of the triplet excitation energy transfer (TEET) rates. The donor and acceptor, zinc(II) and free-base porphyrin, respectively, were separated by oligo-p-phenyleneethynylene (OPE) bridges, where the number of phenyleneethynylene groups was varied between two and five, giving rise to edge-to-edge separations ranging between 12.7 and 33.4 A. The study was performed in 2-MTHF between room temperature and 80 K. It was found that the distance dependence was exponential, in line with the McConnell model, and the attenuation factor, beta, was temperature dependent. The experimentally determined temperature dependence of beta was evaluated by using a previously derived model for the conformational dependence of the electronic coupling based on results from extensive quantum chemical, DFT and time-dependent DFT (TD-DFT), calculations. Two regimes in the temperature interval could be identified: one high-temperature, low-viscosity regime, and one low-temperature, high-viscosity regime. In the first regime, the temperature dependence of beta was, according to the model, well described by a Boltzmann conformational distribution. In the latter, the molecular motions that govern the electronic coupling are slowed down to the same order of magnitude as the TEET rates. This, in effect, leads to a distortion of the conformational distribution. In the high-temperature regime the model could reproduce the temperature dependence of beta, and the extracted rotational barrier between two neighboring phenyl units of the bridge structure, E(i)=1.1 kJ mol(-1), was in line with previous experimental and theoretical studies. After inclusion of parameters that take the viscosity of the medium into account, successful modeling of the experimentally observed temperature dependence of the distance dependence was achieved over the whole temperature interval.

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Section: Discussionsupporting

confidence: 54%

Temperature Dependence of Electronic Coupling through Oligo‐p‐phenyleneethynylene Bridges

Eng¹,

Mårtensson²,

Albinsson³

2008

Chemistry A European J

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“…The orbital overlap of adjacent π systems correlates linearly with the cosine between their planes, and the electron-transfer properties between the two π systems is proportional to cos 2 of their torsion angles. [85][86][87] Thus, in Figure 3, the longest-wavelength onset of each spectrum, which reflects the HOMO-LUMO band gap of the compound under investigation, is plotted against cos 2 Φ. The values of the interplane torsion angles Φ were determined by X-ray structural analysis and are reported elsewhere.…”

Section: Uv Absorption Spectroscopymentioning

confidence: 99%

Synthesis of Rotationally Restricted and Modular Biphenyl Building Blocks

Vonlanthen¹,

Rotzler²,

Neuburger³

et al. 2009

Eur J Org Chem

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A series of modular biphenyl building blocks with stepwise adjusted torsion angles and terminally functionalized with leaving groups have been synthesized. The two phenyl rings of the biphenyl synthon are clamped by alkyl chains of various lengths. The desired building blocks 3 and 4 were obtained by copper-mediated C-C biaryl coupling reactions followed by the construction of interlinking alkyl bridges. The key intermediates 14 and 15 were transformed into the corresponding cycloheptadienones 16 and 17, which were reduced to the desired propyl-bridged biphenyls 3b and 3c. The butyl-bridged derivatives 4b and 4c were obtained from

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“…The magnitude of the electronic coupling between the terminal chromophores shows ap recise dependence on the dihedral angle around ab ridging biphenyl group, controlled by selecting the bound cations. [55][56][57] Recently,V enkataraman et al [46] and Wandlowski et al [47][48][49][50][51][52] reported the influence of f on changes in the singlemolecule conductivity in substituted biphenyls or conformationally constrained biphenyls in which the biphenyl rings are connected by a( CH 2 ) n link at the 2-and 2'-positions.O nt wisting of the biphenyl system from coplanar (f= 08)t op erpendicular (f= 908), the conductance decreased by af actor of 30. [48] However,r eports of systematics tudies on the influence of f on the electronic coupling and redox processes of bimetallic complexes [ML n (bridge)ML n ] are still scarce.…”

Section: Introductionmentioning

confidence: 97%

Conformational Tuning of the Intramolecular Electronic Coupling in Molecular‐Wire Biruthenium Complexes Bridged by Biphenyl Derivatives

Kong

Xue

Jang

et al. 2015

Chemistry A European J

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The synthesis and characterization of a series of biphenyl-derived binuclear ruthenium complexes with terminal {RuCl(CO)(PMe3)3} moieties and different structural arrangements of the phenyl rings are reported. Electrochemical studies revealed that the two metal centers of the binuclear ruthenium complexes interact with each other through the biphenyl bridge, and the redox splittings ΔE1/2 show a strong linear correlation with cos(2) ϕ, where ϕ is the torsion angle between the two phenyl rings. A combination of electrochemical, UV/Vis/NIR, and in situ IR differential spectroelectrochemical analysis clearly showed that: 1) the intramolecular electronic couplings in the binuclear ruthenium complexes could be modulated by changing ϕ; 2) the electronic ground state of the mixed-valent cations changes from delocalized to localized through the biphenyl bridge with increasing torsion angle ϕ, that is, the redox processes of these complexes change from significant involvement of the bridging ligand to an oxidation behavior with less participation of the bridge.

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Charge on the move: how electron-transfer dynamics depend on molecular conformation

Cited by 175 publications

References 49 publications

Temperature Dependence of Electronic Coupling through Oligo‐p‐phenyleneethynylene Bridges

Temperature Dependence of Electronic Coupling through Oligo‐p‐phenyleneethynylene Bridges

Synthesis of Rotationally Restricted and Modular Biphenyl Building Blocks

Conformational Tuning of the Intramolecular Electronic Coupling in Molecular‐Wire Biruthenium Complexes Bridged by Biphenyl Derivatives

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