Intramolecular electronic energy transfer in rhodamine–azulene bichromophoric molecule (original) (raw)
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The Journal of Physical Chemistry C, 2008
Charge and electronic energy transfer (ET and EET) are well-studied examples whereby different molecules can signal their state from one (the donor, D) to the other (the acceptor, A). The electronic energy transfer from the donor (Rh) to the acceptor (Az) is used to build an all-optical full adder on a newly synthesized bichromophoric molecule Rh-Az. The results are supported and interpreted by a full kinetic simulation. It is found that the optimal design for the implementation of the full adder relies in an essential way on the intramolecular transfer of information from the donor to the acceptor moiety. However, it is not the case that the donor and the acceptor each act as a half adder.
The mechanism of short-range intramolecular electronic energy transfer in bichromophoric molecules
The Journal of Physical Chemistry, 1984
A study of intramolecular energy transfer (intra-ET) in a series of bichromophoric molecules consisting of cyclic a-diketones incorporating an ortho-, meta-, or para-substituted benzene ring is reported. Most spectroscopic properties of these molecules are described by a superposition of those of their constituent chromophores. Unique for the bichromophore molecule is the fact that, depending on the molecular geometry, energy absorbed by the aromatic chromophore is transferred in part to the a-diketone and both chromophores emit their characteristic fluorescence spectra. An extensive study was made of the intramolecular electronic energy transfer process in solution as a function of temperature. The results indicate that the transfer efficiency is strongly structure dependent suggesting that a Dexter type exchange interaction is responsible for singlet-singlet intra-ET between close chromophores in a bichromophoric molecule. The thermal dependence observed in some cases is attributed to conformational factors. A general theoretical analysis of intra-ET in bichromophoric molecules provides expressions for donor fluorescence decay and for its fluorescence quantum yield in terms of the average distance between donor and acceptor moieties and the flexibility of the chains connecting donor and acceptor. Comparison with the present experimental data supports the predictions of this analysis. It is concluded that intra-ET in bichromophoric molecules is indeed governed by short-range exchange interactions.
Journal of Photochemistry and Photobiology A: Chemistry, 1996
Results are presented on the intramolecular electronic energy transfer (intra-EET) in bichromophoric molecules of the type benzene-adiketone, in which the interchromophore bridge contains methyl substituents/3 to the c~-dicarbonyl acceptor chromophore. These results show that singlet-singlet intra-EET is independent of substitution and can be explained by a model assuming Dexter-type short-range exchange interaction. For singlet-triplet and triplet-triplet transfer, there are indications that the phosphorescence yield of the acceptor is larger than that for non-substituted bichromophoric molecules. This can be explained by through-bond interaction promoting EET via a long-range superexchange mechanism, by variations in the non-radiative decay of the triplet state of the acceptor or by chemical reaction.
Intramolecular electronic energy transfer via exchange interaction in bichromophoric molecules
Chemical physics letters, 1983
X theory is presented for intranlolecular electronic encgy transfer in bichromophoric molecules. Expressions are given for the donor moiety fluorescence (phosphorescence) decay and for Its fluorescence (phosphorescence) quantum yield in rerms of rhc areragc di&mce between the donor and acceptor moieties and the donor-acceptor bridge flexibility_ Comparison with available experimental data supports the predictions of the analysis.
A molecular scale full adder based on controlled intramolecular electron and energy transfer
Materials Science and Engineering: C, 2006
Electron and electronic energy transfer processes are ways by which different molecules can signal their state from one (the Donor, D) to the other (the Acceptor, A). This transfer is often studied as an intermolecular process but it can also occur intramolecularly, that is between two bridged parts of a bichromophoric molecule.
Dual fluorescence and intramolecular electronic energy transfer in a bichromophoric molecule
The Journal of Physical Chemistry, 1980
The bichromophoric molecule containing phenanthrene and a-diketone moieties connected by two chains of five methylene groups has been studied. Most spectroscopic properties of this molecule are described by a superposition of those of its constituent chromophores. Unique for the combined molecule is the fact that energy absorbed by the phenanthrene chromophore is transferred in part to the a-diketone and both chromophores emit their characteristic fluorescence spectra. An extensive study was made of the intramolecular energy transfer process in solution as a function of the excitation frequency and of the sample temperature. It was clearly demonstrated that energy is transferred very efficiently to the a-diketone moiety from a thermally activated state of the bichromophoric molecule. The rate of this energy transfer is comparable to the relaxation rate of the activated state. In contrast, the transfer process from the ground vibrational level of the first excited state of the phenanthrene moiety is rather slow (-lo7 d).
Molecular Engineering, 1994
The design, structures and spectral properties of a number of bichromophoric molecules are presented. These bichromophori¢ molecules are composed of an aromatic ring connected by two methylene chains to an a-diketone moiety. Both absorption and emission spectra can be attributed to a superposition of the individual spectra of the separate chromophores. The critical transfer radius for electronic energy transfer from the aromatic (donor) chromophore to the a-diketone (acceptor) chromophore was calculated from the spectral overlap between the fluorescence spectrum of the aromatic moiety and the absorption spectrum of the a-diketone moiety. The results show that this series of molecules is well suited for a mechanistic study of short-range intramolecular electronic energy transfer.
Intramolecular Energy Transfer from Upper Triplet States in Rigidly-Linked Bichromophoric Molecules
Journal of the American Chemical Society, 1995
Intramolecular triplet energy transfer has been studied in bichromophoric molecules that incorporate an anthracene donor and ketone or alkene acceptors connected by two rigid, bicyclic saturated hydrocarbon units. Twolaser excitation of the anthracene group results in production of the T2 state which subsequently undergoes energy transfer to the acceptors ( k w 1O1O s-'), as indicated by depletion of the T-T absorption. In 1, decay of the acceptor (ketone) triplet state involves a competition between ring opening and back energy transfer to the anthracene T1 state. In 2-4, rotation of the alkene triplets to perpendicular geometries relieves ring strain in the bicyclic connecting units, thus providing a barrier to back energy transfer. A fraction of the twisted triplets relaxes to the ground state without irreversible chemistry
Ultrafast Intramolecular Electronic Energy-Transfer Dynamics In a Bichromophoric Molecule
J. Phys. Chem. …, 2004
Intramolecular electronic energy-transfer (intra-EET) dynamics has been investigated in 2-(9-anthryl)-1Himidazo [4,5-f] [1,10]-phenanthroline (AIP), a newly synthesized bichromophoric molecule, using the steadystate and time-resolved absorption and fluorescence spectroscopic techniques. In AIP, anthracene (AN) and 1H-imidazo [4,5-f] [1,10]-phenanthroline (IP) molecules are directly linked to each other through a CC σ bond and without any intervening molecular bridge. Two constituent chromophoric moieties of this bichromophoric molecule interact relatively weakly in the ground state. In the excited singlet state, however, the AN moiety transfers its excitation energy quantitatively (the efficiency of energy transfer, φ EET , is near unity) and rapidly (the rate of energy transfer, k EET , is 1.8 × 10 11 s-1 in methanol) to the unexcited IP moiety. k EET decreases linearly with increase in viscosity of the solvents, and the process is significantly retarded in rigid glass matrixes. These observations suggest that, for an efficient EET process, the molecule needs to attain a conformational geometry, which is different from that of the ground state, by undergoing a conformational relaxation process following photoexcitation. The theoretically calculated energy-transfer rate (5.1 × 10 9 s-1) due to the Förster dipole-dipole-induced resonance-interaction mechanism is about 2 orders of magnitude smaller than the experimentally determined energy-transfer rate. Hence, the Dexter throughspace exchange-interaction mechanism, which becomes predominant at shorter interchromophoric separation (R ∼ 6.3 Å in AIP) and requires specific conformation for efficient orbital overlap, should have the major contribution to the intra-EET process in AIP. Viscosity dependence of k EET suggests that we possibly measure the rate of the conformational relaxation process using the intra-EET process as the probe.
The ultrafast energy transfer process in naphtole–nitrobenzofurazan bichromophoric molecular systems
Journal of Photochemistry and Photobiology A: Chemistry, 2007
This work presents an experimental and computational study of the intramolecular electronic energy transfer process occurring in two newly synthesized bichromophoric species: )oxy]acetate (r-Bi). In both f-Bi and r-Bi the donor chromophore is the [(4-chloro-1-naphthyl)oxy]acetate moiety, whereas the acceptor units belong to the family of the 4dialkylaminonitrobenzoxadiazoles, well-known fluorescent probes. The two bichromophores differ in the structural flexibility. In f-Bi, acceptor and donors are linked by a diethanolamine moiety, whereas in r-Bi through a (3S, 4S)3,4-dihydroxypyrrolidine ring. By means of steady-state and timeresolved UV-vis spectroscopies we carried out a detailed analysis of the photo-response of donor and acceptor chromophores as individual molecules and when covalently linked in f-Bi and r-Bi. The intramolecular energy transfer process occurs very efficiently in both the bichromophores. The rate constant and the quantum efficiency of the process are k ET = (2.86 ± 0.16) × 10 11 s −1 and Q = 0.998 in f-Bi, and k ET = (1.25 ± 0.08) × 10 11 s −1 and Q = 0.996 in r-Bi. Semiempirical calculations were utilized to identify the energy and the nature of the electronic states in the isolated chromophores. Molecular mechanics calculations have been performed to identify the most stable structures of the bichromophoric compounds. The predictions of Förster theory are consistent with the experimental results and provide a suitable way to evaluate the structural differences between the two compounds.