Coupled chromophores

Matro A and Cina J A 1995 Theoretical study of time-resolved fluorescence anisotropy from coupled chromophore pairs J. Phys. Chem. 99 2568-82... 

Coupled chromophores Coupler Couplers Coupling Coupling agents... 

Ghromophore Interaction. A great number of systems containing several polymethine chromophores exist. As the simplest objects of this sort, dyes with coupled chromophores, or bis-dyes, can be considered (3,10) as follows (15), where M is either a conjugated or a nonconjugated bridge. 

Mixed Quantum/Classical Approach Coupled Chromophores and the Time Averaging Approximation... 

For the case of coupled chromophores the approximation is to average the matrix k(i) [98]. Thus in the time-averaging approximation (TAA) we replace ic(f) in Eq. (7) with... 

The UV/Vis absorption spectra of 1, 4 and 6 are reported in Fig. 4 and show clearly the effect of coupling chromophores, A bathochromic shift is observed because of the preference of the a transition according to Fig. 2. Moreover, there is an amplification of the absorption because the absorptivity of 6 exceeds the expected threefold absorptivity of 1 by far see Fig. 4. The linear alignment of chromophores... 

Tanaka, J., Ozeki-Minakata, K., Ogura, F., and Nakagawa, M. Absolute configuration of a coupled chromophore system by exciton analysis of circular dichroism. Nature, Phys. Set. (London) 241, 22-23 (1973). 

If a molecule consists of several weakly coupled chromophores it may be advantageous to speak of intramolecular CT transitions. The MIM method for calculating the absorption spectra of complex molecules, which has been mentioned in the discussion of substituent effects in Section 2.4.2, is based on this idea. 

The explicit form of the interaction Hamiltonian // ,(() consists of a series of multipolar terms, but for most purposes the electric-dipole (El) approximation is sufficient. Although the results are calculated within this approximation for each molecular center detailed analysis of the coupling provides results equivalent to the inclusion of higher-order multipole terms for the pair. The same assumption underlies the well-known coupled-chromophore model of optical rotation (Kuhn 1930 Boys 1934 Kirkwood 1937). The Hamiltonian for the system may thus be written as... 

Hansen AE, Ballhausen CJ (1965) Electronic structure of copper acetate monohydrate based on a coupled chromophore model. Trans Far Soc 61 631... 

Figure 12. A representation of the coupled chromophore model. The orbitals designated (a) represent the frontier four-otbitals of one monomer chlorophyll unit, those labeled (b), the orbitals of the second monomer unit. Upon mixing, symmetry determines combinations of the monomer orbitals, yielding those of the dimer, labeled with (d).

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