Spectroscopic and Theoretical Studies of Optically Active Porphyrin Dimers: A System Uninterpretable by Exciton Coupling Theory

Abstract

The electronic excited states of a meso-meso beta-beta doubly linked bis-porphyrin are comprehensively investigated by measuring its circular dichroism (CD) and magnetic circular dichroism (MCD) spectra. The observed spectroscopic properties are rationalized by DFT calculations. The frontier molecular orbitals (MOs) are constructed by the linear combinations of the constituent monomers' four MOs. Comparison of a theoretical CD spectrum based on time-dependent DFT (TDDFT) with the experimental spectra resulted in the assignment of the helical conformation of the dimer. This assignment is contrary to the previous assignment based on the point-dipole approximation (exciton coupling theory).

Density functional theory study of electronic absorption spectra and intermolecular interactions of porphyrin–borate complexes

“…The obtained geometries of the monomeric porphyrin diacids are consistent with those revealed by X-ray crystallography [21,22]. Properties of covalently or noncovalently linked porphyrin dimers have also been theoretically explored [23][24][25][26]. Therefore, we herein attempt to elucidate the electronic absorption spectra and the intermolecular interactions of TMPyP-borate complexes by means of DFT, in order to provide the guidance for designing porphyrin nanoparticles without the unfavorable self-aggregation.…”

“…doi:10.1016/j.theochem.2010.06.017 energies were calculated by means of Gaussian09 [28] package in supercomputing center of CAS. Considering the accuracy and convenience of DFT, B3LYP function on the basis set of 6-31G(d) level was employed for the geometry optimization of TMPyP, borates and TMPyP-borate complexes [18,[23][24][25][26]29,30]. On the basis of the optimized structures, the ground state electronic energies were calculated by B3LYP/6-31G(d,p) method.…”

Synthesis of Porphyrinquinone and Doubly‐Fused Diporphyrin Quinone Through Oxidation of Diarylporphyrins Using a Hypervalent Iodine Compound

“…To date, only quinoid compounds derived from meso ‐ meso ‐linked and meso ‐ meso‐ , β – β‐, β′ – β′‐ triply‐linked diporphyrins ( 5 and 6 , Figure ) have been reported. Quinoids derived from doubly‐linked diporphyrin have not been reported to date, although Osuka's group and others have reported a similar type of porphyrin analogue 7 as well as related diporphyrins 8 and 9 (Figure ) . Herein, we also report the structure and properties of 4 .…”

Model Systems for Fluorescence and Singlet Oxygen Quenching by Metalloporphyrins

“…This eliminates electrontransfer processes that have been observed in other conjugated dimer systems. [24,25] The UV/Vis absorption spectra of the dimers 5 are shown in Figure 3. As expected, the absorption of the free base porphyrin at 650 nm is spectrally distinct from the absorption of the metalloporphyrins 3M.…”