Covalently Linked Porphyrin Dimers as Model Systems of the Photosynthetic Special Pair: Spectroscopy, Energetics and Photochemistry

Using a self-assembled supramolecular approach, a closer model for the photosynthetic reaction center 'special pair' assembled with an electron acceptor conjugate, is reported. As the 'special pair' donor, magnesium meso-(benzo-15-crown-5)porphyrin was self-assembled with K + to form a highly stable Mg porphyrin dimer with a co-facial geometry arrangement, which is a better electron donor since it is nearly 130 mV easier to oxidize compared to the earlier reported Zn porphyrin dimer analog. Further, pyridine and alkyl ammonium cation-functionalized fullerene was attached via axial coordination and crown ether-alkyl ammonium cation complexation to form the four-fold, donor-acceptor complex. The self-assembled supramolecular complex, constructed using this approach, possesses defined geometry and orientation. Efficient charge separation from the singlet excited state of the Mg porphyrin dimer to the fullerene entity and a relatively slow charge recombination, were revealed by time-resolved emission and nanosecond transient absorption spectral studies, supporting the impending exploitation of these novel biomimetic model systems for light energy harvesting applications.

Download Full-text

Transfer of electronic excitation energy in covalently-linked porphyrin dimers (ethane-bisporphyrins)

Journal of Applied Spectroscopy ◽

10.1007/bf00662155 ◽

1986 ◽

Vol 45 (5) ◽

pp. 1186-1190

Author(s):

E. I. Zen'kevich ◽

A. M. Shul'ga ◽

A. V. Chernook ◽

G. P. Gurinovich

Keyword(s):

Excitation Energy ◽

Electronic Excitation ◽

Electronic Excitation Energy ◽

Covalently Linked ◽

Porphyrin Dimers

Download Full-text

Quinone substituted monometallated porphyrin dimers: Evidence for “superexchange” mediated electron transfer in multicomponent photosynthetic model systems

Journal of Inorganic Biochemistry ◽

10.1016/0162-0134(89)84173-x ◽

1989 ◽

Vol 36 (3-4) ◽

pp. 205

Author(s):

JonathanL. Sessler ◽

MartinR. Johnson

Keyword(s):

Electron Transfer ◽

Model Systems ◽

Mediated Electron Transfer ◽

Porphyrin Dimers

Download Full-text

Synthesis and electrochemical investigation of covalently linked porphyrin dimers containing a β-brominated subunit.

Journal of Porphyrins and Phthalocyanines ◽

10.1142/s1088424603000756 ◽

2003 ◽

Vol 07 (09) ◽

pp. 595-609 ◽

Cited By ~ 3

Author(s):

Zhongping Ou ◽

Pietro Tagliatesta ◽

Mathias O. Senge ◽

Jianguo Shao ◽

Karl M. Kadish

Keyword(s):

Cyclic Voltammetry ◽

Single Crystal ◽

Electrochemical Investigation ◽

Visible Spectroscopy ◽

Electronic Interactions ◽

X Ray ◽

Uv Visible ◽

Covalently Linked ◽

Porphyrin Dimers

Ten meso-tetraphenylporphyrin-type heterodimers containing a partly or completely β-brominated subunit were synthesized and characterized by UV-visible spectroscopy, cyclic voltammetry and spectroelectrochemistry, showing the presence of low electronic interactions between the two subunits. The investigated compounds are represented as M [( tripp - tpp ( Br 4)] M and M [ tripp - tpp ( Br 8)] M ( M = 2 H , Zn , Ni , Co and Cu ) where tripp - tpp ( Br 4) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,12,13-tetrabromoporphyrinyl)]-benzene and tripp - tpp ( Br 8) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,7,8,12,13,17,18-octabromoporphyrinyl)]-benzene. One of the synthesized dimers, H 2[ tripp - tpp ( Br 8)] H 2, was characterized by a single-crystal X-ray investigation.

Download Full-text

Excitonic Interactions in Covalently Linked Porphyrin Dimers with Rotational Freedom

Journal of Porphyrins and Phthalocyanines ◽

10.1002/(sici)1099-1409(199906)3:5<346::aid-jpp139>3.0.co;2-e ◽

1999 ◽

Vol 03 (05) ◽

pp. 346-354 ◽

Cited By ~ 6

Author(s):

REGIEN G. STOMPHORST ◽

ROB B. M. KOEHORST ◽

GERT VAN DER ZWAN ◽

BERT BENTHEM ◽

TJEERD J. SCHAAFSMA

Keyword(s):

Absorption Spectra ◽

Dipole Approximation ◽

Point Dipole ◽

Excitonic Interactions ◽

Conformational Freedom ◽

Point Dipole Approximation ◽

Covalently Linked ◽

Porphyrin Dimers ◽

Rotational Freedom ◽

Soret Region

Experimental and calculated absorption spectra are compared for four different porphyrin dimers covalently linked by alkyl- or phenyl bridges. The spectra of the corresponding monomers were used as a reference to determine the experimental exciton,ic shift(s) of the absorption spectrum in the Soret region. The excitonic interaction was calculated using the point dipole approximation and taking into account the restricted conformational freedom of the monomeric units in the dimers due to steric constraints. The constraints were independently verified by magnetic dipole-dipole broadening of the EPR spectra of several ( CuTPP )2-substituted dimers. The observed and calculated absorption spectra agree at least semiquantitatively.

Download Full-text