Università degli Studi di Roma “Tor Vergata” Facoltà di Scienze Matematiche, Fisiche e Naturali

Dipartimento di Scienze e Tecnologie Chimiche

Prof. Pietro Tagliatesta

Reaction center of PSII

K. N. Ferriera; T. M. Iverson and coworkers Science 2004, 303, 1831

P680

  Natural Photosystems

Photosystem II (PSII) from Thermosynecochoccus Elongatus

Absorption spectrum of Rhodobacter Sphaeroides reaction center

W. Zynth; J. Wachtveitl ChemPhysChem 2005, 6, 871

400 500 600 700 8000.0

0.2

0.4

0.6

0.8

1.0

1.2

Abs

Wavelength (nm)

500 550 600 650 700

Q bands

MgN

N

NN

O

O

O O

O

  Natural Pigments

Chlorophylls

5,10,15,20-Tetraphenylporphyrin

NNH

N HN

R2

R1 R1

R2

R3

R4R4

R3

R

R

R

R

Tetrapyrrole macrocycle

R = aryl, alkyl R1, R2, R3, R4 = aryl, alkyl, alogen, nitro group, amino group…

UV-vis spectrum

Fullerenes: structures

C60 C70

Fullerenes and C60

Functionalization of Fullerenes

C60

Reazione di Prato

Reazione concarbeni

N

CH3

R

ROR'

D

C C

NHCO

CNH

O

Spacer:

  Porphyrin-fullerene covalent systems: P spacer C60

kET (s-1) kBET (s-1) τ

2.2.1010 2.0 . 106 500 ns

1.3 .1010 3.7 . 105 2.7 µs

3.7 . 1010 1.5 . 106 666 ns

  Multichromophoric systems: P C60 P

FeZn

NN

N N

NH

O

NNH

N HN

NH

O

NH

ON

CH3

Guldi, D. M.; Imahori, H.; Fukuzumi S. et al. J. Phys. Chem. A 2004, 108, 541.

e- + e-

NN

N N

Zn CH3

N

CH3

spacer

H. Imahori; D. M. Guldi; T. Okada; S. Fukuzumi and coworkers Angew. Chem. Int. Ed. 2002, 41, 2344

τRIP = 0.34 s

in DMF a 178 K

  Oligomer as spacer: “molecular wires”

Zn

NN

N N

N

CH3O

On

n

n = 1, 2Guldi, D. M.; Martin, N. and coworkers Chem.Eur.J. 2005, 11, 1267

Zn

NN

N N

CH3

n = 2, 3, 4

n

D. I. Schuster; L. Echegoyen; D. M. Guldi; J. P. C. Tomè and coworkers Chem. Eur. J. 2005, 11, 3377

oligo-phenylenevinylenes

oligo-acetylenes

( )DAET Rkk β−= exp0

β = damping factor

n τ (ns) 2  555 3  625 4  714

In THF solution:

β = 0.06 Å-1

n = 1 PhCN τRIP = 230 ns THF τRIP = 830 ns

n = 2 PhCN τRIP = 370 ns THF τRIP = 1000 ns

β = 0.03 Å-1

H2-TPP

  In our laboratory

  New β-substituted porphyrins

  Molecular wires directly linked to the β-pyrrole position

  Use of oligo-phenyleneethynylenes as molecular wire

** n

  Rigid structure between the chromophores

  Extended π delocalization along the linker

1)

NNH

N NH

Br

HO

H

H

O

H

or

Pd(dba)2/AsPh3Toluene/NEt3 65 °C

H

ONN

H

N NH

n

n = 1 90%

n = 2 65%

n = 3 70%

HO

H

or

2)

3)

Rese:

  Synthesis of new porphyrin-”wire”-fullerene systems

N

HNN

NHN

CH3

60%

N

HNN

NH

N

CH3

57%

N

HNN

NH

N

CH3

52%

C60, Toluene reflux

  Steady state fluorescence studies

550 600 650 700 750 800 8500

1x108

2x108

3x108

4x108

5x108

n = 1 n = 2 n = 3

Inte

nsity

(cps

)

Wavelength (nm)

Free base Zinc complex

The fluorescence quencing efficiency is distance dependent

Compound Quencing efficiency Toluene THF Benzonitrile

H2P-EP1-C60 93% >99% >99%

ZnP-EP1-C60 98% >99% >99%

H2P-EP2-C60 47% 60% 71% ZnP-EP2-C60 81% 94% 95% H2P-EP3-C60 20% 23% 24% ZnP-EP3-C60 45% 58% 66%

550 600 650 700 750 800 8500

1x108

2x108

3x108

4x108

5x108

6x108

7x108

8x108

9x108

n = 1 n = 2 n = 3

Inte

nsity

(cps

)

Wavelength (nm)

N

HNN

NHN

CH3

n

n = 1, 2, 3

Transient spectroscopy

Interazioni π-π tra porfirine e C60

Structures of ferrocene-porphyrin

Structures of the triads

Collaboratori alla ricerca

Prof. Dirk M. Guldi (University of Erlangen-Germany) Prof. Roberto Pizzoferrato Dr. Ph.D. Angelo Lembo Dr.ssa Ph.D. Alina Ciammaichella Dr.ssa Francesca Limosani Ph.D. student Dr. Fabio Possanza Ph.D. student Sig. Alessandro Leoni