Three-component noncovalent assembly consisting of a central tetrakis-4-pyridyl porphyrin and two lateral gable-like bis-Zn porphyrins.
A pentaporphyrinic assembly was formed in one step, quantitatively, from a gable like zinc(II) bis-porphyrin and a free-base meso-tetrakis(4-pyridyl)porphyrin, because of the formation of four zinc-nitrogen coordination bonds. The X-ray crystal structure obtained shows a symmetrical structure, the free-base porphyrin being located at the center of a square formed by the four zinc atoms of the two zinc(II) bis-porphyrins. The two phenanthrolines connecting the zinc porphyrins are respectively above and below the plane of the central free-base porphyrin because of favorable CH-pi interactions between several porphyrinic assemblies within the crystal. Spectrophotometric and spectrofluorimetric titrations and studies reveal a high association constant for the porphyrinic assembly in the order of 10(14) M(-2). As expected, energy transfer from the zinc porphyrin component to the central free-base porphyrin quenches the fluorescence of the zinc porphyrin components whereas no sensitization of the emission of the free-base porphyrin was observed. Hypotheses on this unusual behavior are discussed.
Beyler
Maryline
M
Laboratoire de Chimie Organo-Minérale, Institut de Chimie, Université de Strasbourg-CNRS/UMR 7177, 4, rue Blaise Pascal, 67070 Strasbourg-Cedex, France.
Heitz
Valérie
V
Sauvage
Jean-Pierre
JP
Ventura
Barbara
B
Flamigni
Lucia
L
Rissanen
Kari
K
D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011166:Porphyrins / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry*
D009942:Organometallic Compounds; D011166:Porphyrins; D015032:Zinc