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Synthesis and Photophysical Studies of New Porphyrin–Phthalocyanine Dyads with Hindered Rotation
Author(s) -
Tomé João P. C.,
Pereira Ana M. V. M.,
Alonso Cristina M. A.,
Neves Maria G. P. M. S.,
Tomé Augusto C.,
Silva Artur M. S.,
Cavaleiro José A. S.,
MartínezDíaz M. Victoria,
Torres Tomás,
Rahman G. M. Aminur,
Ramey Jeff,
Guldi Dirk M.
Publication year - 2006
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200500558
Subject(s) - porphyrin , chemistry , phthalocyanine , intersystem crossing , photochemistry , tetraphenylporphyrin , ultrafast laser spectroscopy , homo/lumo , molecule , spectroscopy , organic chemistry , singlet state , excited state , physics , quantum mechanics , nuclear physics
Abstract A series of novel porphyrin–phthalocyanine (Por‐Pc) dyads 1 – 3 have been synthesized by using standard methodologies for unsymmetrically substituted phthalocyanine preparation. These two chromophoric units have been directly linked for the first time, that is, without any spacer, through the β‐pyrrolic position of a meso ‐tetraphenylporphyrin, thus allowing a close proximity of the two units in a rigid arrangement. For this, a novel porphyrin–phthalonitrile precursor 4 had to be prepared. The UV/Vis spectra indicate that the basic electronic characteristics of both individual units (i. e., porphyrin and phthalocyanine) are retained in the hybrid Por‐Pc molecules. The short Por‐Pc separation in dyads 1 – 3 leads to strong excitonic coupling and ultrafast energy transfer (ca. 10 12 s –1 ), as determined by femtosecond transient absorption measurements, from the highly energetic 1 *(ZnPor) unit to the 1 *(ZnPc), which evolves to populate the long‐lived 3 *(ZnPc) by intersystem crossing. Interestingly, the energy transfer seems to occur more efficiently in dyads 2 and 3 , which have smaller HOMO–LUMO energy gaps. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)