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Molecular Anion Binding and Substrate Photooxidation in Visible Light by 2,7‐Diazapyrenium Cations
Author(s) -
Blacker A. John,
Jazwinski Jaroslaw,
Lehn JeanMarie
Publication year - 1987
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19870700102
Subject(s) - chemistry , molecule , photochemistry , quenching (fluorescence) , fluorescence , visible spectrum , binding constant , absorption spectroscopy , stability constants of complexes , ion , pyrene , absorption (acoustics) , crystallography , binding site , organic chemistry , biochemistry , physics , optoelectronics , quantum mechanics , acoustics
The 2,7‐diazapyrenium group (DAP 2+ ) combines the features of pyrene, of methylviologen, and of nucleicacid intercalators and may thus present a variety of interesting properties. The cations 1 and 2 and the bis‐diazapyrenium species 3 have been synthesized and shown to bind molecular anions like aromatic polycarboxylates, giving rise to pronounced shifts of 1 H‐NMR signals, modifications of UV/VIS absorption spectra, and quenching of fluorescence. The complexes formed probably have a face‐to‐face structure, and their stability constants are remarkably high, in particular for the bis‐diazapyrenium cation 3 which is susceptible to form intercalative chelate complexes such as 9 (log K s ≈ 3 for 1 , up to ca . 7 or more for 3a ). Neutral molecules like adenine are also bound, but much less strongly. Visible‐light irradiation of Me 2 DAP 2+ ( 1 ) in presence of various electron donors, such as EDTA, gives the reduced species Me 2 DAP + wich has been characterized by UV/VIS and ESR spectroscopy. The results indicate that Me 2 DAP 2+ ( 1 ) functions as a methylviologen analogue, photoactive in visible light . Thus 2,7‐diazapyrenium cations are attractive subunits for incorporation into macropolycyclic structures to give photo‐ and electroactive receptor molecules.