Supramolecular Zinc Phthalocyanine-Imidazolyl Perylenediimide Dyad and Triad: Synthesis, Complexation, and Photophysical Studies

Two new supramolecular architectures based on zinc phthalocyanine (Pc) and imidazolyl‐substituted perylenediimide (PDI), ZnPc/DImPDI/ZnPc 1 and ZnPc/ImPDI 2, have been prepared. A strong electron‐donor, 8, which contained eight tert‐octylphenoxy groups was synthesized to ensure high solubility, ther...

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Published in:Chemistry, an Asian journal an Asian journal, 2011-11, Vol.6 (11), p.3110-3121
Main Authors: Céspedes-Guirao, F. Javier, Ohkubo, Kei, Fukuzumi, Shunichi, Fernández-Lázaro, Fernando, Sastre-Santos, Ángela
Format: Article
Language:English
Subjects:
Chemistry
electron transfer
Imides - analysis
Imides - chemistry
Indoles - analysis
Indoles - chemical synthesis
Indoles - chemistry
Ions - chemistry
Magnetic Resonance Imaging
Organometallic Compounds - analysis
Organometallic Compounds - chemical synthesis
Organometallic Compounds - chemistry
Perylene - analogs & derivatives
Perylene - analysis
Perylene - chemistry
perylenediimide
Photoelectron Spectroscopy
photophysics
Radiation-Sensitizing Agents - analysis
Radiation-Sensitizing Agents - chemical synthesis
Radiation-Sensitizing Agents - chemistry
Spectroscopy, Fourier Transform Infrared
supramolecular chemistry
Zinc
zinc pthalocyanine
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Summary:Two new supramolecular architectures based on zinc phthalocyanine (Pc) and imidazolyl‐substituted perylenediimide (PDI), ZnPc/DImPDI/ZnPc 1 and ZnPc/ImPDI 2, have been prepared. A strong electron‐donor, 8, which contained eight tert‐octylphenoxy groups was synthesized to ensure high solubility, thereby reducing aggregation in solution and providing σ‐donor features while avoiding regioisomeric mixtures. Also, PDI units were functionalized with tert‐octylphenoxy groups at the bay positions, which provide solubility to avoid aggregation in solution, together with one and two imidazole moieties in the amide position, 6 and 4, respectively, to be able to strongly coordinate with the ZnPc complex. Supramolecular complexation studies by 1H NMR spectroscopy and ESI‐MS demonstrate a high coordinative binding constant between imidazole‐substituted 4 or 6 and 8. The same results were confirmed by UV/Vis and fluorescence titration studies. UV/Vis titration studies revealed the formation of a 1:1 complex ZnPc/ImPDI 2 for the systems 8 and 6 and a 2:1 complex ZnPc/DImPDI/ZnPc 1 for the interaction of 8 and 4. The binding constant in both cases was determined to be on the order of 105 M−1. Femtosecond laser flash photolysis measurements provided a direct proof of the charge‐separated state within both supramolecular assemblies by observing the transient absorption band at 820 nm due to the zinc phthalocyanine radical cation. The lifetimes of charge‐separated states are (9.8±3) ns for triad 1 and (3±1) ns for dyad 2. As far as we know, this is the first time that a radical ion pair has been detected in a supramolecular assembled ZnPc–PDI system and has obtained the longest lifetime of a charge‐separated state published for ZnPc–PDI assemblies. Se han preparado dos nuevos sistemas supramoleculares basados en ftalocianina de zinc y en perilenobisimida sustituida con grupos imidazolilo, ZnPc/DImPDI/ZnPc 1 y ZnPc/ImPDI 2. Se ha sintetizado la ftalocianina 8 con ocho grupos terc‐octilfenoxilo con objeto de aumentar la solubilidad, reducir la agregación en disolución, introducir grupos dadores de electrones y, por último, evitar mezclas de regioisómeros. Además, las 6 y 4 también se han funcionalizado con grupos terc‐octilfenoxilo en las posiciones bahía, los cuales les confieren solubilidad e impiden la agregación en disolución, y con una o dos unidades de imidazol en la posición imida, respectivamente, con objeto de coordinar fuertemente la ZnPc. Los estudios de complejación
ISSN:1861-4728
1861-471X
DOI:10.1002/asia.201100273