title: Supramolecular zinc phthalocyanine-imidazolyl perylenediimide dyad and triad: synthesis, complexation, and photophysical studies.
abstract: 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, ZnPc-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, PDI-6 and PDI-4, respectively, to be able to strongly coordinate with the ZnPc complex. Supramolecular complexation studies by (1)H NMR spectroscopy and ESI-MS demonstrate a high coordinative binding constant between imidazole-substituted PDI-4 or PDI-6 and ZnPc-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 ZnPc-8 and PDI-6 and a 2:1 complex ZnPc/DImPDI/ZnPc 1 for the interaction of ZnPc-8 and PDI-4. The binding constant in both cases was determined to be on the order of 10(5) 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.
authors: División de Química Orgánica, Instituto de Bioingeniería, Universidad Miguel Hernández, Elche 03202, Spain.
authors: F Javier
authors: FJ
authors: Céspedes-Guirao
authors: Kei
authors: K
authors: Ohkubo
authors: Shunichi
authors: S
authors: Fukuzumi
authors: Fernando
authors: F
authors: Fernández-Lázaro
authors: Angela
authors: A
authors: Sastre-Santos
mesh_terms: D007094:Imides / Q000032:analysis / Q000737:chemistry*; D007211:Indoles / Q000032:analysis / Q000138:chemical synthesis* / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D054833:Isoindoles; D008279:Magnetic Resonance Imaging; D009942:Organometallic Compounds / Q000032:analysis / Q000138:chemical synthesis* / Q000737:chemistry; D010569:Perylene / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D056951:Photoelectron Spectroscopy; D011838:Radiation-Sensitizing Agents / Q000032:analysis / Q000138:chemical synthesis* / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D017967:Zinc Compounds
chemical_list: D007094:Imides; D007211:Indoles; D007477:Ions; D054833:Isoindoles; D009942:Organometallic Compounds; D011838:Radiation-Sensitizing Agents; D017967:Zinc Compounds; C521332:perylenediimide; C052159:Zn(II)-phthalocyanine; D010569:Perylene