Fluorescent and Electroactive Cyclic Assemblies from Perylene Tetracarboxylic Acid Bisimide Ligands and Metal Phosphane Triflates

Abstract

Tetraaryloxy-substituted perylene tetracarboxylic acid bisimides with one or two 4-pyridyl receptor substituents at the imide functionality were synthesized and employed in transition metal directed self-assembly with Pd(II) and Pt(II) phosphane triflates. Upon mixing of the components, quantitative formation of functional molecular square-type complexes containing four dye molecules and model complexes of a 2:1 (perylene bisimide ligand:transition metal ion) stoichiometry was observed. The isolated metallosupramolecular squares were characterized by 1H and 31P [1H] NMR spectroscopy as well as conventional electrospray ionization (ESI) and ESI-FTICR mass spectrometry, which gave evidence for the structure and the high stability of these giant cyclic dye assemblies (molecular weight (3a) 8172, Pt-Pt corner diagonal ca. 3.4 nm). Studies of the optical absorption and fluorescence properties and the electrochemistry and spectroelectrochemistry of both the perylene bisimide ligands and the perylene bisimide metal complexes show that Pt(II) coordination does not interfere with the optical and electrochemical properties of the perylene bisimide ligands; this gives squares with high fluorescence quantum yields (phiF (3a)=0.88) and three fully reversible redox couples. The latter could be unambiguously related to quantitative formation of perylene bisimide radical cations (E1/2 = +0.93 V vs. Fc/Fc+), radical anions (E1/2= - 1.01 V vs. Fc/Fc+), and dianions (E1/2 = -1.14 V vs. Fc/Fc+); these redox reactions change the charge state of the cyclic assembly from +12 to zero. In contrast, Pd(II) coordination influenced the electrochemical properties of the assembly because of an irreversible palladium reduction at E1/2= -1.15 V versus Fc/Fc+. Finally, dynamic ligand exchange processes between different metallosupramolecular assemblies were investigated by multinuclear NMR and electrospray mass spectrometry. These studies confirmed the reversible nature of the pyridine-Pt(II)/Pd(II) coordination process.

Restricted conformation dynamics of single functionalized perylene bisimide molecules on SiO2surfaces and in thin polymer films

“…The synthesis of pyridyl-substituted perylene bisimide (PP) and dialkyl-substituted perylene bisimide (DAP) investigated in the present experiments is described elsewhere [18,19]. PP and DAP molecules are shown in Figure 1.…”

“…DAP serves merely as a reference system to provide in comparison with PP information on the degree of pyridyl mediated surface attachment of PP. Substituting four phenoxy groups at the carbocyclic scaffold further on called "bay groups" [18,19] (one of these four groups is marked in Figure 1, left) enhances solvation in toluene (Merck, spectroscopic grade). For ensemble experiments 10 -7 M stock solutions of PBI dye molecules were prepared in toluene.…”

“…PBI type molecules can be functionalised e. g. via substituted pyridyl rings [18]. Making use of different types of (multi-)pyridyl substituted PBI a whole class of supramolecular architectures has been realized via coordination chemistry and characterized also on a single molecule level [19].…”

Characterization of Self‐Assembled Metallodendrimers in Solution, in the Gas Phase, and at Air/Solid Interfaces

“…Pd squares exchange ligands remarkably faster than their Pt analogs. Similar to our results, Wü rthner et al showed that mixing different metallosupramolecular squares, yielded squares that contain statistical amounts of ligands through dynamic ligand-exchange processes [25] . (asterisks indicate small contributions from defects originating from dendron synthesis).…”

Charge transport through perylene bisimide molecular junctions: An electrochemical approach

“…The syntheses of P-PBI, T-PBI, and aT-PBI were reported in previous publications [30,46] and the syntheses of Py-PBI, aPy-PBI, Cl-PBI, and S-PBI followed procedures known from literature [47][48][49]. Experimental details and compound characterizations are given as Supporting Information (SI).…”