A new series of multicomponent ZnPc−Ru(bpy)3 systems, 1a − c, consisting of a zinc-phthalocyanine linked through conjugated and/or nonconjugated connections to a ruthenium(II) tris(bipyridine) ...complex, has been synthesized. The ruthenium complexes 1a − c were prepared from phthalocyanines 2a − c, bearing a 4-substituted-2,2‘-bipyridine ligand by treatment with Ru(bpy)2Cl2·2H2O. Different synthetic strategies have been devised to prepare the corresponding dyad precursors (2a − c). Compound 2a, for example, with an ethenyl bridge, was synthesized by statistical condensation of 4-tert-butylphthalonitrile and 5-(E)-2-(3,4-dicyanophenyl)ethenyl-2,2‘-bipyridine (3) in the presence of zinc chloride. Compounds 2b and 2c, having, respectively, an amide or an ethynyl bridge, were prepared following a different synthetic approach. The method involves the coupling of an appropriate 5-substituted-2,2‘-bipyridine to an unsymmetrical phthalocyanine suitably functionalized with an amino (4) or an ethynyl group (5). The photophysical properties of the dyads that are ZnPc−Ru(bpy)3 1a − c and related model compounds have been determined by a variety of steady-state (i.e., fluorescence) and time-resolved methods (i.e., fluorescence and transient absorption). Clearly, intramolecular electronic interactions between the two subunits dominate the photophysical events following the initial excitation of either chromophore. These intramolecular interactions lead, in the case of photoexcited ZnPc, to faster intersystem crossing kinetics compared to a ZnPc reference, while photoexcited Ru(bpy)32+ undergoes a rapid and efficient transduction of triplet excited-state energy to the Pc.
The phthalocyanine–fullerene dyad Pc-C60 is an intramolecular donor–acceptor system that can be used as photoactive material in photovoltaic devices. The photocurrent shows maxima below 400 and 700
...nm, but only a small response in the range around 500
nm. To improve the spectral match to the solar emission spectrum, an energy transfer process from the conjugated polymer poly 2-methoxy-5-(3′,7′-dimethyloctyloxy)-1-4-phenylene vinylene MDMO-PPV (antenna system) to the dyad compound can be used. The photophysics of the energy transfer process was studied with luminescence measurements and sub-picosecond time-resolved transmission changes. The influence of the polymeric antenna system on the photovoltaic device properties was measured with spectrally resolved photocurrent (IPCE) measurements. Photocurrent in nearly the full visible spectral range was obtained. In addition, Pc-C60 was also added as third component to MDMO-PPV:PCBM mixtures. The photocurrent around 700
nm was increased, however with reduction in the short-circuit current under white light illumination.
Cyclooligomeric phthalocyanines with the special feature of having a dehydroannulene core are described. Compounds 4a,b and 5a,b were prepared by an oxidative coupling mediated by copper from the ...corresponding diethynyl unsymmetrically substituted phthalocyanines 8a,b, which are easily accessible from the corresponding diiodo compounds 6a,b by a palladium−copper-catalyzed coupling. Appropriate conditions to selectively form cyclodimers and cyclotrimers using Glaser and Eglinton methodologies have been attempted. In this way, two compounds, 4a and 5b, each representative of a kind of oligomers, could be appropriately isolated and characterized by MALDI-MS. The UV−vis spectra of compounds 4a and 5b show a split Q-band shifted to the red with respect to the corresponding precursor 8a,b. This can be interpreted, in light of previous results, as a consequence of intramolecular electronic coupling between the Pc subunits. Extensive formation of aggregates in chloroform can be also inferred from the spectra. No significant differences could be observed in the spectra by comparison with that of the open-chain analogue 11, most probably due to a saturation phenomenon of the optical properties already pointed out in the literature for other alkynyl-linked open-chain dimers.
The first phthalocyanine−fullerene system having a flexible bridge containing an azacrown subunit has been synthesized, and investigations of its excited state processes through femtosecond flash ...photolysis experiments and of its electrochemical properties have been carried out.
Two families of “push−pull” phthalocyanines 1−3 having an unusually strong dipole moment have been prepared. The syntheses of unsymmetrically substituted phthalocyanines 1a,b and 2 bearing one or two ...electron-withdrawing 4-nitrophenylethynyl moieties, respectively, and six alkoxy substituents were performed by combination of a zinc or nickel templated cyclotetramerization and cross-coupling palladium mediated methodologies. In a similar way, the “push−pull” compounds 3a,b having a reversal substitution pattern, characterized by the presence of one electron-donor 4-(dimethylamino)phenylethynyl unit and six strong acceptor alkylsulfonyl substituents were prepared. The compounds show very large second-order nonlinear optical responses.
Two functionalized phthalocyanine-based chromophore systems having two iodophthalocyaninatozinc(II) rings bound together through a butadiynyl linkage
1a,
b have been synthesized by oxidative Eglinton ...coupling of the corresponding monomer, and fully characterized. The electronic characteristics of these extensively linearly π-conjugated compounds were modulated by the introduction of different peripheral substituents into the phthalocyanine moieties and investigated by UV–visible spectroscopy. The reactivity of the two iodo substituents was explored to prepare a novel bisphthalocyanine containing two ethynylphenyl moieties, thus pointing out the possibility of incorporating other electro and/or photoactive moieties in the BisPc system, taking advantage of the iodo-functionalization.
Phthalocyanines with an extensive two-dimensional 18 pi-electron system have been intensively investigated as nonlinear optics materials (NLO) and exhibit exceptional stability, versatility, and ...processability features. De La Toree, et al focus on the main new trends and important advances obtained in the field of the NLO properties of phthalocyanines and analogues, especially in 2 dimensional systems such as Pcs and porphyrins.
Exfoliation of graphite was achieved using a zinc phthalocyanine oligomer that is also an electron donor. The resulting functionalized graphene material was investigated by Raman and electron ...spectroscopy and was trialed in a photoelectrochemical cell.
