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Michael Hanack - One of the best experts on this subject based on the ideXlab platform.
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Glycosylated Metal Phthalocyanines.
Molecules (Basel Switzerland), 2015Co-Authors: Michael HanackAbstract:In the first part; the syntheses of mono-; di-; and tetra-glycosylated phthalonitriles is described; which are the most used starting materials for the preparation of the corresponding glycosylated metal (mostly zinc) Phthalocyanines. In the second section; the preparation of symmetric and unsymmetric mono-; tetra-; and octa- glycosylated zinc Phthalocyanines are reviewed; in which the sugar is attached to the phthalocyanine macrocycle; either anomerically or via another one of its OH-groups.
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soluble axially substituted Phthalocyanines synthesis and nonlinear optical response
Journal of Materials Science, 2006Co-Authors: Michael Hanack, Yu Chen, Werner J Blau, Danilo Dini, Ying Liu, Ying Lin, Jinrui BaiAbstract:This review lays special stress on describing the synthesis of soluble axially substituted or bridged indium, gallium and titanium phthalocyanine complexes and their electronic absorption characteristics, photophysical and nonlinear optical properties. The enhanced solubility of the axially substituted or bridged phthalocyanine monomers and dimers, compared to the chloro analogues, shows that the usual tendency of Phthalocyanines to form aggregates can be effectively suppressed by axial substitution. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond. The nanosecond nonlinear absorption and the optical limiting of indium, gallium and titanium Phthalocyanines seem to be dominated by a strong triplet state absorption in the optical region comprised between the Q- and B-bands in their UV/Vis absorption spectra.
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axially modified gallium Phthalocyanines and naPhthalocyanines for optical limiting
Chemical Society Reviews, 2005Co-Authors: Michael Hanack, Yu Chen, Yasuyuki Araki, Osamu ItoAbstract:Phthalocyanines (Pcs) offer a high architectural flexibility in structure, which facilitates the tailoring of their physical, optoelectronic and chemical parameters over a very broad range. This tutorial review describes the recent advances in the synthesis of soluble axially substituted or bridged gallium phthalo- and naphthalocyanine compounds, and their photophysical and nonlinear optical properties. The exploitation of the chemical reactivity of the Ga–Cl bond can allow the preparation of a series of highly soluble axially substituted and bridged Pc complexes. Axial substituents in Pcs influence favourably nonlinear optical absorption for the presence of a dipole moment perpendicular to the macrocycle in the axially substituted Phthalocyanines. All Z-scans performed exhibit a decrease of transmittance about the focus typical of an induced positive nonlinear absorption of incident light. Substitution and dimerization of the phthalocyanine monomer resulted in significant reductions in the saturation energy density of the material displaying clear evidence of the usefulness of structurally modifying the gallium phthalocyanine unit. Similar to indium Phthalocyanines, gallium Phthalocyanines are also among the most promising materials that have been investigated as limiters of intense light and the current series presents a selection of structural modifications useful for varying their nonlinear optical properties.
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Studies on Phosphorus Phthalocyanines and Triazatetrabenzcorroles
European Journal of Organic Chemistry, 1998Co-Authors: Lakshminarayanapuram R. Subramanian, Michael HanackAbstract:The previously reported reaction of Phthalocyanines [H2(pc)] with PBr3, which was claimed to give a phosphorus(III) phthalocyanine “(PcPIII)”, has been reinvestigated in detail with both unsubstituted and alkyl-substituted Phthalocyanines, 1-4. The products exhibit unusual electronic and mass spectra compared to normal Phthalocyanines and have been identified as oxophosphorus(V) triazatetrabenzcorroles 5–8. The corresponding dihydroxyphosphorus(V) phthalocyanine hydroxides 9–12 have also been synthesized for the first time by insertion of phosphorus(V) into Phthalocyanines and have been characterized in detail. The different reactivities of PBr3 and POX3 (X = Cl, Br) toward Phthalocyanines are discussed.
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Symmetrically and Unsymmetrically Substituted Phthalocyanines
Materials Syntheses, 1Co-Authors: M. J. Ferreira Calvete, Michael HanackAbstract:A symmetrically and an unsymmetrically substituted phthalocyanine was synthesized by template reaction between the correspondent dinitriles and the metal salts. Considerations were made regarding the mechanistic process, as well as product distribution in the case of the unsymmetrically substituted phthalocyanine, which was synthesized by statistical condensation. These types of Phthalocyanines are very important materials for nonlinear optic applications and for further functionalization to produce e.g. phthalocyanine polymers.
Tomás Torres - One of the best experts on this subject based on the ideXlab platform.
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abab Phthalocyanines scaffolds for building unprecedented donor π acceptor chromophores
ChemistryOpen, 2017Co-Authors: Ettore Fazio, Gema De La Torre, Michael Gratzel, Javier Jaramillogarcia, Maria Medel, Maxence Urbani, Mohammad K Nazeerudin, Tomás TorresAbstract:Unique donor–π–acceptor Phthalocyanines have been synthesized through the asymmetric functionalization of an ABAB phthalocyanine, crosswise functionalized with two iodine atoms through Pd-catalyzed cross-coupling reactions with adequate electron-donor and electron-acceptor moieties. These push–pull molecules have been optically and electrochemically characterized, and their ability to perform as chromophores for dye-sensitized solar cells has been tested.
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probing supramolecular interactions between a crown ether appended zinc phthalocyanine and an ammonium group appended to a c60 derivative
Chemistry: A European Journal, 2016Co-Authors: Marcus Lederer, Tomás Torres, Uwe Hahn, Jeanmarc Strub, Jeanfrancois Nierengarten, Sarah Cianferani, Alain Van Dorsselaer, Dirk M. GuldiAbstract:Self-assembly driven by crown ether complexation of zinc Phthalocyanines equipped with one 18-crown-6 moiety and fullerenes bearing an ammonium head group afforded a novel donor–acceptor hybrid. In reference experiments, fullerenes containing a Boc-protected amine functionality have been probed. The circumvention of zinc phthalocyanine aggregation is important for the self-assembly, which required the addition of pyridine. From absorption and fluorescence titration assays, which provided sound and unambiguous evidence for mutual interactions between the electron donor and the electron acceptor within the hybrids, association constants in the order of 8.0×105 m−1 have been derived. The aforementioned is based on 1:1 stoichiometries, which have been independently confirmed by Job's plot measurements. In the excited state, which has been examined by transient absorption experiments, intermolecular charge separation evolves from the photoexcited zinc phthalocyanine to the fullerene subunit and leads to short-lived charge-separated states. Interestingly, photoexcitation of zinc phthalocyanine dimers/aggregates can also be followed by an intermolecular charge separation between vicinal Phthalocyanines. These multicomponent supramolecular ensembles have also been shown by in-depth electrospray ionization mass spectrometry (ESI-MS) studies, giving rise to the formation and detection of a variety of non-covalently linked species.
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electron donating behavior of few layer graphene in covalent ensembles with electron accepting Phthalocyanines
Journal of the American Chemical Society, 2014Co-Authors: Mariaeleni Ragoussi, Dirk M. Guldi, Gema De La Torre, Georgios Katsukis, Alexandra Roth, Jenny Malig, Tomás TorresAbstract:We describe herein the first example of highly exfoliated graphene covalently linked to electron accepting Phthalocyanines. The functionalization of the nanocarbon surface with alkylsulfonyl Phthalocyanines was attained by means of a “click” chemistry protocol. The new ensemble was fully characterized (thermogravimetric analysis, atomic force microscopy, transmission electron microscopy and Raman, as well as ground-state absorption) and was studied in terms of electron donor–acceptor interactions in the ground and in the excited state. In particular, a series of steady-state and time-resolved spectroscopy experiments demonstrated photoinduced electron transfer from the graphene to the electron-accepting Phthalocyanines. This is the first example of an electron donor–acceptor nanoconjugate, that is, few-layer graphene/phthalocyanine, pinpointing the uncommon electron donating character of graphene.
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Phthalocyanines from outstanding electronic properties to emerging applications
Chemical Record, 2008Co-Authors: Christian G Claessens, Uwe Hahn, Tomás TorresAbstract:This review paper gives a brief overview on how the outstanding chemical and physical properties of Phthalocyanines and phthalocyanine derivatives are being studied and employed in order to construct state-of-the-art technological devices. In a first instance, a short account on how the nature of the phthalocyanine structure and its organization in condensed phases play an important role in their conducting and ultraviolet-visible absorption properties is presented. Consequently, these basic electronic and photophysical features of Phthalocyanines allow us to explain why phthalocyanine-based multicomponent covalent or noncovalent donor-acceptor systems may give rise to very interesting photophysical properties, in particular in terms of their ability to generate very long-lived photoinduced charge-separated states. A concise survey on the organization of these multifunctional systems shows how a profound understanding of the morphology at the nanometer-scale of these phthalocyanine-based molecular materials is needed in order to control their physical properties in condensed phases. All the previously mentioned chemical and physical features combined together led us to the description of the latest attempts at incorporating Phthalocyanines into photovoltaic devices for solar energy conversion and onto quantum dots for photodynamic therapy or quantum computing. © 2008 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 8: 75–97; 2008: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20139
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single wall carbon nanotubes bearing covalently linked Phthalocyanines photoinduced electron transfer
Journal of the American Chemical Society, 2007Co-Authors: Beatriz Ballesteros, Gema De La Torre, Christian Ehli, G Aminur M Rahman, F Agullorueda, Dirk Guldi M And, Tomás TorresAbstract:HiPco single-walled carbon nanotubes (SWNTs) have been sidewall-functionalized with phthalocyanine addends following two different approaches: a straightforward Prato reaction with N-octylglycine and a formyl-containing phthalocyanine, and a stepwise approach that involves a former Prato cycloaddition to the double bonds of SWNTs using p-formyl benzoic acid followed by esterification of the derivatized nanotubes with an appropriate phthalocyanine molecule. The two materials obtained by these routes comprise different carbon/Pc-addenda ratios, as evidenced by Raman, TGA, and photophysical studies. The occurrence of electron transfer from photoexcited Phthalocyanines to the nanotube framework in these ZnPc-SWNT ensembles is observed in transient absorption experiments, which confirm the absorption of the one-electron oxidized ZnPc cation and the concomitant bleaching of the van Hove singularities typical from SWNTs. Charge-separation (i.e., 2.0 × 1010 s-1) and charge-recombination (i.e., 1.5 × 106 s-1) dyn...
Tebello Nyokong - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and photophysicochemical properties of zinc phthalocyanine derivatized with benzothiazole or carbazole photosensitizers
Polyhedron, 2013Co-Authors: Phindile Khoza, Edith Antunes, Tebello NyokongAbstract:Abstract The synthesis of new zinc phthalocyanine complexes containing 3-(2-benzothiazol-2-yloxy) (complex 3) and 3-(carbazol-2-yloxy) (complex 4) substituents at the non-peripheral positions are reported. The new compounds were characterized by elemental analysis, FT-IR, 1H NMR, mass spectrometry and UV–Vis spectroscopy. The effects of carbazole and benzothiazole substitutents on the photophysical and photochemical parameters of ZnPc are reported. These new Phthalocyanines are non-aggregated in common solvents and show improved photophysicochemical properties. The 3-(2-benzothiazol-2-yloxy) substituted complex showed the longest triplet lifetime ever reported for a zinc phthalocyanine (1.7 ms).
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synthesis photophysical and photochemical properties of substituted zinc Phthalocyanines
Dalton Transactions, 2007Co-Authors: Ilke Gurol, Vefa Ahsen, Mahmut Durmus, Tebello NyokongAbstract:The synthesis, photophysical and photochemical properties of the 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}oxy) and 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}thio) zinc(II) Phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc(II) Phthalocyanines (6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn(II) Phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.
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effects of substituents on the photochemical and photophysical properties of main group metal Phthalocyanines
Coordination Chemistry Reviews, 2007Co-Authors: Tebello NyokongAbstract:The review focuses on the photochemical (singlet oxygen and photobleaching quantum yields) and photophysical (triplet quantum yields and lifetimes and fluorescence lifetimes) properties of metallophthalocyanine complexes containing main group metals (Zn, Al, Ge, Si, Sn, Ga and In) and some unmetallated phthalocyanine complexes. Five tables containing photophysical and photochemical data for sulfonated Phthalocyanines, tetra-, octa-substituted and unsubstituted Phthalocyanines in a variety of solvents, are included in the review.
Yu Chen - One of the best experts on this subject based on the ideXlab platform.
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soluble axially substituted Phthalocyanines synthesis and nonlinear optical response
Journal of Materials Science, 2006Co-Authors: Michael Hanack, Yu Chen, Werner J Blau, Danilo Dini, Ying Liu, Ying Lin, Jinrui BaiAbstract:This review lays special stress on describing the synthesis of soluble axially substituted or bridged indium, gallium and titanium phthalocyanine complexes and their electronic absorption characteristics, photophysical and nonlinear optical properties. The enhanced solubility of the axially substituted or bridged phthalocyanine monomers and dimers, compared to the chloro analogues, shows that the usual tendency of Phthalocyanines to form aggregates can be effectively suppressed by axial substitution. Axial substitution in phthalocyanine complexes has provoked relevant changes on the electronic structure of the molecule by altering the π-electronic distribution due to the dipole moment of the central metal-axial ligand bond. The nanosecond nonlinear absorption and the optical limiting of indium, gallium and titanium Phthalocyanines seem to be dominated by a strong triplet state absorption in the optical region comprised between the Q- and B-bands in their UV/Vis absorption spectra.
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axially modified gallium Phthalocyanines and naPhthalocyanines for optical limiting
Chemical Society Reviews, 2005Co-Authors: Michael Hanack, Yu Chen, Yasuyuki Araki, Osamu ItoAbstract:Phthalocyanines (Pcs) offer a high architectural flexibility in structure, which facilitates the tailoring of their physical, optoelectronic and chemical parameters over a very broad range. This tutorial review describes the recent advances in the synthesis of soluble axially substituted or bridged gallium phthalo- and naphthalocyanine compounds, and their photophysical and nonlinear optical properties. The exploitation of the chemical reactivity of the Ga–Cl bond can allow the preparation of a series of highly soluble axially substituted and bridged Pc complexes. Axial substituents in Pcs influence favourably nonlinear optical absorption for the presence of a dipole moment perpendicular to the macrocycle in the axially substituted Phthalocyanines. All Z-scans performed exhibit a decrease of transmittance about the focus typical of an induced positive nonlinear absorption of incident light. Substitution and dimerization of the phthalocyanine monomer resulted in significant reductions in the saturation energy density of the material displaying clear evidence of the usefulness of structurally modifying the gallium phthalocyanine unit. Similar to indium Phthalocyanines, gallium Phthalocyanines are also among the most promising materials that have been investigated as limiters of intense light and the current series presents a selection of structural modifications useful for varying their nonlinear optical properties.
Mahmut Durmus - One of the best experts on this subject based on the ideXlab platform.
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axially paraben substituted silicon iv Phthalocyanines towards dental pathogen streptococcus mutans synthesis photophysical photochemical and in vitro properties
Journal of Photochemistry and Photobiology A-chemistry, 2015Co-Authors: Gokce Canan Taskin, Mahmut Durmus, Fatma Yuksel, Vanya Mantareva, Vesselin Kussovski, Ivan Angelov, Devrim AtillaAbstract:Abstract A series of silicon(IV) Phthalocyanines axially substituted with methylparaben, ethylparaben, propylparaben and butylparaben groups were synthesized and studied as photosensitizers for antimicrobial photodynamic therapy. The absorption, fluorescence, photodegradation and singlet oxygen generation properties of the synthesized Si(IV) Phthalocyanines were studied. In vitro antibacterial photodynamic therapy was investigated against cariogenic pathogenic bacterium Streptococcus mutans . Axially propylparaben substituted Si(IV) phthalocyanine showed significant photodynamic efficacy (log 4) at concentration of 10 μM and mild irradiation (60 mW cm −2 , 50 J cm −2 , LED 637 nm). The low inactivation capacity was observed for the other studied Si(IV) Phthalocyanines. The uptake and localization properties of axially propylparaben substituted Si(IV) phthalocyanine showed a sufficient level of accumulation in planktonic cultured bacterium and a complete penetration depth into the biomass of the 48-h bacterial biofilm.
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synthesis photophysical and photochemical properties of substituted zinc Phthalocyanines
Dalton Transactions, 2007Co-Authors: Ilke Gurol, Vefa Ahsen, Mahmut Durmus, Tebello NyokongAbstract:The synthesis, photophysical and photochemical properties of the 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}oxy) and 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}thio) zinc(II) Phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc(II) Phthalocyanines (6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn(II) Phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.