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  • 1
    UID:
    b3kat_BV044853449
    Format: 83 Seiten, 182 Seiten in verschiedener Zählung , Illustrationen, Diagramme (teilweise farbig)
    Note: Habilitationsschrift Humboldt-Universität zu Berlin 2016
    Language: German
    Subjects: Engineering , Chemistry/Pharmacy
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    RVK:
    RVK:
    Keywords: Hochschulschrift
    Author information: Schwalbe, Matthias 1980-
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  • 2
    UID:
    b3kat_BV001141245
    Format: 153 Bl. , Ill., graph. Darst.
    Note: Leipzig, Univ., Diss.
    Language: German
    Keywords: Hochschulschrift
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  • 3
    UID:
    b3kat_BV025313589
    Format: 112 S. , graph. Darst.
    Note: Berlin, Humboldt-Univ., Dipl.-Arb., 1997
    Language: German
    Keywords: Hochschulschrift
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  • 4
    UID:
    edochu_18452_23913
    Format: 1 Online-Ressource (10 Seiten)
    Content: Photosensitizing units have already been applied to enable light-driven catalytic reduction of CO2 with mononuclear rhenium complexes. However, dinuclear catalytic systems that are able to activate CO2 in a cooperative bimetallic fashion have only rarely been combined with photosensitizers. We here present detailed studies on the influence of additional photosensitizers on the catalytic performance of a dirhenium complex (Re2Cl2) and present correlations with spectroscopic measurements, which shed light on the reaction mechanism. The use of [Ir(dFppy)3] (Ir, dFppy=2-(4,6-difluorophenyl)pyridine)) resulted in considerably faster CO2 to CO transformation than [Cu(xant)(bcp)]PF6 (Cu, xant=xantphos, bcp=bathocuproine). Emission quenching studies, transient absorption as well as IR spectroscopy provide information about the electron transfer paths of the intermolecular systems. It turned out that formation of double reduced species [Re2Cl2]2− along with an intermediate with a Re−Re bond ([ReRe]) can be taken as an indication of multi-electron storage capacity. Furthermore, under catalytic conditions a CO2-bridged intermediate was identified.
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 5,7, Seiten 644-653
    Language: English
    URL: Volltext  (kostenfrei)
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  • 5
    UID:
    edochu_18452_24193
    Format: 1 Online-Ressource (9 Seiten)
    Content: Complexes based on nitrogen and sulfur containing ligands involving 3d metal centers are known for the electrocatalytic reduction of CO2. However, photocatalytical activation has rarely been investigated. We herein present results on the light-driven CO2 reduction using either Ir(dFppy)3 [Ir, dFppy = 2-(4,6-difluorophenyl)pyridine] or [Cu(xant)(bcp)]+, (Cu, xant = xantphos, bcp = bathocuproine) as photosensitizer in combination with TEA (triethylamine) as sacrificial electron donor. The 3d metal catalysts have either dptacn (dipicolyl-triazacyclononane, LN3) or dpdatcn (dipicolyl-diazathiocyclononane, LN2S) as ligand framework and Fe3+, Co3+ or Ni2+ as central metal ion. It turned out that the choice of ligand, metal center and solvent composition influences the selectivity for product formation, which means that the gaseous reduction products can be solely CO or H2 or a mixture of both. The ratio between these two products can be controlled by the right choice of reaction conditions. With using Cu as photosensitizer, we could introduce an intermolecular system that is based solely on 3d metal compounds being able to reduce CO2.
    Content: Peer Reviewed
    In: Lausanne : Frontiers Media, 9
    Language: English
    URL: Volltext  (kostenfrei)
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  • 6
    UID:
    edochu_18452_24241
    Format: 1 Online-Ressource (6 Seiten)
    Content: The synthesis and characterization of a hetero-dinuclear compound is presented, in which a copper(I)trishistidine type coordination unit is positioned directlyabove a zinc porphyrin unit. The close distance betweenthe two coordination fragments is secured by a rigid xan-thene backbone, and a unique (intramolecular) copperporphyrin-p-bond was determined for the first time in themolecular structure. This structural motif was further ana-lyzed by temperature-dependent NMR studies: In solutionat room temperature the coordinative bond fluctuates,while it can be frozen at low temperatures. Preliminary re-activity studies revealed a reduced reactivity of the cop-per(I) moiety towards dioxygen. The results adumbratewhy nature is avoiding metal porphyrin-p-bonds by fixingreactive metal centers in a predetermined distance toeach other within multimetallic enzymatic reaction cen-ters.
    Content: Peer Reviewed
    In: Weinheim, 27,12, Seiten 3991-3996
    Language: English
    URL: Volltext  (kostenfrei)
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  • 7
    UID:
    edochu_18452_27190
    Format: 1 Online-Ressource (8 Seiten)
    Content: Atomic‐level manipulation of catalysts is important for both fundamental studies and practical applications. Here, the central metal atom in an atomically precise Ag25 nanocluster (NC) is replaced with a single Pd, Pt, and Au atom, respectively, and employed as a model system to study the structure–property–activity relationship at the atomic level. While the geometric structures are well‐preserved after doping, the electronic structures of Ag25 NCs are significantly altered. The combination of Ag25 and TiO2 enhances the charge separation at the interface, exhibiting a 10 times higher hydrogen production rate in photocatalytic hydrogen evolution reaction compared to bare TiO2. Further results show that heteroatoms doping has a negative impact on performance, particularly in the cases of Pd and Au doping. Ultraviolet photoelectron spectroscopy measurements and density functional theory calculations suggest that the lower activities are due to an energy mismatch between the levels of doped NCs and TiO2. These findings not only reveal the impact of heteroatoms doping on the electronic properties and photocatalytic activities of NCs, but can also guide the design of heterometallic NCs for photocatalytic applications.
    Content: Heteroatoms doping alters the electronic structures of Ag25 nanoclusters (NCs), while keeping the geometric structures unchanged. In this way, the geometrical effects and the electronic effects are clearly distinguished. The photocatalytic activities of as‐prepared NCs deposited onto TiO2 are investigated. The performances follow the order of Ag25 ≥ PtAg24 〉 PdAg24 ≥ AuAg24. image © 2023 WILEY‐VCH GmbH
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 7,6
    Language: English
    URL: Volltext  (kostenfrei)
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  • 8
    UID:
    edochu_18452_28230
    Format: 1 Online-Ressource (9 Seiten)
    ISSN: 1867-3880 , 1867-3899 , 1867-3880 , 1867-3899
    Content: In search of a better understanding of the structure‐property relationship of heteroleptic CuI photosensitizers, two structurally closely related complexes are investigated in detail. Although both compounds bear the same 4‐methoxyphenyl substituents at the phenanthroline moiety (i. e. at 5,6‐position in Cu1 and at 4,7‐position in Cu2), substitution at the 4,7‐position increases the attenuation coefficient in the 300–500 nm range by a factor of more than two. Even more drastic is the difference in emission lifetime (11 vs. 628 ns), which rises by a factor of almost 60 when positions 4 and 7 (i. e. Cu2) are chosen. A combination of solid‐state structural analysis, TDDFT calculations, transient absorption spectroscopy and quenching studies is then applied to elucidate the reasons for the superior photophysical properties of Cu2. Subsequently, a non‐emissive and long‐lived excited state (715 ns) has been revealed for Cu1. In a next step, both complexes were successfully used in the photocatalytic splitting of water and the reduction of CO2 to CO to test the influence of this behavior on the activity. Most importantly, Cu2 not only performs significantly better than Cu1, but also than the benchmark system and the noble‐metal‐based complex [Ir(dFppy)3].
    Content: Peer Reviewed
    In: Weinheim : Wiley-VCH, 15,16, 1867-3880
    In: 1867-3899
    Language: English
    URL: Volltext  (kostenfrei)
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