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Control of Excited-State Supramolecular Assembly Leading to Halide Photorelease
摘要： Ground- and excited-state control of halide supramolecular assembly was achieved through the preparation of a series of ester- and amide-functionalized ruthenium polypyridyl complexes in CH2Cl2. Hydrogen-bonding amide and alcohol groups on the receptor ligand were found to direct interactions with halide, while halide association with the ethyl ester groups was not observed. The various functional groups on the receptor ligands tuned the ground-state equilibrium constants over 2 orders of magnitude (1 × 10^5 to 1 × 10^7 M^?1), and the fractional contribution of each hydrogen-bond donor to the total equilibrium constant was determined. Pulsed-laser excitation of the complexes resulted in excited-state localization on the ester- or amide-functionalized ligands. In the case where the excited state was oriented toward an associated halide ion (the amide complexes), an 80 ± 10 meV Coulombic repulsion was induced that lowered the excited-state equilibrium constant (K*_eq) and resulted in halide photorelease. The rate constants for excited-state halide release (k*_21) were determined, and the values varied based on the functional groups present in the receptor ligand. Complexes with more hydrogen-bonding donors had smaller rate constants for halide photorelease. In a complex without a specific receptor ligand, the excited-state dipole was not oriented toward the associated halide, and the excited state was therefore found to have a larger equilibrium constant for halide association than the ground state.
关键词： halide supramolecular assembly,excited-state equilibrium,photorelease,hydrogen-bonding,ruthenium polypyridyl complexes
更新于2025-11-19 16:56:35
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Synthesis of Ruthenium Tris-Diimine Photosensitizers Substituted by Four Methylphosphonate Anchoring Groups for Dye-Sensitized Photoelectrochemical Cell Applications
摘要： The design and synthesis of ruthenium tris-diimine photosensitizers appropriately functionalized to be (i) anchored onto transparent conductive oxides (TCO) and (ii) covalently coupled with a water-splitting catalyst represents an important target for solar fuel production in dye-sensitized photoelectrochemical cells (DS-PECs). In this study, two different synthetic routes to prepare heteroleptic [Ru(4,4′-(CH2PO3Et2)2-bpy)2(N^N)](PF6)2 complexes are evaluated, the scope and limitations of the organometallic pathway involving half-sandwich η6-arene ruthenium complexes as synthetic intermediates being especially studied. The spectroscopic and electrochemical characterization of a series of novel structures varying by the nature of the third diimine N^N ligand is reported.
关键词： Photoelectrochemistry,Photosensitizers,Anchoring groups,Ruthenium
更新于2025-11-19 16:56:35
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Towards the Development of Photo‐Reactive Ruthenium(II) Complexes Targeting Telomeric G‐Quadruplex DNA
摘要： The design and characterization of new ruthenium(II) complexes aimed at targeting G-quadruplex DNA is reported. Importantly, these complexes are based on oxidizing 1,4,5,8-tetraazaphenanthrene (TAP) ancillary ligands known to favour photo-induced electron transfer (PET) with DNA. The photochemistry of complexes 1–4 has been studied by classical methods, which revealed two of them to be capable of photo-abstracting an electron from guanine. From studies of the interactions with DNA through luminescence, circular dichroism, bio-layer interferometry, and surface plasmon resonance experiments, we have demonstrated the selectivity of these complexes for telomeric G-quadruplex DNA over duplex DNA. Preliminary biological studies of these complexes have been performed: two of them showed remarkable photo-cytotoxicity towards telomerase-negative U2OS osteosarcoma cells, whereas very low mortality was observed in the dark at the same photo-drug concentration.
关键词： ruthenium complexes,photo-electron transfer,photocytotoxicity,G-quadruplexes,DNA structures
更新于2025-09-23 15:23:52
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Ru(II) and Ir(III) complexes containing ADA and DAD triple hydrogen bonding motifs: Potential tectons for the assembly of functional materials.
摘要： The synthesis and characterisation of series of [Ru(II)(bpy)2L] and [Ir(ppy)2L] complexes containing ligands L with the potential to engage in triple hydrogen bonding interactions is described. L1 and L2 comprise pyridyl triazole chelating units with pendant diaminotriazine units, capable of donor-acceptor-donor (DAD) hydrogen bonding, while L3 and L4 contain ADA hydrogen bonding units proximal to N^N and N^O cleating sites, respectively. X-ray crystallography shows the L1 and L2 containing Ru(II) complexes to assemble via R22(8) hydrogen bonding dimers, while [Ru(II)(bpy)2L4] assembles via extended hydrogen bonding motifs to form one dimensional chains. By contrast, the expected hydrogen bonding patterns are not observed for the Ru(II) and Ir(III) complexes of L3. Spectroscopic studies show that the absorption spectra of the complexes result from combinations of MLCT and LLCT transitions. The L1 and L2 complexes of Ir(III) and Ru(II) complexes are emissive in the solid state and it seems likely that hydrogen bonding to complementary species may facilitate tuning of their 3ILCT emission. Low frequency Raman spectra provide further evidence for ordered interactions in the solid state for the L4 complexes, consistent with the results from X-ray crystallography.
关键词： crystal engineering,ruthenium,Hydrogen bonding,iridium,X-ray crystallography
更新于2025-09-23 15:23:52
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Primary and secondary photochemical transformations of biologically active precursor - Nitro-Nitrosyl ruthenium complex
摘要： Photolysis of [Ru(II)NOPy2(NO2)2OH] (A) complex was studied under blue light (445 nm) irradiation. The primary photo-process results in the formation of nitric oxide (NO) and a paramagnetic RuIII compound, the latter was detected by EPR technique. The quantum yield (6–11%) of primary photolytic process was determined from the evolution of UV–vis spectra in different solvents (water, ethanol, dimethyl sulfoxide and acetonitrile). The secondary processes compete with the NO-release and lead to a variety of ruthenium forms including new nitrosyl forms. Namely, processes of hydroxyl protonation, pyridine photocleavage and nitro – nitrito bond isomerization take a place. HPLC combined with IR and 15N – NMR spectroscopies clarified the composition of the new forms and their transformations during the photolysis. Supporting EPR and IR DFT calculations confirmed the structure of photoproducts. The oxidation of NO in the secondary processes significantly influences on the total amount of nitric oxide release and reaction routes.
关键词： Nitrosyl ruthenium,Photocleavage,Photochemistry,Nitric oxide release
更新于2025-09-23 15:23:52
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Photoinduced electron transfer kinetics of linked Ru-Co photocatalyst dyads
摘要： Two new supramolecular photocatalyst dyads based on the [Ru(2,2′-bipyridine)3]2+ photosensitizer linked to a macrocyclic Co(II)tetra(pyridyl) catalyst for proton reduction are reported. The dyads differ primarily in the bridging ligand which links the molecular modules; the first being a short and flexible linker, and the second a longer and electronically conjugated linker. Ultrafast transient optical spectroscopy was used to monitor the photoinduced kinetics of the dyads following visible excitation of the photosensitizer module. Direct comparison of transient spectra and kinetics indicates that there are indeed substantial differences between the ultrafast transient optical spectroscopy of the dyads, but there is no indication of oxidative quenching of the photosensitizer module by the catalyst module. These initial design and characterization studies of the linked Ru(II)—Co(II) dyads provide an important foundation for advanced designs of systems for efficient solar energy conversion by molecular architectures.
关键词： Ruthenium,Cobalt,Photoinduced electron transfer,Modular assembly,Photocatalyst dyads
更新于2025-09-23 15:22:29
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Second Derivative Spectrophotometric Determination of Iron(II) and Ruthenium(III) Using 1, 10-phenanthroline
摘要： A simple and sensitive derivative spectrophotometric method has been developed for the determination of Fe(II) and Ru(III) using the baseline to peak measurement techniques. In the present method 1,10-phenanthroline (o-phen) used as a complexing agent. Fe(II) and Ru(III) forms a complex with o-phen at pH 5 and 4, respectively. Based on baseline-to-peak measurement techniques deep red Fe(II)-o-phen complex shows the maximum peak at 535 nm, while the yellow product of Ru(II) - o-phen complex at 466 nm. Beer’s law obeyed in the range of 0.1 - 2.0 μg mL-1 for Fe(II) and 5.0 - 20.0 μg mL-1 for Ru(III) which is supported by correlation coefficient 0.99853 and 0.99914, respectively. The present method has been applied successfully for the determination of Fe (II) in pharmaceutical formulations and Ru(III) in some synthetic mixtures.
关键词： Iron(II),Second Derivative Spectra,Ruthenium(III),1,10-Phenanthroline
更新于2025-09-23 15:22:29
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Nanoporous water oxidation electrodes with a low loading of laser-deposited Ru/C exhibit enhanced corrosion stability
摘要： For the oxidation of water to dioxygen, oxide-covered ruthenium metal is known as the most efficient catalyst, however, with limited stability. Herein, we present a strategy for incorporating a Ru/C composite onto a novel nanoporous electrode surface with low noble metal loading and improved stability. The Ru/C is coated on the pore walls of anodic alumina templates in a one-step laser-induced deposition method from Ru3(CO)12 solutions. Scanning electron microscopy proves the presence of a continuous Ru/C layer along the inner pore walls. The amorphous material consists of metallic Ru incorporated in a carbonaceous C matrix as shown by X-ray diffraction combined with Raman and X-ray photoelectron spectroscopies. These porous electrodes reveal enhanced stability during water oxidation as compared to planar samples at pH 4. Finally, their electrocatalytic performance depends on the geometric parameters and is optimized with 13 μm pore length, which yields 2.6 mA cm?2, or 49 A g?1, at η = 0.20 V.
关键词： ruthenium catalyst,nanostructures,water splitting,electrochemistry,noble metals
更新于2025-09-23 15:22:29
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Resonance Raman Spectro-Electrochemistry to Illuminate Photo-Induced Molecular Reaction Pathways
摘要： Electron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)2]2+ (tbtpy = tri-tert-butyl-2,2′:6′,2′′-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy?)]+, while the second reduction generates [(tbtpy?)Ru(tbtpy?)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.
关键词： ruthenium bis-terpyridine complex,resonance Raman,in situ spectro-electrochemistry,TDDFT,UV-vis
更新于2025-09-23 15:22:29
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A Phosphonate Substituted Ruthenium(II) Bipyridyl Derivative as Photoelectrochemical Probe for Sensitive and Selective Detection of Mercury(II) in Biofluids
摘要： A ruthenium(II) bipyridyl derivative photoelectrochemical probe, Ru-1, is synthesized and coupled with TiO2 nanoparticles (Ru-1/TiO2) for the specific recognition and highly sensitive PEC detection of Hg2+ in a series of biofluids. The probe is designed with a chromophore, a thiocyanate recognition unit, a π-conjugated photoelectron transfer pathway, and a phosphonate anchor. TiO2 nanoparticles with strong affinity to phosphonate and suitable conduction band energy are used as intermediate layers to increase the Ru-1 adsorption amount and amplify the photocurrent response. Under irradiation, the Ru-1/TiO2/FTO with strong visible light harvesting capacity, aqueous stability and efficient photoelectron transfer, shows a high and stable photocurrent response. In the presence of Hg2+, however, the specific Hg2+ and NCS coordination changes the photophysical properties of Ru-1, imposing the probe with a wider band gap, a weaker absorbance, and a poorer photoelectron and hole separation efficiency, thus resulting in a significant photocurrent decrease. Based on the Hg2+ induced photocurrent change, the Ru-1/TiO2/FTO shows good selectivity and high sensitivity towards the PEC detection of Hg2+, with wide linear ranges from 10-12 to 10-7 and 10-7 to 10-3 g/mL, and a low limit of detection of 0.63 pg/mL. The PEC probe is recyclable and accurate for selective detection of Hg2+ in urine, serum and cell extracts. The whole analysis can be completed within 15 minutes. These good analytical performances indicate the PEC method might have great potential for the onsite detection of small molecules in bio-systems.
关键词： Hg2+ detection,photoelectrochemical probe,TiO2 nanoparticles,ruthenium(II) bipyridyl derivative,biofluids
更新于2025-09-23 15:21:21