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Главная страница Новости науки Journal of Photochemistry and Photobiology A: Chemistry
Новости науки
ScienceDirect Publication: Journal of Photochemistry and Photobiology A: Chemistry
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  • Porphyrin-based hybrid silica-titania as a visible-light photocatalyst

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Julien G. Mahy, Carlos A. Paez, Carole Carcel, Catherine Bied, Andrew S. Tatton, Christian Damblon, Benoît Heinrichs, Michel Wong Chi Man, Stéphanie D. Lambert

    Abstract

    A silylated porphyrin derivative is co-hydrolyzed with Ti(OiPr)4 to produce a hybrid TiO2 photocatalyst, and three different ratios between porphyrin and TiO2 are made. In this way, the porphyrin fragments are held in the resulting matrix through strong Si-O-Ti covalent bonds to limit porphyrin leaching. Thanks to its photoactive character the porphyrin fragment can act as an actuator for the TiO2 to degrade organic pollutants using light from ultra-violet to the visible range. The photocatalysts are synthesized using an easy aqueous route allowing “green conditions” for synthesis. For comparative purposes, the corresponding pure TiO2 and a grafted catalyst are also synthesized and studied. For all samples, a mixture of anatase/brookite TiO2 is obtained, resulting in crystalline materials with low temperature synthesis. The three porphyrin-doped samples prepared in water prove to be efficient photocatalysts for the degradation of p-nitrophenol (PNP) under visible light, and an improvement in photoactivity is observed when the amount of porphyrin increases. The photocatalyst activity is very stable over time as the PNP degradation remains nearly constant after 264 h of testing, showing no leaching of porphyrin. In recycling tests, the grafted sample presents bond breaking between POR-Si and TiO2 and a decrease in photoactivity towards pure TiO2 sample activity. A comparison with the commercial Evonik P25 catalyst shows that the porphyrin-doped TiO2 is nearly 6 times more photoactive under visible light for PNP degradation.

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  • A large Stokes shift, sequential, colorimetric fluorescent probe for sensing Cu2+/S2- and its applications

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Ji-Zhen Li, Tao-Hua Leng, Zhi-Qiang Wang, Li Zhou, Xue-Qing Gong, Yong-Jia Shen, Cheng-Yun Wang

    Abstract

    Copper ions (Cu2+) and sulfide (S2−) are important markers in many physiologies and pathological processes. In this work, a new near-infrared fluorescent probe 1 for colorimetric and sequential detection of Cu2+/S2− was designed and developed. The probe showed a rapid (less than 1 min), highly selective and sensitive response toward copper ions. Notably, the probe could also be applied to detect S2− through reversible formation-separation of complex 1-Cu2+ and CuS with a large Stokes shift of 234 nm. The detection limit for Cu2+ and S2− was found to be 1.8 × 10-8 M and 1.5 × 10-8 M, respectively. Furthermore, the binding stoichiometry between 1 and Cu2+ was found to be 1:1, the binding mode was also demonstrated using density functional theory (DFT) calculations and contrastive compound research. In addition, the probe was successfully applied in real water samples assay for the detection of Cu2+, and the strip papers experiments also showed that probe 1 can be used to detect Cu2+ and S2−.

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    A novel near-infrared fluorescent probe for colorimetric and sequential detection of Cu2+/S2− was designed and developed.

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  • Modelled kinetics of the rate of hydrogen evolution as a function of metal catalyst loading in the photocatalysed reforming of methanol by Pt (or Pd)/TiO2

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Andrew Mills, Michael Bingham, Christopher O’Rourke, Michael Bowker

    Abstract

    The rate of hydrogen evolution, r(H2), due to the photocatalysed reforming of methanol, MeOH, is studied as a function of Pt loading on P25 TiO2 both in the aqueous (at room temperature) and gas phase (at 100 °C). A similar study, using Pd on P25, has been reported earlier [M. Bowker et al. J. Catalysis, 2003, 217, 427–433] and a perimeter-based Metal-Support Interface (MSI) kinetic model used to interpret the results. Here a new kinetic model is introduced which appears to provide a better fit to all the r(H2) vs wt% metal data sets, in which the rate of reaction is proportional to an extended area around each metal island, rather than its perimeter. A simple theoretical rationale is provided for this expanding photocatalytic area and overlap (EPAO) kinetic model in which each metal island forms an electric field with the surrounding TiO2 so as to act as a sink for electrons photogenerated in the surrounding TiO2 film, thereby allowing it to effect the reduction of water, leaving the remaining photogenerated holes to oxidise the methanol adsorbed on the TiO2. Some support for this very simple kinetic and theoretical model is provided by the results of a brief study of the oxidation of soot deposited on and around a Pt 'dot' on a sol-gel TiO2 film, in that, upon irradiation of this system a zone of activity is visibly revealed by the gradual disappearance of the soot around the Pt ‘dot’, the radius of which appears to be proportional to the radius of the metal ‘dot’.

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  • Investigation of ultrafast energy transfer mechanism in BODIPY–Porphyrin dyad system

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Fatih Mehmet Dumanoğulları, Yusuf Tutel, Betül Küçüköz, Gökhan Sevinç, Ahmet Karatay, Halil Yılmaz, Mustafa Hayvali, Ayhan Elmali

    Abstract

    Novel β-fused BODIPY-Porphyrin compounds that contain free base porphyrin (TPP2BDP) and its Ni(II) complex (NiTPP2BDP) were synthesized to investigate intramolecular energy transfer mechanisms of β-fused BODIPY-porphyrin dyads and effect of the unfilled d shell metal ion on energy transfer mechanism. Fluorescence spectra of compounds exhibited that BODIPY emission was diminished upon excitation of the BODIPY unit because of the energy transfer from BODIPY to porphyrin unit. Femtosecond pump-probe spectroscopy measurements revealed that energy transfer of investigated compounds are faster than previous studies in literature. Rapid energy transfer (about 500 fs) from BODIPY to porphyrin was observed for both compounds when BODIPY unit is excited due to direct linkage of BODIPY to porphyrin unit. Intersystem crossing mechanism was also observed for the compound that contains free base porphyrin (TPP2BDP), whereas d-d transition was observed for the compound that contains metalloporphyrin (NiTPP2BDP) due to unfilled d orbital of Ni(II) ion.

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  • Novel insights into the properties of AgBiO3 photocatalyst and its application in immobilized state for 4-nitrophenol degradation and bacteria inactivation

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Bhanupriya Boruah, Rimzhim Gupta, Jayant M. Modak, Giridhar Madras

    Abstract

    This study focuses on the synthesis of novel AgBiO3 nanoparticles by the hydrothermal route and investigating its properties responsible for waste water treatment. The temperature and time of hydrothermal reaction was optimized to 150 °C and 24 h to obtain highly active crystalline nanoparticles, as determined by XRD. The oxidation state of each element in the material was determined from XPS analysis. The morphology and size of the nanoparticles was obtained from SEM and TEM analysis. The optical and electrochemical properties of the material were studied by UPS and Mott Schottky plot. AgBiO3 was found to have a low band gap that facilitates the absorption of higher wavelength range as confirmed by Tauc plots and UV–vis DRS analysis. The excellent photocatalytic activity of the immobilized material towards the degradation of 4-nitrophenol and inactivation of E. coli was confirmed from kinetic studies and stability tests. A maximum degradation of 90% was achieved for 4-NP and a 5-log reduction was observed for viable E. coli cells in 5 h and 1 h respectively. Scavenger studies were performed to identify that superoxide radicals were responsible for the photocatalytic activity of the material. To eliminate the cost of separation and ease the reusability of the material, the nanoparticles were immobilized on cellulose acetate. Leaching of Ag and Bi ions from immobilized as well as free AgBiO3 nanoparticles into water was obtained via ICP-MS analysis. The results indicated that the leaching of Ag and Bi was controlled to a considerable extent due to immobilization on cellulose acetate matrix.

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  • Smart sensing of cyanide and iron(III) by anthracene based probe through relay recognition approach

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Ganesan Punithakumari, Sivan Velmathi

    Abstract

    A new anthracene coupled dicyanovinyl based receptor (1) was synthesized and characterized using spectroscopic techniques like FT-IR, 1H-NMR and 13C-NMR and HRMS. The propensity of the synthesized receptor to effectively sense Fe3+ and CN ions was studied using UV–vis, fluorescence spectroscopy and density functional theory techniques. Upon interaction with various anions, receptor (1) showed rapid and selective sensing of cyanide ion via colorimetric as well as fluorescence turn-on response in acetonitrile medium. In addition, sequential recognition of Fe3+ ion among various cations also observed by receptor(1)–CN. Limit of detection for cyanide was found to be 8.11 × 10−6M. The fluorescence turn on response of receptor(1) with cyanide ion was successfully applied for the bio-imaging studies of cell line RAW264.7. The relay recognition of Fe3+ was applied for the construction of IMP and INH logic gates.

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  • Loading of alkaline hydroxide nanoparticles on the surface of Fe2O3 for the promotion of photocatalytic activity

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): M. Khajeh Aminian, S.K. Fatah

    Abstract

    This study focused on surface modification of iron oxide (Fe2O3) by loading alkaline oxide nanoparticles to investigate the effect of surface interactions on photocatalytic activity of this material. Fe2O3 was loaded by NaOH, KOH, and CsOH, with 0.05, 0.1, 0.4, and 1 wt% by impregnation method. The photocatalytic evaluation was carried out in a gas phase for degradation of Iso-Propyl alcohol (IPA) to acetone. The prepared samples were characterized by X-ray diffraction, UV–vis diffuse reflectance spectroscopy, and scanning electron microscopy SEM. The photocatalytic evaluation resulted the photoactivity of Fe2O3 increases to an optimum extent by loading of alkaline hydroxides on the surface. The enhancement of photoactivity of Fe2O3 after loading can be attributed to the surface chemical reactions and transfer of photogenerated electrons from the conduction band of Fe2O3 to alkaline nanoparticles. Also, multi-electron oxygen reduction is another way supposed to facilitate the photocatalytic reaction.



  • Synthesis of tetra-substituted phthalocyanines bearing 2-(ethyl(m-tolyl)amino)ethanol: Computational and photophysicochemical studies

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Armağan Günsel, Ahmet T. Bilgiçli, Burak Tüzün, Hasan Pişkin, Göknur Yaşa Atmaca, Ali Erdoğmuş, M. Nilüfer Yarasir

    Abstract

    This work presents the synthesis of 4-(2-(ethyl(m-tolyl) amino) ethoxy) phthalonitrile (1) as ligand and its peripherally tetrasubstituted metal-free (2) and metallophthalocyanines (3–5) derivatives. Synthesized compounds were characterized by standart spectroscopy methods. The molecular structure of the ligand (1) was confirmed by single-crystal X-ray diffraction experiment. The crystallographic information file (cif) was uploaded to the data center with CCDC number 1,853,485. The optimized structure of the ligand (1) and the phthalocyanines (2–5) were obtained by using different metods such as B3lyp, HF and m062x method 3–21 g, 6–31 g, sdd basis set. In b3lyp/6–31++g(d,p) basis set, 1H and 13C NMR chemical shifts, IR spectrum and UV–vis spectrum were measured in gas, chloroform and dimethylsulfoxide phase by means of the obtained optimized structure. Besides, the photophysical and photochemical properties of newly synthesized phthalocyanines (2–5) were investigated in DMSO, comparatively. Singlet oxygen quantum yields of the phthalocyanines (2–5) are ranging from 0.28 to 0.70.

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  • Photoexcitation of self-n-doped fullerene ammonium halides: The role of halide ion and a possible synergistic dual-redox cycle mechanism within their aggregate

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Jinhao Zhao, Zhouchen Lin, Shaowei Fang, Xinrui Xie, Huanhuan Wang, Zhenfeng Pang, Jing Zhang, Xueqian Kong, Ming Lei

    Abstract

    Halide ion’s doping of fullerene core is crucial on the properties of highly conductive self-n-doped fullerene ammonium halides, which are a kind of promising electron transport material for photovoltaics. Herein, to understand their photoexcited electron transfer (ET) property, antimicrobial photodynamic inactivation (aPDI) activities of these materials were tested based on their unique electronic structure and bacterial electrokinesis. We observed that illuminated self-n-doped fullerene ammonium iodides (PCBANI and PCBDANI) could exhibit significant improvement of activity against two important plant pathogenic fungi, Sclerotinia sclerotiorum and Fusarium graminearum as electron donor, compared with that in dark. Through comprehensive studies, such as aPDI activity, hyphal cell morphology, ultrafast transient absorption spectroscopy, solid state nuclear magnetic resonance (ssNMR), level of total cellular reactive oxygen species (ROS), we verified that not ROS but I radical’s oxidative stress is responsible for the improved aPDI activity. Moreover, the photobiological activity of self-n-doped fullerene ammonium halides is dependent on the reducing capacity of halide anions. The ET rate from anion to an excited fullerene core decreased successively from I– to Br– and then Cl–, illustrating that the generation rate of I radical species was the fastest and consistent with the high activity of fullerene ammonium iodides. Remarkably, adding potassium iodide did not enhance PCBANI’s antifungal activity. These results disclose that the unique electronic structure of iodide and fullerene core in self-n-doped PCBANI aggregates are critical for its aPDI activity. Consequently, we propose a possible dual-redox cycles mechanism involving photoexcited fullerene radical anions and I radical species in self-n-doped fullerene ammonium iodide aggregate to exhibit sustainable aPDI activity. This work reveals that halide ions play an equally important role as fullerene core in photoexcited ET property of self-n-doped fullerene ammonium halides.

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  • Photoinduced electron transfer kinetics of linked Ru-Co photocatalyst dyads

    Publication date: 15 March 2019

    Source: Journal of Photochemistry and Photobiology A: Chemistry, Volume 373

    Author(s): Lars Kohler, Karen L. Mulfort

    Abstract

    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.

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