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The protocol presents conversion of levulinic acid (LA) to γ-valerolactone (GVL), using polymer-supported carboxyl functionalized Zn–porphyrin (PSCFZnPP) as a photocatalyst under visible light at ambient conditions. The formation of GVL was achieved using 2-propanol as a hydrogen source over PSCFZnPP photocatalyst in a homemade photoreactor under 12-W LED light. The formation of GVL was achieved with 72% yield by transfer hydrogenation in 16 h at room temperature and confirmed by 1H-NMR and 13C-NMR at various intervals. The transformation of LA was confirmed by the presence of CH multiplet in 1H-NMR and deshielding of CH3 protons in GVL around 1 ppm, after 16 h with disappearance of OH of the substrate. It was further evidenced by the disappearance of ketonic carbonyl C peak height and reduction of LA in 13C-NMR. Finally, PSCFZnPP exhibited reusability for five times using optimized conditions without significant changes in the yield and structure. [ABSTRACT FROM AUTHOR]

A polymer-supported Brønsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety (PSBAZnPP), has been synthesized and characterized by Fourier transform nuclear magnetic resonance (FT-NMR) and Fourier transform infrared spectroscopy (FTIR). The thermal stability was determined by thermogravimetric analysis (TGA), and surface morphology and elemental composition were investigated by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDAX). The heterogeneous PSBAZnPP showed high efficacy as a photocatalyst for degradation of azo dyes, such as methyl red (MR), methyl orange (MO) and Congo red (CR), in the presence of visible-light irradiation at ambient condition using atmospheric air/H2O2. The concentration of the dyes was measured by UV–visible spectroscopy, and the degradation of the dyes was confirmed by GC–MS analysis. Further decolorization and degradation of MO were confirmed by using ultra-high-pressure liquid chromatography (UPLC). The optimum degradation was achieved by adding 10 mg catalyst for all azo dyes for 60 min in the presence of air. The effect of scavengers was studied to indicate the most active species generated during photocatalysis. PSBAZnPP furnished a good response toward the photodegradation of MR, MO and CR under optimized conditions. Finally, the mechanism of photocatalytic degradation process was suggested. Relevant active species produced in the PSBAZnPP/H2O2 or PSBAZnPP/air system under visible light were recognized by using different types of scavengers, viz. EDTA, p-benzoquinone (PBQ), terephthalic acid (TPA), sodium azide and sodium nitrate, for determination of formation of holes, O 2 · , OH · , 1 O 2 and an aqueous electron (e−), respectively. The comparative acidity of the synthesized PSBAZnPP catalyst was measured using UV–Vis and then equated to relations of the Hammett value (H0). The efficiency of catalyst correlates with a considerable proton level required for degradation of organic dyes. [ABSTRACT FROM AUTHOR]

Detection of volatile organic compounds (VOCs) by electronic optical nose based on sensing thin films is becoming more interesting in modern industry and daily life. The thin films of zinc-porphyrin and zinc-phthalocyanine fabricated by Langmuir-Blodgett (LB) technique onto quartz substrates have been used as sensing elements for electronic optical nose application. Absorption spectra range of the both organic elements in a chloroform solution and the LB solid state thin films were acquired by using a UV-1700 spectrometer. As an electronic gas sensing test, the optical absorbance performance after the exposure of LB films to different VOCs, and dry air was investigated. The results indicated that the ZnTPP and ZnPc LB films showed different gas sensitivity due to different molecule structure. Besides, a 2 × 1 colorimetric array is fabricated by immobilizing sensing thin film on a silica substrate, and the vapor molecules of pyridine and methanol can be easily detected. [ABSTRACT FROM AUTHOR]

A novel porphyrin dye ZnP-triazine-(gly) 2 , consisting of a zinc-metallated porphyrin unit covalently linked through its peripheral aryl-amino group with a 1,3,5-triazine group which is functionalized by two carboxylic acid groups of glycine moieties, has been synthesized. Photophysical and electrochemical measurements, as well as theoretical DFT calculations, suggest that the compound exhibits appropriate light absorption characteristics and frontier molecular orbital levels for use as sensitizer in dye-sensitized solar cells (DSSCs). The ZnP-triazine-(gly) 2 based solar cell was found to exhibit a power conversion efficiency (PCE) value of 4.72%. A significant improvement of the overall photovoltaic efficiency of the solar cell was achieved up to 7.34% upon co-sensitization with a tertiary aryl-amine D with two ethynyl-pyridine substituents and cyano-acetic acid anchoring group, which exhibits complementary light absorption characteristics with the porphyrin dye. The higher PCE value of the co-sensitized solar cell is attributed to its enhanced short circuit current ( J sc ), which is due to improved light harvesting efficiency, reduced porphyrin aggregation, and faster electron injection and charge collection, as well as its enhanced open circuit voltage ( V oc ), which is due to increased electron density in the TiO 2 conduction band of the photoanode. These results are in accordance with electrochemical impedance spectra (EIS) of the solar cells, which revealed higher charge recombination resistance ( R rec ), longer electron lifetime ( τ e ), and shorter electron transport time ( τ d ) for the co-sensitized solar cell. [ABSTRACT FROM AUTHOR]

Abstract: In-situ UV–visible and EPR Spectroelectrochemistry of a free base porphyrin, 5,10,15,20-tetrakis[3,4-(1,4-dioxan)phenyl]porphyrin, and its zinc derivative, 5,10,15,20-tetrakis[3,4-(1,4-dioxan)phenyl]porphyrinatozinc(II) were performed. On one-electron oxidation of the free base porphyrin in dichloromethane/0.1 M BuN4PF6 using an optically transparent thin layer cell, the initial Soret band retains its intensity and an equally intense new band appears at 453 nm. The initial Q bands disappear, and new bands appear at 516, 555 and 694 nm. At 295 K, it exhibits an isotropic EPR signal with a peak to peak separation of about 6 G and centered at g = 2.004. On one-electron oxidation of the zinc-porphyrin in similar conditions, the Soret band loses its intensity, and a new band appears at 466 nm. The in-situ generated one-electron oxidized species exhibits an isotropic EPR signal at 295 K which is centered at g = 2.0035. The formations of aggregates/self-assemblies of zinc-porphyrin were monitored by UV–vis spectroscopy, fluorescence imaging by confocal microscope, TEM, SEM and DLS measurements. A tentative mechanism has been also proposed for the generation of different aggregates, with varying size and shape, in water–DMF binary mixtures. [Copyright &y& Elsevier]

The fabrication of a zinc-porphyrin(ZnP)-viologen(V) linked compound with six methylene group (ZnP(6)V)–gold nanoparticle (AuP) composite films on indium-tin-oxide (ITO) electrodes were performed by the electrostatic layer-by-layer adsorption technique. The photocurrents in ZnP(6)V–AuP composite films were larger than those in ZnP(6)V films, and were much larger than those in ZnP films as a reference. The large enhancement of the photocurrents in ZnP(6)V–AuP composite films are most likely attributable to the combination of localized surface plasmon resonance due to AuP and photoinduced intramolecular electron-transfer due to the V moiety in the linked compound. [ABSTRACT FROM AUTHOR]

The fabrication of a zinc-porphyrin(ZnP)–viologen(V) linked compound with six methylene group (ZnP(6)V)–silver nanoparticle (AgP) composite films on indium-tin-oxide (ITO) electrodes were carried out by the electrostatic layer-by-layer adsorption technique. The photocurrents in ZnP(6)V–AgP composite films were larger than those in ZnP(6)V films, and were much larger than those in ZnP films as a reference. The large enhancement of the photocurrents in ZnP(6)V–AgP composite films are most likely ascribed to the combination of localized surface plasmon resonance due to AgP and photoinduced intramolecular electron-transfer due to the linking of V moiety. [ABSTRACT FROM AUTHOR]

We have designed and synthesis a new compound of zinc-porphyrin bearing four pyrene groups (ZnP-t-P(py)4) and prepared a new hybrid materials of ZnP-t-P(py)4 with graphene oxide (GO) via non-covalent interactions. The ZnP-t-P(py)4, along with four pendant pyrene entities ZnP-t-P(py)4, stacking on the (GO) surface due to π- π interactions, has been revealed by AFM measurements. FTIR, UV-vis absorption confirm the non-covalent functionalization of the GO. Raman spectral measurements revealed the electronic structure of the GO to be intact upon hybrid formation. In this donor-acceptor nanohybrid, the fluorescence of photoexcited ZnP-t-P(py)4 is effectively quenched by a possible electron-transfer process. The fluorescence and photoelectrical response measurements also showed that this hybrid may act as an efficient photoelectric conversion material for optoelectronic applications. [ABSTRACT FROM AUTHOR]

Abstract: In this work an attempt to obtain a more compact system for gas sensing, designed directly on a transducer, is presented. In the nature, a mucous layer covers the olfactory receptor cells of mammalians and selectively tunes the chemical interactions between odorous molecules and sensing systems. Such natural double layer design was reproduced in this study using a double coating comprised of a proper hydrophobic Teflon-like overlayer tuning the humidity interference between the odorous molecules and the sensitive matrix below consisting of a Zn-porphyrin film. This double coating was applied on both surfaces of the quartz crystal microbalance used for transducing into electrical signals the chemical signals deriving from the adsorption of volatile molecules. [Copyright &y& Elsevier]