Meso Positions Of Porphyrin Ring Research Articles

Exploring novel porphyrin photocatalyst for the conversion of frying oil to biodiesel: A step for globular economy

The current protocol addresses the outcomes on the photo-transesterification of frying sunflower oil (FSO) catalysed by porphyrin comprising sulphonic acid functionalized pyridinium ionic liquid (PcSAFPyIL). A novel photocatalyst was synthesized and confirmed by 1H and 13C NMR, Powder XRD, FT-IR, XPS, and fluorescence emission spectrophotometry. The energy band gap (1.85 eV) was determined by cyclic voltammetry, Hammett acidity (H0 = 0.217) by UV–visible spectrophotometer and metal free nature by powder XRD and XPS. The photocatalytic activity of PcSAFPyIL in the visible region was confirmed by reflecting intense Soret band (421 nm) and four Q bands (515, 554, 591 and 647 nm). This may be due to inherent aromatic characters and conjugation with chromophore groups at meso-position of porphyrin ring. The obtained photocatalyst was scrutinized for the photo-transesterification of FSO in a lab-made photoreactor. The ideal reaction parameters were found to be 20 mg photocatalyst quantity with 1:12 (FSO: ROH) under exposure of 2 x 5 W LED at room temperature, to afford 90 % biodiesel in 24 h. Moreover, the formation of biodiesel was confirmed by (1H, 13C) NMR, FT-IR, DEPT-135, and GC–MS. Further, stability, heterogeneous nature and the gram scale reaction PcSAFPyIL was also efficiently accomplished using the optimized photocatalytic conditions. Additionally, the physicochemical properties of the biodiesel fuel B15 (15 % blended with marketed diesel) and pure marketed diesel are consistent. Moreover, the engine performance and emission characteristics of B15 such as brake-specific fuel consumption (BSFC), break thermal efficiency (BTE) found comparable and better than commercial diesel.

Ambipolar chemical sensors based on the self-assembled film of an amphiphilic (phthalocyaninato) (porphyrinato) europium complex

An amphiphilic mixed (phthalocyaninato) (porphyrinato) europium triple-decker complex Eu2(Pc)2(TPyP) has been synthesized and characterized. Introducing electron-withdrawing pyridyl substituents onto the meso-position of porphyrin ring in the triple-decker to ensure the sufficient hydrophilicity and suitable HOMO and LUMO energy levels and thus successfully realize amphiphilic ambipolar organic semiconductor. Importantly, high sensitive, reproducible p-type and n-type responses towards NH3 and NO2 respectively, based on the self-assembled film of the Eu2(Pc)2(TPyP) fabricated by a simple solution-based Quasi–Langmuir–Shäfer (QLS) method, have been first revealed. The good conductivity and crystallinity for the QLS film of Eu2(Pc)2(TPyP) render it excellent sensing property for both electron-donating gas NH3 in 5–30ppm range and electron-accepting gas NO2 in 400–900ppb range due to the optimized molecular packing in the uniform-sized nanoparticles depending on the effective intermolecular interaction between the triple-decker molecules, among the best results of phthalocyanine-based chemical sensors for room-temperature detection of NH3 and NO2, respectively. Furthermore, the responses of the QLS film are all linearly correlated to both NH3 and NO2 with excellent sensitivity of 0.04%ppm−1 and 31.9%ppm−1, respectively, indicating the great potential of semiconducting tetrapyrrole rare earth triple-decker compounds in the field of chemical sensors.

Bis(9,9-dihexyl-9H-fluorene-7-yl)amine (BDFA) as a new donor for porphyrin-sensitized solar cells

Two novel zinc porphyrin dyes (coded as ZZX-N1 and ZZX-N2) with a bis(9,9-dihexyl-9H-fluorene-7-yl)amine (BDFA) as an electron donor and a benzoic acid as an acceptor were designed and synthesized in a donor–π–acceptor configuration for dye-sensitized solar cells. ZZX-N1 with two small 3,5-di-tert-butylphenyl groups on the meso positions of porphyrin ring and ZZX-N2 with two large 2,6-dioctoxylphenyl groups displayed similar absorption spectra with an onset ∼700nm, and ∼28nm red-shift was observed when compared to YD2 because of stronger electron donating ability of bis(9,9-dihexyl-9H-fluorene-7-yl)amine (BDFA) than bis(4-hexylphenyl)amine in YD2. ZZX-N1-sensitized cells exhibited higher energy conversion efficiency than ZZX-N2-sensitized device (5.78% vs. 3.61%). The electrochemical impedance study showed higher electron recombination resistance in the interface of TiO2/dye/electrolyte in ZZX-N1-sensitized cell than in ZZX-N2-sensitized cell. The transient decay measurements showed the longer electron lifetime of former than the later. The density functional theory calculations suggested that this could be due to small voids among ZZX-N1 dye molecules on the TiO2 surface, preventing the charge recombination with the redox couple. The results demonstrated the potential of BDFA as an excellent functional group for high efficiency solar cells.

Photocatalytic Hydrogen Evolution Based on Efficient Energy and Electron Transfers in Donor–Bridge–Acceptor Multibranched‐Porphyrin‐Functionalized Platinum Nanocomposites

Two donor-bridge-acceptor conjugates (5,10,15,20-tetrakis[4-(N,N-diphenylaminobenzoate)phenyl] porphyrin (TPPZ) and 5,10,15,20-tetrakis[4-(N,N-diphenylaminostyryl)phenyl] porphyrin (TPPX)) were covalently linked to triphenylamine (TPA) at the meso-position of porphyrin ring. The triphenylamine entities were expected to act as energy donors and the porphyrins to act as an energy acceptor. In this paper, we report on the synthesis of these multibranched-porphyrin-functionalized Pt nanocomposites. The conjugates used here not only served as a stabilizer to prevent agglomeration of Pt nanoparticles, but also as a light-harvesting photosensitizer. The occurrence of photoinduced electron-transfer processes was confirmed by time-resolved fluorescence and photoelectrochemical spectral measurements. The different efficiencies for energy and electron transfer in the two multibranched porphyrins and the functionalized Pt nanocomposites were attributed to diverse covalent linkages. Moreover, in the reduction of water to produce H(2), the photocatalytic activity of the Pt nanocomposite functionalized by TPPX, in which the triphenylamine and porphyrin moieties are bonded through an ethylene bridge, was much higher than that of the platinum nanocomposite functionalized by TPPZ, in which the two moieties are bonded through an ester. This investigation demonstrates the fundamental advantages of constructing donor-bridge-acceptor conjugates as highly efficient photosensitizers based on efficient energy and electron transfer.

Switching Porphyrin Fluorescence on and off through Redox

Three new zinc porphyrins ( [5,15-bisferrocenyl-porphyrinato]-zinc(II)(4), [5,15-bisferrocenyl-10,20-bis(4-nitro-phenyl)-porphyrinato]-zinc(II)(5), and [5,10,15,20- tetraferrocenyl-porphyrinato]-zinc(II) (6)) with ferrocenyl units at the meso-positions of porphyrin ring have been prepared and characterized. Towards further understanding the fluorescence quenching and recovery of ferrocene-porphyrins, the fluorescence spectra of these compounds was detailedly studied.