Exploring the Effects of Axial Pseudohalide Ligands on the Photophysical and Cyclic Voltammetry Properties and Molecular Structures of MgIITetraphenyl/porphyrin Complexes

Synthesis, Characterization, X-ray Molecular Structure, Antioxidant, Antifungal, and Allelopathic Activity of a New Isonicotinate-Derived meso-Tetraarylporphyrin

The present article describes the synthesis of an isonicotinate-derived meso-arylporphyrin, that has been fully characterized by spectroscopic methods (including fluorescence spectroscopy), as well as elemental analysis and HR-MS. The structure of an n-hexane monosolvate has been determined by single-crystal X-ray diffraction analysis. The radical scavenging activity of this new porphyrin against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical has been measured. Its antifungal activity against three yeast strains (C. albicans ATCC 90028, C. glabrata ATCC 64677, and C. tropicalis ATCC 64677) has been tested using the disk diffusion and microdilution methods. Whereas the measured antioxidant activity was low, the porphyrin showed moderate but encouraging antifungal activity. Finally, a study of its effect on the germination of lentil seeds revealed interesting allelopathic properties.

CO2 to CO Electroreduction, Electrocatalytic H2 Evolution, and Catalytic Degradation of Organic Dyes Using a Co(II) meso-Tetraarylporphyrin

The meso-tetrakis(4-(trifluoromethyl)phenyl)porphyrinato cobalt(II) complex [Co(TMFPP)] was synthesised in 93% yield. The compound was studied by 1H NMR, UV-visible absorption, and photoluminescence spectroscopy. The optical band gap Eg was calculated to 2.15 eV using the Tauc plot method and a semiconducting character is suggested. Cyclic voltammetry showed two fully reversible reduction waves at E1/2 = -0.91 V and E1/2 = -2.05 V vs. SCE and reversible oxidations at 0.30 V and 0.98 V representing both metal-centred (Co(0)/Co(I)/Co(II)/Co(III)) and porphyrin-centred (Por2-/Por-) processes. [Co(TMFPP)] is a very active catalyst for the electrochemical formation of H2 from DMF/acetic acid, with a Faradaic Efficiency (FE) of 85%, and also catalysed the reduction of CO2 to CO with a FE of 90%. Moreover, the two triarylmethane dyes crystal violet and malachite green were decomposed using H2O2 and [Co(TMFPP)] as catalyst with an efficiency of more than 85% in one batch.

Zinc(ii) triazole meso-arylsubstituted porphyrins for UV-visible chloride and bromide detection. Adsorption and catalytic degradation of malachite green dye

Three new triazole meso-arylporphyrins (4a-c) were synthesized by the copper(i)-catalyzed azide alkyne cycloaddition (CuAAC) "click" reaction in high yield. The corresponding zinc(ii) coordination compounds (5a-c) have also been prepared. All 4a-c and 5a-c porphyrin species were fully characterized by elemental analysis, electrospray ionization and MALDI-TOF mass spectrometry, infrared spectroscopy, proton nuclear magnetic resonance, UV-visible, fluorescence and cyclic voltammetry. The zinc(ii) 5a-c complexes have been tested as detectors for Cl- and Br- anions. UV-visible titrations reveal that these host systems exhibit strong anion binding affinities. The efficiency of the adsorption of the malachite green dye (MG) dye on the 4a-c free base porphyrins and the corresponding zinc(ii) complexes 5a-c was investigated by a kinetic study using these synthetic porphyrin derivatives as adsorbents. The use of our triazole Zn(ii) complexes in the catalytic degradation of the MG dye is the first example where a metalloporphyrin is involved in the MG dye decolorization reaction. The degradation reactions were carried out using an ecological oxidant (H2O2), where the efficiency of the decolorization has been characterized by UV-visible spectroscopic analysis. Several factors affecting the degradation phenomenon have been studied. The energetic parameters concerning the degradation process have also been determined.

Crystal structure of (diethyl ether-κO)[5,10,15,20-tetra-kis-(2-iso-thio-cyanato-phen-yl)porphyrinato-κ4 N]zinc diethyl ether solvate

The crystal structure of the title compound, [Zn(C48H24N8S4)(C4H10O)]·C4H10O, consists of discrete porphyrin complexes that are located on a twofold rotation axis. The ZnII cation is fivefold coordinated by four N atoms of the porphyrin moiety and one O atom of a diethyl ether mol-ecule in a slightly distorted square-pyramidal environment with the diethyl ether mol-ecule in the apical position. The porphyrin backbone is nearly planar with the metal cation slightly shifted out of the plane towards the coordinating diethyl ether mol-ecule. All four iso-thio-cyanato groups of the phenyl substituents at the meso-positions face the same side of the porphyrin, as is characteristic for picket fence porphyrins. In the crystal structure, the discrete porphyrin complexes are arranged in such a way that cavities are formed in which additional diethyl ether solvate mol-ecules are located around a twofold rotation axis. The O atom of the solvent mol-ecule is not positioned exactly on the twofold rotation axis, thus making the whole mol-ecule equally disordered over two symmetry-related positions.

Magnesium Tetra(phenylethynyl)porphyrin: Stepwise Synthetic Route, Crystal Structures, and Longer Singlet Excited-State Lifetime than Zinc Congener

Magnesium tetra(arylethynyl)porphyrins (aryl=Ph or 4-CF₃ C₆ H₄ ) were synthesized via 5,15-di(triisopropylsilylethynyl)-10,20-di(arylethynyl)porphyrin to ensure good solubility and high synthetic yields. Magnesium tetra(phenylethynyl)porphyrin was subjected to structural analyses and physico-chemical characterization. Single-crystal X-ray analysis revealed porous crystal structures featuring solvent molecules in their pores. From femtosecond transient absorption measurements we concluded that the singlet excited-state lifetime of magnesium tetra(phenylethynyl)porphyrin is with 7.4 ns substantially longer than that of its zinc congener with 2.8 ns; this is attributed to the lower atomic weight of magnesium compared with zinc.

Tetrakis(ethyl-4(4-butyryl)oxyphenyl)porphyrinato zinc complexes with 4,4'-bpyridin: synthesis, characterization, and its catalytic degradation of Calmagite

This work reports on the synthesis and characterization of a new porphyrins complex:[Zn(TEBOP)(4,4'-bpy)](4,4'-bipyridine)(5,10,15,20-(tetraethyl-4(4-butyryl)oxyphenyl)porphyrinato)zinc(ii) (3). Single crystal X-ray diffraction, photophysical and electrochemical characteristics were studied. The prepared complex, penta-coordinated zinc(ii) porphyrin derivatives shows moderate ruffling distortion and the zinc atom is nearly planar with the porphyrin core. Tolyl and ethyl-4(4-butyryl)oxyphenyl) moieties at the meso positions present a bathochromic shift of the absorption bands, and a notable increase in the absorption coefficient of the Q(0,0) and Q(0,1) bands was observed with a higher fluorescence quantum yield and lifetime compared with the free base porphyrin. The electrochemical investigation shows a reversible reduction of the synthesized complexes. The catalytic power and the adsorption properties of the prepared complexes were studied for Calmagite degradation, an azoic organic dye. The results reveal that the studied compounds could be used as catalysts for the decolourisation of dyes in the presence of H2O2.

Magnesium porphyrins with relevance to chlorophylls

A review on the chemistry of magnesium porphyrins, which have significant interest owing to the relevance to chlorophyll molecules, is presented with emphasis on bicarbonate adducts of magnesium porphyrin and chlorophyll.

An Azobenzenyl Anion Radical Complex of Magnesium: Synthesis, Structure, and Reactivity Studies

Azobenzenyl anion radical complex of magnesium [HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg(PhNNPh) (THF) (2) was obtained for the first time through the reaction of [HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]MgBr (1) with potassium graphite in the presence of azobenzene. Complex 2 is a useful electron-transfer reagent as shown by the reactivity with diphenyl disulfide, diphenyl diselenide, oxygen, sulfur, and Me₃SiN₃ yielding the magnesium thiolate [HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg(SPh)(THF) (3), magnesium selenolate [HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg(SePh)(THF) (4), peroxido complex {[HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg(THF)}₂(μ-η²-η²-O₂) (5), persulfido complex {[HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg(THF)}₂(μ-η²-η²-S₂) (6), and azido complex [HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]MgN₃ (7), respectively. Furthermore, treatment of 2 with Me₃SiCHN₂ results in a rearrangement product {[HC(C(Me)N-2,6-ⁱPr₂C₆H₃)₂]Mg[CNN(SiMe₃)]}₂ (8).