Cationic Complexes Research Articles

Tweaking the conjugation effects on a pair of new triazene compounds by targeted deprotonation: a spectroscopic and theoretical overview.

Triazene compounds (-NNN(H)-) exhibit versatility in biological, physical, and chemical applications. In their anionic form (-NNN-)(-), they can act as coordinating sites for metals, forming metallic complexes. In this study, two new isomeric triazene compounds with meta- and para-substituents in their neutral and anionic forms were investigated. A combination of detailed experimental spectroscopic characterization and computational chemistry analyses were employed. The new compounds, 1-(2-benzamide)-3-(3-nitrophenyl) triazene (m-TZN) and 1-(2-benzamide)-3-(4-nitrophenyl) triazene (p-TZN), were compared to 1,3-diphenyltriazene (dph-TZN) to understand the effects of functionalization and targeted triazene deprotonation. The anionic forms are stable, and our investigation suggests that these new compounds are suitable tridentate ligands that can act as chelating agents for metallic cations in stable complexes, similar to those found in vitamin B12. The absorption, vibrational, and electronic properties of the newly synthesized triazene compounds were extensively characterized using FT-IR/FT-Raman and UV-Vis spectroscopy. Their distinct molecular properties, intramolecular hydrogen bond effects, stability, and electronic transitions were investigated using the ORCA software. These analyses involved DFT and TD-DFT calculations at the ωB97X-D3/Def2-TZVP level of theory with THF CPCM implicit solvation to determine the molecular topology and electronic structure. The advanced STEOM-DLPNO-CCSD method for excited states was employed, enabling an in-depth analysis of ground and excited-state chemistry, accounting for precise electronic correlation and solvation effects. Explicit THF solvation was tested on the full TD-DFT ωB97X-D3/Def2-TZVP level and using ONIOM on the STEOM calculation. Reactivity was studied using Fukui functions, and action as chelating agents was investigated using GFN-xTB2 and DFT.

Elusive Active Intermediates and Reaction Mechanisms of ortho-/ipso-Hydroxylation of Benzoic Acid by Hydrogen Peroxide Mediated by Bioinspired Iron(II) Catalysts.

Aromatic hydroxylation of benzoic acids (BzOH) to salicylates and phenolates is fundamentally interesting in industrial chemistry. However, key mechanistic uncertainties and dichotomies remain after decades of effort. Herein, the elusive mechanism of the competitive ortho-/ipso-hydroxylation of BzOH by H2O2 mediated by a nonheme iron(II) catalyst was comprehensively investigated using density functional theory calculations. Results revealed that the long-postulated FeV(O)(anti-BzO) oxidant is an FeIV(O)(anti-BzO•) species 2 (anti- and syn- are defined by the orientation of the carboxyl oxygen of BzO to the oxo), which rules out the noted two-oxidant mechanism proposed previously. We propose a new mechanism in which, following the formation of an FeV(O)(syn-BzO) species (3) and its electromer FeIV(O)(syn-BzO•) (3'), 3/3' either converts to salicylate and phenolate via intramolecular self-hydroxylation (route A) or acts as an oxidant to oxygenate another BzOH to generate the same products (route B). In route A, the rotation of the BzO group along the C-O bond forms 2, in which the BzO group is orientated by π-π stacking interactions. An electrophilic ipso-addition forms a phenolate by concomitant decarboxylation or an ortho-attack forms a cationic complex, which readily undergoes an NIH shift and a BzOH-assisted proton shift to form a salicylate. In route B, 3 oxidizes an additional BzOH molecule directed by hydrogen bonding and π-π stacking interactions. In both routes, selectivity is determined by the chemical property of the BzO ring. These mechanistic findings provide a clear mechanistic scenario and enrich the knowledge of hydroxylation of aromatic acids.

Three Iodoargentate-Based Hybrids Decorated by Metal Complexes: Structures, Optical/Photoelectric Properties and Theoretical Studies.

So far, the development of new iodoargentate-based hybrids, especially those compounds with metal complex cations, and the understanding of their structure-activity relationships have been of vital importance but full of challenges. Herein, using the in-situ-generated metal complex cations as structural directing agents, three new iodoargentate-based hybrids, namely, [Co(phen)3]Ag2PbI6 (phen = 1,10-phenanthroline; 1), [Ni(5,5-dmpy)3]Ag7I9·CH3CN (5,5-dmpy = 5,5-dimethyl-2,2-bipyridine; 2) and [Co(5,5-dmpy)3]Ag5I8 (3), have been solvothermally prepared and then structurally characterized. Compound 1 represents one new heterometallic Ag-Pb-I compound characteristic of the chain-like [Ag2PbI6]n2n- anions. Compound 2 features the straight one-dimensional (1D) [Ag7I9]n2n- anionic moieties, while compound 3 contains infrequent two types of curved [Ag5I8]n3n- anions. Optical properties reveal that the title compounds exhibit interesting semiconductor behaviors with the band gaps of 1.59-2.78 eV, which endow them with good photoelectric switching performances under the alternate light irradiations. We also present their Hirshfeld surface analyses, and the theoretical studies (band structures, density of states (DOS) and partial density of states (PDOS)).

Electronic Structure of the Complete Series of Gas-Phase Manganese Acetylacetonates by X-ray Absorption Spectroscopy.

Metal centers in transition metal-ligand complexes occur in a variety of oxidation states causing their redox activity and therefore making them relevant for applications in physics and chemistry. The electronic state of these complexes can be studied by X-ray absorption spectroscopy, which is, however, due to the complex spectral signature not always straightforward. Here, we study the electronic structure of gas-phase cationic manganese acetylacetonate complexes Mn(acac)1-3+ using X-ray absorption spectroscopy at the metal center and ligand constituents. The spectra are well reproduced by multiconfigurational wave function theory, time-dependent density functional theory as well as parameterized crystal field and charge transfer multiplet simulations. This enables us to get detailed insights into the electronic structure of ground-state Mn(acac)1-3+ and extract empirical parameters such as crystal field strength and exchange coupling from X-ray excitation at both the metal and ligand sites. By comparison to X-ray absorption spectra of neutral, solvated Mn(acac)2,3 complexes, we also show that the effect of coordination on the L3 excitation energy, routinely used to identify oxidation states, can contribute about 40-50% to the observed shift, which for the current study is 1.9 eV per oxidation state.

Cover Feature: Highly Electrophilic Mononuclear Cationic Aluminium Alkoxide Complexes: Syntheses, Reactivity and Catalytic Applications (Chem. Eur. J. 55/2023)

Cover Feature: Highly Electrophilic Mononuclear Cationic Aluminium Alkoxide Complexes: Syntheses, Reactivity and Catalytic Applications (Chem. Eur. J. 55/2023)

Neutral and Cationic Molybdenum Imido Alkylidene Cyclic Alkyl Amino Carbene (CAAC) Complexes for Olefin Metathesis.

The first neutral and cationic Mo imido alkylidene cyclic alkyl amino carbene (CAAC) complexes of the general formulae [Mo(N-Ar)(CHCMe2Ph)(X)2(CAAC)] and [Mo(N-Ar)(CHCMe2Ph)(X)(CAAC)][B(ArF)4] (X = Br, Cl, OTf, OC6F5; CAAC = 1-(2,6-iPr2-C6H3)-3,3,5,5-tetramethyltetrahydropyrrol-2-ylidene) have been synthesized from molybdenum imido bishalide alkylidene DME precursors. Different combinations of the imido and "X" ligands have been employed to understand synthetic peculiarities. Selected complexes have been characterized by single crystal X-ray analysis. Due to the pronounced σ-donor/π-acceptor characteristics of CAACs, the corresponding neutral and cationic molybdenum imido alkylidene CAAC complexes do not require the presence of stabilizing donor ligands such as nitriles. Calculations on the PBE0-D3BJ/def2-TZVP level for PBE0-D3BJ/def2-SVP optimized geometries revealed partial charges at molybdenum similar to the corresponding molybdenum imido alkylidene N-heterocyclic carbene (NHC) complexes with a slightly higher polarization of the molybdenum alkylidene bond in the CAAC complexes. All cationic complexes have been tested in olefin metathesis reactions and showed improved activity compared to the analogous NHC complexes for hydrocarbon-based substrates, allowing for turnover numbers (TONs) up to 9500 even at room temperature. Some Mo imido alkylidene CAAC complexes are tolerant towards functional groups like thioethers and sulfonamides.

Chromogenic azomacrocycles with imidazole residue: Structure vs. properties

New diazo macrocycles linked by hydrocarbon chain bearing imidazole or 4-methylimidazole residue have been synthetized with satisfactory yield (24–55%). The structure of macrocycles was confirmed by X-ray analysis and spectroscopic methods (1H NMR, MS, FTIR). Metal cation complexation studies were carried out in acetonitrile and acetonitrile-water system. It was found that azomacrocyles form triple-decker complexes with lead(II). The highest values of stability constant were found for lead(II) complexes of 21-membered derivatives. For the first time azomacrocycles bearing imidazole residue were immobilized on a porous glass. Obtained materials can act as lead(II) or copper(II) colorimetric optical sensors with color digital analysis as detection using simple portable devices.

Synthesis, characterization, electrical, and magnetic properties of polyvinyl alcohol/carboxymethyl cellulose blend doped with nickel ferrites nanoparticles for magneto‐electronic devices

AbstractSolid polymer electrolytes are an intriguing technology in terms of magneto‐opto electronic applications due to having a high dielectric constant, a small band gap, and excellent magnetic characteristics. In order to improve structural, optical, dielectric, conductivity, and magnetic characteristics, this research seeks to prepare nickel ferrite (NiFe2O4) nanoparticles and polyvinylalcohol (PVA)/carboxymethyl cellulose (CMC) films containing NiFe2O4. Nanoparticles of NiFe2O4 are prepared using the co‐precipitation method. The CMC/PVA–NiFe2O4 nanocomposites films are prepared using casting solution. To improve their structural, optical, conductivity, dielectric, and magnetic characteristics, these films electrolytes were examined using XRD, TEM, FT‐IR, UV–vis, and VSM measurements. According to the XRD analysis, the CMC/PVA blend polymer matrix demonstrates a considerable increase in amorphous nature with the NiFe2O4 nanoparticles (NPs) content, producing a highly flexible polymer backbone, increasing ionic conductivity of the CMC/PVA–NiFe2O4 nanocomposite films. The complexation of dopant cations with the CMC/PVA polymer matrix's backbone is confirmed by the FT‐IR spectroscopy. According to the UV–visible technique, the dopant NiFe2O4 concentration considerably affects the optical energy band gap, and Urbach energy of the pure CMC/PVA. At higher loading, these effects are more pronounced. At room temperature, ac conductivity, the dielectric behavior, and electrical modulus formalism were studied. The blend's highest AC conductivity is 4.77 × 103 S/cm. After increasing the loading of NiFe2O4 to 1.5 wt%, it increased to 8.07 × 104 S/cm. There has also been research on dielectric permittivity and electric modulus to further understand conductivity relaxation and charge storage qualities. The polymer nanocomposite, generally, displayed better optical, dielectric constant, conductivity, and magnetic characteristics compared to pure CMC/PVA being useable in terms of high energy storage nanoelectronics' manufacturing.Highlights NiFe2O4 nanoparticles were prepared by using the co‐precipitation method. Nanocomposite films of CMC/PVA–NiFe2O4 were successfully prepared by casting method. XRD patterns confirmed the increase in the degree amorphousity for nanocomposites films compare pure blend. From optical energy gap results for samples prepared was enhanced after addition NiFe2O4. The dielectric and magnetic properties showed that all nanocomposites films exhibited enhanced as compared to pure CMC/PVA film.

Hydrazine-thermal syntheses, structures, and photocatalytic properties of tellurostannate hybrids with iron (II) complex unit

Iron containing tellurostannates [Fe(dien)2]2Sn2Te6 (dien = diethylenetriamine) (1), [Fe(tepa)(N2H4)]2Sn2Te6 (tepa = tetraethylenepentamine) (2), and [{Fe(trien)}2(μ-1κ:2κ-SnTe4)] (trien = triethylenetetramine) (3) were solvothermally prepared in different ethylene polyamines with the assistance of hydrazine in lower temperature range. In 1 and 2, two SnTe4 tetrahedral units are joined via edge-sharing forming a free dimeric [Sn2Te6]4− anion with Fe(II) complex cation acting the counter ion. In compound 3, the SnTe4 tetrahedron connected two [Fe(trien)]2+ complex units as a bidentate μ-1κ:2κ bridging ligand, to generate the neutral binuclear complex [{Fe(trien)}2(SnTe4)]. The compounds 1–3 had narrow semiconducting band gaps of 1.76, 1.73 and 1.71 eV, respectively. They showed sensitive photocurrent response under Xe light irradiation with steadied current densities in the range of 0.45–0.76 μA·cm−2. They were catalytically active in the photodegradation of crystal violet (CV) with the degradation ratio varying between 59.5% and 93.5%. Compound 3 exhibited the highest photocatalytic activity, which was attributed to its highest strength of photocurrent response.

Unlocking the Potential of Lithium Metal Batteries With a Sulfite‐Based Electrolyte

AbstractLithium metal batteries (LMBs) have the potential to significantly increase the energy density of advanced batteries in the future. Nonetheless, the dendritic lithium structures and low Coulombic efficiency (CE) of LMBs currently impede their applied implementation. Herein, a sulfite‐based electrolyte (SBE/FEC), including 1.0 m lithium bis(fluorosulfonyl)imide in a blend of ethylene sulfite and diethyl sulfite, and 5 wt% fluoroethylene carbonate is proposed. SBE/FEC is a highly efficient inhibitor against the growth of lithium dendrites through the formation of robust solid electrolyte interphase (SEI) layer. Raman spectroscopy and theoretical calculation indicate that in SBE/FEC, a significant portion of FSI− exists in associated complexes, playing a vital role in the creation of LiF‐rich passivation. Besides, the sulfite solvents decompose and yield polysulfide complexes in the SEI layer. A direct correlation between the proportion of cation–anion complexes and the contact angle between electrolyte and separator is elucidated through molecular dynamics simulations. The SBE/FEC system exhibits high CEs (98.3%) with Li||Cu cells, along with a steady discharge capacity of ≈137 mA h g−1 in Li||LiFePO4 cell. This study presents an effective approach for enhancing LMBs with sulfite‐based electrolytes, which can lead to high‐energy‐density next‐generation rechargeable batteries.

Spherical silica particles coated with lamellar nanocomposites based on a hydrophobic functionalized phyllosilicate

The surface of spherical silica particles (monodisperse, 2.6 µm) was modified with inorganic–organic lamellar ordered hybrids for applications as hydrophobic dye supports in cosmetics. The inorganic–organic multilayers comprised a 2:1 phyllosilicate (two sheets of linked SiO4 tetrahedra with one sheet of M2–3(OH)6 octahedra, where M is either magnesium or aluminum), consisting of octyl chains directly bonded to the inorganic sheets via Si–C covalent bonds. Octyltriethoxysilane was allowed to react at room temperature with spherical silica and aluminum acetylacetonate in a mixed aqueous solution of NaOH and NaCl at pH 10. The formation of a 2:1 phyllosilicate grafted with an octyl chain was confirmed by X-Ray powder diffraction, where a lamellar structure with the d001 value of 2.4 nm was displayed. The lamellar structure included the isomorphic substitution of Si by Al and the formation of C–Si–O–Aloct bonds, as shown in 29Si–and 27Al–magic angle spinning (MAS)–nuclear magnetic resonance (NMR) spectra. Further, the 23Na–MAS NMR spectrum indicated the incorporation of Na aquo complex cations into the organophyllosilicate. The hydrated Na ions were exchanged with a cationic dye (methylene blue) to be adsorbed. An anionic dye (Phloxine B), which has frequently been used as cosmetic pigments, was adsorbed onto the resulting hybrid particles when Al3+ was present in the dye solution. The hydrophobic dye supports can be used instead of plastic beads to reduce marine pollution.

Highly Electrophilic Mononuclear Cationic Aluminum Alkoxide Complexes: Syntheses, Reactivity and Catalytic Applications.

Herein, we report on the synthesis of β-diketiminate supported aluminum complexes bearing terminal alkoxide and mono-thiol functional groups: LAlOMe(Et) (2), LAlOtBu(Et) (3), and LAlSH(Et) (4), (L= [HC{C(Me)N-(2,6-iPr2C6H3)}2]). Complexes 2 and 3 are further utilized as synthons to generate some fascinating cationic aluminum alkoxide complexes, [LAlOMe(µ-OMe)-Al(Et)L][EtB(C6F5)3] (5), [LAlOMe(OEt2)][EtB(C6F5)3] (6), and [LAlOtBu(OEt2)][EtB(C6F5)3] (8). These electrophilic cationic species are well characterized by spectroscopic and crystallographic techniques. The assessment of Lewis acidity by the Gutmann-Beckett method revealed superior Lewis acidity of the cations substituted with electron demanding alkoxy groups in comparison to the known methyl analogue [LAlMe][B(C6F5)4]. This has been further endorsed by computational calculations to determine the NBO charges and hydride ion affinity for complexes 6 and 8. These complexes are also capable of activating triethylsilane in stoichiometric reactions. The applicability of these complexes has been realized in the hydrosilylation of ethers, carbonyls, and olefines. Additionally, the solid state structure of a new THF stabilized aluminum halide cation [LAlCl(THF)][B(C6F5)4] (11) has also been reported.

Synthesis and Characterization of Transition Metal Complex Cation Heptaborate Structures

Heptaborate structures with transition metal complex cations were synthesized and characterized using elemental analysis, melting point determination, FT-IR, TGA/DTA analysis, UV analysis, x-ray diffraction (XRD) analysis methods. In the infrared spectra of heptaborate salt structures, peaks of (-M-N)phen and (-M-N)pyrd stretching vibrations, which indicate the presence of transition metal complex, were observed. As the characteristic vibrations of the heptaborate structure, the -OH peaks of the B-OH bonds present in the structures and the asymmetric and symmetrical stretching vibrations, which confirm the presence of four trigonal borate molecules in the structures, appeared as sharp peaks. It was observed that the thermal analysis decomposition curves of heptaborate salt structures with transition metal complex cations were similar. Depending on the similar degradation characteristics of the molecules, it is seen that the hydrate waters settled outside the coordination sphere in all structures move away from the structures in a single step. As the second degradation step of heptaborate salt structures, the removal of water in amounts that can be attributed to the removal of -OH groups in the borate rings in the form of water vapor in all structures was detected. It was seen that this degradation step took place in a single step in all structures and the related experimental theoretical mass losses were compatible with each other. Combustion degradation of organic ligands was observed as the final degradation step of heptaborate salt structures with metal cation complexes. While peaks belonging to heptaborate rings were observed from the recorded powder x-ray diffraction patterns, electronic transition data also supported that the metal cation complex was in octahedral geometry.

Enantioselective Aldol Reaction with Difluoroenoxysilanes Catalyzed by Cationic Palladium Aqua Complexes

AbstractThe enantioselective addition of difluoroenoxysilanes to aromatic aldehydes, catalyzed by cationic palladium aqua complexes, has been described. The reaction is operationally simple, does not require anhydrous conditions and performs at room temperature. The palladium catalysts, previously discovered and reported by Sodeoka, are easily prepared in two steps from PdCl2(MeCN)2. The aldol compounds were obtained in good yields and with enantiomeric ratios up to 93 : 7, the reaction being more efficient using electron‐rich aldehydes.

Intratumoural Delivery of mRNA Loaded on a Cationic Hyper-Branched Cyclodextrin-Based Polymer Induced an Anti-Tumour Immunological Response in Melanoma.

mRNA technology has demonstrated potential for use as an effective cancer immunotherapy. However, inefficient in vivo mRNA delivery and the requirements for immune co-stimulation present major hurdles to achieving anti-tumour therapeutic efficacy. Therefore, we used a cationic hyper-branched cyclodextrin-based polymer to increase mRNA delivery in both in vitro and in vivo melanoma cancer. We found that the transfection efficacy of the mRNA-EGFP-loaded Ppoly system was significantly higher than that of lipofectamine and free mRNA in both 2D and 3D melanoma cancer cells; also, this delivery system did not show cytotoxicity. In addition, the biodistribution results revealed time-dependent and significantly higher mEGFP expression in complexes with Ppoly compared to free mRNA. We then checked the anti-tumour effect of intratumourally injected free mRNA-OVA, a foreign antigen, and loaded Ppoly; the results showed a considerable decrease in both tumour size and weight in the group treated with OVA-mRNA in loaded Ppoly compared to other formulations with an efficient adaptive immune response by dramatically increasing most leukocyte subtypes and OVA-specific CD8+ T cells in both the spleen and tumour tissues. Collectively, our findings suggest that the local delivery of cationic cyclodextrin-based polymer complexes containing foreign mRNA antigens might be a good and reliable concept for cancer immunotherapy.

Electropolymerization processing of side-chain engineered EDOT for high performance microelectrode arrays

Microelectrode Arrays (MEAs) are popular tools for in vitro extracellular recording. They are often optimized by surface engineering to improve affinity with neurons and guarantee higher recording quality and stability. Recently, PEDOT:PSS has been used to coat microelectrodes due to its good biocompatibility and low impedance, which enhances neural coupling. Herein, we investigate on electro-co-polymerization of EDOT with its triglymated derivative to control valence between monomer units and hydrophilic functions on a conducting polymer. Molecular packing, cation complexation, dopant stoichiometry are governed by the glycolation degree of the electro-active coating of the microelectrodes. Optimal monomer ratio allows fine-tuning the material hydrophilicity and biocompatibility without compromising the electrochemical impedance of microelectrodes nor their stability while interfaced with a neural cell culture. After incubation, sensing readout on the modified electrodes shows higher performances with respect to unmodified electropolymerized PEDOT, with higher signal-to-noise ratio (SNR) and higher spike counts on the same neural culture. Reported SNR values are superior to that of state-of-the-art PEDOT microelectrodes and close to that of state-of-the-art 3D microelectrodes, with a reduced fabrication complexity. Thanks to this versatile technique and its impact on the surface chemistry of the microelectrode, we show that electro-co-polymerization trades with many-compound properties to easily gather them into single macromolecular structures. Applied on sensor arrays, it holds great potential for the customization of neurosensors to adapt to environmental boundaries and to optimize extracted sensing features.

Neutral and cationic nickel(II) complexes with substituted salicylaldehydes: Characterization, antibacterial activity, and interaction with biomacromolecules

Four neutral and six cationic nickel(II) complexes of the substituted salicylaldehydes (X–diCl–saloH), namely 3,5–dichloro–salicylaldehyde (3,5–diCl–saloH) and 5–fluoro–salicylaldehyde (5–F–saloH), were synthesized in the absence or presence of the N,N′–donors 1,10–phenanthroline (phen), 2,9–dimethyl–1,10–phenanthroline (neoc), or 2,2′–bipyridylamine (bipyam) as co–ligands and were characterized by various techniques. The obtained complexes bear the general formulas [Ni(X–salo)2(H2O)2], [Ni(3,5–diCl–salo)2(neoc/phen)] and [Ni(X–salo)(N,N′–donor)2](PF6). The crystal structures of three complexes were determined by single–crystal X–ray crystallography revealing a bidentate coordination of the salicylaldehydes. The interaction of the compounds with calf–thymus DNA was studied by diverse techniques which revealed an intercalative interaction for the neutral complexes [Ni(X–salo)2(H2O)2] and [Ni(3,5–diCl–salo)2(neoc/phen)]and the co–existence of electrostatic interactions for the cationic complexes [Ni(X–salo)(N,N′–donor)2](PF6). The compounds bind tightly and reversibly to serum albumins. The antibacterial activity of the compounds was investigated against Staphylococcus aureus ATCC 6538, Bacillus subtilis ATCC 6633, Escherichia coli NCTC 29,212 and Xanthomonas campestris ATCC 1395 and the complexes bearing neoc as co–ligand proved the most potent.

Removal of Paracetamol and Cu2+ from Water by Using Porous Carbons Derived from Agrowastes

Dende and babassu coconuts are largely used in tropical countries, namely in Brazil, for the extraction of oils from kernels. The remaining biowastes are industrially processed to produce porous carbons (PCs). PCs derived from dende and babassu biowastes and produced at an industrial scale have been characterized by textural, chemical, and ecotoxicological parameters. A commercial activated carbon (CC) of mineral origin has been used as a benchmarking material. Although the CC sample presented a higher surface area (SBET = 1083 m2/g), the PCs derived from the biowastes were richer in micropores (Vmicro = 0.25–0.26 cm3/g), while the CC carbon presented wider pore size distribution with a higher mesopore volume (Vmeso = 0.41 cm3/g). All the adsorbents used in this work have shown a non-acute ecotoxic behavior for the bacterium Vibrio fischeri (EC50-30 min > 99% v/v). The adsorbents have been tested for paracetamol and Cu2+ adsorption in mono- and bicomponent solutions. The uptake capacities of paracetamol (qe, 98–123 mg g−1) and Cu2+ (qe, 15–18 mg g−1) from monocomponent solutions were similar to the ones obtained in the bicomponent solutions, indicating no competition or cooperative effects but a site-specific adsorption. This finding represents an advantage for the removal of these adsorbates when present in the same solution as they can be adsorbed under similar rates as in the single systems. Paracetamol adsorption was related to micropore filling, π-π interactions, and H-bonding, whereas Cu2+ removal was attributed to the cation exchange mechanism and complexation to the hydroxyl groups at the carbons’ surface.

Oxidation of 5,15-Dioxaporphyrin: Its Generality and Novelty as an Oxaporphyrin Analogue.

5,15-Dioxaporphyrin (DOP) is a novel meso-oxaporphyrin analogue and exhibits unique 20π-antiaromaticity, unlike its mother congener of 18π-aromatic 5-oxaporphyrin, commonly known as its cationic iron complex called verdohem, which is a key intermediate of heme catabolism. To reveal its reactivities and properties as an oxaporphyrin analogue, the oxidation of tetra-β-arylated DOP (DOP-Ar4 ) was explored in this study. Stepwise oxidation from the 20π-electron neutral state was achieved, and the corresponding 19π-electron radical cation and 18π-electron dication were characterized. Further oxidation of the 18π-aromatic dication resulted in the formation of a ring-opened dipyrrindione product by hydrolysis. Considering a similar reaction of verdoheme to ring-opened biliverdin in the heme degradation in nature, the current result consolidates the ring-opening reactivity of oxaporphyrinium cation species.

Oxidation of 5,15‐Dioxaporphyrin: Its Generality and Novelty as an Oxaporphyrin Analogue

Abstract5,15‐Dioxaporphyrin (DOP) is a novel meso‐oxaporphyrin analogue and exhibits unique 20π‐antiaromaticity, unlike its mother congener of 18π‐aromatic 5‐oxaporphyrin, commonly known as its cationic iron complex called verdohem, which is a key intermediate of heme catabolism. To reveal its reactivities and properties as an oxaporphyrin analogue, the oxidation of tetra‐β‐arylated DOP (DOP‐Ar4) was explored in this study. Stepwise oxidation from the 20π‐electron neutral state was achieved, and the corresponding 19π‐electron radical cation and 18π‐electron dication were characterized. Further oxidation of the 18π‐aromatic dication resulted in the formation of a ring‐opened dipyrrindione product by hydrolysis. Considering a similar reaction of verdoheme to ring‐opened biliverdin in the heme degradation in nature, the current result consolidates the ring‐opening reactivity of oxaporphyrinium cation species.