Developments in the Dehydrogenative Electrochemical Synthesis of 3,3′,5,5′-Tetramethyl-2,2′-biphenol

The symmetric biphenol 3,3′,5,5′-tetramethyl-2,2′-biphenol is a well-known ligand building block and is used in transition-metal catalysis. In the literature, there are several synthetic routes for the preparation of this exceptional molecule. Herein, the focus is on the sustainable electrochemical synthesis of 3,3′,5,5′-tetramethyl-2,2′-biphenol. A brief overview of the developmental history of this inconspicuous molecule, which is of great interest for technical applications, but has many challenges for its synthesis, is provided. The electro-organic method is a powerful, sustainable, and efficient alternative to conventional synthesis to obtain this symmetric biphenol up to the kilogram scale. Another section of this article is devoted to different process management strategies in batch-type and flow electrolysis and their respective advantages.     

Colorimetric determination of the activity of acetylcholinesterase and its inhibitors by exploiting the iodide-catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine by hydrogen peroxide

We describe a sensitive and selective colorimetric method for the determination of the activity of the enzyme acetylcholinesterase (AChE) and its inhibitors. Detection is based on the fact that acetylthiocholine iodide (ATCI) catalyzes the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂ to form a blue product (ox-TMB) with an absorption peak at 652 nm, but that oxidation is suppressed if ACTI previously is hydrolyzed by AChE to form thiocholine which decolorizes ox-TMB. In the presence of inhibitor, the activity of AChE is inhibited, thereby inducing the recovery of the blue coloration. Based on these findings, a highly sensitive method is developed for the determination of AChE and its inhibitors. The assay only requires mixing of buffer, solutions of ATCI, TMB, H₂O₂ and a sample containing AChE and photometric measurement. It works in the 0.05 to 5 mU?mL^?1 enzyme activity range and has a detection limit as low as 30 μU?mL^?1. The inhibitor neostigmine causes 50 % enzyme inhibition in 14.5 nM concentration. This analytical system has a wide scope in that it may be applied to the determination of the activity of various other hydrolases with proper substrates.

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Graphical abstract The blue product formed by the iodide-catalyzed oxidation of 3,3′5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide is decolorized if acetylthiocholine iodide (ATCI) is hydrolyzed by acetylcholinesterase (AChE) to form thiocholine. If, however, AChE is inhibited, color formation will take place again.

     

Crystal structure of 1,1′-biphenyl-2,2′,3,3′-tetracarboxylic and 1,1′-biphenyl-2,2′,3,3′,5,5′,6,6′-octacarboxylic acids: solid-state chiralization and dissociation

X-ray diffraction analysis revealed unexpected stereochemical features accompanying crystal self-assembly of the two title oligocarboxylic acids.     

Resolution and determination of the absolute configuration of 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene-2-carboxaldehyde

Racemic 3,3′,4,4′-tetramethyl-1,1′-diphosphaferrocene-2-carboxaldehyde 1 was resolved via the formation of diastereomeric dioxolanes with (S)-(+)-1-phenyl-1,2-ethanediol. Four stereoisomers were separated by column chromatography. The absolute configuration of one of them (2′′R, 4′′S,1R) was established by X-ray diffraction. Acid hydrolysis of the dioxolanes afforded quantitatively (R)- and (S)-enantiomers of 1. Optical rotatory dispersion (ORD) spectra of both enantiomers are also reported.     

Two metastable high hydrates of energetic material 3,3′,5,5′-tetranitro-4,4′-bipyrazole

Poly-stoichiometry of hydrated phases is relatively uncommon for organic materials and extended libraries of such species adopting different aqua-to-substrate ratios are still rare. The kinetically controlled higher hydrates could be particularly interesting for their structural relationships, which presumably may imprint some features of the substrate/substrate and aqua/substrate bonding in solutions, and provide insights into the nucleation stage. Two metastable high hydrates are prepared by crash crystallization. The crystal structures of 3,3′,5,5′-tetranitro-4,4′-bipyrazole tetrahydrate, C₆H₂N₈O₈·4H₂O, (1), and 3,3′,5,5′-tetranitro-4,4′-bipyrazole pentahydrate, C₆H₂N₈O₈·5H₂O, (2), are intrinsically related to the previously reported anhydrate and monohydrate, while displaying natural evolution of the patterns upon progressive watering. The accumulation of the water molecules causes their clustering, with the generation of one-dimensional tapes and two-dimensional layers in the genuine channel hydrates (1) and (2), respectively, versus the pocket hydrate structure of C₆H₂N₈O₈·H₂O. The hydration primarily affects the pyrazole sites. It conditions the emergence of N—H…O and O—H…N hydrogen bonds, which is a destructive factor for pyrazole/pyrazole N—H…N hydrogen bonding. At the same time, extensive noncovalent interactions of the organic molecules, namely, lone pair–π-hole O…N interactions of the NO₂/NO₂ and NO₂/pyrazole types, are more competitive to the hydrogen bonding and the motifs of mutual organic/organic stacks remain intact with the increase in hydration. These trends agree with the results of Hirshfeld surface analysis. The contributions of the contacts involving H atoms are increased in line with the growing number of water molecules, while the fraction of O…N/N…O (NO₂) contacts is nearly invariant. One may postulate the significance of the lone pair–π-hole interactions to the aggregation of nitro species in solutions and their relevance for the sebsequent development of the solid-state patterns through nucleation.     

Two new frameworks for biphenyl-3,3′,5,5′-tetracarboxylic acid and nitrogen-containing organics

Two complexes, {Zn(bptc)_0.5(bib)} _n (I) and {Mn₂(bptc)(pip)(H₂O)} _n (II) (H₄bptc = biphenyl-3,3′,5,5′-tetracarboxylic acid; bib = 1,4-bis(2-methylimidazol-1-yl)butane; pip = 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA and solid fluorescence spectra. The results show that I and II both have 3D network architectures. I has porous architecture with a 16² topology structure. Effective porosity calculated by Platon is 5.5 %. Moreover, it has a two-fold interpenetrating structure allowed by a 70.73° torsion between the benzene rings of the bptc^4? ligand and the flexibility of bib. II has a tetranuclear structure composed of binuclear architecture units with the torsion of 43.44° between the benzene rings of the bptc^4? ligand. TGA shows that the skeletons of I and II are stable up to 372°C and 553°C, respectively. I exhibits fluorescence.     

Thin-layer Spectroelectrochemistry of 3,3′,5,5′-Tetramethyl-benzidine on Pt Minigrid Optically Transparent Electrode

3,3′,5,5′-Tetramethylbenzidine(TMB)-H2O2-horseradish peroxidase(HRP) voltammetric enzyme linked immunoassay system1 has very high sensitivity, low detection limit and wide detection range for the determination of some plant viruses. However, the understanding of the mechanism of HRP catalyzed by H2O2 oxidizing TMB in this system is of significance. In the previous paper, we have reported the spectroelectro- chemical study of TMB on SnO2: F film optically transparent electrode in the …     

Ultrathin two-dimensional MnO2 nanosheet as a stable coreactant of 3,3′,5,5′-tetramethylbenzidine chromogenic substrate for visual and colorimetric detection of iron(II) ion

Microchimica Acta - The authors report on a chromogenic system based MnO2 nanosheet and the chomgenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB). The MnO2 nanosheet can oxidize TMB...     

Mechanism of the Oxidation of 3,3′,5,5′-Tetramethylbenzidine Catalyzed by Peroxidase-Like Pt Nanoparticles Immobilized in Spherical Polyelectrolyte Brushes: A Kinetic Study

Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H₂O₂) catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB−Pt). Due to the high stability of SPB−Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time-dependent concentration of the blue-colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H₂O₂ and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir–Hinshelwood mechanism. A true rate constant k, characterizing the rate-determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase-like nanoparticles.     

Specificity of photonics of 3,3′-diethyl-5,5′-dichloro-9-ethylthiacarbocyanine dimers in the presence of cucurbit[7]uril

Molecules of 3,3′-diethyl-5,5′-dichloro-9-ethylthiacarbocyanine form dimers in aqueous solutions, which are capable of fluorescence and intersystem crossing to the triplet state. In the presence of cucurbit[7]uril and alkali metals or ammonium cations, dye dimer complexes are formed, which exhibit phosphorescence and thermally activated delayed (E-type) fluorescence in air-saturated solutions at room temperature. With the use of quantum-chemical calculations, the structure of dimeric dye complexes with cucurbit[7]uril is suggested.     

2,2′,3,3′,5,5′-Hexaphenyl-[1,1′-biphenyl]-4,4′-diols as Monomer Units for Redox Polymers: Synthesis and Polymerization Strategies

Abstract

2,2′,3,3′,5,5′-Hexaphenyl-[1,1′,-biphenyl]-4,4′-diol (Ib), which is prepared by the oxidative coupling of 2,3,6-triphenylphenol, and its oxidized form (IIIb) constitute a powerful oxidation-reduction system. The oxidative coupling reaction is carried out in the presence of molecular oxygen with copper(I) chloride as a catalyst and butyronitrile as ligand and solvent. An approach to the incorporation of such biphenols into an oxidation-reduction polymer is presented.     

Spectrophotometric determination of total protein in serum using a novel near-infrared cyanine dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine

The application of near-infrared (NIR) dyes (λ _em > 750 nm) to the analysis of biological samples shows much promise, because the long emission wavelengths of such dyes allow interferences from biomolecule matrices to be minimized. In this paper, a novel NIR dye, 5,5′-dicarboxy-1,1′-disulfobutyl-3,3,3′,3′-tetramethylindotricarbocyanine (DCDSTCY) has been developed for the spectrophotometric determination of total protein in serum. Under acidic conditions, the binding of DCDSTCY to proteins caused a new peak at 878 nm, the height of which was proportional to the concentration of protein. The linear range of the method was found to be 0.04–0.5 μg mL⁻¹ for bovine serum albumin (BSA) and human serum albumin (HSA), and detection limits of 5 ng mL⁻¹ were obtained for these substances. The maximum binding number of BSA with DCDSTCY was measured to be 133. The method proposed here has been applied to the quantitation of total protein in serum, and recoveries of 96.6–104% were achieved. Figure Near-infrared probe for protein determination     

Resolution and determination of the absolute configuration of 3,3′4,4′-tetramethyl-1,1′-diphosphaferrocene-2-carboxylic acid

(±)-3,3′4,4′-Tetramethyl-1,1′-diphosphaferrocene-2-carboxylic acid 1 was resolved via diastereomeric salts with brucine. The (R)-absolute configuration of (+)-1 was determined by X-ray crystallography.     

Determination of glucose by a kinetic method on a thin-layer chromatogram using the oxidation of 3,3′,5,5′-tetramethylbenzidine with hydrogen peroxide

The oxidation of 3,3′,5,5′-tetramethylbenzidine with hydrogen peroxide in aqueous solutions in the presence of iron(II, III) was studied on the surface of chromatography paper and TLC plates following the general approach to the purposeful selection of indicator reactions in kinetic methods of analysis. Among the 17 studied model analytes, the strongest inhibitory activity was detected for benzoic acid and glucose. The inhibitory effect of substances is likely due to their interaction with hydroxyl radicals forming in the indicator reaction. The most intense signal of glucose was detected on the surface of silica. Glucose was detected as a light spot against the blue background (R _f ∼ 0.5). A procedure for the semiquantitative determination of glucose on a thin-layer chromatogram based on the dependence of the reflectometer-registered value of the reflectance coefficient on the logarithm of the analyte concentration is proposed. In the range 3 × 10⁻⁵–0.01 M, two concentrations of glucose differing by one half order of magnitude can be distinguished. The detection limit is 1 × 10⁻⁵ M. The procedure was applied to the determination of glucose in beverages, saliva samples, and in a fructose preparation.     

Synthesis of poly(2,2′,3,3′-indole)

New approaches to the synthesis of poly(2,2′,3,3′-indole) were developed based on the photochemical dehydropolycondensation of indole in the presence of iodine and the photochemical polycondensation of 1-(1H-indol-3-yl)-2-iodo-1-ethanone in the absence of catalyst and solvent. A suggested mechanism for the formation of the oligomeric chain in these reactions includes the intermediate formation of 3,3′-diindole with subsequent polycondensation via elimination of hydrogen atoms at position 2 of the dimer pyrrole fragment.     

Peculiarities of the phase behavior of 1,3,3′,5,5′-alkoxybenzoate biphenyls in mixtures with chiral and discotic mesogenes

A synthesis of 1,3,3′,5,5′-alkanoyloxy-(Ia) and 1,3,3′,5,5′-alkoxybenzoate biphenyls (Ib) has been performed. Peculiarities of phase behavior of liquid crystalline 1,3,3′,5,5′-alkoxybenzoate biphenyls (Ib) in mixtures with discotic (1-nitro-2,3,6,7,10,11-hexadecyloxytriphenylene — II and triphenylene 2,3,6,7,10, 11-hexaundecyloxybenzoate — III) and chiral (cholesterol undecylate — IV) were studied with the aim of identifying the type of mesomorphysm. Ib was found to be mutually soluble with II and III and partially soluble with IV. The construction and analysis of the phase diagram of the mixtures of I with II throughout the range of concentrations makes it possible to assign the studied biphenyl Ib to discotic mesogens. An area of the smectic phase, which is formed from the chiral nematic IV and the discotic mesogen Ib (which displays dimorphism in the mesophase) have been found for the first time in the mixtures of these compounds. During cooling, in the mixture with molar ratio 1:1 dendritic textures with grained branches are formed, which are similar to those described in literature for TGB (twist grain boundary) phases. Relying on our studies, we suggest that Ib has a columnar type of the structure in the low-temperature area and a nematic, probably chiral, type in the high-temperature area of the mesophase.     

Microwave Accelerated Synthesis of 2,2′,3,3′-Biphenyltetracarboxylic Dianhydride

Polyimides have been widely used in aerospace and microelectronics due to their excellent mechanical properties and thermo oxidative stability[1].However,most of aromatic polyimides are severe difficult to process because of their bad solubility in common solvents and intractable in their fully imidized forms,which restrict their applications and developments[2,3].