Enzymatic Electrosynthesis of Alkanes by Bioelectrocatalytic Decarbonylation of Fatty Aldehydes

An enzymatic electrosynthesis system was created by combining an aldehyde deformylating oxygenase (ADO) from cyanobacteria that catalyzes the decarbonylation of fatty aldehydes to alkanes and formic acid with an electrochemical interface. This system is able to produce a range of alkanes (octane to propane) from aldehydes and alcohols. The combination of this bioelectrochemical system with a hydrogenase bioanode yields a H₂/heptanal enzymatic fuel cell (EFC) able to simultaneously generate electrical energy with a maximum current density of 25 μA cm^?2 at 0.6 V and produce hexane with a faradaic efficiency of 24 %.     

From S,N‐Heteroacene to Large Discotic Polycyclic Aromatic Hydrocarbons (PAHs): Liquid Crystal versus Plastic Crystalline Materials with Tunable Mechanochromic Fluorescence

A novel type of discotic polycyclic aromatic hydrocarbon (PAH) based on an enlarged dibenzo[a,c]phenazine core has been developed. The large conjugated mesogenic core with increased dipole moment derived from S,N heteroatoms facilitates the formation of highly ordered columnar superstructures both in solution and bulk. Columnar mesophases, including liquid crystal (LC) and plastic crystal (PC) assemblies could form unprecedentedly based on the same PAH core. The cores are delicately modulated by the peripherical alkoxy chains. Both mesogens have mechanochromic fluorescent (MCF) character, which is also structure dependent and correlated with the different mesophase formation. For the first time, MCF properties can be realized in such a large conjugated mesogenic system.     

Brønsted Acid Enabled Nickel‐Catalyzed Hydroalkenylation of Aldehydes with Styrene and its Derivatives

A Brønsted acid enabled nickel‐catalyzed hydroalkenylation of aldehydes and styrene derivatives has been developed. The Brønsted acid acts as a proton shuttle to transfer a proton from the alkene to the aldehyde, thereby leading to an economical and byproduct‐free coupling. A series of synthetically useful allylic alcohols were obtained through one‐step reactions from readily available styrene derivatives and aliphatic aldehydes in up to 88 % yield and with high linear selectivity.     

Gold‐Catalyzed Regiospecific C−H Annulation of o‐Ethynylbiaryls with Anthranils: π‐Extension by Ring‐Expansion En Route to N‐Doped PAHs

We describe a novel, short, and flexible approach to diverse N‐doped polycyclic aromatic hydrocarbons (PAHs) through gold‐catalyzed π‐extension of anthranils with o‐ethynylbiaryls as reagents. This strategy uses easily accessible starting materials, is simple due to high step and atom economy, and shows good functional‐group compatibility as well as scale‐up potential. Mechanistically, the tandem reaction is proposed to involve a nucleophilic addition/ring opening/regiospecific C?H annulation/protodeauration sequence terminated by a Friedel–Crafts‐type cyclization. Photophysical studies of the products indicated violet‐blue fluorescence emission with quantum yields up to 0.45.     

Bottom‐up Construction of π‐Extended Arenes by a Palladium‐Catalyzed Annulative Dimerization of o‐Iodobiaryl Compounds

A straightforward method was developed for construction of aromatic compounds with a triphenylene core. The method involves Pd‐catalyzed annulative dimerization of o‐iodobiaryl compounds by double C?I and C?H bond cleavage steps. Simple reaction conditions are needed, requiring neither a ligand nor an oxidant, and the reaction tolerates a wide range of coupling partners without compromising efficiency or scalability. Significantly, the tetrachloro‐substituted synthon, 1,6,11‐trichloro‐4‐(4‐chlorophenyl)triphenylene, can be generated and used to prepare a series of fully fused, small graphene nanoribbons by a late‐stage arylation with arylboronic acids and a subsequent Scholl reaction. The synthetic strategy enables bottom‐up access to extended π‐systems in a controlled manner.     

Host-guest complexation behaviour of emissive calix[3]naphthobipyrrole toward aromatic guests

A new hexapyrrolic macrocycle composed of three naphthobipyrrole units has been synthesized which exhibited different emission changes with hydrogen pyrophosphate and benzoate ions. Phosphate ions caused red shifting of the fluorescence band of calixnaphthobipyrrole while benzoate ions resulted in quenching of the same. The fluorescence quenching was further utilized for investigating binding preferences of the probe with neutral aromatic guest molecules substituted with groups having varied electron withdrawing abilities. The extent of quenching with the neutral guests increased with the increasing electron deficiency on the aromatic ring of the guest. The fluorescence quenching has been ascribed to electron transfer from the host to the guest species.     

Iron‐Catalyzed Aminative Cyclization/Intermolecular Homolytic Aromatic Substitution Using Oxime Esters and Simple Arenes

Intermolecular C?H alkylation of simple arenes in the presence of an iron catalyst has been achieved in a cascade manner with an aminative cyclization triggered by N?O bond cleavage of an alkene‐tethered oxime ester. Various arenes, including electron‐rich and electron‐poor arenes, and heteroarenes can be employed in the reaction system. Regioselectivity and radical trapping experiments support the involvement of alkyl radical species, which undergo a homolytic aromatic substitution (HAS) to afford the arylation products.     

Determination of Aromatic Hydrocarbons,Phenols, and Polycyclic Aromatic Hydrocarbons in Water by Stir bar Sorptive Extraction and Gas Chromatography–Mass Spectrometry

The paper presents procedures for stir bar sorptive extraction for selected priority substances that include polycyclic aromatic hydrocarbons, phenols, and benzene and its aromatic homologs. Three extraction and instrumental analysis procedures were developed for the determination of 16 compounds. The developed solid-phase extraction methods using a movable element had high recoveries above 70%. Extraction methods were optimized by selecting an appropriate time and temperature of the process, the sample pH, and stirring speed. The detection limits for the polycyclic aromatic hydrocarbons ranged from 0.33?µg/dm³ for naphthalene to 2.22?µg/dm³ for phenanthrene. Slightly higher limits of quantification were obtained for phenols: from 9.21?µg/dm³ for phenol to 0.51?µg/dm³ for 2,4,6-trimethylphenol. The highest limit of quantification for the tested compounds was obtained for benzene, with a value of 36.6?µg/dm³, while for toluene and ethylbenzene, the values did not exceed 2.7?µg/dm³.     

Phase-transfer catalysis in reactions of electrophilic aromatic substitution

Electrophilic substitution in aromatic compounds under conditions of phase-transfer catalysis is considered. Catalysts of phase transfer of electrophilic reagents are used; their efficiency and the mechanism of their action in organic solvent-water systems are discussed.This review is based on materials of the report delivered at the Conference Phase-Transfer Catalysis. New Ideas and Methods (March 1994).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1895–1900, October, 1995.     

Effect of substituents on the first ionization potentials of aromatic and heteroaromatic compounds. The {ie2532-1} resonance parameters of Si-, Ge-, Sn-, and Pb-containing fragmentsresonance parameters of Si-, Ge-, Sn-, and Pb-containing fragments

The first vertical ionization potentials (IP) of monosubstituted benzenes, hexafluorobenzenes, naphthalenes, anthracenes, furans, thiophenes, and selenophenes and the secondIP of monosubstituted tellurophenes are related to the inductive, resonance, and polarization parameters of substituents by dependences of the type {ie2532-2}. The contribution of polarizability effect, {ie2532-3}, to theIP value is determined by the degree of delocalization of the positive charge in radical cations formed upon photoionization of the compounds studied. The {ie2532-4} resonance parameters of nineteen Si-, Ge-, Sn-, and Pb-containing substitutents in naphthalene, furan, and thiophene series were calculated. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2434–2438, December, 1998.