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Attempts to carry out intramolecular annulation of 9,10‐diarylbenzo[h]quinolines and 9,10‐di(hetero)arylphenanthrenes to aromatics with expanded π‐conjugated systems by using different methods are described. The starting compounds (9,10‐diarylbenzo[h]quinolines and 9,10‐di(hetero)arylphenanthrenes) were prepared by C−C bond activation in 1‐azabiphenylene or biphenylene followed by insertion of internal alkynes. Interestingly, unlike in purely carbon‐based aromatics, the course of the annulation turned out to be highly dependent on the structure of maternal compounds. In a handful of cases were obtained the expected or desired products. In others, unexpected rearrangements of the basic molecular frameworks were observed. [ABSTRACT FROM AUTHOR]

This work reports a biomimetic synthesis of polyarylated fluorene derivatives. The molecules are formed via intramolecular electrophilic aromatic substitution, resembling a cyclization leading towards the natural selaginpulvilins from selaginellins. The scope of the reaction was investigated, and the products were obtained in 60–95 % yields. Some of the compounds decompose to a stable radical. We investigated the nature and the origin of the radical using experimental methods, including EPR or electrochemical measurements, as well as theoretical methods, such as DFT calculations. Based on our observations, we hypothesize, that phenoxy radicals are formed in the first instance, which however undergo internal rearrangement to thermodynamically more stable carbon‐centered radicals. The preliminary data also show the cytotoxic properties of some of the molecules. [ABSTRACT FROM AUTHOR]

Catalytic cyclotrimerization routes to symmetrical [9]helical indenofluorene were explored by using different transition–metal complexes and thermal conditions. Depending on the reaction conditions, the cyclotrimerizations were accompanied by dehydro‐Diels–Alder reaction giving rise to another type of aromatic compounds. Structures of both symmetrical [9]helical cyclotrimerization product as well as the dehydro‐Diels–Alder product were confirmed by single‐crystal X‐ray diffraction analyses. Limits of enantioselective cyclotrimerization were assessed as well. DFT calculations shed light on the reaction course and the origin of diminished enantioselectivity. [ABSTRACT FROM AUTHOR]

Plasma polymers (PPs) can easily modify material surfaces to improve their bio‐applicability due to match‐made surface‐free energy and functionality. However, cell adhesion to PPs typically composed of various functional groups has not yet been fully understood. We explain the origin of strong resistance to trypsin treatment previously noted for nonendothelial cells on amine PPs. It is caused mainly by nonspecific adhesion of negatively charged parts of transmembrane proteins to the positively charged amine PP surface, enabled by thin glycocalyx. However, endothelial cells are bound primarily by their thick, negatively charged glycocalyx and sporadically by integrins in kinetic traps, both cleaved by trypsin. Cell scratching by atomic force microscopy tip confirmed the correlation of trypsin resistance to the strength of cell adhesion. [ABSTRACT FROM AUTHOR]

Herein, we report the design and synthesis of a series of novel cationic nitrogen‐embedded polyaromatic hydrocarbons with a planar geometry. The synthetic pathway is based on catalytic C−C/C−H bond activation relay that enabled preparation of regioselectively 5,6,10,11‐tetrasubstituted naphtho[2,1,8‐ija]quinolizinium salts bearing various types of substituents. Single‐crystal X‐ray analyses of selected compounds confirmed planarity of the quinolizinium core. Most of the prepared compounds exhibited strong fluorescence (Φs up to >99 %) ranging from 420–600 nm depending on the substitution pattern. According to DFT calculations LUMO is always distributed over the quinolizinium framework regardless of the attached substituents, whereas delocalization of HOMO is related to the substitution pattern. Electrochemical measurements show irreversible reduction of all compounds, which is supported by the calculated location of LUMO orbitals. [ABSTRACT FROM AUTHOR]

The enantioselective synthesis of chiral [7]‐helical dispirodihydro[2,1‐c]indenofluorenes (DSF‐IFs) was achieved for the first time in good yields with high er values (er up to 99 : 1). The crucial step of the whole reaction sequence was the enantioselective intramolecular [2+2+2] cycloaddition of tethered triynediols to indenofluorenediols, which was catalyzed by a Rh/SEGPHOS® complex. Further transformations led to the corresponding DSF‐IFs. The prepared helically chiral DSF‐IFs combine circularly polarized luminescence (CPL) activity (glum=∼10−3) with exceptionally high fluorescence quantum yields (up to Φlum=0.97). [ABSTRACT FROM AUTHOR]

A first series of fluorinated [n]helical compounds (n=5 and 6) with the dihydroindenofluorene scaffold was prepared in 5 or 9 (octafluorinated dihydroindenofluorene) steps and their photophysical properties were determined. Rh‐catalyzed intramolecular [2+2+2] cyclotrimerization of triyndiols, which were prepared in a modular fashion from simple starting material such as fluorinated haloarylcarbaldehydes, to the intermediate [n]helical dihydroindeno[2,1‐c]fluorene‐5,8‐diols was the crucial synthetic step and proceeded with high efficacy. Their further transformation gave the desired selectively fluorinated bispirodihydroindeno[2,1‐c]fluorenes. Their absorption and emission spectra were recorded. The fluorescence quantum yields were up to 92 % and the emission maxima were red‐shifted in comparison with their non‐fluorinated counterparts (386‐413 nm). [ABSTRACT FROM AUTHOR]

This work presents a general approach for synthesis of substituted [5]‐helical dispiroindeno[2,1‐c]fluorenes based on Rh‐catalyzed intramolecular cyclotrimerization of triynes. This approach was further extended for the first synthesis of configurationally stable [7]‐helical dispiroindeno[2,1‐c]fluorenes. A series of variously substituted derivatives was prepared and their photophysical and electrochemical properties were evaluated. Their fluorescence emission maxima were in the region of 351–428 nm and quantum yields up to 88 % are the highest measured among the full‐carbon helical compounds. [ABSTRACT FROM AUTHOR]

Catalysis, C-C bond cleavage, cyclotrimerization, dispiroindenofluorenes, [9]helical structure Keywords: catalysis; C-C bond cleavage; cyclotrimerization; dispiroindenofluorenes; [9]helical structure EN catalysis C-C bond cleavage cyclotrimerization dispiroindenofluorenes [9]helical structure 1 1 1 10/24/23 20231018 NES 231018 B Direction signs b show a driver which turn to take to reach the desired destination. [Extracted from the article]

A series of unsymmetrically substituted diastereoisomeric (Ra,R) and (Sa,R) bipyridine N,N′‐dioxides was synthesized by using oxidative coupling of the corresponding metallated tetrahydroisoquinoline N‐oxides in the presence of iodine. The N,N′‐dioxides contained substituted aryl groups with electron‐donating or electron‐accepting groups in the near vicinity of the N,N′‐dioxide moiety. Their catalytic activity was tested in a series of reactions of allyltrichlorosilane with various substituted benzaldehydes, thiophenecarbaldehyde, and cinnamaldehyde. The reactions proceeded with high enantioselectivities (up to 98 % ee) with catalyst loadings as low as 0.5 mol‐%. Furthermore, allylation reactions of (E)‐3‐iodomethacrylaldehyde were also carried out to give chiral (E)‐1‐iodo‐2‐methylpenta‐1,4‐dien‐3‐ol, a convenient building block for the synthesis of natural products. The allylations proceeded with high enantioselectivities (up to ca. 99 % ee) with a catalyst loading of 2.5 mol‐%. A series of unsymmetrically substituted diastereoisomeric (Ra,R) and (Sa,R) bipyridine N,N′‐dioxides were tested as catalysts for the enantioselective allylation of various aldehydes. Homoallylic alcohols were obtained with enantiopurities of up to 99 % ee. [ABSTRACT FROM AUTHOR]

Plasma polymers with NHx groups were deposited from cyclopropylamine in low pressure radio frequency (RF) discharges. The amount of NHx decreased with increasing average power Pav, whereas the layer dissolution in water decreased and high Pav led to a slight film swelling. The C2C12 cells demonstrated very high adhesion to the layers regardless of the deposition conditions. Although the surface chemistry of amine-rich layers should enhance the cell proliferation, the WST-1 assay, and immunocytochemistry revealed lower cell proliferation and viability on the layers exhibiting above 18% of relative thickness loss in water. Promising results were obtained on the layers with better water stability and bearing 7-10% of NHx. [ABSTRACT FROM AUTHOR]

The Ir-catalyzed borylation of [4]helicene under different reaction conditions was studied for the first time. The results indicate that monoborylation proceeds to give a mixture of 2- and 3-borylated products in good yields (up to 74 % isolated yield). It was possible to shift the selectivity in favor of the 3-borylated product by using sterically demanding ligands. The monoborylated [4]helicenes were further arylated by using a Suzuki-Miyaura cross-coupling or oxidized to the corresponding phenols in very good yields. [ABSTRACT FROM AUTHOR]

A comparative study of the catalytic allylations and crotylations of ( E)- and ( Z)-haloacrylaldehydes by Lewis bases (chiral N, N′-dioxides) and Brønsted acids (chiral phosphoric acids) was undertaken. The reactions proceeded with high enantio- and diastereoselectivities with slightly better asymmetric induction observed in the case of N, N′-dioxide catalysis. The formed enantioenriched chiral unsaturated haloalcohols could be considered general building blocks, as they could be used in the syntheses of more complex natural products possessing substituted 1,3-diene fragments. This was exemplified by the formal total syntheses of pteronenone and antillatoxin. [ABSTRACT FROM AUTHOR]

3-Hydroxypiperidine scaffolds were enantioselectively constructed in an atom-economical way by sequential action of light and rhodium upon N-allylglyoxylamides. In a formal sense, the allylic CH bond was selectively cleaved and enantioselectively added across the ketonic carbonyl group with migration of the double bond (carbonyl-ene-type reaction). [ABSTRACT FROM AUTHOR]

Biosensors have been extensively developed and applied for biomedical and environmental studies. Although there are many different types of biosensing techniques, all these methods require immobilization of biomolecules. Therefore, this is a critical issue in the development of any sort of biosensor affecting its operational properties. In this work, we address this critical issue by employing cyclopropylamine plasma polymerization to deposit stable amine thin films on the surface of quartz crystal microbalance (QCM) biosensors. The antibody specific to human serum albumin (anti-HSA) is attached to the QCM surface via cross-linkage obtained by intermediate reaction with glutaraldehyde. All steps of the bio-immobilization are controlled by XPS and FTIR to characterize surface and layer (bulk) chemistry. The results obtained with the antibody linked through the CPA plasma-polymerized layer are comparable with the results obtained previously when the same antibody AL-01 was linked to the surface using the self-assembled thiol monolayer based on cystamine. [ABSTRACT FROM AUTHOR]

The present investigation of cyclopropylamine (CPA) plasma polymerization in pulsed and continuous wave radio frequency (RF) discharges leads to the proposition of conditions at which amine-rich films exhibit a good stability in contact with water. The analyses reveal complex structure of CPA plasma polymers containing hydrocarbon chains, primary and secondary amines, nitriles and possibly imines. The decomposition of the monomer in plasma is progressing with the composite parameter W/ F (RF power over monomer flow rate) but, in pulsed discharges, it is possible to deposit the films with N/C ratio above 0.24 using higher monomer flow rate. At the optimized monomer flow rate the 280 nm thick film exhibits only 20% thickness loss after 48 h immersion in water and still contains about 5 at% of the NH x environment. [ABSTRACT FROM AUTHOR]

The enantioselective allylation of an aromatic aldehyde to give a chiral homoallylic alcohol was employed as the key step in the syntheses of a flobufen metabolite and dapoxetine. In the former case, the homoallylic alcohol moiety (99 % ee) was converted into a five-membered lactone ring with good preservation of the optical purity, and the target compound, a flobufen metabolite, was obtained in 95 % ee. In the latter case, the homoallylic alcohol moiety (97 % ee) was transformed over several steps into a 3-aminopropanol moiety. During the course of the synthesis, the gradual loss of optical purity was observed, and the target compound, dapoxetine, was obtained in 85 % ee. [ABSTRACT FROM AUTHOR]

Variable-angle spectroscopic ellipsometry is employed for the optical characterization of non-stoichiometric silicon nitride thin films exhibiting inhomogeneity formed by refractive index and extinction index changes through the film thickness. For all the film samples, the best fit of the experimental data is achieved if, in addition to the inhomogeneity, an overlayer or roughness of the upper boundary is included. However, distinguishing of these two defects is found not to be possible. The influence of working gas ratio, deposition temperature and on/off time on the film properties is studied. The refractive index and extinction coefficient is found to increase with increasing working gas ratio and less significantly with decreasing deposition temperature. It is also found that the inhomogeneity increases with decreasing deposition temperature, and the deposition rate of the films decreases with increasing working gas ratio. The influence of the on/off time on the film properties is practically unimportant. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Keywords: catalysis; circularly polarized luminescence; enantioselective cyclotrimerization; helical compounds; indenofluorene EN catalysis circularly polarized luminescence enantioselective cyclotrimerization helical compounds indenofluorene 11237 11237 1 08/07/21 20210805 NES 210805 B Helicenes are intriguing and inherently chiral compounds b with fascinating 3D architecture. Cover Feature: Rhodium-Catalyzed Enantioselective Synthesis of Highly Fluorescent and CPL-Active Dispiroindeno[2,1-c]fluorenes (Chem. Eur. J. 44/2021) Catalysis, circularly polarized luminescence, enantioselective cyclotrimerization, helical compounds, indenofluorene. [Extracted from the article]

The cover picture shows an old, stone‐made, spiral staircase that resembles the unique helical structure of helicenes. Despite the fact that helicenes are known for more than 100 years, their chemistry of post‐functionalization is still significantly underdeveloped. This lack of “tools” limits the synthesis and exploration of the distinctive optoelectrical properties of new materials based on carbohelicenes. Details on the post‐functionalization of [4]helicene by a C–H activation/borylation process are discussed in the article by D. Nečas, et al. on p. 5647 ff. [ABSTRACT FROM AUTHOR]