Phenyl Substituents Research Articles

Trans-Bis[bis-(di-phenyl-phosphan-yl)methane-κ2P,P']di-chlorido-ruthenium(II): a triclinic polymorph.

The title compound, [RuCl2(C25H22P2)2] or [RuCl2(dppm)2] (dppm = bis-(di-phenyl-phosphan-yl)methane, C25H22P2) crystallizes as two half-mol-ecules (completed by inversion symmetry) in space group P (Z = 2), with the RuII atoms occupying inversion centers at 0,0,0 and 1/2, 1/2, 1/2, respectively. The bidentate phosphane ligands occupy equatorial positions while the chlorido ligands complete the distorted octa-hedral coordination spheres at axial positions. The bite angles of the phosphane chelates are similar for the two mol-ecules [(P-Ru-P)avg. = 71.1°], while there are significant differences in the twisting of the methyl-ene backbone, with a distance of the methyl-ene C atom from the RuP4 plane of 0.659 (2) and 0.299 (3) Å, respectively, and also for the phenyl substituents for both mol-ecules due to variations in weak C-H⋯Cl inter-actions.

Phenanthroimidazole-functionalized coumarins: Synthesis and luminescence

Four phenanthroimidazole-functionalized coumarins (C-PI-Bu, C-PI-CN, C-PI-TRZ, and C-PI-Cz) containing a 7-diethylaminocoumarin unit and a phenanthroimidazole (PI) unit with different phenyl substituent at the N1-position, were successfully synthesized and characterized by NMR (1H and 13C), high-resolution mass spectrometry and elemental analysis. The structure-property relationships of the compounds were revealed by systematically investigating their thermal stability, photophysical and electrochemical properties. All four compounds exhibit bright blue-green emission with high fluorescence quantum yield (75.36 %–97.00 %) in dichloromethane solution and green emission in the solid-state. The organic light-emitting diodes (OLEDs) with a device of ITO/PEDOT:PSS (30 nm)/TBADN:coumarin derivative (x, wt%) (25 nm)/TPBi (35 nm)/Liq (2 nm)/Al (150 nm) were fabricated and characterized. The above OLEDs showed the best EL performances with a maximum brightness (Lmax) of 8500 cd/m2, a maximum current efficiency (CEmax) of 3.45 cd/A, and a maximum external quantum efficiency (EQEmax) of 1.30 %.

Synthesis and antibacterial activities of some novel hybrid compounds based on 2‐mercapto‐3‐arylquinazolin‐4(3H)‐one scaffold bearing specific coumarin

AbstractTwo series of novel hybrid compounds, in which a variety of 2‐mercapto‐3‐arylquinazolin‐4(3H)‐ones (3a‐d)/6‐bromo‐2‐mercapto‐3‐phenylquinazolin‐4(3H)‐one (9) act as fundamental moieties are incorporated in particular 3‐(2‐bromoacetyl)‐2H‐chromen‐2‐one (4) or 2‐chloro‐N‐(2‐oxo‐2H‐chromen‐3‐yl)acetamide (5) via alkylation of the thiol group in quinazolin‐4(3H)‐one ring, were synthesized. The key intermediates (3a‐d) and (9) were prepared by the reaction of anthranilic acid (1)/2‐amino‐5‐bromobenzoic acid (8) with carbon disulfide and appropriate aromatic amines in an alkaline medium. These compounds’ structures were confirmed by comparing their physical characteristics and spectral data to the earlier ones. Ten novel products (6a‐d, 7a‐d, 10, 11) were synthesized and the structures were determined by their IR, 1H‐NMR, 13C‐NMR and HR‐MS spectral data. Subsequently, their antimicrobial activities were estimated in vitro test against four bacterial strains including P. aeruginosa NRRL B‐14781 and E. coli NRRL B‐409 (Gram‐negative), B. cereus ATCC 10876 and L. monocytogenes ATCC 13932 (Gram‐positive), by agar well diffusion assay. The outcome showed that all hybrid compounds have potential inhibition of tested Gram‐negative bacteria. Compound (6d) revealed remarkable antibacterial effects on P. aeruginosa and E. coli growth. Besides, compounds (6a), (7a), (7d) and (10) have also inhibitory effects on B. cereus strain at tested concentrations. The compounds mentioned above contain the 3‐chlorophenyl/phenyl substituent at position 3 in the quinazoline ring.

Investigations of flexible cycloalkyl substituents on pyridine‐imine based nickel(II)‐ and palladium(II)‐catalyzed ethylene oligomerization

AbstractCycloalkyls show rich conformational change. According to our previous work, the flexible cycloalkyl substituted α‐diimine system generated polyethylene with good elastic properties and much higher branching densities. In this contribution, we introduce the cycloalkyls into the pyridine‐imine catalytic system. A series of novel pyridine‐imine ligands and the corresponding nickel(II) and palladium(II) complexes with cycloalkyl and phenyl substituents for ethylene oligomerization were designed, synthesized and characterized. The nickel(II) complexes with cycloalkyl substituent showed high oligomerization activity (up to 5.90 × 106 g mol−1 h−1) and generated ethylene oligomers with low to moderate branching density (17–57/1000C). The palladium(II) complexes showed moderate oligomerization activity (up to 8.33 × 103 g mol−1 h−1) and can yield high branching density (107–187/1000C) oligomers. In addition, compared to the catalyst with rigid phenyl substituent, the catalysts with flexible cycloalkyl substituents exhibited higher oligomerization activity and yielded ethylene oligomers with higher branching density under the same conditions. © 2023 Society of Industrial Chemistry.

Structure-guided design and synthesis of ATP-competitive N-acyl-substituted sulfamide d-alanine-d-alanine ligase inhibitors

d-Alanine-d-alanine ligase (Ddl) catalyses the ATP-dependent formation of d-Ala-d-Ala, a critical component in bacterial cell wall biosynthesis and is a validated target for new antimicrobial agents. Here, we describe the structure-guided design, synthesis, and evaluation of ATP-competitive N-acyl-substituted sulfamides 27–36, 42, 46, 47 as inhibitors of Staphylococcus aureus Ddl (SaDdl). A crystal structure of SaDdl complexed with ATP and d-Ala-d-Ala (PDB: 7U9K) identified ATP-mimetic 8 as an initial scaffold for further inhibitor design. Evaluation of 8 in SaDdl enzyme inhibition assays revealed the ability to reduce enzyme activity to 72 ± 8 % (IC50 = 1.6 mM). The sulfamide linker of 8 was extended with 2-(4-methoxyphenyl)ethanol to give 29, to investigate further interactions with the d-Ala pocket of SaDdl, as predicted by molecular docking. This compound reduced enzyme activity to 89 ± 1 %, with replacement of the 4-methoxyphenyl group in 29 with alternative phenyl substituents (27, 28, 31–33, 35, 36) failing to significantly improve on this (80–89 % remaining enzyme activity). Exchanging these phenyl substituents with selected heterocycles (42, 46, 47) did improve activity, with the most active compound (42) reducing SaDdl activity to 70 ± 1 % (IC50 = 1.7 mM), which compares favourably to the FDA-approved inhibitor d-cycloserine (DCS) (IC50 = 0.1 mM). To the best of our knowledge, this is the first reported study of bisubstrate SaDdl inhibitors.

Rational design and eco-friendly one-pot multicomponent synthesis of novel ethylidenehydrazineylthiazol-4(5H)-ones as potential apoptotic inducers targeting wild and mutant EGFR-TK in triple negative breast cancer

A novel series of ethylidenehydrazineylthiazol-4(5H)-ones were synthesized using various eco-friendly one-pot multicomponent synthetic techniques. The anticancer activity of compounds (4a-m) was tested against 11 cancer cell lines. While the IC50 of all compounds was evaluated against the most sensitive cell lines (MDA-MB-468 and FaDu). Our SAR study pinpointed that compound 4a, having a phenyl substituent, exhibited a significant growth inhibition % against all cancer cell lines. The frontier anticancer candidates against the MDA-MB-468 were also examined against the wild EGFR (EGFR-WT) and mutant EGFR (EGFR-T790M) receptors. Most of the synthesized compounds exhibited a higher inhibitory potential against EGFR-T790M than the wild type of EGFR. Remarkably, compound 4k exhibited the highest inhibitory activity against both EGFR-WT and EGFR-T790M with IC50 values (0.051 and 0.021 µM), respectively. The pro-apoptotic protein markers (p53, BAX, caspase 3, caspase 6, caspase 8, and caspase 9) and the anti-apoptotic key marker (BCL-2) were also measured to propose a mechanism of action for the compound 4k as an apoptotic inducer for MDA-MB-468. Investigation of the cell cycle arrest potential of compound 4k was also conducted on MDA-MB-468 cancer cells. We also evaluated the inhibitory activities of compounds (4a-m) against both EGFR-WT and EGFR-T790M using two different molecular docking processes.

Nitrene Cyclization of 2-(Trichloromethyl)-5-phenylpyrimidines: Application to the Synthesis of 2-(Trichloromethyl)pyrimido[4,5-b]indoles and Related Heterocycles

AbstractAn aromatic C–H nitrene insertion of 2-(trichloromethyl)pyrimidines bearing a phenyl substituent at the C-5 position is described. Treatment of 4-chloro-5-phenyl-2-(trichloromethyl)pyrimidines with sodium azide in DMF or the reflux of 4-azido-5-phenyl-2-(trichloromethyl)pyrimidines in toluene provided 2-(trichloromethyl)pyrimido[4,5-b]indole derivatives in moderate yields. Excellent yields of this heterocyclic system were obtained through the aromatic C–H insertion with the Du Bois catalyst. This is an attractive approach for synthesizing pyrimido[4,5-b]indoles with a trichloromethyl substituent in the pyrimidine moiety.

Novel Sulfone 2-Aminobenzimidazole Derivatives and Their Coordination Compounds: Contribution of the Ethyl and Phenyl Substituents on Non-Covalent Molecular Interactions; Biological Antiproliferative Activity

New sulfone 2-aminobenzimidazole derivatives were designed and synthesized. Their nickel(II), copper(II), zinc(II), cadmium(II) and mercury(II) compounds were obtained and fully characterized by spectroscopic and analytical techniques. Single crystal X-ray structural analysis was performed in order to study the relevant intra and inter non-covalent interactions, mainly H···π, lone pair···π, and π···π, highlighting the difference between the terminal ethyl and phenyl groups in such interactions. Dimeric and trimeric supramolecular syntons were found for some of these compounds. Additionally, their antiproliferative activity was investigated, finding that the copper(II) compounds with the sulfone phenyl derivative were the most active.

High-Efficiency Mono-Cyclopentadienyl Titanium and Rare-Earth Metal Catalysts for the Production of Syndiotactic Polystyrene.

Syndiotactic polystyrene (SPS) refers to a type of thermoplastic material with phenyl substituents that are alternately chirally attached on both sides of an aliphatic macromolecular main chain. Owing to its excellent physical and mechanical properties, as well as its chemical stability, high transparency, and electrical insulation characteristics, SPS is used in a wide variety of technical fields. SPS is commonly produced via the stereoselective transition metal-catalyzed coordination polymerization method mediated by stereospecific catalysts, which consists of anionic mono-cyclopentadienyl derivative η5-coordinated single active metal centers (referred to as "mono-Cp'-M"), with active center metals involving Group 4 transition metals (with an emphasis on titanium) and rare-earth (RE) metals of the periodic table. In this context, the use of mono-cyclopentadienyl titanocene (mono-Cp'Ti) catalysts and mono-cyclopentadienyl rare-earth metal (mono-Cp'RE) metallocene catalysts for the syndiospecific polymerization of styrene is discussed. The effects of the mono-cyclopentadienyl ligand structure, cationic active metal types, and cocatalysts on the activity and syndiospecificity of mono-Cp' metallocene catalysts are briefly surveyed.

Diastereoselective Synthesis of α-Aryl-Substituted LnDOTA Chelates from Achiral Starting Materials by Deracemization Under Mild Conditions.

Substituted derivatives of the DOTA framework are of general interest to alter chelate properties and facilitate the conjugation of chelates to other molecular structures. However, the scope of substituents that can be introduced into the α-position has traditionally been limited by the availability of a suitable enantiopure starting materials to facilitate a stereoselective synthesis. Tetra-substituted DOTA derivatives with phenyl and benzoate substituents in the α-position have been prepared. Initial syntheses used enantiopure starting materials but did not afford enantiopure products. This indicates that the integrity of the stereocenters was not preserved during synthesis, despite the homo-chiral diastereoisomer being the major reaction product. The homochiral diastereoisomer could be produced as the major or sole reaction product when starting from racemic or even achiral materials. Deracemization was found to occur during chelation through the formation of an enolate stabilized by the aryl substituent. This general ability of aryl groups to enable deracemization greatly increases the range of substituents that can be introduced into DOTA-type ligands with diastereochemical selectivity.

Design and synthesis of isoniazid-based pyrazolines as potential inhibitors of Mycobacterium tuberculosis with promising radical scavenging action: In-vitro and in-silico evaluations

In view of the devastating tuberculosis infections and emerging resistance against available drugs, novel 5-phenyl-3-(thiophen-2-yl)-4,5-dihydro-1H-pyrazol-1-yl)(pyridin-4-yl)methanones were designed and efficiently synthesized. The in-vitro biological screening of the synthesized isoniazid-based pyrazolines reveals their remarkable antimycobacterial and antioxidant ability. The pyrazoline analog 4i containing 2,4-dimethoxy phenyl substituent exhibited the highest anti-TB action against the H37Rv Mtb strain with an MIC of 6.35 μM, while the pyrazoline analog 4f with 2-nitrophenyl substituent demonstrates the highest radical quenching ability with an IC50 of 96.19 μM. Through DFT execution, the quantum-mechanical properties, reactivity indices, and molecular electrostatic potential mapping of the synthesized entities were determined, showing their optimum chemical and biological compatibility. The potent antitubercular effect of the synthesized entities was further supported by docking assessment against one of the most promising antitubercular targets, InhA (PDB Id: 2X23), displaying a significant binding range of −8.3 to −9.6 kcal/mol, and favorable binding interactions with the key residues like TYR 158, THR 196. etc. The pharmaceutical compliance of the synthesized moieties was further assessed through in-silico ADMET screening, which illustrates their excellent drug likeliness and appreciable pharmacokinetic behavior.

Pyramidalization at the sp2‐Hybridized ipso‐Carbon Atom of Phenyl Compounds

AbstractIn this study we investigate the pyramidalization of the sp2‐hybridized center at the ipso‐carbon atom Ci of phenyl compounds on the theoretical side by DFT calculations of toluene, t‐butylbenzene, and ethylbenzene and on the experimental side by a scatter plot analysis of 14,169 structures of ethylbenzene compounds Cβ−CαH2−C6H5 with three open positions for variation at Cβ, accumulated in the Cambridge Structural Database. In a 360° rotation about the bond between Cα of the substituent and the ipso‐carbon atom Ci of the phenyl ring, the pyramidalization performs three maxima and minima. A comparison of structures with pyramidalization and its hypothetical counterparts without pyramidalization shows that pyramidalization is associated with a gain of energy. The data reveal that it is the carbon atom Cα of the phenyl substituent, which on pyramidalization bends away from the phenyl plane. Pyramidalization of sp2‐hybridized centers is an omnipresent member in molecular weak interactions.

In silico design, docking simulation, and ANN-QSAR model for predicting the anticoagulant activity of thiourea isosteviol compounds as FXa inhibitors

AbstractNovel oral anticoagulants are frequently used for the pharmacotherapy of thromboembolic disorders but still have drawbacks and side effects. While numerous synthetic and semisynthetic derivatives of nontoxic isosteviol possess potential therapeutic properties, including anticoagulant activity. Besides, thiourea is recognized in medicinal chemistry research as a component of a common framework of many drugs or bioactive compounds. The present work combines molecular modeling and docking approach for searching and designing novel thiourea isosteviol-based compounds as potential FXa inhibitors. Elaborated regression model well reflects the relationships between experimentally determined anticoagulant activity and molecular descriptors and may be used for the prediction of FXa inhibitory activity of novel thiourea isosteviol compounds. Among 20 descriptors incorporated into the ANN model, 60% are 2D topological descriptors, 25% describe three-dimensional molecular structure, and remaining 15% belong to constitutional descriptors. Additionally, docking simulation confirms the prominent binding of the newly in silico designed molecules with the active sites of the protein, which may be the lead molecules and can be further optimized for the efficient pharmacodynamic and pharmacokinetic profiles. Based on the results obtained, thiourea derivatives of isosteviol with 3-chloro-4-fluorophenyl, 3-fluoro-4-chlorophenyl or 4-(oxazol-5-yl)phenyl substituent may be promising FXa inhibitors. Findings reported in the present work can be used as valuable information for the development of anticoagulants.

Synthesis, Molecular Docking and Molecular Dynamic Studies of Thiazolidineones as Acetylcholinesterase and Butyrylcholinesterase Inhibitors

Neurodegenerative diseases are chronic, progressive, age-related, and characterized by the loss of function of neurons caused by the accumulation of free radicals and oxidative stress. Although the prevalence of neuro disorders is rising, therapeutic efficacy is still limited due to various variables, including the blood-brain barrier. Hence, to identify molecules targeting different enzymes like acetylcholinesterase, butyrylcholinesterase and peroxiredoxins, a series of thiazolidineone derivatives were designed and synthesized. Schiff base was synthesized and cyclised with thioglycolic acid to yield thiazolidineones (T1-T10). Structural characterization was performed by IR, Mass and 1H NMR spectral studies and then subjected to in silico analysis against acetylcholinesterase (6O4W) and butyrylcholinesterase (1P0P). Compound T-9 (–10.10 kcal/mol) and T-8 (–7.65 kcal/mol) have shown excellent binding with 6O4W and 1P0P, respectively, compared with other derivatives. In addition, the compounds were checked for antioxidant activity by analyzing the interactions with peroxiredoxins (1URM), and compound T-4 was active. According to the physicochemical and ADME properties of Qikprop, synthesized compounds can be considered druglike molecules. In vitro, acetylcholinesterase inhibitory activity reveals compound T-8 as the most potent AChE inhibitor. In vitro, antioxidant activity found that compound T-4 has significant antioxidant activity. The compound T-8, with better docking scores and decisive acetylcholinesterase inhibitory action, was further explored to validate the molecular interactions through molecular dynamics studies. It was observed that compounds with the benzyl sulfonyl group (T-6 to T-10) showed higher AChE inhibitory potency than derivatives with phenyl substituents in place of the benzyl sulfonyl group (T-1 to T-5). Therefore, it is inferred that the sulfonyl group and substituents at the para position are essential for the higher inhibitory activity of compounds. Thus, there is plenty of scope for further study in developing these as promising lead compounds.

Gamma Radiolysis of Phenyl-Substituted TODGAs: Part II

ABSTRACT The radiolytic degradation chemistry of three phenylated analogs of N,N,N’,N’-tetraoctyl diglycolamide (TODGA) was investigated: 2-(2-(di-n-octylamino)-2-oxoethoxy)-N,N-di-n-octyl-2-phenylacetamide (PhTODGA), which has a phenyl substituent bound to a central methylene, 2-(2-(di-n-octylamino)-2-oxo-1-phenylethoxy)-N,N-di-n-octylpropanamide (PhMeTODGA), which also contains a methyl substituent bound to the methylene on the other side of the ether moiety, and, 2-(2-N-n-hexyl-N-phenylamino)-2-oxoethoxy)-N-n-hexyl-N-phenylacetamide (DHDPDGA), which has phenyl substituents located on the amide groups instead of the central methylenes. In Part II of this series of papers radiolytic degradation products were identified after separation with liquid chromatography by High Resolution, Accurate-Mass mass spectrometry and collision-induced dissociation. At least twenty-two radiolytic degradation products were identified for PhTODGA, twenty-nine for PhMeTODGA, and over three dozen for DHDPDGA. The suite of radiolytic degradation products of these three investigated ligands was significantly larger than has been reported for previously studied diglycolamides, owing to their asymmetric nature, and to the identification of several new degradation mechanisms, including addition of methyl, hydroxyl, and nitrogen oxide radicals, that have not been previously reported for diglycolamides. Degradation products that contained addition of a NO2 or NO3 group were particularly prevalent for DHDPDGA, likely due to the phenyl side-groups. Several of these newly observed mechanisms do not appear to depend on the presence of the phenyl groups, suggesting these novel mechanisms may apply to other diglycolamides

Synthesis and crystal structure of a bench-stable pyridinium ketene hemiaminal: 1-(1-eth-oxy-ethen-yl)-2-[meth-yl(phen-yl)amino]-pyridin-1-ium tri-fluoro-methane-sulfonate.

The novel bench-stable N-quaternized ketene N,O-acetal, C16H19N2O+·CF3O3S-, was synthesized and its structure determined. The title compound is a rare example of a pyridinium ketene hemiaminal for which a crystal structure has been determined, joining the 2-chloro-1-(1-ethyoxyethen-yl)pyridin-1-ium tri-fluoro-methane-sulfonate salt from which it was synthesized. The cationic species of the title compound can be defined by three individually planar fragments assembling into a non-coplanar cation. The phenyl substituent extending from the amino nitro-gen atom and the ethyoxyvinyl substituent extending from the pyridine N atom are oriented on the same side of the mol-ecule and maintain the closest coplanar relationship of the three fragments. Supra-molecular inter-actions are dominated by C-H⋯O inter-actions from the cation to the SO3 side of the tri-fluoro-methane-sulfonate anion, forming a two-dimensional substructure.

Impact of pendant substituents on post-polymerization functionalization and electronic properties in stereoregular non-conjugated pendant electroactive polymers

Recent reports on non-conjugated pendant electroactive polymers (NCPEPs) have demonstrated the significance of altering structural variables specifically the stereoregularity, the nature of the pendant group and the length of the spacer connecting that group to the backbone for tuning of their optoelectronic properties. The only synthetic approach that allows for selectively studying the effects of tuning these variables without additional superimposed effects of varied molecular weights and tacticities is the post-polymerization functionalization methodology in which parent polymers are synthesized first and then functionalized with the respective pendant groups and spacers. However, specifically for tuning of the pendant group itself, the scope of such post-polymerization functionalization methods remains largely underexplored. Here, the compatibility of the established photochemical thiol-ene post-polymerization method with various pendant groups is investigated for functionalization of stereoregular and stereorandom poly(allyl methacrylates) made via anionic polymerization using an organolithium initiator. Carbazole and a family of four 3,6-disubstituted carbazoles with phenyl, methoxy, nitrile and t-butyl substituents were investigated as the respective pendant groups. With the phenyl, methoxy and nitrile substituted pendant groups limitations of the scope of the thiol-ene methodology due to limited solubility and vulnerability to photochemical side reactions could be demonstrated. In contrast, t-butyl substituents did not impede the post-polymerization functionalization. The corresponding functionalized NCPEPs were characterized and effects of substitution of the carbazole pendant group with t-butyl groups on the optoelectronic properties of the polymers are discussed. Overall, this work demonstrates critical limitations of the thiol-ene functionalization method as well as their origin when applied to differently substituted pendant groups.

Tuning Crystal Packing and Magnetic Properties in a Series of [Dy12] Metallocubanes Based on Azobenzene Derivatives of Salicylic Acid.

A series of four new Dy12 dodecanuclear clusters based on azobenzene derivative ligands of salicylic acid (L1-L4) has been synthesized and characterized in the crystalline phase using X-ray diffraction on single crystal and powder, IR spectroscopy, elemental analysis, and DSC-TGA methods. It was revealed that all obtained clusters exhibit the formation of the similar metallic cluster nodes, as vertex-sharing heterocubanes, obtained from four Dy3+ cations, three bridging hydroxyl groups, and O atoms from the salicylic ligands. The coordination geometry around the Dy(III) centers has been carefully analyzed. Whereas Dy12-L1 and Dy12-L2 with L1 and L2 containing Me and OMe groups in para positions of the phenyl rings, respectively, form similar porous 3D diamond-like molecular networks due to CH-π interactions, for Dy12-L3 with L3 bearing NO2-electron-withdrawing group, the generation of 2D molecular grids assembled by π-π staking is observed, and for Dy12-L4 with L4 bearing phenyl substituent, 3D hexagonal channels have been generated. The complexes Dy12-L1, Dy12-L2, and Dy12-L3 exhibit a zero-field slow magnetic relaxation effect. After UV irradiation of Dy12-L1, a decrease of the magnetic anisotropy energy barrier displaying the possibility of control over magnetic properties by the external stimulus has been observed.

Enantiopure J-Aggregate of Quaterrylene Bisimides for Strong Chiroptical NIR-Response.

Chiral polycyclic aromatic hydrocarbons can be tailored for next-generation photonic materials by carefully designing their molecular as well as supramolecular architectures. Hence, excitonic coupling can boost the chiroptical response in extended aggregates but is still challenging to achieve by pure self-assembly. Whereas most reports on these potential materials cover the UV and visible spectral range, systems in the near infrared (NIR) are underdeveloped. We report a new quaterrylene bisimide derivative with a conformationally stable twisted π-backbone enabled by the sterical congestion of a fourfold bay-arylation. Rendering the π-subplanes accessible by small imide substituents allows for a slip-stacked chiral arrangement by kinetic self-assembly in low polarity solvents. The well dispersed solid-state aggregate reveals a sharp optical signature of strong J-type excitonic coupling in both absorption (897 nm) and emission (912 nm) far in the NIR region and reaches absorption dissymmetry factors up to 1.1 × 10-2. The structural elucidation was achieved by atomic force microscopy and single-crystal X-ray analysis which we combined to derive a structural model of a fourfold stranded enantiopure superhelix. We could deduce that the role of phenyl substituents is not only granting stable axial chirality but also guiding the chromophore into a chiral supramolecular arrangement needed for strong excitonic chirality.

New Insights into the Catalytic Activity of Second Generation Hoveyda–Grubbs Complexes Having Phenyl Substituents on the Backbone

One of the most effective synthetic pathways to produce unsaturated compounds and polymers, meant for both industrial and pharmaceutical applications, is olefin metathesis. These useful reactions are commonly promoted by ruthenium-based precatalysts, namely the second-generation Grubbs’ catalyst (GII) and complexes bearing a styrenyl ether ligand, referred to as the second-generation Hoveyda–Grubbs’ catalyst (HGII). By altering the steric and electronic characteristics of substituents on the backbone and/or on the nitrogen atoms of the NHC ligand, it is possible to increase the reactivity and stability of second-generation ruthenium catalysts. The synthesis of an HG type II complex bearing two anti-phenyl backbone substituents (anti-HGIIPh-Mes) with mesityl N-substituents is reported. The catalytic performances of the new complex were investigated in standard ring-closing metathesis (RCM) and ring-opening metathesis polymerization (ROMP) and compared to those of the analogue complex syn-HGIIPh-Mes and to the classic HGII complex. A thorough analysis of the temperature dependence of the performances, along with a detailed comparison with the commercially available HGII, is conducted. The HGIIPh-Mes complexes are more thermally stable than their parent HGII, as shown by the fact that their activity in the ROMP of 5-ethylidene-2-norbornene does not alter when the polymerization is carried out at room temperature after the complexes have been held at 180 °C for two hours, making them particularly interesting for materials applications.