Arylamine Moieties Research Articles

Exploring Solvent and Substituent Effects on the Excited State Dynamics and Symmetry Breaking of Quadrupolar Triarylamine End-Capped Benzothiazole Chromophores by Femtosecond Spectroscopy.

We investigate herein the excited state dynamics and symmetry breaking processes in three benzothiazole-derived two-photon absorbing chromophores by femtosecond fluorescence and transient absorption (fs-TA) spectroscopies in solvents of various polarity. The chromophores feature a quasi-quadrupolar D-π-A-π-D architecture comprised of an electron-withdrawing benzothiazole core and lateral triphenylamine donors (Qbtz-H), while the acceptor strength of the central unit is enforced by attached cyano groups (Qbtz-CN) and the electron-donating strength of the arylamine moieties by introduction of peripheral methoxy groups (Qbtz'-CN). Steady state spectroscopy reveals positive solvatochromism, which is mostly pronounced for Qbtz'-CN. Femtosecond spectroscopy of Qbtz-H reveals the coexistence of the Franck-Condon (FC) state and states populated after symmetry breaking (SB) in low-polarity solvents such as toluene and tetrahydrofuran, while the SB state becomes favorable in polar acetonitrile. For the other two molecules possessing a stronger electron-accepting unit and thus more polar excited state, SB takes place even in low-polarity solvents, as shown by fs-TA spectroscopy. Global fitting of the fs-TA spectra together with investigation of the evolution associated spectra (EAS) reveals the existence of an initial FC state in Qbtz-H, in all studied solvents, which relaxes toward Intermediate Charge Transfer (I-CT) and SB states. On the other hand, for Qbtz-CN and Qbtz'-CN in more polar solvents, the FC state undergoes ultrafast relaxation toward symmetry-broken charge transfer (SB-CT) states which in turn show very fast recombination to the ground state. Our measurements confirm that the extent of symmetry breaking is larger for D-π-A-π-D systems with the stronger acceptor core and increases further by increasing electron-donating strength of triarylamine moieties, giving rise to symmetry breaking in these nonionic quadrupolar molecules with ethynylene (triple bond) π-spacers also in less polar solvents.

Boron, sulfur-doped polycyclic aromatic hydrocarbon emitters with multiple-resonance-dominated lowest excited states for efficient narrowband deep-blue emission

Different from boron, nitrogen-based multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters, boron (B), sulfur (S)-doped polycyclic aromatic hydrocarbons (PAHs) containing 5,9-dithia-13b-boranaphtho[3,2,1-de]anthracene (BSS) skeleton and arylamine moieties in para-positions of boron atoms are developed as a novel kind of MR-TADF emitters for narrowband deep-blue electroluminescence. The molecular design not only utilizes heavy-atom effect of sulfur atoms in BSS skeleton to enhance spin-orbital coupling and promote reverse intersystem crossing, but also uses arylamines as peripheral substituents to modify excited state characteristics. By decreasing electron-donating ability and downshifting HOMO level of arylamines, the lowest excited state for resultant emitter is converted from intersegmental charge transfer state to multiple resonance state localized on BSS skeleton, leading to blue-shifted and narrowed emissions. The B,S-doped PAH emitter bearing carbazole moiety exhibits deep-blue electroluminecence with full-width at half maximum of 29 nm, Commission Internationale de l'Éclairage color coordinates of (0.13, 0.09), and the maximum external quantum efficiency of 21.8 %, representing a new approach toward efficient narrowband deep-blue emission beyond boron, nitrogen-based MR-TADF emitters.

Highly Active Small Aminated Quinolinequinones against Drug-Resistant Staphylococcus aureus and Candida albicans.

Two subseries of aminated quinolinequinones (AQQs, AQQ1–16) containing electron-withdrawing group (EWG) or electron-donating group (EDG) in aryl amine moiety were successfully synthesized. Antimicrobial activity assessment indicates that some of the AQQs (AQQ8–10 and AQQ12–14) with an EDG in aryl amine exhibited strong antibacterial activity against Gram-positive bacterial strains, including Staphylococcus aureus (ATCC® 29213) and Enterococcus faecalis (ATCC® 29212). In contrast, AQQ4 with an EWG in aryl amine displayed excellent antifungal activity against fungi Candida albicans (ATCC® 10231) with a MIC value of 1.22 μg/mL. To explore the mode of action, the selected AQQs (AQQ4 and AQQ9) were further evaluated in vitro to determine their antimicrobial activity against each of 20 clinically obtained resistant strains of Gram-positive bacteria by performing antibiofilm activity assay and time-kill curve assay. In addition, in silico studies were carried out to determine the possible mechanism of action observed in vitro. The data obtained from these experiments suggests that these molecules could be used to target pathogens in different modes of growth, such as planktonic and biofilm.

Electrochromic Polycationic Organoboronium Macrocycles with Multiple Redox States

AbstractPolycationic macrocycles are attractive as they display unique molecular switching capabilities arising from their redox properties. Although diverse polycationic macrocycles have been developed, those based on cationic boron systems remain very limited. We present herein the development of novel polycationic macrocycles by introducing organoboronium moieties into a conjugated organoboron macrocyclic framework. These macrocycles consist of four bipyridylboronium units that are connected by fluorene and either electron‐deficient arylborane or electron‐rich arylamine moieties. Electrochemical studies reveal that the macrocycles undergo reversible multi‐step redox processes with transfer of up to 10 electrons. Switchable electrochromic behavior is demonstrated via spectroelectrochemical studies and the observed color changes are rationalized by correlation with computed electronic transitions using DFT methods.

Electrochromic Polycationic Organoboronium Macrocycles with Multiple Redox States.

Polycationic macrocycles are attractive as they display unique molecular switching capabilities arising from their redox properties. Although diverse polycationic macrocycles have been developed, those based on cationic boron systems remain very limited. We present herein the development of novel polycationic macrocycles by introducing organoboronium moieties into a conjugated organoboron macrocyclic framework. These macrocycles consist of four bipyridylboronium units that are connected by fluorene and either electron-deficient arylborane or electron-rich arylamine moieties. Electrochemical studies reveal that the macrocycles undergo reversible multi-step redox processes with transfer of up to 10 electrons. Switchable electrochromic behavior is demonstrated via spectroelectrochemical studies and the observed color changes are rationalized by correlation with computed electronic transitions using DFT methods.

Electro- and Photochemical Reduction of CO2 by Molecular Manganese Catalysts: Exploring the Positional Effect of Second-Sphere Hydrogen-Bond Donors.

A series of molecular Mn catalysts featuring aniline groups in the second-coordination sphere has been developed for electrochemical and photochemical CO2 reduction. The arylamine moieties were installed at the 6 position of 2,2'-bipyridine (bpy) to generate a family of isomers in which the primary amine is located at the ortho- (1-Mn), meta- (2-Mn), or para-site (3-Mn) of the aniline ring. The proximity of the second-sphere functionality to the active site is a critical factor in determining catalytic performance. Catalyst 1-Mn, possessing the shortest distance between the amine and the active site, significantly outperformed the rest of the series and exhibited a 9-fold improvement in turnover frequency relative to parent catalyst Mn(bpy)(CO)3 Br (901 vs. 102 s-1 , respectively) at 150 mV lower overpotential. The electrocatalysts operated with high faradaic efficiencies (≥70 %) for CO evolution using trifluoroethanol as a proton source. Notably, under photocatalytic conditions, a concentration-dependent shift in product selectivity from CO (at high [catalyst]) to HCO2 H (at low [catalyst]) was observed with turnover numbers up to 4760 for formic acid and high selectivities for reduced carbon products.

Synthesis of chiral anti-1,2-diamine derivatives through copper(I)-catalyzed asymmetric \u03b1-addition of ketimines to aldimines

Chiral 1,2-diamines serve as not only common structure units in bioactive molecules but also useful ligands for a range of catalytic asymmetric reactions. Here, we report a method to access anti-1,2-diamine derivatives. By means of the electron-withdrawing nature of 2- or 4-nitro-phenyl group, a copper(I)-catalyzed asymmetric α-addition of ketimines derived from trifluoroacetophenone and 2- or 4-NO2-benzylamines to aldimines is achieved, which affords a series of chiral anti-1,2-diamine derivatives in moderate to high yields with moderate to high diastereoselectivity and high to excellent enantioselectivity. Aromatic aldimines, heteroaromatic aldimines, and aliphatic aldimines serve as suitable substrates. The nitro group is demonstrated as a synthetical handle by several transformations, including a particularly interesting Fe(acac)3-catalyzed radical hydroamination with a trisubstituted olefin. Moreover, the aryl amine moiety obtained by the reduction of the nitro group serves as a synthetically versatile group, which leads to the generation of several functional groups by the powerful Sandmeyer reaction, such as -OH, -Br, -CF3, and -BPin.

DESIGN, SYNTHESIS AND STRUCTURAL ELUCIDATION OF ARYLOXYAMINOACETYLENIC DERIVATIVES AS ANTIDEPRESSANT ACTIVITY

Depression is the most common illness that affects a large number of individuals in all countries. It is believed that decreased levels of neurotransmitters such as serotonin, norepinephrine and dopamine are the main cause of depression. Selective serotonin reuptake inhibitors (SSRIs) and norepinephrine reuptake inhibitors (SNRIs), their mechanism is to increase the amount of neurotransmitters in the CNS. Design, synthesis and molecular docking of novel compounds namely amino acetylenic derivatives of aryloxy as isostere for aryloxypropylamine. The reaction of 7-methoxy-2-naphthol with propargylbromide generated 7-methoxy-2-(prop-2-yn-1-yloxy) naphthalene (ZR-1). ZR-1 was subjected to Mannich reaction yielded the derivatives of aryloxybutynylamines (ZR-2 to ZR-7). The Mp, FTIR, 1H-NMR, C13-NMR, DSC, elemental analysis and HPLC were consistent with the assigned structures. The molecular docking results obtained for aminoacetylenic compounds showed that the new novel 7-methoxy-2- {[4- (piperidine) but-2-yn-1-yl]oxy}-naphthalene (ZR-4) provide effective π overlap with binding sites of SERT protein by ionic, hydrogen bonding and overlap of aryl and cyclic amine moieties with the amino acids of transporter protein, which produce the binding energy (-109,69 kcal/mol) for ZR-4 relative to paroxetine (-114.18 kcal/mol), that may lead to promising drug in the treatment of depression.

Tailoring of the self-assembled structures and optical waveguide behaviour of arylaminofluorenone derivatives

In this work, the fluorenone molecule was symmetrically difunctionalised in the 3,6-positions with four different arylamine moieties. Using slow evaporation, the four fluorenone derivatives (FO1-4) exhibit good ability to arrange into microstructures in the solid state. The electronic and steric effects of arylamine substituents influence both optical features and aggregation processes, as evidenced by photophysical and XRD characterization. SEM investigations have shown that the four FO1-4 derivatives arrange in four different microstructures. More specifically, the self-assembled 1D microribbon – shaped structure of FO1 exhibited an excellent optical loss coefficient (α) as low as 0.006 dBμm−1, suggesting a potential use of these materials in the field of optical waveguide.

Synthesis of secondary arylamine copolymers with Iron(II) clathrochelate units and their functionalization into tertiary Polyarylamines via Buchwald-Hartwig cross-coupling reaction

We report the synthesis of three secondary arylamine copolymers bearing iron(II) clathrochelate units (CLP1-3). Three of the latter copolymers were post-modified into their tertiary arylamine moieties (PCLP1-3) using a mild palladium-catalyzed Buchwald-Hartwig cross-coupling reaction. Interestingly, the functionalization of the secondary arylamine groups has resulted in the formation of highly soluble target compounds PCLP1-3, which allowed for their simple isolation and full analysis via various techniques. It is noteworthy that a prototypical secondary arylamine iron(II) clathrochelate monomer CLM1 was synthesized and post-modified into its tertiary arylamine target compound CLM2. The current study discloses the first examples on making secondary arylamine copolymers with clathrochelate constituents, and proves the possible post-modification of the latter compounds into tertiary arylamine, which proves the modularity of iron(II) clathrochelate unit to make functional polymers. Formation of the monomers and copolymers was confirmed by 1H- and 13C- nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), Thermogravimetric Analysis (TGA), scanning electron microscopy (SEM), and UV–Vis absorption spectroscopy.

Synthesis of tetrahydroindazol-4(5H)one and 7-thione from reaction of functionalized cyclic enaminones with hydrazine

Functionalized enaminones; 3-N-(aryl)amino-1--oxo-cyclohex-2-ene-2-dithiocarboxylates cyclohex-2-en-1-ones and 3-N-(aryl)amino-2-(N-aryl)thioamido-cyclohex-2-en-1-ones were obtained upon reaction of 3-N(aryl)amino-5,5-dimethyl-1-oxo-cyclohex-2-enes with carbon disulfide in presence of sodium hydroxide in DMSO, followed by methylation with dimethyl sulfate or with phenyl and p-bromophenyl isothiocyanates in toluene or under solvent-free condition, respectively. The cyclization of the dithioesters or the thioamides with hydrazine hydrate was accompanied by a displacement of the 3-N- arylamine moiety by a hydrazine group to give 6-hydrazino-4,4-dimethyl-1,3,4,5-tetrahydroindazole-7-thione or 3-N-(aryl)amino-4,5,6,7-tetrahydro-1H-indazole-4(5H)one respectively. Structure of the indazole derivatives formed was further confirmed from their reaction with acetone or p-nitrobenzaldehyde. The new structures were confirmed using 1HNMR, 13CNMR, 2DNMR, DEPT experiments and mass spectra.

A novel trans-amination process in 3-arylamino- 5,5-dimethylcyclohex-2-en-1-one with nucleophiles and antimicrobial activity of selected products

Reaction of dimedone with arylamines afforded the respective enaminones. Some N-acetyl derivatives were prepared. The reaction of enaminones with hydroxylamine was found to be dependent on the nature of the arylamine moiety and the molar ratio of hydroxylamine to give the mono-, di- or tri-oximes. Cyclization of the trioxime by acetic anhydride gave dihydrobenzo[c][1,2,5]oxadiazol-4(5H)-one-5-O-acetyloxime. Coupling of the synthesized enaminones with benzene diazonium chloride gave 2,4-bis-phenylhydrazones or a mixture of 2-mono hydrazones and bis-hydrazones depending on the nature of the arylamine moiety. Trans-amination of the arylamine of the bis hydrazones with hydroxylamine gave the same1,3-bis oxime derivative. The structures of the synthesized compounds were confirmed by IR, 1HNMR, 13C NMR spectra. The antimicrobial activity of some selected products showed promising results.

Regio- and Enantioselective Iridium-Catalyzed Amination of Racemic Branched Alkyl-Substituted Allylic Acetates with Primary and Secondary Aromatic and Heteroaromatic Amines.

The air- and water-stable π-allyliridium C,O-benzoate modified by ( S)-tol-BINAP, ( S)-Ir-II, catalyzes highly regio- and enantioselective Tsuji-Trost-type aminations of racemic branched alkyl-substituted allylic acetates using primary or secondary (hetero)aromatic amines. Specifically, in the presence of ( S)-Ir-II (5 mol%) in DME solvent at 60-70 °C, α-methyl allyl acetate 1a (100 mol%) reacts with primary (hetero)aromatic amines 2a-2l (200 mol%) or secondary (hetero)aromatic amines 3a-3l (200 mol%) to form the branched products of allylic amination 4a-4l and 5a-5l, respectively, as single regioisomers in good to excellent yield with uniformly high levels of enantioselectivity. As illustrated by the conversion of heteroaromatic amine 3m to adducts 6a-6g, excellent levels of regio- and enantioselectivity are retained across diverse branched allylic acetates bearing normal alkyl or secondary alkyl substituents. For reactants 3n-3p, which incorporate both primary and secondary aryl amine moieties, regio- and enantioselective amination occurs with complete site-selectivity to furnish adducts 7a-7c. Mechanistic studies involving amination of the enantiomerically enriched, deuterium-labeled acetate 1h corroborate C-N bond formation via outer-sphere addition.

Highly Efficient Tuning of Ferromagnetic Spin Interactions in High-Spin Arylamine Structures by Incorporation of Spin Bearing Carbazole Units.

Arylamine moieties oxidized to radical cations are considered promising spin bearing units in high-spin-type compounds. Here, we report the first use of carbazole-3,6-diamine units as efficient, rigid spin containing units. The use of rigid spin bearing units enhances significantly spin exchange interactions. The design using density functional theory calculations shows the progressive increase of the exchange coupling constant dependent on the considered model molecules. Two of the most representative molecules containing flexible (dimer 1) and rigid spin coupling unit (dimer 2) were synthesized. Electrochemical and pulsed-electron paramagnetic resonance nutation studies showed that both dimers can be oxidized to yield a majority of dicationic diradicals exhibiting S = 1 ground states. The high values of the dimer 2 exchange coupling constant obtained both computationally ( J/ kB = 145 K; HHeis. = - JS1 S2) and experimentally ( J/ kB = 90-100 K) indicate the beneficial role of the carbazole moiety incorporated into spin bearing units.

Design, Synthesis and Biological Evaluation of Novel 4-Substituted Coumarin Derivatives as Antitumor Agents.

Herein, fifteen new compounds containing coumarin, 1,2,3-triazole and benzoyl- substituted arylamine moieties were designed, synthesized and tested in vitro for their anticancer activity. The results showed that all tested compounds had moderate antiproliferative activity against MDA-MB-231, a human breast cancer cell line, under both normoxic and hypoxic conditions. Furthermore, the 4-substituted coumarin linked with benzoyl 3,4-dimethoxyaniline through 1,2,3-triazole (compound 5e) displayed the most prominent antiproliferative activities with an IC50 value of 0.03 μM, about 5000 times stronger than 4-hydroxycoumarin (IC50 > 100 μM) and 20 times stronger than doxorubicin (IC50 = 0.60 μM). Meanwhile, almost all compounds revealed general enhancement of proliferation-inhibiting activity under hypoxia, contrasted with normoxia. A docking analysis showed that compound 5e had potential to inhibit carbonic anhydrase IX (CA IX).

Study on bridging moiety effect on asymmetric double D–Π–A dyes

Abstract A series of four new asymmetric di-anchoring dyes is reported, containing identical π spacer, acceptor, phenothiazine (PTZ) and arylamine (ArnN) moieties in the donor part but different bridging moieties (L): N–C bond, C–C bond, phenylamine and triphenylamine. Spectral, electrochemical, and photovoltaic experiments and density functional theory calculations were performed to understand the bridging moiety influence on the performance of A–π–ArnN–L–PTZ–π–A dyes. Among these four dyes, the dye incorporating the triphenylamine bridging unit shows the best photovoltaic performance: an open-circuit voltage (Voc) of 0.72 V, a short-circuit photocurrent density (Jsc) of 11.57 mA cm−2, and a fill factor (FF) of 0.63, corresponding to an overall conversion efficiency of 5.21% under a simulated AM 1.5 G illumination condition. The results indicated that the presence of the biaryl torsion at the bridging position effectively improved the photovoltaic performance of the dye-sensitized solar cells.

Controlling Molecular Conformation for Highly Efficient and Stable Deep-Blue Copolymer Light-Emitting Diodes.

We report a novel approach to achievedeep-blue, high-efficiency, and long-lived solution-processed polymer light-emitting diodes (PLEDs) via a simple molecular level conformation change of an emissive conjugated polymer.We introduce rigid β-phase segments into a 95% fluorene-5% arylamine copolymer emissive layer. The arylamine moieties at low density act as efficient exciton formation sites in PLEDs, whereas the conformational change alters the nature of the dominant luminescence from a broad, charge transfer like emission to a significantly blue-shifted and highly vibronically structured excitonic emission. As a consequence, we observe a significant improvement in the Commission International de L'Eclairage ( x, y) coordinates from (0.149, 0.175) to (0.145, 0.123) while maintaining high efficiency and improved stability. We achieve a peak luminous efficiency, η = 3.60 cd/A, and a luminous power efficiency, ηw = 2.44 lm/W, values that represent state-of-the-art performance for single copolymer deep-blue PLEDs. These values are 5-fold better than for otherwise-equivalent, β-phase poly(9,9-dioctylfluorene) PLEDs (0.70 cd/A and 0.38 lm/W). This report represents the first demonstration of the use of molecular conformation as a simple but effective method to control the optoelectronic properties of a fluorene copolymer; previous examples have been confined to homopolymers.

Multifunctional Antioxidants with High Activity at Elevated Temperatures Based on Intramolecular Synergism

Multifunctional antioxidants with three active fragments were prepared through a simple two‐step synthesis process. These novel compounds exhibited higher efficiency when inhibiting the oxidation of hydrocarbons compared to commercial products at 180 °C. The rational framework gives rise to the unique intramolecular synergism between arylamine moiety and sulfide moiety that can scavenge radicals and decompose peroxides simultaneously.

Thiophene–Arylamine Hole‐Transporting Materials in Perovskite Solar Cells: Substitution Position Effect

AbstractTwo facile thiophene–arylamine hole‐transporting materials, obtained by varying the substitution position of arylamine moieties on the thiophene π linker, are reported. The substitution position effect of two hole‐transporting materials on the performance of perovskite solar cells is further investigated theoretically and experimentally. The compound in which arylamine moieties are located on the 2,5‐substitution position of thiophene shows better conjunction than that with the 3,4‐substituent. When used as hole‐transporting materials in CH3NH3PbI3‐based solar cells, the 2,5‐substituent exhibits a power conversion efficiency (PCE) of 15.13 %, which is over 40 % higher than that of the 3,4‐substituent. Moreover, the PCE of 2,5‐substituent based device is comparable with that of 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,9′‐spirobifluorene (spiro‐OMeTAD).

Spiro[fluorene-9,9′-xanthene]-based hole transporting materials for efficient perovskite solar cells with enhanced stability

Spiro[fluorene-9,9′-xanthene]-based hole transporting materials functionalized with four-armed arylamine moieties located at different positions are synthesized for perovskite solar cells.