Pd/C-catalyzed Reductive Mono-N-alkylation of Nitrophenol Derivatives in One-pot Way

A range of different nitrophenol derivatives were converted in one‐pot to the corresponding secondary alkyl aminophenols in good to excellent yields by using ketones as alkyl source and hydrogen over 10 wt% Pd/C as reducing agent. In all examples, except for one, the secondary amine was the sole alkylation product isolated. When aldehydes were used as alkyl source, the corresponding tertiary amine as a sole alkylation product was isolated.     

Photoinitiating behavior of benzophenone derivatives covalently bonded tertiary amine group for UV‐curing acrylate systems

A series of benzophenone derivatives (N‐BPs) containing tertiary amine group used as hydrogen abstraction‐type (type II) photoinitiators were synthesized through the addition reaction of secondary amines with 4‐(2,3‐epoxypropyloxy) benzophenone. The chemical structures were characterized with ¹H NMR, FTIR spectroscopy, and UV spectrum measurements. The N‐BPs showed the higher absorption in 300–400 nm than benzophenone (BP). The photoinitiating activity was examined based on the photopolymerization of 1,6‐hexanediol diacrylate using photo‐DSC method. The results showed that the photoinitiating efficiency was negatively affected by the molecular structure of alkyl group connected to the tertiary amine with the order of isopropyl (N‐BPI) < methyl (N‐BPM) < ethyl (N‐BPE) < propyl (N‐BPP). Moreover, the diethanolamine‐modified benzophenone derivative (N‐BPOH) had the highest‐photoinitiating efficiency for free radical polymerization systems among the N‐BPs. Copyright © 2011 John Wiley & Sons, Ltd.     

Photosensitization of carbazole derivatives in cationic polymerization with a novel sensitivity to near‐UV light

Photosensitizers based on the carbazole structure were designed and developed for cationic polymerization. Along with triarylsulfonium and diaryliodonium salts, the carbazole derivatives showed a high photosensitization effect in the cationic photopolymerization of epoxides. The photophysical properties of the carbazole derivatives were studied in terms of electronic absorption, fluorescence, and phosphorescence spectrometry. Moreover, a unique photosensitization mechanism of the carbazole derivatives was discussed after studies of the fluorescence quenching, redox behavior, and kinetics of the photopolymerization by time‐resolved fluorescence spectrometry, cyclic voltammetry, and photo differential scanning calorimetry, respectively. The results confirmed the redox photosensitization of the carbazole derivatives in cationic polymerization. The photosensitization of the carbazole and its ring or N‐alkylated derivatives occurred predominantly in singlet excited states at the rate of the diffusion limit, whereas the carbazole derivatives with carbonyl substituents sensitized onium salts via triplet excited states on the basis of the Rehm–Weller equation in the photoinduced electron‐transfer process. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 90–100, 2000     

Color‐Tunable Solid‐State Fluorescence Emission from Carbazole‐Based BODIPYs

Several carbazole‐based boron dipyrromethene (BODIPY) dyes were synthesized by organometallic approaches. Thiazole, benzothiazole, imidazole, benzimidazole, triazole, and indolone substituents were introduced at the 1‐position of the carbazole moiety, and boron complexation of each dipyrrin generated the corresponding compounds 1 , 2 a , and 3 – 6 . The properties of these products were investigated by UV/Vis and fluorescence spectroscopy, cyclic voltammetry, X‐ray crystallography, and DFT calculations. These compounds exhibited large Stokes shifts, and compounds 1 , 2 a , and 3 – 5 fluoresced both in solution and in the solid state. Complex 2 a showed the highest fluorescence quantum yield (Φ_F) in the solid state, therefore boron complexes of the carbazole–benzothiazole hybrids 2 b – f , which had several different substituents, were prepared and the effects of the substituents on the photophysical properties of the compounds were examined. The fluorescence properties showed good correlation with the results of crystal‐packing analyses, and the dyes exhibited color‐tunable solid‐state fluorescence.     

Photostabilizing activity of tertiary hindered amines

The influence of the N-alkyl group of tertiary hindered amines on the photostabilization of polymers was studied. The photostabilizing effects of the tertiary amine derivatives of 4-benzoyloxy-2,2,6,6-tetramethylpiperidine ( 1a ) in polypropylene were compared. All tertiary amine derivatives having α-H to hindered N showed higher effectiveness than 1a . Model liquid phase photoxidations were carried out by irradiating (UV-lamp) the solutions of tertiary hindered amines containing tert-butyl hydroperoxide as a photoinitiator. The tertiary hindered amines were oxidized more easily than corresponding parent hindered amine and converted to the parent amine, which was identified as its salt, resulting from the carboxylic acid produced from the N-alkyl group by oxidation. The thermal reaction of the tertiary hindered amines with tert-butyl hydroperoxide was also studied in the liquid phase. The tertiary hindered amines decomposed tert-butyl hydroperoxide more rapidly than the parent secondary hindered amine, and generated the parent amine. It was also found that the photostabilizing effects of tertiary hindered amines for polyolefins were higher than that of the parent secondary hindered amine.     

Fluoro‐protected carbazole main‐chain polymers as a new class of stable blue emitting polymers

The protection of the 3,6‐positions of 9‐alkyl‐9H‐carbazole repeat units with fluorine substituents in 2,7‐linked main‐chain polymers as well as in copolymers with triaryl amine repeat units affords blue emitting materials with enhanced electrolytic stability. The electronic conjugation of this new class of materials is more extended than that of the equivalent polymers where the 3,6‐positions are protected with methyl substitutions as a result of the smaller steric hindrance of their fluorine substituents. Attachment of fluorine‐protecting groups at the 3,6‐positions of carbazole repeat units in the homopolymers resulted in materials with relatively high ionization potentials (5.71 eV). However, introduction of triaryl amine comonomers as alternating repeat units provided carbazole/triaryl amine copolymers with a low ionization potential (5.25 eV), a very high quantum yield of fluorescence in solution (0.96), and narrow emission bands [full width at half maximum (FWHM) = 52 nm]. The preparation of this new class of materials together with a study of their electronic and photophysical properties is presented. Copyright © 2007 John Wiley & Sons, Ltd.     

Phase structure and thermomechanical properties of primary and tertiary amine‐cured epoxy/silica hybrids

Several kinds of organic–inorganic hybrids were synthesized from an epoxy resin and a silane alkoxide with a primary amine‐type curing agent or tertiary amine curing catalyst. In the hybrid systems cured with the primary amine‐type curing agent, the storage modulus in the high‐temperature region increased, and the peak area of the tan δ curve decreased. Moreover, the mechanical properties were improved by the hybridization of small amounts of the silica network. However, these phenomena were not observed in the hybrid systems cured with the tertiary amine catalyst. The differences in the network structures of the hybrid materials with the different curing processes were characterized with Fourier transform infrared (FTIR). In the hybrid systems cured with the primary amine‐type curing agent, FTIR results showed the formation of a covalent bond between silanol and hydroxyl groups that were generated by the reaction of an epoxy group with an active hydrogen of the primary amine. However, this phenomenon was not observed in the hybrids cured with the tertiary amine. The hybrids with the primary amine showed a homogeneous microstructure in transmission electron microscopy observations, although the hybrids cured with the tertiary amine showed a heterogeneous structure. These results mean that the differences in the interactions between the organic and inorganic phases significantly affect the properties and microstructures of the resultant composites. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1071–1084, 2001     

比率型SO2荧光探针的构建及细胞成像研究

本文构建了一种基于苯并吲哚季铵盐结构的荧光探针用于检测SO₂衍生物。该荧光探针能够快速、灵敏、高选择性地检测HSO₃^-和SO₃^2-,并显示出颜色和荧光变化双重响应。其比率荧光强度（I₄₆₂/I₅₈₈）与HSO₃^-的浓度（0～16 μmol/L）之间具有良好的线性关系,检测限低至12 nmol/L。¹HNMR表明该探针的响应机制为1,4-亲核加成反应。激光共聚焦荧光成像结果表明,CZBI具有良好的细胞膜通透性,并且可以通过比率荧光成像实现对细胞内SO₂衍生物的监测。     

Discovery of Novel D‐A and D‐π‐A Structured Carbazole‐Based Formazan Dyes: Synthesis,Characterization, and Spectroscopic Studies

In the current study, new carbazole‐based formazan dyes, D‐A and D‐π‐A, were synthesized, and their spectroscopic properties were studied for the first time. For this aim, carbazole aldehyde compounds were modified by the derivatization of carbazole, a natural electron‐donor compound, from 3‐ and 9‐position. Then, hydrazone derivatives were synthesized from these aldehyde derivatives. Finally, D‐A ( 5A–C ) and D‐π‐A ( 6A–C ) carbazole–formazan dyes were obtained by the interaction of the hydrazone compounds with p‐substituted aniline. After characterization of the structures of these compounds, photophysical properties of the carbazole–formazans were studied in the different polarity media (i.e., acetonitrile, toluene, and chloroform) in order to detect the solvent effects. Because of the π‐conjugated bridge and the electron acceptor nitro group at the para position, D‐π‐A structured carbazole–formazan dye 6C showed the highest Stokes shift of 155 nm.     

Organometallic Rhenium Complexes Divert Doxorubicin to the Mitochondria

Doxorubicin, a well‐established chemotherapeutic agent, is known to accumulate in the cell nucleus. By using ICP‐MS, we show that the conjugation of two small organometallic rhenium complexes to this structural motif results in a significant redirection of the conjugates from the nucleus to the mitochondria. Despite this relocation, the two bioconjugates display excellent toxicity toward HeLa cells. In addition, we carried out a preliminarily investigation of aspects of cytotoxicity and present evidence that the conjugates disrupt the mitochondrial membrane potential, are strong inhibitors of human Topoisomerase II, and induce apoptosis. Such derivatives may enhance the therapeutic index of the aggressive parent drug and overcome drug resistance by influencing nuclear and mitochondrial homeostasis.     

2,6,8‐Trisubstituted 3‐Hydroxychromone Derivatives as Fluorophores for Live‐Cell Imaging

We present the synthesis and photophysical characterisation of a series of structurally diverse, fluorescent 2,6,8‐trisubstituted 3‐hydroxychromone derivatives with high fluorescence quantum yields and molar extinction coefficients. Two of these derivatives ( 9 and 10 a ) have been studied as fluorophores for cellular imaging in HeLa cells and show excellent permeability and promising fluorescence properties in a cellular environment. In addition, we have demonstrated by photophysical characterisation of 3‐isobutyroxychromone derivatives that esterification of the 3‐hydroxyl group results in acceptable and useful fluorescence properties.     

Synthesis and Photoluminescent Properties of New Aza‐Indenofluorene Derivatives

The carbazole derivatives 5a – h were synthesized by four steps involving Suzuki coupling of boronic acid 1 with 1‐bromo‐2‐nitrobenzene, followed with the Cadogan ring closure reaction. Their UV and photoluminescence properties are also reported, and the compounds showed medium‐to‐strong photoluminescence between 370 and 446 nm at the concentration of 1 × 10⁻⁵ M CH₂Cl₂. Also, the X‐ray structure of the carbazole derivative 6 was elucidated by an X‐ray diffractometer. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 24:18–24, 2013; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21058     

Cytotoxicity of Mahanimbine from Curry Leaves in Human Breast Cancer Cells (MCF-7) via Mitochondrial Apoptosis and Anti-Angiogenesis

Mahanimbine (MN) is a carbazole alkaloid present in the leaves of Murraya koenigii, which is an integral part of medicinal and culinary practices in Asia. In the present study, the anticancer, apoptotic and anti-invasive potential of MN has been delineated in vitro. Apoptosis cells determination was carried out utilizing the acridine orange/propidium iodide double fluorescence test. During treatment, caspase-3/7,-8, and-9 enzymes and mitochondrial membrane potentials (Δψm) were evaluated. Anti-invasive properties were tested utilizing a wound-healing scratch test. Protein and gene expression studies were used to measure Bax, Bcl2, MMP-2, and -9 levels. The results show that MN could induce apoptosis in MCF-7 cells at 14 µM concentration IC₅₀. MN-induced mitochondria-mediated apoptosis, with loss in Δψm, regulation of Bcl2/Bax, and accumulation of ROS (p ≤ 0.05). Caspase-3/7 and -9 enzyme activity were detected in MCF-7 cells after 24 and 48 h of treatment with MN. The anti-invasive property of MN was shown by inhibition of wound healing at the dose-dependent level and significantly suppressed mRNA and protein expression on MMP-2 and -9 in MCF-7 cells treated with a sub-cytotoxic dose of MN. The overall results indicate MN is a potential therapeutic compound against breast cancer as an apoptosis inducer and anti-invasive agent.     

Crosslinking of vinyl‐terminated biphenyl and naphthalene side‐chain liquid‐crystalline poly(epichlorohydrin) derivatives

We performed the crosslinking of vinyl‐terminated biphenyl and naphthalene side‐chain liquid‐crystalline polyethers using peroxide‐type initiators with and without the addition of tertiary amine promoters. The crosslinking temperatures were chosen in the range of mesophase stability to allow the mesophase order to be frozen. The biphenyl derivatives, with a high isotropization temperature, were crosslinked to a large extent. This led to anisotropic thermosets. To crosslink naphthalene derivatives, amine promoters were needed, but degrees of crosslinking were lower, and anisotropic elastomers were obtained. Crosslinking processes were studied by differential scanning calorimetry, polarized optical microscopy, and Fourier transform infrared spectroscopy. The nature of the frozen mesophase was confirmed by X‐ray diffraction studies on mechanically oriented samples. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2237–2244, 2002     

Blocking ACAT‐1 Activity for Tumor Therapy with Fluorescent Hyperstar Polymer‐Encapsulated Avasimible

Targeting the distinct cholesterol metabolism of tumor cells is proposed as a novel way to treat tumors. Blocking acyl‐CoA cholesterol acyltransferase‐1 (ACAT‐1) by the inhibitor avasimible (Ava), which elevates intracellular free cholesterol levels, is shown to effectively induce apoptosis. However, Ava faces disadvantages of poor water solubility, a short half‐life, and no capability for fluorescence detection, which have greatly limited its application. Herein, a fluorescent hyperstar polymer (FHSP) is developed to encapsulate Ava to improve its ability to inhibit HeLa cells and K562 cells. The results of this study show that the obtained Ava–FHSP micelles possess a high drug loading capacity of 22.7% and bright green fluorescence. Ava and Ava–FHSP are cytotoxic to both HeLa and K562 cells and cause reductions in cell size, nuclear lysis, and chromatin condensation and hindered proliferation of both cell types by causing S phase cell cycle arrest. Further mechanistic analysis indicates that Ava–FHSP reduces the protein and messenger RNA expression of ACAT‐1 and significantly increases intracellular free cholesterol levels, which can increase endoplasmic reticulum stress and finally cause cell apoptosis. All these results suggest that this fluorescent hyperstar polymer represents a potential therapeutic tumor strategy by changing the cholesterol metabolism of tumor cells.     

Synthesis of dithiocarbamate bearing azobenzene group and use for RAFT polymerization of vinyl monomers

A novel dithiocarbamate bearing azobenzene group, 2‐(phenylazo‐phenoxy‐carbonyl) prop‐2‐yl 9H‐carbazole‐9‐carbodithioate (APCDT), was synthesized and used as a RAFT agent in the polymerization of methyl methacrylate (MMA). The results showed that the controllability to the polymerization of MMA was promoted with APCDT as RAFT agent compared to 2‐(ethoxycarbonyl) prop‐2‐yl 9H‐carbazole‐9‐carbodithioate (EPCDT) under the same experimental conditions. The reason was attributed to the higher chain transfer constant of APCDT than that of EPCDT in the presence of more bulkier and more electrophilic azobenzene moiety. In addition, the RAFT polymerizations of St and methylacrylate (MA) using APCDT as the RAFT agent were also carried out. The ultraviolet spectrum and fluorescence spectrum of the obtained polymers were investigated. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2886–2896, 2007     

HPLC determination of γ‐aminobutyric acid and its analogs in human serum using precolumn fluorescence labeling with 4‐(carbazole‐9‐yl)‐benzyl chloroformate

In this study, a simple analytical method for the determination of γ‐aminobutyric acid, gabapentin, and baclofen by using high‐performance liquid chromatography with fluorescence detection was developed. An amidogen‐reactive fluorescence labeling reagent, 4‐(carbazole‐9‐yl)‐benzyl chloroformate was first used to sensitively label these analytes. The completed labeling of these analytes can be finished rapidly only within 5 min at the room temperature (25°C) to form 4‐(carbazole‐9‐yl)‐benzyl chloroformate labeled fluorescence derivatives. These labeled derivatives expressed strong fluorescence property with the maximum excitation and emission wavelengths of 280 and 380 nm, respectively. The labeled derivatives were analyzed using a reversed‐phase Eclipse SB‐C18 column within 10 min with satisfactory shapes. Excellent linearity (R² > 0.995) for all analytes was achieved with the limits of detection and the limits of quantitation in the range of 0.25?0.35 and 0.70?1.10 μg/L, respectively. The proposed method was used for the simultaneous determination of γ‐aminobutyric acid and its analogs in human serum with satisfactory recoveries in the range of 94.5–97.5%.     

Conjugated polyelectrolytes and neutral polymers with poly(2,7‐carbazole) backbone: Synthesis,characterization, and photovoltaic application

Poly(2,7‐carbazole) neutral polymers (PC‐N, PC‐NOH, and PC‐P) and polyelectrolytes (PC‐NBr and PC‐SO₃Na) with hydrophilic pendant groups of ammonium, phosphonate, and sulfonate were synthesized as interlayers for cathode modifications in bulk‐heterojunction photovoltaic cells (BHJ PVCs). The absorptions of the polymers were determined by the poly(2,7‐carbazole) backbone, showing absorption peaks at ～390 nm for their solutions and films. Because of large intermolecular interactions, excimer emissions with wavelengths higher than 500 nm were found in the photoluminescence spectra of the films of the polymers, which weakened the light emissions of the polymers. PC‐N, PC‐NBr, PC‐NOH, and PC‐P possessed comparable HOMO levels of ?5.23 eV and LUMO levels of ?2.4 eV, but HOMO and LUMO levels of PC‐SO₃Na were up‐lying to ?4.91 and ?2.12 eV, respectively. PC‐N, PC‐NBr, PC‐NOH, and PC‐P were selected to construct thin interlayers in BHJ PVCs with PFO‐DBT35:PCBM = 1:4 as the active layer. Compared with traditional Al cathode, bilayer cathodes with the interlayers showed improvements of open‐circuit voltages and short‐circuit currents of the PVCs. PC‐NOH was the best for the photovoltaic performances and over 20% increase of power conversion efficiency (PCE) was achieved. The bilayer cathodes would have great potential to further elevate PCE of BHJ PVCs with other active layer materials. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Triphenylamine and carbazole‐modified iridiumIII 2‐phenylpyridine complexes: Synthesis,anticaner application and targeted research

Four half‐sandwich iridium^III (Ir^III) triphenylamine or carbazole‐modified 2‐phenylpyridine (TPA/Cz‐PhPy) complexes ([(η⁵‐Cp*)Ir(C^N)Cl]) were synthesized and characterized. Compared with cisplatin, these complexes show higher activity to A549, HepG2 and HeLa cells, with the IC₅₀ values changed from 2.5 ± 0.1 μM to 14.8 ± 2.6 μM. Additionally, complexes could effectively prevent the migration of cancer cells. Ir^III TPA/Cz‐PhPy complexes could bind to protein and transport through serum protein, catalyze the oxidation of nicotinamide‐adenine dinucleotid (NADH) and induce the accumulation of reactive oxygen species, and eventually lead to apoptosis, which was also confirmed by flow cytometry. Moreover, prominent targeted fluorescence property confirmed that Ir^III TPA/Cz‐PhPy complexes were involved in non‐energy dependent intracellular uptake mechanism, effectively accumulated in lysosomes and damage the integrity of acidic lysosomes, and eventually induce cell death. Above all, TPA/Cz‐appended half‐sandwich Ir^III phenylpyridine complexes are promising anticancer agents with dual functions, including migration inhibition and lysosomal damage.     

Water Solubilization of Fullerene Derivatives by β‐(1,3‐1,6)‐d‐Glucan and Their Photodynamic Activities toward Macrophages

Anionic and neutral fullerene derivatives were dissolved in water by using β‐(1,3‐1,6)‐d ‐glucan (β‐1,3‐glucan) as a solubilizing agent. In the water‐solubilized complexes, the concentrations of fullerene derivatives were ≈0.30 mm and the average particle sizes were ≈90 nm. The β‐1,3‐glucan‐complexed fullerene derivative with a carboxylic acid was found to have higher photodynamic activity toward macrophages under visible‐light irradiation (λ >610 nm) than other β‐1,3‐glucan‐complexed fullerene derivatives. This result suggests that carboxylic acid moieties in the complex enhance the binding affinity with β‐1,3‐glucan receptors on the surface of macrophages when the β‐1,3‐glucan is recognized. In contrast, all β‐1,3‐glucan‐complexed fullerene derivatives showed no photodynamic activity toward HeLa cells under the same conditions.