Controlled synthesis and fluorescent properties of poly(9-(4-vinylbenzyl)-9H-carbazole) via nitroxide-mediated living free-radical polymerization

The functional polymer containing carbazole unit, [(poly(9-(4-vinylbenzyl)-9H-carbazole) (PVBK)], was successfully prepared via nitroxide-mediated living free-radical polymerization of 9-(4-vinylbenzyl)-9H-carbazole (VBK). The controlled features of the polymerization were confirmed by the linear increase in the molecular weight with the monomer conversion while keeping the relative narrow molecular weight distribution (M_w/M_n ? 1.51), and successful chain extension with styrene. The resulting polymer absorbed light in the 305-355 nm range and exhibited fluorescent emission at 350 nm. The fluorescent intensity of the polymer was lower than that of monomer and was affected by the properties of the different solvents, which decreased in the following order: DMF > THF > CHCl₃ at the same concentration of carbazole units. The fluorescence intensity of the polymer was apparently influenced by chromophore concentration, and the maximum value was obtained when the carbazole unit concentration was around 8 × 10⁻⁵ mol/L. Moreover, it was shown that the strong fluorescence of PVBK can be quenched by methyl acrylate (MA).     

Photophysical properties of poly[2-(9-carbazolyl)ethyl methacrylate] films: Energy migration and carrier generation in films having no excimer-forming site

Photophysical properties of poly[2-(9-carbazolyl)ethyl methacrylate] film have been studied. This polymer shows a clear monomer fluorescence spectrum from carbazole chromophores and has no detectable excimer emission, even in the solid state. Highly efficient sensitized photoconductivity by electron acceptor doping shows effective electronic excitation energy migration through carbazole chromophores.     

Synthesis of conjugated 2,7-bis(trimethylsilylethynyl)-(phenylethynyl)nfluoren-9-one and 9-(p-methoxyphenyl)-9-methyl derivatives: optical properties

2,7-Substituted 9-fluorenones and 9,9-disubstituted fluorene have been synthesized and their fluorescence properties analyzed. The synthesis of conjugated 2,7-bis(trimethylsilylethynyl)-(phenylethynyl)_nfluoren-9-one (or the 9-(p-methoxyphenyl)-9-methyl) structures was carried out by the heterocoupling reaction between the 2,7-di(halo)fluoren-9-one (or 2,7-dibromo-9-(p-methoxyphenyl)-9-methylfluorene) and p-trimethylsilylethynyl(phenylethynyl)_n (n=1,2), catalyzed by the dichloro bis(triphenylphosphine)palladium and cuprous iodide system, in a divergent synthesis.The π-extended conjugated compounds exhibit fluorescence radiation emission (blue light-emitting), with important quantum yield for the 9-(p-methoxyphenyl)-9-methyl-2,7-bis(trimethylsilylethynyl)-(phenylethynyl)_nfluorenes which increases with the conjugation.     

Solution properties of poly[1-(9-carbazyl)-2,3-(diethoxycarbonyl)-butane-1,4-diyl]

Poly[1-(9-carbazyl)-2,3-(diethoxycarbonyl)-butane-1,4-diyl] (I), obtained by radical copolymerization of 9-vinylcarbazole with diethylfumarate, has been characterized by viscometry and light scattering. The Huggins constant in benzene at 25 is k_H = 0.33. The Mark-Houwink relationship suggests that benzene is a good solvent for the alternating copolymer I (a = 0.67; K = 1.46·10^?2 ml/g). The unperturbed dimension of the chain is given by value (R₀²/M)^0.5 = 5.73·10^?9 cm·mol^0.5 g^?0.5. The steric factor σ = 2.51 indicates a higher flexibility for this polymer than for poly[1-(9-carbazyl)ethylene].     

First chemoenzymatic synthesis of (R)- and (S)-1-(9H-fluoren-9-yl)ethanol

A simple chemoenzymatic synthesis of 1-(9H-fluoren-9-yl)ethanol stereoisomers is described. The enantiomers were resolved by a kinetically controlled transesterification with vinyl acetate in the presence of commercially available lipases. High-throughput screening and subsequent exhaustive investigation of the utility of the lipases in a stereoselective process of introducing chirality have been carried out. Lipase A from Candida antarctica as a cross-linked aggregate (CAL-A-CLEA) was the most efficient enzyme for the resolution of the title compound providing (S)-1-(9H-fluoren-9-yl)ethanol and its (R)-acetate in enantiopure form (>99% ee). Under mild reaction conditions, excellent enantioselectivity (E = 407), and good isolated yields of the products were obtained.     

Photochemical Properties of 1-(9-Phehanthryl)-2-(2-Quinolyl)ethylene

Spectral and photochemical properties of 1-(9-phehanthryl)-2-(2-quinolyl)ethylene (9Ph2QE) in neutral and protonated forms have been investigated. It has been found that both isomers of 9Ph2QE are photoactive. The quantum yield of trans–cis photoisomerization (? _tc = 0.47) in the neutral form is typical of the diabatic photoisomerization; on passing to the protonated form, ? _tc increases up to 0.70. Thus, the double annelation of the 2-styrylquinoline phenyl group to form 9Ph2QE makes it possible to conserve the α-effect, which consists in an increase in the quantum yield to ? _tc > 0.5 on passing from the neutral to protonated form, whereas the effect disappears for other types of annelation (naphthylquinolylethylenes, 1-(9-anthryl)-2-(2-quinolyl)ethylene).     

Synthesis of σ-(o-carboran-9-yl)- and σ-(m-carboran-9-yl)-π-cyclopentadienyldicarbonyliron and their rearrangement in reactions with bromine to π-(o-carboran-9-yl)cyclopentadienyl- and π-(m-carboran-9-yl)cyclopentadienyl-dicarbonylironbromides,respectively

9-o- and 9-m-carboranylcarboxylic acids were used to synthesize σ-(o-carboran-9-yl)- and σ-(m-carboran-9-yl)-π-cyclopentadienyldicarbonyliron. The latter complexes, in reactions with bromine, undergo rearrangement with the cleavage of the BFe σ-bond, involving migration of the 9-o- and 9-m-carboranyl groups into the cyclopentadienyl ring, to give π-(o-carboran-9-yl)cyclopentadienyl- and π-(m-carboran-9-yl)cyclopentadienyl-dicarbonyliron bromides, respectively. A simple method to obtain these acids by the oxidation of 9-alkyl-o- and 9-alkyl-m-carboranes with CrO₃ in CH₃COOH has been found.     

Spontaneous cyclization of (acridin-9-ylmethyl)thioureas to spiro [dihydroacridine-9′(10′H),5-imidazolidine]-2-thiones,a novel type of acridine spirocycles

Novel acridine spirocompounds, spiro[dihydroacridine-9′(10′H),5-imidazolidine]-2-thiones have been prepared by the spontaneous cyclization of 1-substituted 3-(acridin-9-ylmethyl)thioureas, which were obtained from 1-(acridin-9-yl)methanamine, N-(acridin-9-ylmethyl)propan-1-amine, and N-(acridin-9-ylmethyl)benzylamine and alkyl/aryl isothiocyanates, as continuation of our previous studies on new acridine spirocycles. Imidazolidine-2-thiones thus obtained were subsequently transformed with mesitylnitrile oxide to imidazolidine-2-one analogues, some of which partly reopened to the corresponding (acridin-9-ylmethyl)ureas. An unusual spirocyclization via a CH carbanion instead of the N-1 nitrogen has been found for 3-(acridin-9-ylmethyl)-1-(acridin-9-yl)thioureas possessing two acridine rings. Structural modifications in positions 1, 3, and 4 of the spiro ring together with ¹H, ¹³C, and ¹⁵N NMR spectroscopy and X-ray crystallography have been employed to rationalize a general propensity of various 9-substituted acridines to undergo easy spirocyclization.     

Electrochemical synthesis and investigation of poly(1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene) and its application in an electrochromic device

1,4-Bis(2-(3,4-ethylenedioxy)thienyl)benzene, prepared by Stille cross-coupling reaction was successfully electrochemically polymerized to give polymer 1,4-bis(2-(3,4-ethylenedioxy)thienyl)benzene (PEBE). Characterizations of the resulting polymer PEBE were performed by cyclic voltammetry (CV), UV–vis, Fourier transform infrared spectroscopy and scanning electron microscopy. Moreover, the spectroelectrochemical and electrochromic properties of the polymer film were investigated. The resulting polymer film has distinct electrochromic properties and shows three different colors (deep red, gray, and light blue) under various potentials. At the dedoped state of the polymer, the π–π* transition absorption peak is located at 510?nm and the optical band gap (E _g) was calculated as 1.92?eV. The PEBE film shows a maximum optical contrast (ΔT%) of 31.0?% at 500?nm with a response time of 0.85?s. The coloration efficiency of PEBE film was calculated to be 182.2?cm²C^?1. An electrochromic device (ECD) based on PEBE and poly(3,4-ethylenedioxythiophene) was also constructed and characterized. The response time was measured as 0.4?s, and the coloration efficiency of the device was calculated to be 225.4?cm²C^?1. Furthermore, this ECD exhibited satisfactory optical memories and redox stability.     

Synthesis of α-(aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetic acid derivatives

α-(Aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetamide and the ethyl acetate, 3 and 8 , have been synthesized by catalytic hydrogenation of 6-cyanomethylene-9-methoxymethylpurine derivatives 2 and 7 which were obtained by the substitution of 6-chloro-9-(methoxymethyl)purine ( 1 ) with α-cyanoacetamide and ethyl cyanoacetate, respectively. Substitution of 3 and 8 with amines gave the corresponding N-substituted α-(aminomethylene)-9-(methoxymethyl)-9H-purine-6-acetamide and the ethyl acetate 4 and 10 . Reaction of 3 with piperidine gave 9-(methoxymethyl)-9H-purine-6-acetamide ( 5 ).     

Palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes using triarylbismuths in one-pot bis-coupling process

An efficient palladium catalyzed atom-economic synthesis of functionalized 9-(diarylmethylene)-9H-fluorenes has been accomplished in one-pot bis-coupling process using triarylbismuths as organometallic reagents. These bis-couplings in 1 hour short reaction time afforded various 9-(diarylmethylene)-9H-fluorenes in good to high yields.     

Preparation of single-enantiomer semiochemicals using 2-methoxy-2-(1-naphthyl)propionic acid and 2-methoxy-2-(9-phenanthryl)propionic acid

Enantioresolution of 3-octanol, 6-methyl-5-hepten-2-ol (sulcatol), and 1-octen-3-ol was conducted using (S)-(+)-2-methoxy-2-(1-naphthyl)propionic acid (MαNP acid) and (S)-(+)-2-methoxy-2-(9-phenanthryl)propionic acid (M9PP acid). In each case, the diastereomeric esters obtained were readily separated by HPLC. The stereochemistry of the esters could be assigned from their respective ¹H NMR analyses. Solvolyses of the esters gave enantiopure alcohols and acids. MαNP and M9PP acids displayed almost equivalent properties in ¹H NMR anisotropy. The chiral resolving ability of M9PP acid was slightly superior to that of MαNP acid in HPLC.     

Dienic sex pheromones : Stereoselective syntheses of (7E,9Z)-7,9-dodecadien-1-yl acetate, (E)-9,11-dodecadien-1-yl acetate,and of (9Z), 11E)-9,11- tetradecadien-1-yl acetate by palladium-catalyzed reactions

Pure (7E,9Z-7, 9-dodecadien-1-yl acetate (1), the sex pheromone of Lobesiabotrana, has been prepared in 21.6% overall yield by a reaction scheme involving; (i) the cross-coupling of (E) - 8 - (2 - tetrahydropyranyloxy) -1 - octenyldisiamylborane with 1 - bromo - 1 - butyne, in the presence of a Pd (O) catalyst and base; (ii) the acetylation of the crude product of this reaction; (iii) the (Z)-stereoselective reduction of the obtained conjugated (E)-enyn-1-yl acetate. (E)-9,11-Dodecadien-1-yl acetate (2), a sex pheromone component of Diparopsiscastanea, has been analogously obtained (in 54.3% overall yield) by cross-coupling of (E) - 10 - (2 - tetrahydropyranyloxy) - 1 - decenyl borane with vinyl bromide, in the presence of a Pd (O) catalyst and base, followed by acetylation of the crude product. Compound 2, which was 87.7% chemically pure, was purified by column chromatography over SiO₂-AgNO₃. Chemically pure (9Z, 11E) - 9,11 - tetradecadien - 1 - yl acetate (3), a sex pheromone component of Spodopteralittoralis, has been prepared (in 30.2% overall yield) by reaction of 10 - (2 - tetrahydropyranyloxy) - 1 - decynylamagnesium bromide with (E)-1-iodo-1-butene, in the presence of a Pd (O) catalyst, followed by acetylation of the crude product and by (Z)-stereoselective reduction of the obtained (E)-enyn-1-yl acetate.The stereoisomeric purity of 1, 2 and 3 has been evaluated by glc analysis on glass capillary columns or by reverse phase hplc analysis.     

Evaporated thin films of insulating poly-(tetrabromo-p-phenylenediselenide)

It has been shown that thin insulating film at the interface transparent conductive oxide/organic electroluminescent film could improve the performance of organic electroluminescent diodes (OLED). Such insulating film can be inorganic or organic. Poly-(tetrabromo-p-phenylenediselenide) (PBrPDSe) has been proved to be an efficient insulating film in OLED. The properties of these evaporated PBrPDSe thin films have been systematically studied by IR absorption, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, electron spin resonance and optical transmission measurements. It is shown that, when the deposition temperature is kept below the decomposition temperature of the polymer, tetrabromo-p-phenylenediselenide molecule is preserved during the deposition process. However the polymer, which is insoluble in powder form, becomes soluble after deposition. It can be concluded that films are mainly composed of oligomers of tetrabromo-p-phenylenediselenide.The electrical properties of SnO₂/PBrPDSe/Al thin films structures have been studied. The current-voltage characteristics exhibit a rectifying behaviour with a forward direction corresponding to a positive bias of the transparent conductive oxide film, the SnO₂.     

Low-potential facile electrosyntheses of high-quality free-standing poly(fluorene-9-carboxylic acid) films

A novel conducting polymer, high-quality poly(fluorene-9-carboxylic acid) (PFCA) film, was synthesized electrochemically by direct anodic oxidation of fluorene-9-carboxylic acid (FCA) in boron trifluoride diethyl etherate (BFEE) containing a certain amount of trifluoroacetic acid (TFA). PFCA films obtained from this media showed good redox activity and stability. Optical properties were studied by UV–vis and fluorescent spectroscopy. Fluorescent spectral studies indicate that solid PFCA film is a good blue-light emitter. To the best of knowledge, this is the first report on direct anodic oxidation of FCA.     

(R)-9-[2-(Hydroxyphosphinylmethoxy)propyl]adenine as the precursor molecule for antivirals

The biological importance and practical significance of phosphonates have been a major driving force for antiviral research in the past two decades. We describe in this Letter the potential of the H-phosphinate derivative (R)-9-[2-(hydroxyphosphinylmethoxy)propyl]adenine as the versatile synthetic intermediate in the preparation of N-alkylphosphonamidate and alkylphosphonate series.     

Synthesis and thermal polymerization of perylene bisimide containing benzocyclobutene groups

Fourfold benzocyclobutene-functionalized perylene bisimide（PBI 4） has been synthesized and its structure was characterized by FTIR,MS and NMR.PBI 4 can react either with itself,or the appropriate dienophiles to form the corresponding products under appropriate temperature.The polymer film obtained from the reaction of PBI 4 with methyl vinyl silicone rubber possessed excellent film forming properties including flatness.The optical properties of PBI 4 and polymer film obtained from the reaction of PBI 4 and methyl vinyl silicone rubber have been determined by UV/vis and fluorescence spectroscopy.     

Synthesis of 4-hydroxy-3-[(E)-2-(6-substituted-9H-purin-9-yl)vinyl]coumarins as lipoxygenase inhibitors

The synthesis of 4-hydroxy-3-[(E)-2-(6-substituted-9H-purin-9-yl)vinyl] coumarins has been achieved from the reactions of 4-hydroxycoumarin with 2-(6-substituted-9H-purin-9-yl)acetaldehydes in DMF under heating. The new compounds showed significant lipoxygenase inhibitory activity (e.g., 6a: IC₅₀ = 6.25 μM).     

Chemosensors based on <Emphasis Type="Italic">N</Emphasis>-(2-aminophenyl)-<Emphasis Type="Italic">N</Emphasis>-(9-anthrylmethyl)amine: II

A series of N-(9-anthrylmethyl)arylimines was prepared by condensation of N-(2-aminophenyl)-N-(9-anthrylmethyl)amine with aromatic aldehydes. The study of the luminescent and complexing properties of compounds obtained showed that 2-{[2-(9-anthrylmethylamino)phenylimino]methyl}-1-naphthol and 1-{[2-(9- anthrylmethylamino)phenylimino]methyl}-6-bromo-2-naphthol were efficient highly selective chemosensors of cations Hg²⁺.     

Synthesis and reactivity of (RS)-6-chloro-7- or 9-(1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl)-7H- or 9H-purines bearing a nitrobenzenesulfonyl group on the nitrogen atom

The O,O-acetalic compounds (RS)-3-methoxy-1-[(2)- or (4)-nitrobenzenesulfonyl)]-1,2,3,5-tetrahydro-4,1-benzoxazepine have been studied in the Lewis acid-mediated condensation with 6-chloropurine. 6-Chloropurine leads to the N-7″ aminalic bond in the cyclic products and mainly to the N-9″ aminalic bond in the acyclic ones. Substitution of the chlorine atom at the 6″ position of the purine moiety is more feasible when the ring is alkylated at N-7″ than at N-9″. Exchange with a hydroxyl group is performed with water traces in deuterated dimethylsulfoxide at room temperature in a solvent-mediated process. The exchange with strong nucleophiles (e.g., thiophenol) does not need further activation.