Novel,N-ethyl-2-styrylquinolinum iodides as fluorophores for monitoring of polymerization process,Part I

A series of of p-substituted 2-styrylquinolinium iodides were prepared by the condensation of N-ethyl-2-methylquinolinium salts with p-substituted benzaldehydes. The spectroscopic properties of the styryl quinolinium dyes are characterized in organic solvents of varying polarities. The electronic absorption and fluorescence emission spectra of the dyes demonstrate their high sensitivity to the nature of substituents introduced into the aromatic ring. The dyes were investigated as fluorescent probes for monitoring the progress of the photochemically initiated free-radical polymerization of a mixture of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate and 1-methyl-2-pyrrolidinone. During the course of the polymerization an increase in the fluorescence intensity of the dyes by at least one order of magnitude was recorded; a feature which renders the dyes as good fluorescent probes for such polymerization reactions. The term “probe sensitivity” has been defined and appears in the range from 0.08 to 11 for the styryl dyes.     

Methine chain substituted styryl cyanine dyes—part I

Twenty-seven styryl dyes having 1-naphthyl and 2-naphthyl substituents at the β-carbon atom (β- to the heterocyclic moiety) of the methine chain have been prepared by condensing p-diethylaminophenyl 2-naphthyl ketone, p-dimethylaminophenyl 1-naphthyl ketone and p-dimethylaminophenyl 2-naphthyl ketone with quaternised salts of variously substituted quinaldines and lepidine. The dyes obtained show hypsochromic shifts in absorption maxima compared with their analogues having no substituent in the methine chain wherever comparable data have been available in the literature. The photosensitisation properties of the dyes have also been studied.     

Photophysical properties and photostability of novel symmetric polycyclicphenazine-type fluorescent dyes and the dye-doped films

Novel symmetric polycyclicphenazine-type fluorescent dyes have been synthesized and characterized in solution and in polymer films. The dyes exhibited two strong absorption bands at around 365-428 nm and 519-567 nm and an intense fluorescence band at around 560-600 nm (Ф = 0.70-0.87) in 1,4-dioxane. The dye-doped polymer films showed excellent wavelength conversion function that efficiently convert ultraviolet and yellow lights into red light (Ф = 0.61-0.92). Moreover, the photostability of the dye-doped PS, PMMA, and PLA films has been investigated.     

Synthesis and electronic spectra of some azo disperse dyes derived from N-2,2,2-trifluoroethyl-1,2,3,4-tetrahydroquinoline

Several monoazo dyes suitable for transfer printing have been prepared from N-2,2,2-trifluoroethyl-1,2,3,4-tetrahydroquinoline and compared with their N-ethyl counterparts. The presence of a trifluoroethyl group brings about considerable improvements in lightfastness properties on both polyester and nylon. Electron withdrawal by the trifluoroethyl substituent leads to hypsochromic shifts of the visible absorption band and also results in a marked positive halochromism.     

Synthesis, absorption and fluorescence properties of N-triazinyl derivatives of 2-aminoanthracene

N-(4,6-dichloro-1,3,5-triazin-2-yl)-2-aminoanthracene was synthesized by substitution of one chlorine atom of 2,4,6-trichloro-1,3,5-triazine with 2-aminoanthracene. A new series of N-triazinyl-2-aminoanthracenes was prepared by nucleophilic substitution of one or both chlorine atoms on N-(4,6-dichloro-1,3,5-triazin-2-yl)-2-aminoanthracene with electron-donating methoxy or phenylamino groups. The UV/Vis absorption, fluorescence and excitation spectra as well as the fluorescence quantum yields of the prepared compounds were measured in 1,4-dioxane, ethyl acetate, dibutyl ether and acetonitrile; nanosecond kinetics of the fluorescence decay was measured in different solvents. The influence of the character of the substituent on triazinyl ring and of the solvent polarity upon the absorption and fluorescence spectra and fluorescence quantum yields are discussed.     

Colour and constitution of 4-chlorothiazole azo dyes: application of PPP method

Electronic absorption spectral data for a series of monoazo dyes derived from 2-amino-4-chloro-5-formylthiazole have been calculated without the inclusion of the 3d atomic orbitals on the sulphur atom by the PPP molecular orbital method. Optimal agreement between experimental and calculated results was achieved by adopting the parameters used by Hallas and Marsden for heterocyclic ring systems. These parameters permit satisfactory prediction of μ_max values for the derived dyes. The relative intensities of the dyes containing a range of complex acceptors are also reasonably well accounted for by the PPP method.     

Polarographic investigation of Cu(II) complexes with π donor ligands

The polarographic reduction of Cu(II) complex chlorides with biguanides and N′- amidinoisoureas have been studied in aqueous 0.5 M KCl solution containing 0.01% gelatin. The complexes [except Cu(enH₂dbg)²⁺] show two well defined waves whose heights are pH dependent. The first (lower - E_1/2) and the second waves have been attributed to mono and bis(ligand)Cu(II) species respectively. Lower rate constant, higher activation energy and more negative E_1/2 values relative to those of a σ bonded Cu(II) chelates have been explained on the basis of chelate ring current and high π-basicity of the ligands. The gradual change of these values with the size of the N-substituents is due to decreased π-basicity of the respective ligands. Ratio of mono and bis biguanide with pH change has been calculated and activation energies for the complexes, calculated polarographically, have been found to be closely related to D_q values obtained from absorption band maxima.     

Synthesis and Electronic Spectra of Some Monoazo Disperse Dyes Derived from N-Methylindoline

Several monoazo dyes suitable for transfer printing have been prepared from N-methylindoline and compared with the corresponding derivatives of N-methyl -12,3,4-tetrahy-droquinoline (kairoline). The presence of a five-membered terminal ring system leads to diminished π-interaction and results in modest hypsochromic and hypochromic shifts of the visible absorption band, relative to the analogous kairo-line derivatives, together with some deterioration in light-fastness properties on synthetic-polymer fibres.     

香豆素类染料的荧光光谱性能及应用性能研究

研究了9只香豆素类荧光染料(Ⅰ-Ⅶ)的光谱性能和应用性能。香豆素类荧光染料在5’-位有取代基可使最大可见吸收波长和荧光发射波长产生红移;当共轭双键长度增加,可使染料颜色变深(V:544,VI:552)。这9只染料用于涤纶染色有很好的应用性能,差别不大;嗯唑环结构(Ⅰ、Ⅱ、Ⅲ)和喹唑酮结构(Ⅵ)的染料耐光牢度明显好于噻唑环结构(Ⅴ)和咪唑环结构(Ⅶ)的染料。     

Novel D-π-A system based on zinc porphyrin dyes for dye-sensitized solar cells: Synthesis, electrochemical, and photovoltaic properties

We have designed and synthesized novel zinc porphyrin dyes which have a D-π-A system based on porphyrin derivatives containing a triphenylamine (TPA) electron-donating group and a phenyl carboxyl anchoring group substituted at the meso position of the porphyrin ring, yielding the push-pull porphyrins as the most efficient green dye for dye-sensitized solar cell (DSSC) applications. The synthesis and characterization of a novel D-π-A system based on zinc-porphyrin derivatives have been investigated through their photophysical and photoelectrochemical studies. A large red-shift of the absorption maxima due to introduction of the TPA moiety at the meso position of the porphyrin ring was expected in the D-π-A porphyrins, but the absorption maxima of HKK-Por dyes were a little red-shifted in contrast to Zn[5,-10,15-triphenyl-20-(4-carboxylphenyl)-porphyrin], due to the tilted structure between TPA and the porphyrin unit. Under the photovoltaic performance measurement, the maximum incident photon-to-current conversion efficiency (IPCE) value of the DSSC based on HKK-Por 5 was slightly higher than the efficiencies of the DSSCs based on other HKK-Por dyes due to the introduction of the alkoxy group into the TPA moiety at the meso position of the porphyrin ring. A maximum photon-to-electron conversion efficiency of 3.36% was achieved with the DSSC based on HKK-Por 5 dye (J_SC = 9.04 mA/cm², V_OC = 0.57 V, FF = 0.66) under AM1.5 irradiation (100 m Wcm⁻²).     

Synthesis, absorption and fluorescence of hydrazone colorants based on pyrrolinone esters

Ten azo dyes were prepared by diazotization of a series of electronically different para substituted anilines and subsequent azo coupling of these diazonium salts with ethyl 4,5-dihydro-5-oxo-2-aryl(1H)pyrrole-3-carboxylate as a the coupling component. All of the dyes were confirmed as keto-hydrazone tautomers and were found as a mixtures of E- and Z-isomers with respect to the exocyclic CN bond by ¹H-NMR spectroscopy. The absorption spectra are all similar irrespective of substituent and solvent. By comparison the fluorescence is strongly dependent on the electronic character of the substituents. All compounds fluoresce in a low temperature solvent glass and in the solid state and only the 4-cyanophenyl and 4-nitrophenyl derivatives show fluorescence in solution at room temperature. The spectroscopic behavior is explained in terms of competition between E/Z isomerization and fluorescence after excitation.     

Spectral properties of chalcone containing triphenylamino structural unit in solution and in polymer matrices

Novel chalcones (3-phenyl-1-phenylprop-2-en-1-ones) substituted on one end (position 3) with electron donating diphenylaminophenyl substituent and on the other end (position 1) with thiophenes with variable electronic effects (CH-1-CH-5) were prepared. The spectral properties of these molecules in solvents such as chloroform, cyclohexane, acetonitrile, methanol and incorporated into polymer matrices of polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) were compared with those of 3-[4-(N,N-dimethylamino)-phenyl]-1-phenylprop-2-en-1-one (CH-1m) and 3-[4-(N,N-dimethylamino)phenyl]-1-(4-nitrophenyl)prop-2-en-1-one (CH-2m). The longest wavelength absorption band of model chalcones CH-1m and CH-2m was in the range of 400-420 nm and did not appear to be influenced by the medium. The fluorescence increased with the addition of acetonitrile, while it was effectively quenched in methanol. The strong electron-attracting nitro group quenched the fluorescence of CH-2m in nearly all solvents. In contrast, the fluorescence became more intense when the molecule was incorporated in a polymer matrix. The longest wavelength absorption band of novel chalcones was observed in the range of 410-450 nm in all media. The fluorescence of chalcones was red-shifted to the range of 530-575 nm and was most intense in chloroform. The quantum yield of fluorecence was the highest in chloroform for the chalcone with a methyl-thiophene (0.49) and low for the chalcone with a fluorenyl-thiophene group (0.07). The fluorescence of all chalcones (CH-1-CH-5) was effectively quenched in polar acetonitrile and methanol, and was less intense relative to chloroform when incorporated into a polymer matrix and more intense relative to other solvents. The lifetime of fluorescence was in the range of 1-4 ns. The Stokes shift was in the range of 4000-5000 cm⁻¹ in chloroform, and lower in all other media. The spectral behavior of model chalcones CH-1m and CH-2m and novel chalcones with diphenylamino substituents was similar, producing observable fluorescence in several polymer matrices. The effect of the solvent on the fluorescence is discussed in terms of negative and positive solvatokinetic effects.     

Colour and constitution of thiophene and thiazole azo dyes: application of CNDO/S and PPP methods

The electronic absorption spectra of a series of thiophene and thiazole azo dyes have been calculated by the CNDO/S method with inclusion of the 3d atomic orbitals on the sulphur atom and by the PPP method. The results calculated by the two methods consistently suggested that the orders of bathochromic effect of the diazo and coupling are as follows.     

N-(1,1-dihydro)polyfluoroalkyl substituted triphenylmethane dyes

A number of new triarylmethane and styryl dyes with 1,1-dihydropolyfluoroalkyl groups at the nitrogen atoms have been prepared. We have studied the influence of polyfluoroalkyl groups on the colour of these triarylmethane and styryl dyes. The accumulation of N-polyfluoroalkyl radicals in the molecule of triarylmethane dyes exerts a hypsochromic shift of absorption maxima. The styryl dyes absorb at shorter wavelengths than the styryl dyes with dimethylamino groups. These demonstrate the lessening of the basicity of the nitrogen atom, bonded with the 1,1-dihydropolyfluoroalkyl radicals. Nevertheless, RNCH₂(CF₂CF₂)_nH groups show themselves in the triphenylmethane and styryl dyes as sufficiently strong auxochromes.     

Synthesis and Electronic Spectra of Some Disperse Dyes Derived from 9-Phenylazo-1-ketojulolidine

Several monoazo dyes have been prepared from 1-ketojulolidine and compared with their julolidine counterparts. The presence of a carbonyl group in the terminal bridging system leads to improved light fastness properties on synthetic-polymer fibres, but also to an essentially constant hypsochromic shift (70 nm) of the first absorption band. The azojulolidine dyes exhibit a marked negative halochromism. Unlike the parent julolidine dyes, the ketofulolidine disperse dyes are not suitable for transfer printing.     

Synthesis and spectroscopic properties of novel azo dyes derived from phthalimide

A set of azo dyes has been synthesised using N -substituted phthalimides as diazo components. 3,5-Dibromo- N -substituted-phthalimidylazo derivatives were cyanated by cyanodehalogenation to give dicyano analogues. All of the synthesised intermediates and dyes have been characterised by mass spectrometry, ¹H-NMR or elemental analyses. The gamut of colour of the prepared dyes spanned much of the visible spectrum: absorption maxima of the dyes in formamide were observed in the range 436 to 609 nm. Consistent with results seen in previous studies of non-phthalimido monoazo disperse dyes, replacement of dibromo groups with dicyano functions in the phthalimide-based set led to large bathochromic shifts in absorption maxima, as did the introduction of acetylamino groups onto the coupler ring ortho to the azo link. However, switching an N -propyl function on the imido ring for a benzyl or 3-cyanopropyl substituent had little effect on absorption maxima. Good correlations between the observed absorption maxima of certain dyes and those of model analogues predicted by Pariser–Parr–Pople molecular orbital calculations were observed when steric effects were absent.     

Binding of some dyes onto crosslinked poly (N-vinylpyrrolidone)

Summary Bindings of some anionic dyes containing sulfonyl group(s), namely, Acid Blue 74 (AB-74), Acid Orange 7 (AO-7), Acid Green 1 (AG-1), Direct Blue 53 (DB-53), and Calconcarboxylic acid (CCA) onto crosslinked poly(N-vinylpyrrolidone) (CPVP) have been investigated using adsorption isotherm parameter. The dyes were linked positively charged on the tertiary nitrogen atom on the pyrrolidone ring in polymer chain resulting keto-enol tautomerism from sulfonyl group on the benzene ring in the dyes molecules. In the experiments of adsorption, L (Langmuir) type adsorption in the Giles classification system was found. Monolayer coverages (n) of polymer/dye system were founds by "B point" methods. Adsorption studies indicated that monolayer coverages of CPVP by the anionic dyes containing sulfonyl group(s) were increased with following order; CCA > AG-1 >> DB-53 > AO-7 > AB-74. Received: 10 April 2000/Revised version: 26 May 2000/Accepted: 6 June 2000     

Novel coumarin fluorescent dyes: Synthesis,structural characterization and recognition behavior towards Cu(II) and Ni(II)

A series of novel coumarin dyes (3–12) were designed and synthesized. The structures of the dyes were characterized by IR, ¹H NMR, ¹³C NMR, ¹⁹F NMR, MS and single crystal X-ray diffraction. 3-(2-Benzoylhydrazonotrifluoroethyl)-7-(N,N-diethylamino)coumarin (11) could recognize Cu²⁺ and Ni²⁺ selectively in aqueous solution. Upon addition of Cu²⁺ or Ni²⁺ to 11 a blue shift or a bathochromatic shift of the absorption band was observed while the emission band blue-shifted with decrease in the fluorescence intensity. Upon addition of Cu²⁺ the color of the solution of 11 changed from orange to red. The results showed that 11 could be used as an optical chemosensor of Cu²⁺ and Ni²⁺.     

Polyfluoroalkyl substituted anthraquinone dyes

A number of new amino- and hydroxy-anthraquinone dyes with 1,1-dihydropolyfluoroalkyl groups at the nitrogen and oxygen atoms have been prepared. The influence of polyfluoroalkyl groups on the colour of these anthraquinone dyes has been studied. The replacement of the hydrogen atom in the oxy group by polyfluoroalkyl radicals causes a stronger hypsochromic shift of the absorption maximum than the same replacement in the amino group.