Synthesis,absorption spectra studies,solvatochromism and halochromism of polymethine cyanine dyes

New polymethine cyanine dyes, including tetramethine and bis‐tetramethine cyanine dyes derived from benzo[2,3‐b;2′,3′‐b′]bis‐pyrazolo[4,5‐b]‐1,4‐(oxa‐, thia‐ and pyra‐)‐zine‐6,12‐dione, were synthesised. Absorption spectra for all the synthesised cyanine dyes were examined in 95% ethanol. The solvatochromism and halochromism for some selected dyes were investigated in pure solvents and in aqueous universal buffer solutions, respectively. Structural confirmations were carried out through elemental and spectroscopic analysis.     

Synthesis,spectral properties and application of novel disazo disperse dyes derived from polyester waste

Terephthalic dihydrazide was obtained through aminolytic depolymerisation of polyester bottle waste by using hydrazine hydrate. It was further reacted with 4‐aminobenzoic acid in the presence of polyphosphoric acid to obtain a cyclic compound, 4,4′‐[5,5′‐(1,4)‐phenylene)bis(1,3,4‐oxadiazole‐5,2‐diyl)dianiline, having a heterocyclic moiety. Diazotisation of this compound followed by coupling with various N,N‐disubstituted anilines afford a series of novel disazo disperse dyes. The structures of these synthesised dyes were confirmed by elemental analysis and Fourier Transform–infrared, proton nuclear magnetic resonance and mass spectroscopy. Ultraviolet–visible spectra of these azo dyes in different polar solvents showed considerable variation in the wavelength of maximum absorbance (λ_max). Application of these dyes on polyester and nylon fabrics using high‐temperature dyeing methods gave brilliant yellowish red hues with fair to moderate light fastness and very good to excellent wash fastness and sublimation fastness.     

Synthesis and spectroscopic investigation of cationic donor‐(π‐bridge)‐acceptor dye, 4‐[N‐(5,6,7,8‐tetrahydroisoquinolinium‐5‐ylidene)methyl]‐N,N‐dialkylaniline iodide

The synthesis and fundamental spectroscopic properties of eight hemicyanine (HC) dyes are presented. The dyes were prepared by the condensation of N‐methyl‐5,6,7,8‐tetrahydroisoquinolinium iodide with p‐(N,N‐dialkylamino)benzaldehydes. The compounds were characterised by nuclear magnetic resonance spectroscopy and their purity was checked with the use of thin‐layer chromatography. The spectroscopic properties of the dyes were determined in three organic solvents. The electronic absorption spectra of the dyes demonstrate moderate sensitivity to the nature of the substituent present in the aromatic ring and low solvent polarity dependence. In contrast to this, the positions of fluorescence bands are affected by the structure of an electron donor and solvent polarity. The 4‐[N‐(5,6,7,8‐tetrahydroisoquinolinium‐5‐ylidene)methyl]‐N,N‐dialkylaniline iodides were applied as fluorescent probes for the monitoring of the progress of free radical polymerisation. The study on the changes in the fluorescence intensity and spectroscopic shifts of the dyes was carried out during thermally initiated polymeriszation of methyl methacrylate. The purpose of these studies was to find a relationship between the changes in the shape and intensity of probe fluorescence and the degree of monomer conversion into polymer.     

Cyanine dyes of new heterocyclic ring systems: Synthesis and structure-spectra studies

New cyanine dyes including monomethine cyanine dyes (simple cyanine dyes) and trimethine cyanine dyes (carbocyanine dyes) incorporating benzo[2,3-b; 2′,3′-b′]bispyrazolo[4,5-b]-1,4-(oxa-, thia-, and pyra)-zine-6,12-dione were prepared. Structure-spectra studies were carried out via measuring the electronic visible absorption spectra of these dyes in 95% ethanol. Structural confirmations were determined through elemental analysis, IR, ¹H NMR spectroscopy and MS spectral data at the Micro Analytical Center, Cairo University.     

Adsorption of anionic dyes on a reversibly swelling cationic superabsorbent polymer

A cationic monomer [2‐(methacryloyloxy)ethyl]trimethylammonium chloride was polymerized using N,N′‐methylenebisacrylamide as the crosslinker to obtain a cationic superabsorbent polymer (SAP). This SAP was characterized by Fourier transform‐infrared spectroscopy, and the equilibrium swelling capacity was determined by swelling in water. The SAP was subjected to cyclic swelling/deswelling in water and NaCl solution. The conductivity of the swelling medium was monitored during the swelling/deswelling and was related to the swelling/deswelling characteristics of the SAP. The adsorption of five anionic dyes of different classes on the SAP was carried out and was found to follow the first‐order kinetics. The Langmuir adsorption isotherms were found to fit the equilibrium adsorption data. The dye adsorption capacity of the SAP synthesized in this study was higher than that obtained for other hydrogels reported in the literature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Direct coloration of textiles with photochromic dyes. Part 2: The effect of solvents on the colour change of photochromic textiles†

Polyester, acrylic and nylon textile substrates dyed with two spirooxazine dyes, 1,3,3‐trimethyl‐spiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1a ) and 6′‐piperidino‐1,3,3‐trimethyl spiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1b ), exhibit significantly higher photochromic colour build‐up when wet compared with after drying. A study of this phenomenon, extended beyond water to the influence of a series of selected organic solvents on photochromic behaviour, using colour measurement of the photochromic textiles under controlled ultraviolet irradiation conditions, is reported. The results of molecular modelling calculations (AM1 in water and PM5 in water) have been used as a means of interpreting the observed effects, in conjunction with qualitative arguments based on solvation and fibre swelling.     

Direct coloration of textiles with photochromic dyes. Part 1: Application of spiroindolinonaphthoxazines as disperse dyes to polyester,nylon and acrylic fabrics†

1,3,3‐Trimethylspiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1a ) and 6′‐piperidino‐1,3,3‐trimethylspiroindoline‐2,3′‐3H‐naphth[2,1‐b][1,4]oxazine ( 1b ) were applied as disperse dyes to polyester, nylon and acrylic fabrics. Under optimised dyeing conditions, photochromic fabrics were produced which, on irradiation with ultraviolet or exposure to sunlight, turned blue ( 1a) or blueish‐purple ( 1b ). Dye 1a showed enhanced photochromic colour change performance compared with dye 1b . The photochromic colour build was highest on nylon and lowest on acrylic fabric. The colour change properties and the technical performance (wash fastness and photostability) of the photochromic fabrics were evaluated using specifically adapted colour measurement methods. The data were analysed in terms of variation of lightness, a*, b*, chroma, hue angle and ΔE, colour difference before and after exposure, and K/S curves as a function of irradiation time. The fabrics generally showed good wash fastness. Although the colour build‐up decreased with exposure to the Xenotest fadeometer, some residual photochromism remained after prolonged exposure.     

Synthesis and application of some novel antimicrobial monoazonaphthalimide dyes: synthesis and characterisation

A series of novel monoazo dyes based on N‐pyridine‐1,8‐naphthalimides were prepared using 4‐amino‐N‐2‐aminomethylpyridine‐1,8‐naphthalimide as the diazo component and N,N‐diethyl‐meta‐toluidine, 3‐(N,N‐diethylamino)acetanilide and N‐hydroxyethyl‐N‐ethylaniline as the coupling components. The synthesised dyes were purified by utilising column and preparative thin‐layer chromatography methods. The characterisations of the prepared dyes were carried out by differential scanning calorimetery, thin‐layer chromatography (R_f values), Fourier Transform infrared, and proton and carbon nuclear magnetic resonance techniques. The in vitro antibacterial activity of the novel synthesised compounds against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and their antifungal activity against Candida albicans were evaluated by use of conventional agar dilution procedures and a minimum inhibitory concentration. Some of these synthesised dyes demonstrated antibacterial activity against Gram‐positive bacteria in addition to antifungal activities.     

Highly Enantioselective Hydrogenation of Quinoline and Pyridine Derivatives with Iridium‐(P‐Phos) Catalyst

The use of a chiral iridium catalyst generated in situ from the (cyclooctadiene)iridium chloride dimer, [Ir(COD)Cl]₂, the P‐Phos ligand [4,4′‐bis(diphenylphosphino)‐2,2′,6,6′‐tetramethoxy‐3,3′‐bipyridine] and iodine (I₂) for the asymmetric hydrogenation of 2,6‐substituted quinolines and trisubstituted pyridines [2‐substituted 7,8‐dihydroquinolin‐5(6H)‐one derivatives] is reported. The catalyst worked efficiently to hydrogenate a series of quinoline derivatives to provide chiral 1,2,3,4‐tetrahydroquinolines in high yields and up to 96% ee. The hydrogenation was carried out at high S/C (substrate to catalyst) ratios of 2000–50000, reaching up to 4000 h⁻¹ TOF (turnover frequency) and up to 43000 TON (turnover number). The catalytic activity is found to be additive‐controlled. At low catalyst loadings, decreasing the amount of additive I₂ was necessary to maintain the good conversion. The same catalyst system could also enantioselectively hydrogenate trisubstituted pyridines, affording the chiral hexahydroquinolinone derivatives in nearly quantitative yields and up to 99% ee. Interestingly, increasing the amount of I₂ favored high reactivity and enantioselectivity in this case. The high efficacy and enantioselectivity enable the present catalyst system of high practical potential.     

Colorimetric and fastness studies and analysis by reversed‐phase high‐performance liquid chromatography with diode‐array detection of the dyeing of silk fabric with natural dye Helichrysum arenarium

In this study, silk fabric samples were dyed by various procedures using Helichrysum arenarium extracts. Alum, ferrous sulfate, stanium chloride, calcium nitrate, and potassium bitartrate were used as mordants. Reversed‐phase high‐performance liquid chromatography with diode‐array detection was utilised for identification of the dyes present in the dyed silk fabrics and the plant extracts. The extraction of dyes was carried out with a hydrochloric acid/methanol/water (2:1:1 v/v/v) mixture. The colour coordinates and K/S values, as well as wash, light, and rub fastness, were determined.     

Synthesis and photochemical reaction of benzo[a]quinoxalino[2,3‐c]phenazine dyes

Novel dyes based on the benzo[a]quinoxalino[2,3‐c]phenazine skeleton and necessary intermediates (benzo[a]phenazine‐5,6‐diones) were synthesized. The heterocyclic dyes and benzo[a]phenazine‐5,6‐diones were characterized using ¹H nuclear magnetic resonance (NMR) spectroscopy and chemical ion (CI) mass spectrometry. Their spectral properties, such as absorption and emission spectra and fluorescence quantum yield, were also measured. Experimental results demonstrated that photolysis of benzo[a]quinoxalino[2,3‐c]phenazine dyes in 2‐propanol and cyclohexene oxide leads to dihydro derivatives. The same product is formed during irradiation of dye/iodonium salt photoredox pairs in monomers. These compounds absorb incident light at longer wavelength and act as in situ sensitizers. Thus, when a composition was irradiated with a xenon lamp through a 395 cutoff filter, higher conversion was achieved than under monochromatic light.     

Reverse osmosis performance and chlorine resistance of new ternary aromatic copolyamides comprising 3,3′‐diaminodiphenylsulfone and a comonomer with a carboxyl group

The preparation of asymmetric flat membranes from a series of novel aromatic polyamides comprising 3,3′‐diaminodiphenylsulfone and a comonomer with a carboxyl group(&BOND;COOH) were studied and the measurements of reverse osmosis (RO) performance and chlorine resistance were carried out. It was confirmed that the introduction of comonomer with a carboxyl group (MC or T_m) to the aromatic polyamides (3I or 3T) comprising 3,3′‐diaminodiphenylsulfone was very effective for the improvement of its RO performance. In particular, 3T‐MC(30), which was prepared from terephthaloyl dichloride and mixed diamine components of 3,3′‐diaminodiphenylsulfone and 3,5‐diaminobenzoic acid, exhibited not only some potential for sea water desalination (FR = 159 L/m² day, Rj = 98.3%) but also higher chlorine resistance than conventional Nomex‐type aramid [MI‐MC(0)]. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 505–513, 2001     

6‐Pyridinium benzo[a]phenazine‐5‐oxide derivatives as visible photosensitisers for polymerisation

Several 6‐pyridinium benzo[a]phenazine‐5‐oxide derivatives have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and mass spectrometry. The spectroscopic and electrochemical properties of these dyes were examined. The dyes were used as reducible sensitisers for selected electron donors (phenylthioacetic acid, phenoxyacetic acid, N‐phenylglycine, and ethyl 4‐N,N‐dimethylaminobenzoate) and as oxidisable sensitisers for electron acceptors (onium and N‐alkoxypyridinium salts). These photoredox pairs were found to be effective visible‐wavelength photoinitiators for the free radical polymerisation of trimethylolpropane triacrylate under visible light. The cationic photopolymerisation of cyclohexene oxide by the studied dyes and the onium salt photoredox pairs was ineffective. The obtained results are discussed on the basis of both free energy change for electron transfer to or from the benzo[a]phenazine dyes and the photochemical properties of the dyes, particularly their photobleaching. The proposed mechanism of dye fading is supported by density functional theory calculations and spectroscopic characterisation of the radical cation of the dye.     

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β‐sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant‐free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β‐sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4‐diethylamino‐4′‐(2‐sulphatoethylsulphonyl‐4,6‐dibromo)azobenzene dyes were prepared by a diazo‐coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build‐up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.     

The evaluation of procedures for dyeing silk with buckthorn and walloon oak on the basis of colour changes and fastness characteristics

In this study, silk fabric samples were dyed according to various procedures with buckthorn (Rhamnus petiolaris Boiss) and walloon oak (Quercus ithaburensis Decaisne) extracts. Reversed‐phase high‐performance liquid chromatography with diode‐array detection was utilised for the identification of dyes present in the dyed silk fabrics and the plant extracts. The extraction of dyes was carried out with a hydrochloric acid/methanol/water (2:1:1; v/v/v) mixture. The colour coordinates of the silk fabrics were measured, and the rubbing, wash and light fastness properties of the dyed silk materials were determined and are discussed.     

Film studies of certain new aromatic–aliphatic polyamides

Two new aromatic–aliphatic polyamides containing azo linkage in the main chain based on 2,2′‐dimethyl‐4,4′‐diaminoazobenzene and adipic/2‐chloro‐5‐methyl‐1,2‐dioic acid (α‐chloro‐δ‐methyl adipic acid) were synthesized and analyzed by thermogravimetry and films were cast. Also three polymers obtained from condensation of 4,4′‐azodibenzoic acid/adipic acid and 2,2′‐bis [4‐(p‐amino phenoxy) phenyl] propane/4,4′‐diaminoazobenzene were studied in terms of mechanical and morphological properties. Film studies were carried out interms of tensile property, scanning electron microscope, dielectric, microwave, and X‐ray diffraction pattern. Thermal studies have been done using thermogravimetric analysis, differential thermal analysis, and pyrolysis‐mass spectral data. The results were correlated with structure and orientation of the molecules. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1305–1316, 2004     

Synthesis of biphenylated cyanate esters: Thermomechanical resin comparisons within two isomeric series

Three isomeric tetraaryl cyanate esters containing biphenyl moieties {bis‐[4‐(4′‐cyanatophenyl)phenyl]propane, 2,2‐bis‐[4‐(3′‐cyanatophenyl)phenyl]propane, and 2,2‐bis‐[4‐(2′‐cyanatophenyl)phenyl]propane} and three isomeric triaryl cyanate esters {2‐(4′‐hydroxyphenyl)‐2‐[4′‐(4‐hydroxyphenyl)phenyl]propane, 2‐(4′‐hydroxyphenyl)‐2‐[4′‐(3‐hydroxyphenyl)phenyl]propane, and 2‐(4′‐hydroxyphenyl)‐2‐[4′‐(2‐hydroxyphenyl)phenyl]propane} were synthesized from their corresponding bisphenols. The structures of the monomers were confirmed with IR and ¹H‐NMR spectroscopy. The curing behavior was investigated with differential scanning calorimetry. Cyanate esters were cured thermally in the absence of a catalyst and were characterized by dynamic mechanical analysis. The results were compared to the properties of commercial bisphenol A polycyanurate. Of the three tetraaryl isomers, 2,2‐bis‐[4‐(2′‐cyanatophenyl)phenyl]propane had the highest melting point, and its corresponding resin had the lowest glass‐transition temperature (T_g). The para isomer displayed the highest T_g value of the three novel tetraaryl resins. The triaryl dicyanate isomers were low‐melting solids, with the ortho and meta isomers existing as liquids at room temperature. The T_g value of the para‐triaryl isomer was the highest of the three triaryl isomers and was about the same as that of bisphenol A polycyanurate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Production of (R)‐3′‐fluorophenylethan‐1‐ol by Trichothecium roseum isolate in a laboratory scale bioreactor

BACKGROUND: Enantiomerically pure, fluorinated compounds play an important role in medicinal chemistry. Trichothecium roseum strains were isolated for the production of (R)‐3′‐fluorophenylethan‐1‐ol. Biocatalytic production of optically active (R)‐3′‐fluorophenylethan‐1‐ol was achieved by asymmetric reduction of 3′‐fluoroacetophenone in a batch culture of Trichothecium roseum using ram horn peptone (RHP). The reaction conditions (pH, temperature and agitation) required to improve the conversion of 3′‐fluoroacetophenone and enantiomeric excess (ee) of (R)‐3′‐fluorophenylethan‐1‐ol were studied. RESULTS: The gram scale production of (R)‐3′‐fluorophenylethan‐1‐ol by the most effective biocatalyst, Trichothecium roseum EBK‐11 using RHP was carried out in a fermenter with 1 L working volume. The results showed that the yield with >99% ee of (R)‐3′‐fluorophenylethan‐1‐ol reached 77%. The concentration of (R)‐3′‐fluorophenylethan‐1‐ol at the end of 62 h fermentation was 2.70 g L^?1. CONCLUSION: An important chiral intermediate for the pharmaceutical industry using T. roseum EBK‐11 in submerged culture containing RHP from waste material was produced up to gram scale with excellent ee (99%). In this work, T. roseum fungus was used for the first time as a biocatalyst for efficient production of a chiral alcohol. Copyright © 2009 Society of Chemical Industry     

New fluorous bipyridine ligands for copper‐catalyzed atom transfer radical polymerization of methyl methacrylate in the thermomorphic mode

The atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) is often carried out under homogeneous conditions, so the residual metal catalyst in the polymer often influences the quality of the polymer and causes environmental pollution in the long run. Novel CuBr/4,4′‐bis(R_fCH₂OCH₂)‐2,2′‐bpy complexes (R_f = n‐C₉F₁₉, n‐C₁₀F₂₁, or n‐C₁₁F₂₃; 2,2′‐bpy = 2,2′‐bipyridine) are insoluble in toluene at room temperature yet readily dissolve in toluene at elevated temperatures to form homogeneous phases for use as catalysts in the ATRP reaction, and the Cu complexes precipitate again upon cooling. The CuBr/4,4′‐bis(n‐C₉F₁₉CH₂OCH₂)‐2,2′‐bpy system produced the best results (e.g., polydispersity index by gel permeation chromatography = 1.26–1.41), in that the residual Cu content in the polymer was as low as 19.3 ppm when the ATRP of MMA was carried out in the thermomorphic mode. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,Thermal Stability and Impact Stability of Novel Tetranitro‐Dipyridotetraazapentalene Derivatives

The synthetic details for the construction of three new dipyridotetraazapentalene derivatives, 5H‐pyrido[3″,4″:4′,5′] [1,2,3]triazolo‐ [1′,2′:1,2][1,2,3]triazolo[5,4‐b]pyridin‐6‐ium inner salt ( 8 ), 5H‐pyrido[3″,2″:4′,5′] [1,2,3]triazolo[1′,2′:1,2] [1,2,3]triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 15 ) and 5H‐pyrido[2″,3″:4′,5′] [1,2,3]‐triazolo[1′,2′:1,2][1,2,3]triazolo[4,5‐b]pyridin‐6‐ium inner salt ( 16 ) are presented. Nitration of ( 8 ) and ( 15 ) afforded the novel tetranitrodipyridotetraazapentalene derivatives, 2,4,8,10‐tetranitro‐5H‐pyrido[3″,4″:4′,5′][1,2,3]triazolo[1′,2′:1,2][1,2,3]‐triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 3 ) and 2,4,8,10‐tetranitro‐5H‐pyrido[3″,2″:4′,5′][1,2,3]triazolo[1′,2′:1,2][1,2,3]‐triazolo[5,4‐b]‐pyridin‐6‐ium inner salt ( 4 ) in good yields. Both isomers, ( 3 ) and ( 4 ), exhibited high thermal stability (differential scanning calorimetric analysis and thermal gravimetric analysis) and were insensitive to impact (hammer/anvil test).