Studies on cyanine dyes. IV. Synthesis of new styryl oxa-cyanine dyes

The condensation reaction of benzoxazole-2-carboxaldehyde (I) with quaternary salts of heterocyclic compounds, in the presence of piperidine as a catalyst, afforded styryl cyanines (II). Interaction of (I) with the non-quaternised heterocyclic compounds at a longer time gave the corresponding dimethine bases (III). On the other hand, benzoxazole-2-carboxaldehyde-3-ethiodide (IV) interacted with quaternised and non-quaternised heterocyclic compounds achieved styryl cyanines of the type (V) and (VI), respectively. Absorption spectra for these compounds in EtOH are discussed.     

Synthesis, spectral characterisation and anti-bacterial activity of various 1,3,4-oxadiazine cyanine dyes

A number of new styryl, aza-styryl, acyclic mero, cyclic mero and mixed cyanine dyes with a benzo[2,3- e ; 2',3'- e ']bis-1,3,4-oxadiazine nucleus were synthesised. The absorption spectra in the visible region of all the synthesised cyanine dyes in 95% ethanol solution were examined and studied in detail. Anti-bacterial activity for a number of selected dyes was evaluated against various bacterial strains. The structural determination was carried out using elemental and spectroscopic analysis.     

Synthesis of novel fluorescent styryl dyes based on the imidazo[1,2-a]pyridinium chromophore and their spectral-fluorescent properties in the presence of nucleic acids and proteins

The imidazo[1,2-a]pyridinium heterocyclic system was used to prepare styryl dyes. Improved synthetic methods were proposed for the parent imidazo[1,2-a]pyridines and their corresponding quaternary salts. The standard method for preparing styrylcyanines was modified for the synthesis of the target imidazo[1,2-a]pyridinium dyes. Spectral-luminescent properties of the obtained dyes in free state and in the presence of nucleic acids, BSA, and BSA/detergent system were studied. 7-[2-(4-Dihexylaminophenyl)-1-ethenyl]-2-(2,4-dimethoxyphenyl)-1-ethylimidazo[1,2-a]pyridin-1-ium iodide (SIP-8) containing C₆ aliphatic tails and 2,4-methoxy substituents in the 2-phenyl ring exhibited specificity to BSA.     

Synthesis and antimicrobial activity of certain novel monomethine cyanine dyes

A series of novel monomethine cyanine dyes were synthesized by using 3-methyl-5-substituted-1-phenyl-pyrano[2,3-c]pyrazole derivatives 2a–c. Reaction of equimolar ratios of 2a–c with 2(4)-methyl heterocyclic quaternary salts afforded the corresponding monomethine cyanines 3a–c. Reaction of compound 5 with 2(4)-methyl heterocyclic quaternary salts gives monomethine 6a–c. Condensation reaction of equimolar ratios of compounds 7 and 9a,b with 2(4)-methyl heterocyclic quaternary salts afforded the corresponding monomethine cyanines 8a–c and 10a,b respectively. The new synthesized monomethine cyanine dyes were identified by elemental analyses, IR, ¹H-NMR and Ms spectral data. The electronic absorption spectra in ethanolic solution of novel monomethine cyanine dyes were measured and the antimicrobial activity of some selected monomethine cyanine dyes was discussed.     

Studies on cyanine dyes II. Preparation of ferrocene cyanines

The condensation of ferrocene aldehyde with quaternary salts of 2-methyl heterocyclic compounds, in the presence of piperidine as a catalyst, afforded ferrocenyl cyanines. Interaction of ferrocene aldehyde with the non-quaternised heterocyclic compounds, in the presence of pyridine and sodium ethoxide as a condensing agent, afforded styryl ferrocenes.     

Studies on cyanine dyes: II. Preparation of ferrocene cyanines

The condensation of ferrocene aldehyde with quaternary salts of 2-methyl heterocyclic compounds, in the presence of piperidine as a catalyst, afforded ferrocenyl cyanines. Interaction of ferrocene aldehyde with the non-quaternised heterocyclic compounds, in the presence of pyridine and sodium ethoxide as a condensing agent, afforded styryl ferrocenes.     

Synthese von Pyrrolo[1,2-a]chinazolinonen,Indolo[1,2-a]chinazolinonen,Pyrrolo[1,2-a]thieno[3,2-e]pyrimidinonen,Benzothieno[3,2-e]-pyrrolo[1,2-a]pyrimidinonen und 6H-Cyclohepta[4,5]thieno-[3,2-e]pyrrolo[1,2-a]pyrimidinonen

A Synthesis of Pyrrolo[1,2-a]quinazolinones, Indolo[1,2-a]-quinazolinones, Pyrrolo[1,2-a]thieno[3,2-e]pyrimidinones, Benzothieno[3,2-e]pyrrolo[1,2-a]pyrimidinones and 6H-Cyclohepta[4,5]-thieno[3,2-e]pyrrolo[1,2-a]pyrimidinones α-Cyano-γ-halo-crotonnitriles ( 1 ) synthesized (e.g. via Knoevenagel reaction and by subsequent halogenation) react with primary arylamines ( 2 ) to substituted 1-aryl-2-amino-3-cyano-pyrroles ( 3 ). We found that the reaction yields pyrrolo[1,2-a]quinazolin-5-ones ( 6 ) in a one-pot procedure if anthranilic esters ( 4 ) and compounds of the general formula 5 are used. The analogous treatment with 2-amino-3-ethoxy-carbonyl-thiophene derivatives ( 8 ) leads to pyrrolo[1,2-a]thieno-[3,2-e]pyrimidin-5-ones, benzothieno[3,2-e]pyrrolo[1,2-a]pyrimidinones and 6H-Cyclohepta[4,5]-thieno[3,2-e]pyrrolo[1,2-a]pyrimidinones as thiadiazastereoid analogs 9 . This reaction is suitable for the synthesis of various heterocyclic ring systems.     

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.     

Study on the dyeing properties of hemicyanine dyes. II. Cationic dyeable polyester

The absorption spectra of two hemicyanine fluorescent dyes, namely, trans‐4‐[p‐(N,N‐di(2‐hydroxyethyl))‐amino‐styryl]‐N‐ethyl pyridinium bromide (DHEASPBr‐C₂) and trans‐4‐[p‐(N,N‐di(2‐hydroxyethyl))‐amino‐styryl]‐N‐octyl pyridinium bromide (DHEASPBr‐C₈), were studied at various levels of pH and high temperatures, and were then employed to dye cationic dyeable polyester. Their dyeing properties, fluorescent reflectance and colorimetric properties were explored. The novel fluorescent dyes existed in two forms of monocation and dication in solutions at low pH and high temperature. Overall, the influence of pH on colour depth and the maximum reflectance of dyed cationic dyeable polyester was extremely small. The adsorption mechanism of DHEASPBr‐C₂ and DHEASPBr‐C₈ on cationic dyeable polyester fibres was in good accord with the Langmuir type. Compared with DHEASPBr‐C₂, DHEASPBr‐C₈ exhibited comparatively faster adsorption rate, higher affinity and dye uptake, while its fluorescence shown by cationic dyeable polyester was slightly weak.     

Novel substituted 2-acetamido thiophene-4-styryl disperse dyes

Ethyl 2-acetamido-3-cyano-5-carbethoxy thiophene-4-acetic acid ester has been synthesised by the Gewald reaction of diethyl acetonedicarboxylate, sulphur and malononitrile, followed by acetylation. A variety of aryl and hetaryl aldehydes were condensed with this thiophene derivative in refluxing DMF in the presence of piperidine to yield novel styryl dyes. The fluorescence in solution and dyeing properties of these styryl dyes on polyester were studied.     

Cyanine dyes as corrosion inhibitors. I. Electrochemical corrosion behaviour of copper metal treated with hydroxystyryl cyanine dye

The effect of 2-(o-hydroxystyryl) pyridinium-1-ethyl iodide cyanine dye on the corrosion behaviour of copper metal in nitric acid solution has been studied. Weight loss measurements, galvanostatic polarization curves, open-circuit potential variation of copper electrode with time and the cathodic protective current values indicate that styryl cyanine dye gives an anticorrosive character. The inhibition effect is more pronounced in the case of copper metal coated by dye thin film than that obtained by its addition to the corrosion medium.     

Synthesis,spectral behaviour and biological activity of pyrazolo-pyrimidine cyanine dyes

New asymmetrical 2(4)-monomethine cyanine dyes (III_a-_c IV_a-_i), monomethine bases (V_a,b), dicationic cyanines (VIII_a__c, IX_a-_c) and styryl cyanines (XI_a-_b) incorporating N-phenyl-1-H-pyrazolo (3, 4-d) saturated or unsaturated pyrimidine were prepared. The new cyanines were identified by spectral determination. Bactericidal and fungicidal activity of selected cyanines (III_a-c, IV_a-i, V_a,bVIII_a-_c, IX_a-c and XI_a,b) were tested against bacterial and fungal strains.     

Novel magnesium and zinc porphyrazines containing galactose moieties: Synthesis via click reaction and characterization

In this study, galactose conjugated new magnesium and zinc porphyrazines were synthesized by the cyclotetramerization reaction of 2,3-bis[1-(2,2,7,7-tetramethyltetra-hydro-bis[1,3]dioxolo[4,5-b;4′,5′-d]pyran-5,methyl)-1H-[1,2,3]triazol-4-yl methylsulfanyl]-but 2-enedinitrile. This substituted dicyano compound was prepared via two different routes. One started from cis-1,2-dicyano-1,2-ethylenedithiolate disodium, [1-(2, 2, 7,7-tetramethyltetrahydrobis[1,3]dioxolo[4,5-b;4′,5′-d]pyran-5-yl-methyl)-1H-[1,2,3]triazo-l-4-yl]methanol and ended in a multi-step reaction sequence via Click procedures. The other reaction was between 5-azidomethyl-2,2,7,7-tetramethyltetrahydro-bis[1,3]dioxolo[4,5-b;4′,5′-d]pyran and (2Z)-2,3-bis(prop-2-yl-1-yl-thio)but-2-enedinitrile. A very soluble galactose linked magnesium porphyrazine derivative in common polar solvents and water was achieved by the deprotected isopropylidene groups in TFA and water media. It is first time, zinc porphyrazine complex has been achieved at one-step reaction by using Zn(BuO)₂ as template agent. The new compounds have been characterized by a combination of elemental analysis, ¹H, ¹³C NMR, IR, UV–vis and MS spectral data.     

Synthesis of an active quaternary phosphonium salt and its application to the Wittig reaction: Kinetic study

The synthesis of liquid crystal methyl [4-(nonyloxy) styryl] benzoate was achieved in four stages. First, toluic acid [1] was brominated with N-bromosuccinimide in refluxing CCl₄ to form 4-bromotoluic acid [2] (BTA); second, BTA was esterified with methanol in SOCl₂/CH₂Cl₂ to afford methyl (4-bromomethyl) benzoate [3] (BME); third, BME was condensed with triphenylphosphine (PPh₃) in CH₂Cl₂ to produce the active Wittig reagent methyl (4-methylbenzoate) triphenylphosphonium bromide [4] (MBPB) and fourth, MBPB reacted with 4-nonyloxybenzaldehyde to produce MNSB in high yield. Each of these four reactions was carried out in a separate homogeneous organic solution and the effects of the reaction conditions in each reaction as well as a kinetic model for each individual reaction were studied. Furthermore, the active reagent was applied to the reaction of 4-nonyloxybenzaldehyde (n-C₉H₁₉O(C₆H₄)CHO) to synthesise cis-(E) and trans-(Z)methyl[4-(nonyloxy)styryl]benzoate (n-C₉H₁₉(C₆H₄)CHCH(C₆H₄)COOCH₃) from a two-phase medium alkaline solution of NaOH/organic solvent. High conversion and high selectivity were obtained via this reaction.     

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 of isomeric azo disperse dyes of pyridobenzimidazole

Condensation of 4-(4-methoxyphenyl)-5H-pyran-2,6-dione (1) and 1,2-diaminobenzene (2) gave 3-(4-methoxyphenyl)-1-oxo-1H, 5H-pyrido [1,2-a]benzimidazole (3). When3was coupled with an aryldiazonium salt two isomeric dyes were obtained in equal proportions. These dyes were characterised as 3-(4-methoxyphenyl)-4-(arylthydrazono)-1-oxo-1H-pyrido-[1,2-a]benzimidazole (4) and 2-(arylhydrazono)-3-(4-methoxyphenyl)-1-oxo-1H-pyrido[1,2-a]benzimidazole (5) on the basis of spectral data. Their structures were confirmed also by an alternative synthetic route.     

Heat deterioration of phospholipids. VI. Clarification of mechanism for the new pseudo Maillard rearrangement reaction by using 2-aminoethyl dihydrogenphosphate

2,3-Dihydro-1H-imidazo[1,2-a]pyridine-4-ylium derivatives with UV absorption at 350 nm were formed by reaction of one molar of any sugar except 2-deoxysugars with two molar of phosphatidylethanolamines involving a new pseudo Maillard rearrangement reaction. To elucidate the reaction mechanism, 2-aminoethyl dihydrogenphosphate, which had a partially similar structural moiety to PE, was reacted with D-galactose. Though the UV absorption at 365 nm was not observed and the four pyridinium derivatives were also not formed in the reactant solution, the UV absorption at 286 nm and browning of the reactant solution were observed. From this reactant solution, two compounds with lambdamax at 283 nm and 297 nm were isolated and former was determined as 5-(hydroxymethyl)furfural (HMF) and later did as phosphoric acid mono{2-[2-formyl-5-(hydroxymethyl)-1H-pyrrol-1-yl]ethyl}ester (PMPEE), which is a new compound, respectively. Because reaction of PMPEE with PE leads to form the pyridinium derivatives, we concluded that a compound like PMPEE was one of intermediates in this new reaction.     

Oxokohlenstoffe und verwandte Verbindungen. 27. Synthese von Dihydrocyclobuta[a]naphthalen-1,2-dionen und Cyclobuta[a]naphthalen-1,2-dionen durch Anellierung von Alkoxy-(1-alkenyl)benzolen mit 3-Chlor-3-cyclobuten-1,2-dion. Anwendungsbereich und Grenzen

Oxocarbons and Related Compounds. 27. Synthesis of Dihydrocyclobuta[a]naphthalene-1,2-diones and Cyclobuta[a]naphthalene-1,2-diones via Annulation of Alkoxy-(1-alkenyl)benzenes with 3-Chloro-3-cyclobutene-1,2-dione. Scope and Limitations The reaction of alkoxy-(1-alkenyl)benzenes with semisquaric chloride ( 3 ) has been investigated systematically. 1,2-Dialkoxy- and 1-alkoxy'-2-alkoxy″-4-(1-alkenyl)benzenes ( 6a–j ) and ( 11a–i ) react with 3 to give the 3,4-dihydrocyclobuta[a]naphthalene-1,2-diones ( 8a–j ) and ( 12a–i ). Treatment of the dihydrocyclobuta[a]naphthalene-1,2-diones with 1.2 equiv. bromine effects dehydrogenation and affords cyclobuta[a]naphthalene-1,2-diones ( 9a–e ) and ( 13b–f ). Any efforts to extend this annulation reaction to dimethoxy-(1-alkenyl)benzenes with the methoxy groups in other than the 1,2-positions, e. g. 14a, b, 16a, b have been unsuccessful. The reaction of 1,2,3-trimethoxy-4-(1-propenyl) [and 4-(1-butenyl)]-benzenes ( 18a ) and ( 18b ) with semisquaric chloride ( 3 ) leads to the elimination of HCl and CH₃OH and gives 5,6-dimethoxy-3-methyl [and 3-ethyl]-cyclobuta[a]naphthalene-1,2-diones ( 20a ) and ( 20b ). The reaction pathway of this novel annulation reaction is discussed.     

The synthesis and photochromism of a 2,2-diaryl-6-styryl-2H-[1]benzopyran: Unexpected palladium-mediated ring-contraction of a 6-bromo-2,2-diaryl-2H-[1]benzopyran

The ligand-free Pd-mediated reaction between styrene and a 6-bromo-2,2-diaryl-2H-[1]benzopyran proceeded anomalously to give a 2-(diarylmethyl)-5-styrylbenzofuran via a tandem Heck coupling - ring-contraction process; none of the styryl substituted 2,2-diaryl-2H-[1]benzopyran was observed. A 2,2-diaryl-6-styryl-2H-[1]benzopyran resulted from the condensation between 4-hydroxystilbene and a 1,1-diarylpropynol and which exhibited photochromism through the reversible electrocyclisation of the pyran unit; no isomerisation - electrocyclisation of the stilbene moiety was detected.     

The synthesis and two-photon excited fluorescence properties of novel branched fluorene derivatives

Two novel, V-shaped fluorene derivatives branched from triphenylamine and their linear analogue were synthesized via Cu-mediated Ullmann condensation and subsequent Pd-catalyzed Heck coupling reaction. Their two-photon excited fluorescence properties as well as their linear absorption and single-photon excited fluorescence properties were examined. When excited at 730 nm by a Ti:sapphire femtosecond laser, the compounds exhibited strong two-photon excited blue fluorescence. The two-photon excited fluorescence cross-sections of V-shaped derivatives in toluene at 730 nm were ∼506 GM in the case of N, N-bis{7-[4′-(N, N-diphenylamino)styryl]-9,9-diethyl-9H-fluorene-2-yl}-aniline) and 397 GM for N, N-Bis{7-[4′-(N, N-diphenylamino)styryl]-9,9-diethyl-9H-fluorene-2-yl}-4-acetyl-aniline), respectively.