Photophysical Properties of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine

Spectral and photophysical investigations of 4′-(p-aminophenyl)-2,2′:6′,2′′-terpyridine (APT) have been performed in various solvents with different polarity and hydrogen-bonding ability.The emission spectra of APT are found to exhibit dual fluorescence in polar solvents, which attributes to the local excited and intramolecular charge transfer states, respectively. The two-state model is proven out for APT in polar solvent by the time-correlated single photon counting emission decay measurement. Interestingly, the linear relationships of different emission maxima and solvent polarity parameter are found for APT in protic and aprotic solvents, because of the hydrogen bond formation between APT and alcohols at the amino nitrogen N25. Furthermore, the effects of the complexation of the metal ion with tpy group of APT and the hydrogen bond formation between APT with methanol at the terpyridinenitrogen N4—N8—N14 are also presented. The appearance of new long-wave absorption and fluorescence bands indicates that a new ground state of the complexes is formed.     

Synthesis of Novel 1-Arylsulfonyl-4-(1′-N-2′, 3′, 4′, 6′-tetra-O-acetyl-β-D-glucopyranosyl)thiosemicarbazides

Some 1-arylsulfonylthiosemicarbazides have been reported as fungicides1 and bacterio-static agents2. Recently, it is well documented that thiosemicarbazide is a novel class ofnon-peptide antagonists for bradykinin B2 , which is beneficial in the symptomat…     

An Improved Synthesis of 2′-Hydroxy-3′,4′,6′-trimethoxyacylophenones

A wide variety of 2′-hydroxypolymethoxyacetophenones and propiophenones, e.g. 1a and 1b are used in the synthesis of flavone and ehromone natural products.¹ Repeated attempts to prepare 1a and 1b by reacting 1,2,3,5-tetramethoxybenzene 2 with acetyl or propionyl chlorides and AlCl₃ in ether² gave products which were difficult to purify.³ We traced the problem to ring-ethoxy contaminants which were isolated and tentatively identified as 3a and 3b.     

Effect of solvent on the crystal structures of copper(II) complexes based on 4′-(4-methoxyphenyl)-2,2′:6′,2″-terpyridine and 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine

Four homoleptic copper(II) complexes, [Cu(Meophtpy)₂](ClO₄)₂ (Meophtpy = 4′-(4-methoxylphenyl)- 2,2′:6′,2″-terpyridine) (I), [Cu(Meophtpy)₂](ClO₄)₂ · 2H₂O (II), [Cu₂(m-Clphtpy)₄](ClO₄)₄ (m-ClPhtpy = 4′-(3-chlorophenyl)-2,2′:6′,2″-terpyridine) (III), and [Cu₂(m-ClPhtpy)₄](ClO₄)₄ (IV) have been synthesized by hydrothermal methods and characterized by IR, elemental analysis and single crystal X-ray diffraction (CIF files CCDC nos. 963375 (I), 885457 (II), 963377 (III), and 963376 (IV)). Complex II is a polymorph of I and complex IV is a polymorph of III. All these complexes are obtained with 95% ethanol solution or 50% ethanol solution and the solvent control on the crystallization are obviously found. In all complexes, the face-to-face interactions between pyridyl rings or phenyl rings facilitate the construction of 3D network in the crystal in addition to hydrogen bonds. The fluorescence properties of these complexes have been investigated.     

Understanding the role of flexible 4′-functionalized polyethylene glycoxy chains on the behavior of platinum(II) (4′-(ethylene glycoxy)-2,2′:6′,2′′-terpyridine: a kinetic and a mechanistic study

The ligand substitution kinetics of 4′-functionalized mononuclear Pt(II) (4′-(ethylene glycoxy)-2,2′:6′,2′′-terpyridine complexes, [Pt(nY-tpy)Cl)Cl] (where Y = ethylene glycoxy, n = number of ethylene, glycoxy units = 1, 2, 3, and 4, and tpy = 2,2′:6′,2′′-terpyridine), with thiourea, 1,3-dimethyl-2-thiourea, 1,1,3,3-tetramethyl-2-thiourea, and iodide were investigated under pseudo-first-order conditions as a function of concentration and temperature by conventional stopped-flow technique. The observed first-order rate constants followed the simple rate law k_obs = k₂[Nu]. The data obtained show that the ethylene glycoxy pendant, trans to the leaving group, acts as a σ-donor into the terpyridine ligand and is effective only up to n = 1, beyond which the substitution reactivity of the complexes are controlled by the steric influence of the appended ethylene glycoxy pendant units, which decreases with increase in the number of ethylene glycoxy units. The activation parameters obtained support an associative mechanism, where bond formation in the transition state is favored. The observed reactivity trends were supported by density functional theory calculations.     

Efficient and mild one-pot synthesis of (E)-8′-arylidene-5′,6′,7′,8′-tetrahydrospiro[oxindole-3,4′-pyrano[3,2-c]pyridin] derivatives with potential antitumor activity

A mild and efficient cyclization procedure for the synthesis of (E)-8′-arylidene-5′,6′,7′,8′-tetrahydrospiro[oxindole-3,4′-pyrano[3,2-c]pyridin] derivatives was achieved via one-pot three-component condensation of isatins, malononitrile and (E)-3-arylidene-1-methylpiperidin-4-ones using piperidine as an efficient catalyst and ethanol as an environmentally benign solvent. The in vitro antitumor activity of these compounds was evaluated in human cervical carcinoma cell line (Hela), human liver hepatocellular carcinoma cell line (HepG2), and human breast carcinoma cell line (MDA-MB-231).     

An expeditious access of 2,5′-dioxo-5′,6′,7′,8′-tetrahydro-1′H-spiro[indoline-3,4′-quinoline]-3′-carboxylate by reaction of isatin,ethyl cyanoacetate and enaminone in water

We have demonstrated three component reaction of isatin, enaminone and ethyl cyanoacetate leading to sprirooxindole scaffold without catalyst in water. The synthetic protocol has several advantages like wide substrate scope, atom-economy and operationally simple experimental procedures which provides rapid access to library of compounds. The mechanistic details of the reaction has been investigated during the course of study.     

Synthesis of 2′-5′,3′-5′ linked triadenylates

2′-5′,3′-5′ Linked triadenylates have been synthesized by direct bisadenylylation of adenosine 2′ and 3′ hydroxyls with an adenosine 5′-phosphorochloridite followed by oxidation.     

Synthesis and mesomorphic properties of 4-methoxyphenyl 4′- n -alkoxy-2′,3′,5′,6′-tetrafluorobiphenyl-1-carboxylates

A novel type of 4-methoxyphenyl 4′-n-alkoxy-2′,3′,5′,6′-tetrafluorobiphenyl-1-carboxylates have been synthesized. Textural observations by polarizing microscopy and DSC measurements of the phase transitions show that all of these compounds are thermotropic liquid crystals with only a nematic mesophase. The relationship between the properties and chemical structures of these compounds is discussed.     

Synthesis of N-Aryl-2-(1′,6′-dihydro-6′-pyridazinone-3′-carbonyl) Thiosemicarbazides and Their Related Heterocyclic Compounds

Introduction Somepyridazineshavebeenexaminedforac- tivityagainstsporozoanandflagellateparasitesand forantiamebicactivity[1]. 6-Aryl-4,5-dihydro-3(2H)-pyridazinonesex- hibitvariousbiologicalpropertiesincludingreduc- tionofbloodpressure,inhibitionofplateletaggre- gation,antiinflammation,andstrongplateletag- gregationinhibitingactioncoupledwithahypoten- siveaction.Italsopossessesweakpositiveinotrop- icactivityforthemanagementofcongestiveheart failure.Threepara-substitueddihydropyridazi- nonesare…     

Synthesis of 1,3,1′,5′,6′,7′-hexahydro-3,3′-biindolyl-2,4′-dione derivatives by cyclization of 3-alkylideneoxindoles with enaminone

The reaction between 3-alkylideneoxindoles 1 and 3-aminocyclohex-2-enone 2 was studied, and an efficient synthesis of 1,3,1′,5′,6′,7′-hexahydro-3,3′-biindolyl-2,4′-dione derivatives was developed by a sequential Michael addition followed by intramolecular condensation catalyzed by nickel dichloride hexahydrate. The reaction mechanism is discussed.     

由2′,4′-二氢-6′-甲氧基-3′,5′-二甲基查耳酮合成新黄酮

在DMSO/I2的氧化作用下,由2′,4′-二氢-6′-甲氧基-3′,5′-二甲基查耳酮可合成一种全新结构的黄酮:7-羟基-5-甲氧基-6,8-二甲基黄酮(产率91%),而在HCl/MeOH作用下则得到了两种黄烷酮:7-羟基-5-甲氧基-6,8-二甲基黄烷酮(产率70%)和5,7-二羟基-6,8-二甲基黄烷酮(产率20%)。     

Asymmetric Synthesis of (S)-Dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethenedioxybiphenyl-2,2′-dicarboxylate

Schizandra chinesis(wuweizi)has long been used in Chinese herbal medicine.Schisandrin C,as a constituent of Schizandra chinesis,shows various pharmacologicalactivities1.The similar compound,dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethenedi-oxy-biphenyl-2,2′-dicarboxylate(α-DDB),discovered by Xie2,3et al.in the investing-ation of schisandrin C,and some derivatives have also exhibited anti-HIV and anti-HBVactivity4.Further study of this kind of biphenyls has attracted considerable attenti…     

Synthesis and Taste Properties of 4,1′,4′,6′‐Tetrahalodeoxysucrose Analogues

The synthesis of a series of 1,4,6‐trideoxy‐1,4,6‐trihalo‐β‐d‐hexulofuranosyl 4‐deoxy‐4‐halo‐α‐d‐hexopyranosides is described. The 4‐chloro‐, 4‐bromo‐ and 4‐iodo‐4‐deoxy‐β‐d‐fructofuranosyl analogues were synthesized from a 3′,4′‐lyxo‐epoxide using the respective alkali metal halides. The corresponding 4‐halodeoxytagatofuranosyl analogues, on the other hand, were obtained by direct halide displacement of the 4′‐O‐trifluoromethanesulfonyl derivative, which was derived by regioselective sulfonylation of 1,6‐di‐O‐trityl‐β‐d‐fructofuranosyl 6‐O‐trityl‐α‐d‐glucopyranoside via its stannylene acetal. The sweetness intensities of these tetrahalodeoxy compounds strongly suggest that both size and configuration of the halogen substituents at C‐4 and C‐4′ are critical for sweetness enhancement.     

Interference from 2,3,5,6-3′,4′-Hexachlorobiphenyl (CB 163) in the Determination of 2,3,4-2′,4′,5′-Hexachlorobiphenyl (CB 138) in Environmental and Technical Samples

Abstract

In Intern. J. Enuiron. Anal. Chem. 66 (1989), 155-161, Roos et al.¹ reported on problems encountered in the determination of 2,3,4-2′,4′,5′-hexachlorobiphenyl (CB 138) in environmental samples. These authors indicated that an interference was present for the capillary column gas chromatographic (HRGC) determination of CB 138. This interference was tentatively identified (without standard) as 2,3,5,6-3′,4′-hexachlorobiphenyl (CB 163). We have synthesized CB 163 and can confirm that it co-elutes with CB-138 on the widely used HRGC phase for polychlorinated biphenyl (PCB) analysis, 5%, phenyl, 95% methylpolysiloxane (CP-SIL8-CB) even on a 50m column. However, we managed to separate CB 163 from CB 138 on the very polar phase, bis-cyanopropylphenyl polysiloxane (SP-2330), using a 30 m column. We have quantified CB 163 and CB 138 in various environmental and technical samples and have found CB 163 to CB 138 ratios from I: 10 up to 3: 10.     

Theoretical study on the hydrolysis mechanism of N,N-dimethyl-N′-(2′,3′-dideoxy-3′-thiacytidine)formamidine

The hydrolysis mechanisms of N,N-dimethyl-N′-(2′,3′-dideoxy-3′-thiacytidine)formamidine (FA-3TC) in the gas phase and in aqueous solution were studied by use of the density functional theory B3LYP/6-31 G(d, p) method. Two possible reaction pathways in the title reaction were considered. In one pathway water attacks the C=N double bond first (path A) while in the other water attacks the C—N single bond first (path B). The calculated results indicate that the first step in both pathways is the rate-limiting process and path A is more favorable than path B in the gas phase. The effect of solvent water on the title reaction was assessed at the B3LYP/6-31 G(d, p) level of theory based on the po-larizable continuum model (CPCM). In water the first mechanism (path A) is also favored.     

Transition metal(II) complexes of 1-(α-hydroxynaphthyl)-2-(3′-methyl-5′-mercapto-1′,2′,4′-triazole)-2-aza-ethane

Summary Binuclear metal complexes of the type [M(HMTE)-(H₂O)₂]₂, where HMTE=1-(-hydroxynaphthyl)-2-(3-methyl-5-mercapto-1,2,4-triazolc)2-aza-ethane and M-Cu^II, Co^II, Ni^II and Mn^II have been prepared and characterized. An octahedral geometry around the metals is proposed. The complexes have been screened as possible fungicides.     

Molecular structure of 1′,3′,3′-trimethyl-6-trifluoromethylsulfonyl-spiro-(indoline-2,2′-benzo[b]pyran)

Photochromic 1, 3, 3 -trimethyl-6-trifluoromethylsulfonyl-spiro(indoline-2,2-ben-zo[b]pyran) (1) was studied by X-ray diffraction analysis. In compound1, the C_spiro-O bond (1.49(1) Å (average)), broken on photoexcitation, is the longest of all the indoline spiropyrans studied.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1969–1971, November, 1994.     

Formation of 3a′,8′-dimethyl-3a′,5′-dihydro-1′H,3′H-dispiro-[cyclohexane-1,3′-furo[3,4-f][2]benzofuran-5′,1″-cyclohexane]-1′,7′(4′H)-dione in the reaction of 3-acetyl-4-methyl-1-oxaspiro[4.5]dec-3-en-2-one with potassium hydroxide

3a′,8′-Dimethyl-3a′,5′-dihydro-1′H,3′H-dispiro[cyclohexane-1,3′-furo[3,4-f][2]benzofuran-5′,1″-cyclohexane]-1′,7′(4′H)-dione was synthesized by reaction of 3-acetyl-4-methyl-1-oxaspiro[4.5]dec-3-en-2-one with potassium hydroxide in water.