Unusual behavior of 3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one towards some phosphorus reagents: Synthesis of novel diethyl 2-phosphonochromone,diethyl 3-phosphonopyrone and 1,3,2-oxathiaphosphinines

The chemical reactivity of 3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one (1) towards some phosphorus reagents was studied. The enaminone 1 was cyclized into diethyl 2-phosphonochromone 2 via its treatment with diethyl phosphite in basic medium. However, its reaction with triethoxy phosphonoacetate gave the substituted pyrone phosphonate 3. In addition, two novel examples of 4-(dimethylamino)-6-(2-hydroxyphenyl)-2-sulfido-4H-1,3,2-oxathia-phosphinines 6 and 7 were obtained from treatment of enaminone 1 with O,O-diethyl dithiophosphoric acid and Lawesson’s reagent. When enaminone 1 was also treated with phosphorus decasulfide, it was turned into 4H-thiochromene-4-thione while its treatment with phosphorus tribromide, phosphorus oxychloride, or phenylphosphonic dichloride, 4H-4-oxo-chromene was isolated in all cases. The possible reaction mechanisms of the formation of these products were discussed. The structures of newly isolated products were established by elemental analysis and spectral tools.     

Synthesis and study of organic nitrates of heterofunctional series. 5. Synthesis of 3,3-bis(hydroxymethyl)oxetane mono- and dinitrates and 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol) mono- and dinitrates

New procedures were developed for the synthesis of 3,3-bis(hydroxymethyl)oxetane dinitrate (1) by O-nitration of the corresponding glycol (3) or its mononitrate (6), which were prepared by the reactions of 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol) (2) mono- (4) and dinitrates (5), respectively, with alkali. A new method was devised for the synthesis of compounds 4 and 5 by the reaction of tetraol 2 with concentrated HNO₃ in dichloroethane. The structures of compounds 1 and 6 were established by X-ray diffraction analysis.     

Synthetic Studies on Tumor-Associated Antigens: Efficient Syntheses of Lea and Sialyl-Lea Oligosaccharides,and Their Deaminated Analogs1

ABSTRACT

Efficient syntheses of tumor-associated Le^a, sialyl Le^a and their deaminated analogs are described. The suitably protected D-glucosamine (4) or D-glucose (5) derivative was successively coupled with the methyl-1-thioglycosides (glycosyl donors) of D-galactose (6) and L-fucose (11) in high yields by using N-iodosuccinimide/trifluoromethanesulfonic acid (NIS/TfOH) as the glycosyl promoter. The resulting trisaccharides (12 and 13) were each converted, by deprotections, to the Le^a determinant (17) and its deaminated analog (18), and by further glycosylation with the phenyl-2-thioglycoside of N-acetylneuraminic acid (25), to the sialyl-Le^a determinant (30) and its deaminated analog (31), respectively.     

DNA and RNA binding studies on a novel bromo-bridged dimeric copper(II) complex stabilized from a Schiff base ligand

Abstract

A novel red copper(II) compound, bis(μ-bromo)bis(2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone)-dicopper(II) (1), has been fostered by equimolar reaction of a Schiff-base ligand, 2-(benzothiazol-2-yl-hydrazono)-1,2-diphenyl-ethanone (LH), with copper(II) bromide in satisfactory yield. 1 has thoroughly been characterized by C, H and N elemental analyses, FT-IR and UV-vis (both in solid state and in solution) spectroscopies, and room-temperature magnetic susceptibility and conductivity measurements. Dimeric 1 bears symmetric rare bromo-bridges in its crystal structure. 1 retains its solid-state identity even in a protic solvent like methanol. 1 in methanol displays two-step one-electron redox response. Theoretical calculations based on DFT were executed to probe the electronic structure of 1 and to augment its color. DNA- and RNA-binding aspects of both LH and 1 have been explored. Thermodynamic binding parameters have been determined. LH is a major-groove binder to DNA, while 1 manifests itself as a minor-groove binder. This binding has been corroborated through molecular docking. Nucleic acid binding aspect of such type of rare bromo-bridged red copper(II) dimer is unprecedented.     

Aggregation-induced emission enhancement in poly(phenylene-ethynylene)s bearing aniline groups

Poly(phenylene ethynylene)s(P1) with 4-vinylaniline pendant groups were successfully prepared by the Sonogashira coupling polymerization between l,4-diethynyl-2,5-bis(pentyloxy)benzene and 4-[2-(2,5-dibromophenyl)vinyl]-aniline. In comparison with its analogue P2 without amino group,the emission of P1 is only enhanced by aggregation when adding n-hexane into its THF solution,exhibiting an aggregation-induced emission enhancement(AIEE) effect.When methanol or water instead of hexane was added into THF solution,P1,however,didn’t show AIEE.The results indicated that amino groups strengthen the inter-chain and intra-chain interactions in P1 and restrict the non-radiative energy transition. This strategy can provide a platform for developing highly sensitive and efficient bio- and chemosensors.     

Synthesis,Reactivities, and Unique Solution Properties of 4,8-BIS(Diethylamino)-Methylene-1,2,3,5,6,7-Hexaselenacyclooctane

The heading novel heterocycle (3) which contains six selenium atoms in its eight-membered ring was prepared by reaction of 1,1-bis(diethylamino)-2-chloroethene (1) with elemental selenium. The compound 3 showed unique spectroscopic properties behaving as the bis(diethylamino)carbeniumdiselenocarboxylate (4) equivalent in reactivities.     

Synthesis and structure of a new polyoxometalate-based inorganic–organic hybrid and application as a chemically bulk-modified electrode

A new Keggin-type polyoxometalate-based inorganic–organic hybrid, [Cu(H₂O)₂(daphen)]₂[SiW₁₂O₄₀]·9H₂O (1) (daphen?=?5,6-diamino-1,10-phenanthroline), was hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, fluorescence spectra, and thermal analysis. Single-crystal X-ray diffraction analysis reveals that in 1, [SiW₁₂O₄₀]^4? is a tetradentate ligand with its four terminal oxygens coordinating to four Cu(II)–daphen fragments to form a 2D sheet with (4,4) topology. On the basis of the insolubility of 1 in water and common organic solvent and its reversible multielectron redox processes, 1 was used to fabricate a bulk-modified carbon paste electrode (1-CPE) by direct mixing. Electrochemistry indicated that 1-CPE is stable over hundreds of cycles and possessed electrocatalytic activity toward the reduction reactions of nitrite.     

Synthesis and luminescence of polymeric metal complexes based on 1,10-phenanthroline and 8-hydroxyquinoline

A ligand containing different coordination groups, 5-([1,10]phenanthroline-[4,5-f]imidazo-2-yl)-8-hydroxyquinoline (PhenI8Q) has been synthesized and two corresponding polymeric metal complexes Cu(II) (1) and Zn(II) (2) were prepared by coordination polymerization of the ligand with copper(II) and zinc(II) halides, respectively. The ligand was characterized by ¹H-NMR, ¹³C-NMR, and Fourier transform-infrared (FT-IR) and its corresponding polymeric metal complexes 1 and 2 were characterized by FT-IR, UV-Vis, elemental analysis, thermal gravimetric analysis, and conductivity measurements. The absorption spectra and luminescence of the ligand, 1, and 2 were investigated by UV-Vis and fluorescence spectroscopy at room temperature. Compared with the ligand, the fluorescence spectra of the polymeric metal complexes exhibit blue shifts in dimethyl sulfoxide (DMSO) solution and bathochromic shifts in the solid state. Complexes 1 and 2 emit blue light with emission maximum (λ _{f max}) at 449 and 431 nm in DMSO solution and at 485 and 484 nm in the solid state, respectively.     

Two oxovanadium complexes incorporating thiosemicarbazones: synthesis,characterization, and DNA-binding studies

An oxovanadium complex [VO(satsc)(phen)] (1) (satsc?=?salicylaldehyde thiosemicarbazone, phen?=?phenanthroline) and its derivative [VO(3,5-dibrsatsc)(phen)] (2) (3,5-dibrsatsc?=?3,5-dibromosalicylaldehyde thiosemicarbazone) have been synthesized and characterized by elemental analysis, infrared, electrospray-mass spectra, ¹H NMR, and magnetic susceptibility measurements. The DNA-binding behaviors of these complexes with calf-thymus DNA (CT-DNA) were investigated by UV-Vis absorption titration, fluorescence spectra, viscosity measurements, thermal denaturation, and circular dichroism. Both 1 and 2 bind to CT-DNA by intercalation and 1 exhibits much stronger binding affinity to CT-DNA than 2.     

1,2-双[2-甲基-5-(3,4-二氟苯基)噻吩-3-基]全氟环戊烯的合成

在冰浴条件下, 2-甲基噻吩(1)与液溴反应生成3,5-二溴-2-甲基噻吩(2); 在－78 ℃条件下, 硼酸三丁酯加入2, 得到2-甲基-3-溴-5-硼酸基噻吩(3); 3,4-二氟溴苯与3反应得到2-甲基-3-溴-5-(3,4-二氟苯基)噻吩(4); 在－78 ℃下全氟环戊烯与4反应, 得到一种新的二芳基乙烯类光致变色化合物1,2-双[2-甲基-5-(3,4-二氟苯基)噻吩-3-基]全氟环戊烯(DT-1). 用IR, NMR, MS和元素分析确定了化合物DT-1的结构, 并对该化合物的光致变色特性进行了初步研究.     

Facile Preparation and Molecular Structure of a Novel Metacyclophane

Abstract

A novel 1,1,10,10,19,19-hexamethyl-5,14,23-trimethoxy[3.3.3]metacyclophane (2) was prepared in 25% yield by Friedel–Crafts cyclization of 4-(2-methoxyphenyl)-2-methylbutan-2-ol (1) at ? 78 °C using TiCl₄ as Lewis acid catalyst in anhydrous dichloromethane. The structure of cyclophane 2 was determined by single-crystal X-ray diffraction, and the impact of substrate concentration on the yield of macrocycle 2 was also examined. The study on the effect of substituents at the phenyl ring showed that the methoxy group in 1 is crucial for its trimerization to give the hexamethyl[3.3.3]metacyclophane derivative. Demethylation of 2 with BBr₃ gave 1,1,10,10,19,19-hexamethyl-5,14,23-trihydroxy[3.3.3]metacyclophane (4) in 96% yield, and its three hydroxyl groups provide the possible modification sites for further construction of supramolecular assemblies.     

New polydentate macrocyclic ligands of hybrid amine-imine and amide-imine types as artificial anion receptors. Synthesis and study of anion binding

Three new macrocyclic Schiff bases containing an amine or amide structural fragment along with imine groups were synthesized by condensation of 2,6-bis(2-aminophenyliminomethyl)pyridine (1) and N, N’-bis(2-aminophenyl)pyridine-2,6-dicarboxamide (2) with 2,5-diformylpyrrole (₃) and 2,2-bis(5-formylpyrrol-2-yl)propane (4). The reaction of compound 1 with 3 proceeds abnormally and is accompanied by redox disproportionation of compound 1 in the first step. The structure of the macrocyclic product of this reaction was established by X-ray diffraction analysis. Spectrophotometric titration showed that hybrid macrocycle 10, which was prepared by condensation of compound 2 with 4, possesses the properties of an anion receptor and selectively binds hydrosulfate and dihydrophosphate anions in the presence of bromide and nitrate anions. The structures of 10 and its adduct with the hydrosulfate anion were calculated by density functional theory.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 161–168, January, 2005.     

Synthesis and characterization of M(II) (M = Cd,Hg and Pb) complexes with naphthodiaza-crown macrocyclic ligand and study of metal ion recognition by fluorescence, 1H NMR spectroscopy,and DFT calculation

To find metal ion recognition by L (L = O₂N₂-donor naphthodiaza-crown macrocyclic ligand), the complexes [ML]²⁺ (M = Cd, Hg and Pb) were synthesized and characterized by IR, ¹H, ¹³C NMR, and mass spectrometry, as well as elemental microanalysis. Hg(II) showed perceptible enhancement of the fluorescence of L in which ultra-low limit of detection for Hg(II) by L was determined as 1 nM in ethanol and DMSO. L reserved selectivity of Hg(II) in its binary mixtures with metal cations in solution. A 1 : 1 stoichiometry was found for the interaction of Hg(II) with L while Benesi–Hildebrand method was applied to calculate its complexation binding constant (K_BH) employing fluorescence spectrophotometry. The monitoring of the chemical shifts in ¹H NMR spectra of these complexes demonstrated that the central macrocycle of L was tailored for the size of Hg(II). Density functional theory calculations using B₃LYP/6–31G* basis set demonstrated that the macrocycle cavity of L was properly fitted for complex formation with Hg(II) cation, while both Cd(II) and Pb(II) cations did not form strong bonds with L from inadequate cation size. The present study shows detection method of Hg(II) and also possible application of naphthodiaza as an appropriate fluorophore macrocyclic ligand for detecting other metal ions.     

Synthesis,structure, and DNA-binding properties of manganese(II) and zinc(II) complexes with tris(<Emphasis Type="Italic">N</Emphasis>-methylbenzimidazol-2-ylmethyl)amine ligand

Tris(N-methylbenzimidazol-2-ylmethyl)amine (Mentb) and its two complexes, [Mn(Mentb)(DMF)(H₂O)](pic)₂ 1 and [Zn(Mentb)(pic)](pic) 2 (pic = picrate), have been synthesized and characterized by physico-chemical and spectroscopic methods. Single crystal X-ray diffraction revealed that the two complexes have different structures. In complex 1, the coordination sphere around Mn(II) is distorted octahedral, whereas in complex 2 the coordination sphere around Zn(II) is distorted trigonal bipyramidal. The DNA-binding properties of the free ligand and its two complexes have been investigated by electronic absorption, fluorescence, and viscosity measurements. The results suggest that the ligand and its two complexes bind to DNA via an intercalation binding mode, and their binding affinity for DNA follows the order 1 > 2 > ligand.     

磺酸咔咯及其镓(Ⅲ)配合物与DNA的相互作用和光核酸酶活性

本文用紫外-可见光谱、荧光光谱、圆二色光谱和粘度法研究了2,17-二(磺酸钠基)-5,10,15-三(五氟苯基)咔咯(1)及其镓配合物(1-Ga)与小牛胸腺DNA(ct-DNA)的相互作用。结果表明1和1-Ga通过外部结合的方式与ct-DNA相互作用,且结合能力1-Ga比1大。琼脂糖凝胶电泳实验显示1和1-Ga均具较好的光核酸酶活性,1-Ga光断裂DNA效果比1好,其光断裂机理与羟基自由基的产生有关。     

Structure of a di-zinc complex of a bis-calix[4]arene conjugate and its sensing of cysteine among the amino acids

Abstract

A triethylene glycol di-imine locked triazole linked bis-calix[4]arene conjugate (L) and its Zn²⁺ complex [Zn₂L], were synthesised, characterised and the three-dimentional (3-D) structure of the complex was established by single crystal XRD. In this complex, the Zn²⁺ centre exhibits distorted tetrahedral geometry with N₂O₂ binding core. The complex showed selectivity towards cysteine (Cys) with greater sensitivity followed by histidine (His) among the naturally occurring amino acids studied based on fluorescence and absorption spectroscopy. The fluorescence quenching of the complex is much greater with Cys as compared to that of His. The detection limit of Cys is 650 ppb. Release of Zn²⁺ from its complex [Zn₂L] followed by its capture by –SH containing molecules was shown based on absorption and emission spectroscopy. This was also shown in one case by ¹H NMR spectroscopy.     

Zinc(II) phthalocyanine containing Schiff base containing sulfonamide: synthesis,characterization, photophysical,and photochemical properties

Abstract

Synthesis and characterization of (E)-4-((5-bromo-2-(λ¹-oxidanyl)benzylidene)amino)-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide (1), its substituted phthalonitrile derivative (2), and its tetra substituted zinc(II) phthalocyanine complex (3) were performed. Compounds 1, 2, and 3 were characterized by methods such as elemental analyses, FT-IR, ¹H-NMR, ¹³C-NMR (except for 3), and MALDI-TOF mass spectra. The photophysical and photochemical properties of this substituted zinc(II) phthalocyanine complex aimed to be used as a photosensitizer were investigated in DMSO solution for determination of their photosensitizing abilities in photocatalytic applications such as photodynamic therapy (PDT). The influence of the substituent as a bioactive compound on the phthalocyanine skeleton on spectroscopic, photophysical, and photochemical properties were also determined and compared with unsubstituted zinc(II) phthalocyanine and some zinc(II) phthalocyanines containing different substituents previously studied. According to photophysical and photochemical investigations, 3 has potential as a photosensitizer for PDT.     

SYNTHESIS AND REACTIONS OF SOME 2-THIENYL- AND 2-THENOYL-DERIVATIVES OF THIAZOLE AND THIADIAZOLINE AND THEIR SELENIUM ANALOGS

Abstract

2-(Thiocyanatoacetyl)thiophene 2 and its selenium analog 3 couple with diazotized anilines and yield 3-aryl-2-imino-5-(2-thenoyl)-2,3-dihydro-1,3,4-thiadiazoles 6 and 3-aryl-2-imino-5-(2-thenoyl)-2,3-dihydro-1,3,4-selenadiazoles 7 respectively. The reactions of both 6 and 7 with nitrous acid, acetic anhydride and benzoyl chloride are described. Azo coupling of 2-amino-4-(2-thienyl)thiazole 17 and its selenazole analog 18 with diazotized anilines yielded the arylazo derivatives 19 and 20 respectively. Reaction of the hydrazidoyl bromide 16 with potassium thiocyanate, potassium selenocyanate, thiourea and selenourea yields 6, 7, 19, and 20 respectively.     

Theoretical investigation on molecular structure of a new mononuclear copper(II) thiocyanato complex with tridentate Schiff base ligand

An asymmetrical Schiff base ligand, 4-bromo-2-(2-pyridylmethyliminomethyl)phenol (HL), and its copper(II) complex, [Cu(L)SCN] (1), have been synthesized. Complex 1 is experimentally characterized by elemental analysis, FT-IR and UV–vis spectroscopic techniques, and cyclic voltammetry. The structure of the complex has been established by single-crystal X-ray diffraction studies, which reveal a square planar geometry of the central copper(II) ion in 1. The neighboring molecules of the complex connect each other by π–π stacking interactions with centroid-to-centroid ring distance 3.653 Å. The ligand can display two possible tautomeric forms; therefore, 1 can have an alternate molecular structure. DFT calculations have been employed to investigate the structure and relative stabilities of the suggested tautomeric forms of the ligand and its corresponding copper(II) complex.     

Synthesis,crystal structures,and catalytic activities of palladium imidazole complexes formed by 2-hydroxyethyl group cleavage

N-4,6-dimethyl-2-pyrimidinylimidazole 1 and its hydroxyethyl derivative 1-(2-hydroxyethyl)-3-(4,6-dimethyl-2-pyrimidinyl)imidazolium chloride 2 have been synthesized and characterized. The attempted synthesis of bis(N-heterocyclic carbene)palladium complexes via the direct reaction of 2 with Pd(OAc)₂ results in the unexpected formation of a bis(N-arylimidazole) palladium complex 3. Additionally, the analogous bis(N-methylimidazole) palladium complex 4 has also been synthesized by the above method. Compounds 1–4 were characterized by elemental analysis, IR, and ¹H NMR. Additionally, their crystal structures have been determined by X-ray diffraction. Complexes 3 and 4 were found to be efficient catalysts for the Suzuki reaction.