Simple and Dendritic Cyclam Derivatives. Photophysical Properties,Effect of Protonation and Zn2+ Coordination,Preliminary Screening as Inhibitors of Tumour Cell Growth

We have synthesized two novel dendrimers (BG1 and BG2) consisting of a 1,4,8,11-tetraazacyclotetradecane (cyclam, 1) core with appended four dimethoxybenzene and eight benzyl units (BG1) and twelve dimethoxybenzene and sixteen benzyl units (BG2). The absorption and luminescence spectra of these compounds and the changes taking place upon protonation and Zn²⁺ coordination of their cyclam core have been investigated in acetonitrile-dichloromethane 1:1 v/v solution. For comparison purposes, the absorption and luminescence spectra of 1,4,8,11-tetrabenzyl-cyclam (2), and dendrons BD1 and BD2, model compounds of the branches of BG1 and BG2 respectively, have also been studied. BD1, BD2, BG1, and BG2 exhibit the absorption and emission spectra of their 1,3-dimethoxybenzene unit, but in the two dendrimers the emission intensity is quenched by the cyclam amine groups and increases upon protonation and metal coordination. In order to test if these cyclam derivatives have an antitumour effect, we have studied their action on proliferation in the human neuroblastoma TS12 cell line. Screening experiments have shown that cell proliferation was (i) strongly reduced by the tetrabenzyl substituted cyclam 2, and (ii) unaffected by cyclam and the benzo dendrimers BG1 and BG2. Antitumour screening experiments have also been performed on the tetranaphthyl substituted cyclam 3 and the naphtho-dendrimer NG2, whose photophysical properties have been previously studied. Cell proliferation came out to be moderately reduced by 3, whereas dendrimer NG2 had no effect, similar to dendrimers BG1 and BG2.     

Synthesis of new benzobisthiazole materials and a study of their mesomorphic and luminescence properties

Novel tetra- and hexacatenar materials based on benzobisthiazole derivatives have been synthesised (4a–c, 5a–c and 6a–c) and their mesomorphic properties have been studied by differential scanning calorimetry, polarised optical microscopy and X-ray diffraction. All compounds in series 4a–c display an enantiotropic hexagonal columnar phase, whereas their analogous compounds in series 5a–c did not show mesomorphic behaviour. Compound 6a displays an unidentified monotropic columnar phase, whereas compounds 6b and 6c show an enantiotropic rectangular columnar mesophase. The mesomorphic properties were found to be dependent on the length, position and number of alkoxy chains attached at the end of the rigid core. These compounds also show photoluminescence properties in the visible region and have good quantum yields. A thermogravimetric analysis was also performed.     

Einige Neue N,S-Substituierte 2-Nitrodienverbindungen Aus Reaktionen Von Mono(p-fluorarylthio)substituierten Dienen Mit Aminen

2-Nitrodiene compound 1 was stirred with p-fluorothiophenol for a long time and compound 3 was obtained. Compound 1 gave bis(thio)substituted 2-nitrodiene compound 4 and tris(thio)substituted compound 5 with 2 moles of p-fluorothiophenol in the presence of NaOH in ethanol. The compounds 9a–g have been prepared from 8a–g and 3. Compound 7 was obtained from the reaction of mono(thio)substituted 2-nitrodiene with morpholine. Compound 3 gives 11a–d in the reaction with piperidines in CH₂Cl₂ (or ether). Compound 13a–b have been obtained from the reaction of compound 3 with primary amines 12a–b. Compound 3 gives 15 and 16 in the reaction with 2,5-dimethylpiperazine in CH₂Cl₂.

     

High Performance Liquid Chromatography of New Potential Anxiolytic Drugs and Related Benzodiazepines: A Comparative Study of Hydrophobicity

Abstract

A comparative study of hydrophobicity in diazepam (5) chlordizepoxide (6), buspirone (7) and four related pyrrolothieno-1,4-dizepine systems (1–4) has been carried out, using HPLC (RPC) technique. The capacity factors (K') of compounds studied have been measured in five different elution conditions (mobile phase in which the percentage of methanol varies). The capacity factors (K'₀) corresponding to the absence of organic solvent in the mobile phase have been calculated. Correlations among hydrophobic parameters of series 1, 2, 3, and 4 have been established and K'₀ of compounds not yet synthesized have been calculated.     

Dioclins A and B,new antioxidant flavonoids from Dioclea reflexa

Dioclins A (1) and B (2), the new flavonoids, have been isolated from the ethyl acetate soluble fraction of the roots of Dioclea reflexa along with 3,5-dihydroxy-4 methoxybenzoic acid (3), lupeol (4) and the rare dipeptide, auratiamide acetate (5). Their structures have been elucidated by spectroscopic techniques. The compounds 1 and 2 showed a significant antioxidant activity in DPPH radical scavenging assay.     

Synthesis,structure, and NMR spectra of a new ferrocenylbenzene tricarbonylchromium complex

Complex 1 (1,2,4-triferrocenylbenzene tricarbonylchromium), possessing four heterometals, has been synthesized efficiently by a new method in one pot. Through detailed study on the NMR chemical shifts of 1 and the ligand 2, the NMR chemical shifts of 1 shift upfield from those of 2. The NMR spectra of 1 have reduced magnetic anisotropy of benzene after Cr(CO)₃ coordination with 2. The ferrocenyl groups have electron donating effect on the central benzene ring of 1.     

吸电子基团对席夫碱及其钯配合物在抑菌及催化活性方面的影响

报道了2,6-二异丙基苯胺缩苯甲醛或2,4-二氯苯甲醛席夫碱(L1和L2)及其钯配合物(1和2)的合成,并通过元素分析、红外光谱、X-射线单晶衍射等方法对席夫碱配体及配合物进行了表征。通过与已报道的席夫碱L1及其钯配合物1结构相比较,发现引入吸电子取代基合成的一个新的席夫碱及其钯配合物(L2和2)对抑菌及催化活性有较大影响。抑菌活性试验表明,配体及配合物均具有良好的抑菌活性,配合物相对于配体具有更好的抑菌效果,配体苯环上的吸电子取代基能有效提高抑菌活性。研究了两组配合物(1和2)对溴代苯和丙烯酸Heck交叉偶联生成苯丙烯酸的催化性能,考察了不同反应因素(缚酸剂种类、反应温度及溶剂)对该反应的影响,确定了反应的最佳条件;催化实验结果显示吸电子基团的引入增加了钯配合物的空间位阻效应进而降低其催化活性。     

Phase equilibria in systems based on Tl4SnSe3 and Tl4SnSe4 ternary compounds

Phase equilibria in the Tl₄SnSe₃-Tl (I), Tl₄SnSe₃-Sn (II), Tl₄SnSe₄-SnSe (III), Tl₄SnSe{ia4}-TlSe (IV), and Tl₄SnSe₃-Tl₄SnSe₄ (V) systems have been studied by differential thermal analysis and power X-ray diffraction. Systems I–V have been found to have eutectic interactions. In systems I and II, width regions of solid solutions based on the ternary compound Tl₄SnSe₃ are formed.     

New Structures from Multiple Rearrangements of Propargylic Dialkoxy Disulfides

Abstract

Sundry dipropargyloxy disulfides have been successfully prepared and their rearrangement paths and products have been found to be dependent upon their substitution pattern. Inter alia compounds of two heretofore unknown structure types— 10 and 11 on the one hand and 14 and 15 on the other—have been obtained and characterized.     

Selective ion clefts based on a three-bridged [43]cyclophane

A variety of new three-bridged cyclophanes, clefts4–14, have been conveniently prepared, and their cation-binding properties have been examined. Compounds4–6 have a special affinity for alkali metal cations. Ethyl ester5 and methyl ester4 selectively formed 2:1 complexes with K⁺ and Na⁺ ions, respectively. Clefts11–13, which possess pyridyl groups, bind Ag⁺ cation exclusively.¹H NMR titration studies confirmed that11 or12, having 2- or 3-pyridyl groups, form a 1:1 complex with Ag⁺ cation, while13, with 4-pyridyl ligating groups, forms a 2:1 complex. Cleft10, with aminimide groups, also shows an affinity for Ag⁺ cation in a 2:1 ratio in a polar solvent, while it forms a 1:1 complex in a nonpolar solvent. The same solvent effect was observed for clefts13 and15c, which is discussed qualitatively.     

Solution structure and equilibrium of new calix[4]resorcinarene complexes—prototype of molecular machines. NMR data

Association properties and molecular machine application of water soluble calix[4]resorcinarene (1) with two aromatic guests (2-naphthol (2) and 1,5-naphthalenediamine (3)) have been investigated by various NMR methods (chemical shift, nOe and diffusion measurements) in aqueous solution at different concentrations and pH range. In neutral solution 1 strongly associates with 2, while only moderately associating with 3. Increase in concentration causes an increase in the stability of 1 + 3 and 1 + 2 + 3 complexes and produces high order complexes. The decrease of pH does not have an influence on 1 + 2 association, but disrupts 1 + 3 assembly. 1 can be used for the separation of 2 + 3 mixture in aqueous solution at moderate concentrations. The pH dependency of the association properties of the 1 + 3 system makes these compounds prime candidates for pH-responsive molecular machines applications.     

Base-mediated one-pot synthesis of 3,4,5,6-tetrahydro-4-substituted benzo[h]quinazoline-2(1H)-thione derivatives and evaluation of their antioxidant activity

One-pot three-component Beginelli-like reactions of a ketone 1, an aryl aldehyde 2, and thiourea 3 in the presence of sodium hydroxide are described. In this reaction, 3,4,5,6-tertrahydro-4-substituted quinazoline-2(1H)-thione derivatives 4a–h were obtained in good yields (73–85%). The compound 4a has been characterized by single crystal X-ray analysis. All the synthesized compounds 4a–h and 5a–b were screened for their in vitro antioxidant activity. Compounds 4c, 4e, and 4h have exhibited an excellent than the standard ascorbic acid. Compounds 4d, 4f, and 4g have also shown good activity. Remaining compounds show moderate antioxidant activity.     

Square planar complexes of Cu(II) and Ni(II) with N<Subscript>2</Subscript>O donor set of two Schiff base ligands: synthesis and structural aspects

Abstract Two new square planar Cu(II) and Ni(II) complexes, [CuL¹(NCO)] (1) and [NiL²(N₃)] (2) have been synthesized with two different tridentate N₂O donor Schiff base ligands L ¹ H (1:1 condensation product of benzoylacetone and 2-diethylaminoethylamine) and L ² H (1:1 condensation product of benzoylacetone and 2-dimethylaminoethylamine), respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal, and single crystal X-ray diffraction studies. Structural studies reveal that in both the complexes metal centers have square planar environment with N₂O donor set of Schiff base ligands and terminal pseudohalide anions (isocyanate for 1 and azide for 2) at four coordination sites of square plane. Graphical abstract Square planar complexes of Cu(II) and Ni(II) with N ₂ O donor set of two Schiff base ligands: synthesis and structural aspects Subhra Basak, Soma Sen, Samiran Mitra, C. Marschner, W. S. Sheldrick Two new square planar Cu(II) and Ni(II) complexes, [CuL¹(NCO)] (1) and [NiL²(N₃)] (2) have been synthesized with two different tridentate N₂O donor Schiff base ligands L ¹ H and L ² H respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal and single crystal X-ray diffraction studies.      

Syntheses,crystal structures,and antibacterial activities of manganese(III), nickel(II), and copper(II) complexes containing a tetradentate Schiff base

Three new mononuclear Schiff-base complexes, namely [Mn(L)Cl] (1), [Ni(L)] (2), and [Cu(L)] (3), where L?=?anion of [N,N′-bis(2-hydroxybenzophenylidene)]propane-1,2-diamine, have been synthesized by reacting equimolar amounts of the respective metal chloride and the tetradentate Schiff base, H₂L, in methanol. The complexes have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction, and other physicochemical studies. Structural studies reveal that 1 adopts a distorted square-pyramidal geometry whereas 2 and 3 are isotypic with distorted square-planar geometries. The antibacterial activities of 1–3 along with their Schiff base have been tested against some Gram(+) and Gram(?) bacteria.     

Fluorination of tertiary alcohols derived from di-O-isopropylidenehexofuranose and O-isopropylidenepentofuranose

The stereo- and regioselectivity of the dehydroxyfluorination of various tertiary alcohols derived from di-O-isopropylidenehexofuranose and 1,2-O-isopropylidenepentofuranose has been studied. Reactions have been accomplished using DAST and PFPDEA (1,1,3,3,3-pentafluoropropene-diethylamine adduct) as fluorinating reagents. Dehydroxyfluorination of allylic alcohol 2a has occurred with an inversion of configuration and allylic rearrangement leading to two chiral regioisomers 6a and 7a. Analogous reaction of 2b has given allylic chiral fluoride 7b as the only product. In case of phenylacetylene, styryl and benzylic alcohols 3a/3b-5a/5b the single diastereoisomers 8a/8b-10a/10b have been obtained. Additionally, the participation of 1,2-O-substituent effect in carbocation stabilization during fluorination have been discussed.     

Synthesis and Characterization of the products from reaction of Metal Carbonyls [M(CO)6 (M Cr,Mo, W), Re(CO)5Br,Mn(CO)3Cp] with Salicylaldehyde Methanesulfonylhydrazone

Five new complexes, [M(CO)₅(salmsh)] (M?=?Cr;?1,?Mo;?2,?W;?3), [Re(CO)₄Br(salmsh)], 4, and [Mn(CO)₃ (salmsh)], 5, have been synthesized by the photochemical reaction of metal carbonyls with salicylaldehyde methanesulfonylhydrazone (salmsh). The complexes have been characterized by elemental analyses, EI mass spectrometry, FT-IR and ¹H NMR spectroscopy. The spectroscopic studies show that salmsh behaves as a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.     

New organotin(IV) complexes with N(4)-methylthiosemicarbazone derivatives prepared from 2,3-dihydroxybenzaldehyde and 2-hydroxy-5-methylbenzaldehyde: synthesis,characterization, and cytotoxic activity

Abstract

The N(4)-methylthiosemicarbazone derivatives H₂DDMT (1) and H₂DMMT (2) have been prepared from the reaction of 4-methylthiosemicarbazide with 2,3-dihydroxybenzaldehyde and 2-hydroxy-5-methylbenzaldehyde, respectively. Six new organotin(IV) complexes, [MeSnCl(DDMT)] (3), [BuSnCl(DDMT)] (4), [PhSnCl(DDMT)] (5), [MeSnCl(DMMT)] (6), [BuSnCl(DMMT)] (7), and [PhSnCl(DMMT)] (8) have been synthesized by direct reaction of corresponding organotin(IV) chloride(s) with these ligands. The ligands and their compounds have been characterized by elemental analysis, molar conductivity, UV–Vis, FT-IR, and NMR (¹H, ¹³C, and ¹¹⁹Sn) spectroscopy. The molecular structures of 1 and 2 were determined by X-ray crystallography. Spectroscopic data suggested that the ligands were coordinated to tin(IV) as dinegative tridentate via phenoxide-O, azomethine-N, and thiolate-S atoms. The crystal structures revealed that the ligands exist in thione form in the solid state. In vitro cytotoxicity assays were carried out for all the compounds against MCF-7 cancer cell line. The results have shown that different organotin(IV) groups showed characteristic differences in their biological activity.     

Guanylurea derivatives of diorganotin(IV) dichloride

A series of organotin complexes with guanylurea (H₂L) have been synthesized. All the complexes 1–8, BuMeSnClHL, PhEtSnClHL, PhMeSnClHL, PhBuSnClHL, BuMeSnL, PhEtSnL, PhMeSnL, and PhBuSnL have been characterized by elemental analysis, FTIR, and multinuclear spectroscopic techniques. Complexes 1–4 are five-coordinate whereas 5–8 are four-coordinate.     

Synthesis of 2,3‐Dihydro‐4H‐furo[3,2‐c] chromen‐4‐ones and 2,3‐Dihydronaphtho[2,3‐b]furan‐4,9‐diones by the Radical Cyclizations of Hydroxyenones with Electron-Rich Alkenes using Manganese(III) Acetate

We have obtained dihydrofurans 3a–j in the radical cyclization of 4‐hydroxycoumarin 1a and 2‐hydroxy‐1,4‐naphtoquinone 1b with electron rich alkenes 2a–i by manganese(III) acetate. Methods A and B, which have different molar ratios were studied comparatively in these reactions, and we observed that method B (molar ratio 2:1:3) gave the best results. Treatment of 4‐hydroxycoumarin 1a and electron rich alkenes 2a–e gave 2,3‐dihydro‐4H‐furo[3,2‐c]chromen‐4‐ones 3a–e in 36–86% yields by the method B. Under the same conditions, the reactions of 2‐hydroxy‐1,4‐naphtaquinone 1b with conjugated alkenes 2b and 2f–i afforded 2,3‐dihydronaphtho[2,3‐b]furan‐4,9‐diones 3f–j in an excellent yields.     

<Emphasis Type="Italic">N</Emphasis>-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

Starting from 4-chloro-3,5-dinitrobenzoic acid 1, compounds 2–10 (N-alkoxy-3,5-dinitro-4-aminobenzoic acid esters where alkoxy stands for methoxy, carboxymethoxy, triphenylmethoxy, or corresponding amides) have been obtained, from which compounds 3–5 and 7–10 are new, and for the known compounds 2 and 6 the synthetic procedure has been improved. The new derivatives have been characterized by appropriate means (IR, UV–Vis, ¹H- and ¹³C-NMR, fluorescence) and their properties were studied. Thus, depending on their structure, the compounds have acid properties, fluorescence and complexing properties with alkaline cations.