Journal of Chemical Research

Treatment of 1H-phenalen-1-one in 95% H₂SO₄ at 180 °C for 2 days yields a highly water soluble red dye. Although a previous literature report, under similar conditions, described this reaction as producing the 2-substituted sulfonato adduct, the ¹H NMR spectrum we obtained for the product was inconsistent with the proposed structure. A detailed ¹H NMR spectroscopic study, however, using ¹H–¹H spin-decoupling and steady-state NOE-difference experiments revealed the product to be 1H-phenalen-1-one-5-sulfonate. Despite the extended planar aromatic π-system typical linear Beer-Lambert behaviour, up to a concentration of ca 2mM, is observed for a solution of the dye in phosphate-buffered water.

The total synthesis of threo-(±)-9,9-dibenzoylsecoisolariciresinol and its isomer based on two Stobbe reactions as C–C bond-forming steps used a protected vanillin and diethyl; succinate to give the skeleton of lignan, followed by reduction to afford threo- and meso-(±)-secoisolariciresinol Both were treated with benzoyl chloride to obtain the natural product threo-(±)-9,9-dibenzoylsecoisolariciresinol and Its isomer meso-(±)-9,9-dibenzoylsecoisolariciresinol for the first time.

Optically pure (S)-α,α-diphenyl-2-pyrrolidine methanol was prepared from L-proline via protection of the amino group, reaction with the Grignard reagents and deprotection of the amino-protected groups in 54.4% yield. The synthetic conditions to prepare (S)-α,α-diphenyl-2-pyrrolidinemethanol were optimised. Single crystal X-ray diffraction analysis revealed that the molecular structure of the compound was enantiomerically pure. The crystals are orthorhombic, space group P2(1)2(1)2(1), with unit cell parameters a = 8.9000(18) Å, b = 9.2405(18) Å, c = 16.671(3) Å, V = 1371.1(5) ų, D_x = 1.227 g cm⁻³, Z =4, T = 113(2)K, F(000) = 628, R¹ = 0.0335 and wR² = 0.0707. The absolute structure parameter was – 1.6(17).

A four-component reaction between aryl aldehydes, ethyl cyanoacetate and dimethyl acetylenedicarboxylate in the presence of cyclohexyl isocyanide has been developed. The reaction furnishes highly functionalised cyclopentadienes in moderate to good yields in a one-pot process.

A new viologen(4,4′-bipyridinium)-based complex [N-ethyl-4,4′-bipyridinium][CdBr₄], in which N-ethyl-4,4′-bipyri-dinium (EQ²⁺) has been generated in situ, has been synthesised via hydrothermal reaction and structurally characterised by single-crystal X-ray diffraction. [N-ethyl-4,4′-bipyridinium][CdBr₄] features an isolated structure, based on an N-ethyl-4,4′-bipyridinium moiety and a cadmium atom terminally bound by four bromine atoms. Photoluminescence investigation reveals a broad and intense emission in blue region, which may originated from π → π^* charge-transfer interaction of the N-ethyl-4,4′-bipyridinium moiety.

Two simple mercapto thiadiazole-based sensors have been synthesised by a convenient method and exhibit excellent sensitivity and selectivity for Hg²+ in DMSO/H₂O (1:1, v/v) aqueous solution. The sensors react with Hg²+ to form stable complexes and the association constants, Ka, are 4.4 × 10⁴ M⁻¹ and 1.0 × 10³ M⁻¹, respectively. Furthermore, the detection limit of one sensor towards Hg²+ is 8.0 × 10⁻⁷ M.

The sterically hindered salicylaldimine ligands N,N‘-(1,5-diaminonaphthalene)-3,5-bu^t2-salicylaldimine (L₁), N,N‘-(2,7-diaminofluaren)-3,5-bu^t2-salicylaldimine (L₂) and N,N‘-(1,8-diaminonaphthaline)-3,5-bu^t₂-salicylaldimine (L₃) have been synthesised by the condensation of 1,5-diaminonaphthalene, 2,7-diaminofluarene, and 1,8-diaminonaphthaline with 3,5-di-tert-butylsalicylaldehyde, respectively. Dinuclear M(II) complexes of L₁ and L₂ and mononuclear M(II) complexes of L₃ have been prepared using Cu(II), Ni(II), Co(II), and Mn(II) salts and characterised. The synthesised sterically-hindered, salen-type complexes were tested as catalysts for the formation of cyclic carbonates from CO₂ and liquid epoxides (propylene oxide, epichlorohydrine, 1,2-epoxybutane and styrene oxide), which served as both reactant and solvent. Ligand structure and the type of metal centre have a marked influence on the catalytic activity. Mn(II) complexes showed the highest catalytic activity.

(E,E)-1-Arylseleno-substituted 1,5-dien-3-ynes can be stereoselectively synthesised in one pot, in good yields with high stereoselectivity, by the Pd(PPh₃)₄-catalysed Stille coupling of (E)-1-iodo-2-arylselenoethenes with trimethyl-stannyl(trimethylsilyl)ethyne, followed by the cross-coupling with (E)-vinyl iodides in the presence of tris(diethylamino) sulfonium trimethyldifluorosilicate (TASF).

A new series of enaminones derived from 3-acetyl-1-aryl-4-benzoyl-5-phenyl-1H-pyrazoles has been obtained and their reactions with hydrazine hydrate, guanidine hydrochloride, 3-amino-1,2,4-triazole, 2-aminobenzimidazole and active methylenenitriles are described. The mechanisms and regioselectivity of the studied reactions are discussed. The results of screening of the antitumor activity of the enaminones against the human breast cancer cell line MCF-7 revealed that the compounds showed less activity than that of the reference drug doxorubicin. Their activity was found to depend on the nature of the substituent group on the 1-aryl moiety. The order of activity of the series is: H > 4–Cl > 4-MeO > 4-Me > 4-NO₂.

A new fluorescent molecular clip based on 2-ethyl cyanoacrylate has been synthesised and its binding properties investigated by fluorescence spectroscopy to show that it can selectively bind Fe³⁺ with fluorescence quenching.

A singly phenoxido-bridged dinuclear Cu^∥ complex, [Cu₂(L)₂(SCN)₂(H₂O)], has been obtained from a Schiff-base ligand (2-[{[2-(dimethylamino)ethyl]imino}methyl]-6-methoxyphenol), generated by condensation of o-vanillin with N,N-dimethylethane-1,2-diamine. The Cu(II) complex has been fully characterised by analytical, spectroscopic, magnetic susceptibility and EPR measurements and DFT calculations, as well as single-crystal X-ray diffraction analysis. It consists of two geometrically distinct square-pyramidal and octahedral copper(II) centres, exhibiting N₂O₃ and N₄O₂ donor sets. In the dimeric unit, the copper atoms are connected by a μ₂-phenolato oxygen atom, belonging to one bridging Schiff-base ligand. Variable-temperature magnetic susceptibility measurements indicate strong antiferromagnetic exchange interactions between the Cu(II) centres, with a 2J value of −89(1) cm⁻¹.

The hydrothermal synthesis and single crystal structure of (C₃H₈N)₂·Zn₃(HPO₃)₄ are described. This compound is built up from ZnO₄ tetrahedra and HPO₃ pyramids sharing vertices to generate a three-dimensional 4:3 network containing 8-ring channels. The protonated organic cations occupy the channels in a head-to-tail arrangement and interact with the framework by way of N–H···O hydrogen bonds. Crystal data: C₆H₂₀N₂O₁₂P₄Zn₃, M_r = 632.23, monoclinic, P2₁/n (No. 14), Z = 4, a = 9.6773 (2) Å, b = 13.8676 (2) Å, c= 15.4482 (3) Å, β = 90.039 (1)°, V = 2073.16 (7) ų, R(F) = 0.028, wR(F²) = 0.062.

A phosphorus-containing dendrimer of up to four generations with phloroglucinol as a core unit was synthesised using a divergent growth method. A repetitive synthetic sequence of several types of reactions was performed by using P(O)Cl₃, 3-hydroxybenzaldehyde, 4-hydroxybenzaldehyde and p-phenylenediamine for the synthesis of this dendritic molecule G₄ involving simple condensation reactions. This Schiff's base macromolecule possesses 12 imine bonds and 6-OH groups on the periphery. The structures of the intermediate generations G₁, G₂, G₃ were confirmed by IR, ¹H, ¹³C, ³¹P NMR and LC/EI MS. The final dendrimer G₄ was characterised by IR, ¹H, ¹³C, ³¹P NMR, Maldi-tof mass spectrometer and C, H, N analysis. The scanning electronic microscopic study and thermogravimetric analysis were also performed for the final dendrimer (G₄).

A diphosphino-functionalised MCM-41 anchored platinum complex (MCM-41-2P-Pt) was conveniently synthesised from commercially available and cheap γ-aminopropyltriethoxysilane via immobilisation on MCM-41, followed by reactiopn with diphenylphosphinomethanol and potassium chloroplatinite. It was found that the title complex is a highly efficient catalyst for the hydrosilylation of olefins with triethoxysilane and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive reactionss without any decrease in activity.

(Z)-2-(4-Bromophenyl)-3-(furan-2-yl)acrylonitrile and (Z)-2-(4-bromophenyl)-3- (thiophen-2-yl)acrylonitrile were prepared by condensation of furan-2-carbaldehyde and thiophene-2-carbaldehyde with (4-bromophenyl)acetonitrile in the presence of catalytic amount of NaOCH₃ at room temperature. A series of novel biphenyl derivatives containing furan and thiophene groups was synthesised from (Z)-2-(4-bromophenyl)-3-(furan-2-yl)acrylonitrile and (Z)-2-(4-bromophenyl)-3- (thiophen-2-yl)acrylonitrile via Suzuki coupling to arylboronic acids. The structures of these compounds were characterised by FTIR, ¹H NMR, ¹³C NMR, and HRMS. The UV-Vis absorption and photoluminescence spectra of the novel compounds in CH₂Cl₂ solution were investigated.

An ethanolic extract of the dried flower petals of Argemone mexicana afforded a new and optically active secondary C₃₁-alkanediol characterised as hentriacontane-3,20-diol on the basis of spectroscopic studies including IR, HRMS, ¹H and ¹³C NMR.

A one-pot synthetic route was developed to synthesise novel naphthyridine derivatives from amino acids and a series of new naphthyridines was prepared and characterised by IR, ¹H NMR, MS and elemental analysis. The preliminary bioassay results reveal that they have medium antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Aspergillus, Escherichia coli and Monilia albican. The compounds containing aliphatic amino acids have greater bioactivity than that of those containing aromatic amino acids against Bacillus subtilis and Staphylococcus aureus.

An efficient method for the synthesis of 4-phenyl-2,4- dihydrochromeno[4,3-c]pyrazoles via the cyclisation reaction of the easily available flavanone-4-arylhydrazones with Vilsmeier reagent (Bis(trichloromethyl) carbonate /DMF) has been developed.