Volume 66, Issue 1

Layered double hydroxides (LDH’s), also known as anionic clays, are lamellar inorganic solids. The structure of most of them corresponds to that of mineral hydrotalcite, consisting of brucite-like hydroxide sheets, where partial substitution of trivalent or divalent cations results in a positive sheet charge compensated by reversibly exchangeable anions within interlayer galleries. These layered materials have good intercalation properties capturing inorganic and organic ions and they are promising materials for a large number of practical applications, both for direct preparation and for after thermal treatment. Over the past decade, significant interest has been devoted to the synthesis of LDHs with new compositions allowing improved applications in many areas. This contribution reviews the recent advances in water treatment, nuclear waste treatment/storage, catalytic, industrial, and advanced applications and biomedical applications of LDH-based nanomaterials.

A new reagent for spectrophotometric determination of Mo(VI) was developed utilizing micellar effects. For this purpose, differences in the ultraviolet and visible spectral properties of Mo(VI), gallic acid, L-serine, and their binary and ternary solutions were studied in the presence and absence of cationic, anionic, and non-ionic surface active agents. L-serine was observed to form binary complexes and a ternary complex with Mo(VI) and gallic acid below its isoelectric point. The maximum Mo(VI) sensitivity was exerted by the Mo(VI) + gallic acid + L-serine + hexadecyltrimethylammonium bromide system at pH of 4.5. This system was proposed for use in the spectrophotometric determination of Mo(VI) as a superior alternative to the Mo(VI) + gallic acid + hexadecyltrimethylammonium bromide system and to most of the instrumental analysis methods referred to in the literature. The mechanism of micellar effects was discussed on the basis of the spectral data obtained above and below the isoelectric point of L-serine and explained in terms of the molecular charge of the substrates and the surfactants.

Influence of chemical composition of nanocrystalline iron’s surface on its activity in the nitriding process of iron and catalytic decomposition of ammonia was studied. The rate of the nitriding reaction was measured by the thermogravimetric method using a tubular differential reactor. Hydrogen concentration in the reactor was also measured. The rate of the catalytic decomposition of ammonia was determined using the reactor’s mass balance. Experiments were conducted at different temperatures within the range from 300°C to 525°C. Iron catalyst for ammonia synthesis was studied. Two sorts of samples with a different content of potassium oxide (0.16 mass % and 0.64 mass % of K2O) were used. The composition of samples from the second group was modified by an addition of different amounts of sulfur. At temperatures above 400°C, when the effect of ammonia decomposition on the gas phase composition was experimentally measured, the presence of potassium and sulfur on the iron surface influenced the rate of the iron nitriding process. The ammonia decomposition rate was higher for samples with a greater amount of potassium. The rate of reactions depended also on the sulfur concentration and dropped when the sulfur content increased. The value of apparent activation energy of ammonia decomposition was in the range of 150 kJ mol−1 to 180 kJ mol−1 while the content of sulfur in the samples increased.

A solution of 2-(octylsulphanyl)benzoic acid in 1,2-dichloroethane was used as a liquid membrane for selective pertraction of Pb2+ cations. Transport processes were carried out in a multi-membrane hybrid system (MHS) consisting of two cation-exchange membranes (CEM) and a flowing liquid membrane (FLM) in the following order: CEM | FLM | CEM. The liquid membrane phase was dehydrated continuously using a pervaporation method (PV). The system was capable of transporting Pb2+ ions selectively from a multi-cation aqueous solution composed of Na+, K+, Ca2+, Mg2+, and Pb2+ nitrates. A comparative study of the carrier efficiency under various feed pH conditions was performed. It was found that the carrier exhibited sufficient selectivity and transport efficiency under a broad range of operational conditions, with a maximum transport rate of Pb2+ ions attaining the value of (1.09 ± 0.03) × 10−10 mol cm−2 s−1 and the selectivity coefficient of up to 40.

We performed the Rupe rearrangement of 1-ethynylcyclohexan-1-ol in near-critical water to study the reaction under high temperature conditions. The final product thus obtained was primarily 1-cyclohexen-1-ylethanone which was identified by GC-MS. The influences of reaction time, temperature, and initial reactant-to-water ratio on the yield of 1-cyclohexen-1-ylethanone were examined. The yield of 1-cyclohexen-1-ylethanone was 49 % in pure water at 260°C for a reaction time of 60 min. However, when additives such as ZnSO4, FeCl3, and NaHSO4, respectively, were introduced to the water to investigate the effect of salts on the Rupe rearrangement reaction, the yield increased markedly to as much as 88 % in 5 mole % NaHSO4 aqueous solution under the same conditions. The catalytic ability of the additives decreased in order: NaHSO4, FeCl3, ZnSO4. On the basis of these results, a possible reaction mechanism of the Rupe rearrangement of 1-ethynylcyclohexan-1-ol in near-critical water was proposed.

Acidic crude palm oil (ACPO) produced from palm oil mills with an acid value of 18 mg g−1 was considered to be a possible feedstock for biodiesel production. Due to its high acidity, conventional transesterification cannot be applied directly for biodiesel production. Methane sulphonic acid (MSA, CH3SO3H) is used to reduce the acidity prior to the alkaline transesterification reaction. The laboratory-scale experiments involved an MSA to ACPO dosage of 0.25–3.5 %, a molar ratio (methanol to ACPO) from 4: 1 to 20: 1, reaction temperature of 40–80°C, reaction time of 3–150 min, and stirrer speed of 100–500 min−1. The optimum esterification reaction conditions were 1 % of catalyst to ACPO, with a molar ratio of methanol to ACPO of 8: 1, a stirring speed of 300 min−1, for 30 min and at 60°C. Under these conditions, the FFA content was reduced from 18 mg g−1 to less than 1 mg g−1 and with a yield of 96 %. The biodiesel produced met the EN14214 standard specifications. MSA was recycled for three times without losing its activity. The biodiesel produced in a two-stage process has a low acid value (0.14 mg g−1).

Two complexes, {[Cd6(o-dppd)2(µ2-Cl)6(µ3-Cl)2(DMF)2(H2O)2Cl2]·DMF·CH3OH}n (I) (DMF = N,N-dimethylformamide; o-dppdH = 1,3-di(pyridin-2-yl)propane-1,3-dione) and [Cu4(o-dppd)2(OAc)4(OH)2]·4H2O (II), were synthesised and characterised by single-crystal X-ray diffraction, elemental analysis, IR, solid fluorescence and TGA. The results showed that complex I had a rodshaped polynuclear chain with hexacoordinating Cd atoms bridged by oxygen, µ2-Cl and µ3-Cl; complex II was a tetranuclear oligomer. In general, supramolecular architectures are constructed through hydrogen-bonding and π-π stacking interactions. I shows luminescence.

Boric acid forms meta-stable complexes with biomolecules like amino and hydroxy acids and stable complexes with the diol group containing carbohydrates, vitamins, and nucleotides, yielding mono-chelate (1: 1 complex) or bis-chelate (1: 2 complex) structures with negatively charged tetrahedral borate anions. Here we report water-soluble, bio-available mixed-ligand boron adducts for potential nutritional and/or pharmaceutical applications. The complexes were prepared by complete esterification of boric acid with a number of acyclic- and cyclic hydroxy-functionalized biomolecules employing sodium as the counter ion. Structural and thermal properties of the complexes were investigated using chemical analysis, 11B NMR, FTIR, and TGA-DTA techniques. Complexes containing salicylic acid as one of the ligands displayed higher thermal and hydrolytic stabilities.

An innovative, powerful, efficient and relatively rapid method was developed to synthesise various β-aminoketone derivatives from cyclohexanone, substituted aromatic amines and aromatic or hetero-aromatic aldehydes via ultrasound-assisted direct-type catalytic Mannich reaction using bismuth(III) triflate in water. Good yields of the desired β-aminoketones were obtained at room temperature by ultrasound-assisted reaction within 1–2 h. The major advantages of the proposed method are undemanding conditions, easy operation, low toxicity, shorter reaction time, anti selectivity and higher yields in comparison with conventional methods.

Ten derivatives of N1 substituted/unsubstituted 5-(4-chlorophenyl)-3-(2-thienyl) pyrazoline were synthesised from chalcone-like intermediate and substituted phenyl hydrazines, hydrazine hydrate, and semi/thiosemicarbazide. The chemical structure of compounds was confirmed by means of IR, 1H NMR, mass spectroscopy, and elemental analysis. The antidepressant and anticonvulsant activities were investigated by Porsolt’s behavioural despair test (forced swimming) and maximum electroshock seizure test, respectively. Rota-Rod test was performed to assess any probable changes in motor coordination induced by the test compounds. Four compounds (IId, IIg, IIi, and IIj) exhibited good activity profile against depression and docking studies confirmed their consensual interaction with monoamine oxidase A. In addition, compounds IIc and IIe showed protection against MES-induced seizures.

3-Nitro-N-(phenylsulphonyloxy)phthalimide (IIIa) and N-(phenylsulphonyloxy)phthalimide (IIIb) were synthesised as key intermediates in good yield. Their structures were confirmed by 1H NMR and FTIR spectral data. The reaction of the key intermediates with allylamine produced 3-allyl-5-nitroquinazoline-2,4-(1H,3H)-dione (IVa) and 3-allylquinazoline-2,4-(1H,3H)-dione (IVb), respectively. Luminescence emission and excitation spectra of IVa and IVb are also presented.