Classical chemical sciences
The study of nature of intermolecular interactions and their control is extremely important in the area of crystal engineering, in order to design a new material of desirable properties and also for crystal structure prediction. A better understanding of these interactions and their influence on the crystal packing can be obtained by evaluating the energetics associated with these interactions. In this regard, we have identified from the literature a series of coumarin-3-carboxylate derivatives and extracted molecular pairs from the crystal packing providing maximum stability to the crystal structure. The lattice energy of all the compouds have been calculated by using PIXELC module in Coulomb-London-Pauli (CLP) package and is partitioned into corresponding coulombic, polarization, dispersion and repulsion contributions. It is found that the weak intermolecular interactions like C-H…O, π…π and C-H…π play an important role in the stabilization of the crystal packing.
Keywords: coumarin3-carboxylate; lattice energy; intermolecular interactions; PIXEL
The 4-oxo-N,2,6-triphenylpiperidine-3-carboxamides (3a-f) were synthesized using arylaldehydes, ammonium acetate and acetoacetanilide, which in turn converted into 5,6,7,8-tetrahydro-4-hydroxy-5,7-diarylpyrido[4,3-d]pyrimidin-2(3H)-ones (4a-f), 2-amino-5,6,7,8-tetrahydro- 5,7-diarylpyrido[4,3-d]pyrimidin-4-ols (5a-f) by condensing with guanidine carbonate and urea respectively.
Keywords: Synthesis; 4-oxo-N, 2, 6-triphenylpiperidine-3-carboxamides, 5,6,7,8-tetrahydro-4-hydroxy-5,7-diarylpyrido[4,3-d]pyrimidin- 2(3H)-ones, 2-amino-5,6,7,8-tetrahydro-5,7-diarylpyrido[4,3-d]pyrimidin-4-ols
3-Diazopyrazolo[3,4-c]pyridazine was synthesized and its transformations were investigated. With reactive methylene compound the corresponding hydrazones were formed. The prepared azo disperse dyes were applied to polyester fabric, and their spectral and color fastness properties measured.
Keywords: 3-diazo-4,5-diphenyl-3H-pyrazolo[3,4-c]pyridazine; active methylenes; color fastness
Various chromatographic techniques applied for the separation and quantitative determination of synthetic anticancer drugs and natural anticancer compounds are reviewed.
Keywords: chromatography; natural and synthetic anticancer drugs
In the present study interaction of Fe(II) and Fe(III) with antiparkinsonian drug molecule, Levodopa (LD), is investigated using potentiometry and spectrophotometry. Identical spectra of both of Fe(II) and Fe(III) complexes of the drug provide an evidence that similar stoichiometry was followed. Molar absorptivities of the complexes, found to be more than 100 M-1 cm-1, showed charge transfer spectra. Addition of an antioxidant decolorized the initial intensive color of the Fe(III) complex, which was evidence of high oxidation state of iron. Catecholic ligands, being strong reductants, chelate a metal ion in high oxidation state and show LMCT bands. These observations lead to conclude that iron has high oxidation state, regardless of initial source of metal.
Keywords: Levodopa; iron(II) and iron(III) chelate; UV-VIS study
The compound 2-amino-5-oxo-4-p-tolyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile, crystallizes in the monoclinic space group P121/c1 with the unit-cell parameters: a= 9.1330(7), b= 13.1343(9), c= 13.1945(8) Å, β = 91.746(4)o and Z = 4. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least-squares procedures to a final R-value of 0.0537 for 1830 observed reflections. The molecules within the unit cell are stabilized by C-H….O, N-H…O N-H….N and C-H…..π type of hydrogen bonding.
Keywords: 2-amino-5-oxo-4-p-tolyl-4,5-dihydropyrano[3,2-c]chromene-3-carbonitrile; scaffolds; hydrogen bond; crystal structure; direct methods
Two new complexes of manganese(III), [Mn(salen)(p-ClC6H4CO2)H2O] and [Mn(msalen)(C6H5CO2)H2O] have been synthesized from their manganese(II) carboxylate precursors [H2salen=N,N-bis(salicylidene)-1,2-diaminoethane and H2msalen=N,N-bis(3- methoxysalicylidene)-1,2-diaminoethane]. Single crystal X-ray diffraction studies show that the Jahn-Teller distorted octahedral complexes are stabilized by H-bonded chains in the solid state.
Keywords: manganese(III); Schiff base; carboxylate; H-bond interactions; supramolecular assembly
The title compound was synthesized by standard routes of synthesis and its structure was established by spectral and X-ray diffraction studies. The compound crystallizes in the triclinic space group P-1 with unit cell parameters a=10.4395(6), b=11.9493(6), c=13.8651(7), = 108.958(5), =103.089(5), = 97.885(4), Z=2. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least squares procedures to a final R-value of 0.0664 for 3330 observed reflections. In the title molecule, the tetrahydropyridine ring adopts a distorted boat conformation and both 4-nitro-phenyl substituents are in axial positions. The dihedral angle between the planes of the nitro-substituted rings is 45.5(1)o. The amino group and carbonyl O atom are involved in intramolecular hydrogen bonding and this interaction leads to the formation of a virtual-six membered ring. In the crystal, CH… O intermolecular interactions stabilizes the crystal packing.
Keywords: Tetrahydropyridine ring; crystal structure; direct methods; intermolecular hydrogen bonding
As part of a study on the molecular interactions between esters and ethers; density, viscosity and speed of sound data were measured for butyl ethanoate + ether mixed solvents. From these data, excess volumes VE, deviation in viscosity Δη, isentropic compressibility KS , deviation in isentropic compressibility Δ KS , intermolecular free length Lf , internal pressure πi , and the excess intermolecular free length Lf E , excess internal pressure πi E , were deduced. These excess or deviation properties were fitted to the Redlich-Kister type equation. Further the experimental mixture viscosities were correlated using Frenkel, Heric, and McAllister (four-body) models. The studied excess or deviation properties were found to be both positive and negative. These results were interpreted in terms of intermolecular interactions and structural effects.
Keywords: density; viscosity; speed of sound; excess volume; butyl ethanoate; interaction parameters
The 3-R-thieno[3,2-d]pyrimidine-2,4(1H,3H)-diones (5a-с) and 3-R-2-thioxo-2,3-dihydrothieno[3,2-d]pyrimidine-4(1H)-ones (5d-g) were synthesized using methyl 3-aminothiophene-2-carboxylate and alkyl-, arylisocyanates and isothiocyanates respectively, which in turn converted into its N- и S- alkyl derivates (8a-e, 9a-g). 2-Aminothieno[3,2-d]pyrimidin-4(3H)-one (14a-c, 16) were received as a result the interaction the methyl 3-aminothiophene-2-carboxylate with benzoyl- and pyrimidin-2-yl cyanamides.
Keywords: thiophenes, thienopyrimidinones, 3-R-thieno[3,2-d]pyrimidine-2,4(1H,3H)-dione, 3-R-2-thioxo-2,3-dihydrothieno[3,2-d]pyrimidin-4(1H)-one, 2-aminothieno[3,2-d]pyrimidin-4(3H)-one, alkylation
Potassium carbonate was found to be an efficient catalyst for synthesis of novel 2-thioxoquinazolin-4(1H)-one derivatives via a one-pot condensation of isatoic anhydride with primary amines and phenyl isothiocyanate in water at room temperature.
Keywords: 2-thioxoquinazolin-4(1H)-ones; potassium carbonate catalyst; room temperature three-component reaction; isatoic anhydride; isocyanates
Some new fused heterocyclic systems such as 1,2,4-triazolo[3,4-b]1,3,4-thiadiazoles and 1,3,4-thiadiazines were synthesized through the reaction of the starting material 4-(4-amino-5-mercapto-4H-1,2,4-triazol-3-yl)phthalazin-1(2H)-one with triethyl orthoformate, furoyl chloride, thiophene-2-aldehyde, phenylisothiocyanate, chloroacetonitrile, and p-nitro-2-bromoacetophenone. Also spiro systems were achieved from reaction of the starting compound with isatine, and fluorenone. The newly synthesized 1,3,4-thiadi
Keywords: triazolothiadiazole; triazolothiadiazine; spiro thiadiazole derivatives; phthalazin-1(2H)-ones; 4-amino-5-mercapto-1,2,4-triazoles
The kinetics of the oxidative decolorization of amaranth with KBrO3 acidified by H2SO4 was followed up by monitoring the decrease of the absorbance of amaranth at max = 520 nm. The reaction was carried out under pseudo-first-order conditions. The concentration of BrO3 - was ca 300 greater than that of amaranth. The rate of reaction increased with increasing concentration of H2SO4 and BrO3 -, while amaranth had no effect on the rate of reaction. The effects of the ions, Cl-, Br- and SO4 -- were investigated and the reaction rate increased with increasing concentrations of chloride and bromide while it decreased with increasing concentration of SO4 --. A reaction mechanism has been proposed.
Keywords: Amaranth Red; decolorization; kinetics; bromate
Materials and environmental chemistry
In the present work, a naturally occurring smectite group clay mineral, montmorillonite, (Mt) has been explored as a vehicle for delivery of an antidepressant drug Venlafaxine hydrochloride, VF. The effect of pH of the drug solution, time and initial drug concentration on drug loading capacity of Mt has been studied. The adsorption isotherm was fitted by the Langmuir model and follows the pseudo-second-order kinetics. The synthesized Mt-VF complexes were characterized by XRD, FTIR, TGA, DSC etc. VF was found to be intercalated in the Mt layers. The release profile of the VF and Mt-VF complex in simulated gastric and intestinal fluids has been discussed. The release behaviour of VF from Mt-VF complexes appears to be sustained/extended for a period of 12 h and reaches upto 52 % in simulated gastric fluid and is stable in intestinal fluid where as pure VF completely gets released in 5.5 h and 3.5 h in simulated gastric and intestinal fluid respectively. Out of all kinetic models used to elucidate the drug release mechanism, the best fitting was observed for first order model. On the basis of present studies it can be stated that the synthesized Mt-VF complexes have the potential for developing in to a sustained release formulation for oral drug delivery of an anti-depressant drug VF. This shows a path which can reduce doses substantially from 4 times in 24 h to twice in 24 h.
Keywords: Venlafaxine hydrochloride; montmorillonite; oral drug delivery
The gelling and metal-chelating properties of alginate were combined to develop an adsorbent for heavy metal removal. Biopolymer beads composed of fly ash and sodium alginate proved to be an effective adsorbent for removal of Zn(II) ions from aqueous solutions. The effect of initial pH (2–10), bead dose (10–80), agitation time (1–24 h), beads composition (0.1g–0.7 g fly ash) and Zn(II) ions initial concentration (5–30 mg L-1) on the adsorption process, as well as to what extent the adsorption data obey Langmuir and Freundlich adsorption isotherms were investigated. The maximum adsorption was found 84.20 % within 8 h and after that reaches equilibrium. The adsorption of Zn(II) ions is quite sensitive to pH of the suspension and shows an optimum uptake value at pH 6.0. Maximum adsorption occurred for 40 beads and in case of composition, beads composed of 0.5 g fly ash has shown good results. It is clear from the experimental results that the pH plays an important role in adsorption of zinc ions. The average size, bulk density and swelling ratio of beads calculated are; 0.12 cm, 0.34 g mL-1 and 28.65 respectively. The synthesized beads were also characterized by FTIR, XRD, SEM, TGA/DTA and other methods.
Keywords: biopolymer beads; sodium alginate; adsorption; isotherm models; wastewater
Cellulose nanocomposite bead modified with metal (MCNB) such as Ce, Al and Fe is synthesized for selective adsorption of arsenate anions As(V) from drinking water in batch system. The adsorbent was characterized by FTIR, FESEM, EDS and EPR studies. In the present report arsenic(V) adsorption performance on cerium modified cellulose bead was described. The maximum adsorption of As(V) is near about 100 percent up to an initial arsenic load of 5.0 mg L-1 at the acidic pH of 3.0 and the equilibrium is reached in 5 h. The much higher adsorption extent and quick equilibrium time compared to the other reported adsorbents makes the present adsorbent as efficient one. Among the three adsorption isotherm models used, Langmuir model fitted the experimental data best. The adsorption is found to be exothermic, spontaneous and random in nature. The process was applied for removal of arsenic from some real sample.
Keywords: Metal loaded cellulose nanocomposite bead; batch study; arsenic adsorption; isotherm; water analysis
Corrosion resistance of galvanized steel (GS) in Simulated concrete pore solution (SCPS) prepared in sea water, in the presence of sodium tungstate and succinic acid has been investigated by polarization study. Inclusion of sodium tungstate and also succinic acid in SCPS reduces the corrosion resistance of GS, Hence it is concluded use of sodium tungstate or succinic acid shall be avoided while GS rebar are used in construction of buildings, bridges especially in marine environment.
Keywords: simulated concrete pore solution; galvanised steel; sodium tungstate; succinic acid
Biochemistry, molecular biology and biotechnology
Enzymes leading to the methylation of homocysteine to produce L-methionine in the mutant Corynebacterium glutamicum X300 were investigated in this present study. S-adenosyl methionine served as a methyl group donor to homocysteine to form L-methionine. The enzymatic pathway examined in this present study was cobalamine-independent pathway. No methylcobalamin homocysteine transmethylase activity was detected in this microorganism.
Keywords: S-adenosylmethionine; methyl group donor; homocysteine; L-methionine; methylcobalamin homocysteine transmethylase
This study is concerned with the preparation of cold and boiled aqueous extracts from the fruits of both Phaseolus vulgaris and Vigna sinensis plants, then isolating the proteinous compounds from these extracts by cold acetone precipitation method and therefore to separate the non-proteinous fraction. The work included the study of the effect of intraperitoneal administration of cold and boiled aqueous extracts, proteinous acetone precipitates, and non-proteinous materials isolated from these extracts on certain blood biochemical constituents (parameters) using a dose of 77 mg kg-1 of body weight in normal and alloxan-induced diabetic mice. The results had been compared with those injected with insulin. The results showed that the boiled crude aqueous extract of Vigna sinensis plant and its isolated proteinous precipitate has a significant decrease effects for the level of the glucose and total lipids in the blood. On the other hand, the non-proteinous substance of cold aqueous extract of Phaseolus vulgaris fruit has a decrease effect for the level of glucose, cholesterol and total lipids in the blood serum of alloxan-induced diabetic mice, therefore may be used in the treatment of diabetes mellitus after make sure there is no side effects as well as we concluded that these materials mentioned above may be used in the treatment of diabetes mellitus.
Keywords: protein; aqueous extracts; Phaseolus vulgaris; Vigna sinensis; alloxan; diabetic mice
Industrial and engineering chemistry
The present work aimed to study the effect of aging on asphalt–rubber system after 12 month of the preparation process. The rheological properties of Qaiyarah asphalt were improved with using reclaimed rubber tires treated with anhydrous aluminium chloride. The reclaimed rubber tire samples in 0.5 and 1.0 % of the total amount of the asphalt (the amount of used anhydrous aluminium chloride catalyst was 0.06, 0.12, 0.25, 0.5, 1 %, respectively) were added to Qaiyarah asphalt sample. The reaction components were introduced into a microwave oven operating at 360 W power for 5, 10 and 15 minutes, respectively. The rheological properties including ductility, penetration, softening point and penetration index were measured before and after aging experiments. It was found that the modified asphalt exposed to atmospheric conditions has lower damage in comparison with untreated one and the longer treatment time was used the less crack and the larger resistance were achieved.
Keywords: asphalt; rheological properties; effect of aging; microwave treatment; anhydrous aluminium chloride