Synthesis and spectroscopic studies of new binuclear transition metal complexes of Schiff bases derived from 4,6-diacetylresorcinol

Two new series of copper(II), nickel(II), cobalt(II), zinc(II), iron(III), chromium(III), vanadyl(IV) and uranyl(VI) complexes with two bifunctional tridentate Schiff base, H₄L¹ and H₂L² ligands have been prepared. The Schiff base, H₄L¹ and H₂L², ligands were synthesized by the condensation of 4,6-diacetylresorcinol with o-aminophenol or o-phenylenediamine. The ligands are either di- or tetra-basic with two symmetrical sets of either OON or NNO tridentate chelating sites. The ligands and their metal complexes have been characterized by elemental analysis, ¹H-n.m.r., FT-IR, mass, electronic, esr spectra and thermal gravimetric analysis and magnetic susceptibility. With the exception of Co^II ion with H₂L² which afforded a trinuclear complex, a variety of binuclear complexes for the rest of the metal complexes were obtained with the ligands in its di- or tetra-deprotonated forms. The bonding sites are the azomethine and amino nitrogen atoms, and phenolic oxygen atoms. The metal complexes exhibit different geometrical arrangements such as square planar, tetrahedral, square pyramid and octahedral arrangement.     

CHARACTERIZATION OF NANOSTRUCTURES:TOOLS AND CHALLENGES

Apart from long-known and applied nanostructures like carbon black for tyres or pigments for coatings nanotechnology has created highly sophisticated structures used for nano/molecular electronics,diagnostics,drug delivery, UV-absorbers etc.Often the main question to be solved analytically is the local determination of tiny amounts of chemicals resulting in an ever increasing need for highly sensitive as well as locally resolved techniques.Applications of techniques like mass spectroscopy,transmission el...     

Synthesis and Characterization of Some Mixed Ligand-Selenito and Tellurito Chromium(III) Complexes

New mixed ligand Cr(III) complexes were prepared where diamine or oxalato ligands are coordinated together with either tellurito, selenito, or hydrogenselenito ions to form nine octahedral complexes. The complexes were characterized by chemical analyses, IR and UV-visible spectra, magnetic, and conductivity measurements. The tellurito and selenito ligands act as monodentate ligands, coupled with the bidentate diamine ligands. On the other hand, they act as bidentate chelate ligands when coordinated together with the oxalate ligand. However, hydrogenselenite ion act as a monodentate ligand coupled with the oxalate ligand. IR spectra indicated that the inorganic ligands are coordinated to the Cr(III) ion through their oxygen atoms. One of the bulky diamine molecules, 1,2-pn or 1,3-pn, was freed from the coordination sphere of Cr(III) on the addition of the bulky inorganic anions and was replaced by two water molecules.     

Colorimetric determination of theophylline and aminophylline with diazotized p-nitroaniline

The reactions of theophylline and aminophylline with diazotized p-nitroaniline in alkaline medium have been studied and developed into a sensitive assay for both drugs. The yellow azo-dyes formed with theophylline and aminophylline show maximum absorption at 440 and 410 nm respectively. Beer's law is valid within the concentration range 2–16 μg/ml for theophylline and 1–8 μg/ml for aminophylline. All variables which affect the reactions were studied and optimized. The proposed method has been successfully applied to determination of the drugs in their commercially available dosage forms. Statistical analysis of the results revealed that the proposed method is as precise and accurate as the official USP procedure.     

A Hybrid Deep Learning Model for Brain Tumour Classification

A brain tumour is one of the major reasons for death in humans, and it is the tenth most common type of tumour that affects people of all ages. However, if detected early, it is one of the most treatable types of tumours. Brain tumours are classified using biopsy, which is not usually performed before definitive brain surgery. An image classification technique for tumour diseases is important for accelerating the treatment process and avoiding surgery and errors from manual diagnosis by radiologists. The advancement of technology and machine learning (ML) can assist radiologists in tumour diagnostics using magnetic resonance imaging (MRI) images without invasive procedures. This work introduced a new hybrid CNN-based architecture to classify three brain tumour types through MRI images. The method suggested in this paper uses hybrid deep learning classification based on CNN with two methods. The first method combines a pre-trained Google-Net model of the CNN algorithm for feature extraction with SVM for pattern classification. The second method integrates a finely tuned Google-Net with a soft-max classifier. The proposed approach was evaluated using MRI brain images that contain a total of 1426 glioma images, 708 meningioma images, 930 pituitary tumour images, and 396 normal brain images. The reported results showed that an accuracy of 93.1% was achieved from the finely tuned Google-Net model. However, the synergy of Google-Net as a feature extractor with an SVM classifier improved recognition accuracy to 98.1%.     

Synthesis and Some Reactions of 4-Aroyl-3-Chloro-6-p-Tolylpyridazines

4-Aroyl-3-chloro-6-p-tolylpyridazines (3a &b) were prepared by the action of phosphorous oxychloride on (2). (3a &b) react with hydrazine hydrate to give the pyrazolinopyridazines (4a &b) and with hydroxylamine hydrochloride to give the isoxazolopyridazines (7a &b), respectively. (4b) was also synthesized by the action of phosphorous oxychloride on the hydrazone (5). The reaction of (3a &b) with primary amines in boiling ethanol gives (8a-e), while their reaction with primary aromatic amines in the presence of solvent gives the Schiff's bases (9a-c).     

Spectroscopic investigations of new binuclear transition metal complexes of Schiff bases derived from 4,6-diacetylresorcinol and 3-amino-1-propanol or 1,3-diamino-propane

The bifunctional carbonyl compound; 4,6-diacetylresorcinol (DAR) serves as precursor for the formation of different Schiff base ligands, which are either di- or tetra-basic with two symmetrical sets of either O2N or N2O tridentate chelating sites. The condensation of 4,6-diacetylresorcinol with 3-amino-1-propanol (3-AP) or 1,3-diaminopropane (DAP), yields the corresponding hexadentate Schiff base ligands, abbreviated as H4La and H2Lb, respectively. The structures of these ligands were elucidated by elemental analyses, IR, mass, 1H NMR and electronic spectra. Reaction of the Schiff base ligands with copper(II), nickel(II), cobalt(II), zinc(II), cadmium(II), iron(III), chromium(III), vanadyl(IV) and uranyl(VI) ions in 1:2 molar ratio afforded the corresponding transition metal complexes. A variety of binuclear complexes for the metal complexes were obtained with the ligands in its di- or tetra-deprotonated forms. The structures of the newly prepared complexes were identified by elemental analyses, infrared, electronic, mass, 1H NMR and ESR spectra as well as magnetic susceptibility measurements and thermal gravimetric analysis (TGA). The bonding sites are the azomethine and amino nitrogen atoms, and phenolic and alcoholic oxygen atoms. The metal complexes exhibit different geometrical arrangements such as square planar, tetrahedral, square pyramid and octahedral arrangement.     

Liquid chromatography and chemometric-assisted spectrophotometric methods for the analysis of two multicomponent mixtures containing cough suppressant drugs

Three methods were applied for the analysis of 2 multicomponent mixtures containing dextromethorphan hydrobromide, phenylephrine hydrochloride, chlorpheniramine maleate, methylparaben, and propylparaben, together with either sodium benzoate (Mix 1) or ephedrine hydrochloride and benzoic acid (Mix 2). In the first method, liquid chromatography was used for their simultaneous determination using an ODS column with a mobile phase consisting of acetonitrile-phosphate buffer, pH 2.7 (40 + 60, v/v), containing 5mM heptanesulfonic acid sodium salt and ultraviolet (UV) detection at 214 nm. Also, 2 chemometric methods, principal component regression, and partial least squares were used. For both chemometric calibrations, a concentration set of the mixture consisting of each compound in each mixture was prepared in distilled water. The absorbance data in the UV spectra were measured for the 76 or 71 wavelength points in the spectral region 210-240 or 210-224 nm considering the intervals of deltagamma = 0.4 or 0.2 nm for Mix 1 and Mix 2, respectively. The 2 chemometric methods did not require any separation step. These methods were successfully applied for the analysis of the 2 multicomponent combinations in synthetic mixtures and in commercial syrups, and the results were compared with each other.