Synthesis and evaluation of some quinoline Schiff bases as a corrosion inhibitor for mild steel in 1 N HCl

N-((2-chloroquinolin-3-yl)methylene)aniline (CQM) and N-((2-chloroquinolin-3-yl)methylene)-5-methylthiazol-2-amine (CQMA) were synthesized. The effect of CQM and CQMA have been investigated against mild steel (MS) in 1 N HCl solutions using conventional weight loss, potentiodynamic polarization, linear polarization, electrochemical impedance spectroscopy, UV–Vis spectroscopy and scanning electron microscopic studies. The losses in the weights of MS samples have proved that both CQM and CQMA are efficient inhibitors. The mixed mode of inhibition was confirmed by electrochemical polarizations. The adsorptions of these inhibitors are found to follow the Langmuir adsorption isotherm. CQM and CQMA adsorbs on the MS sample by chemisorptions.     

Experimental and theoretical study for corrosion inhibition of mild steel 1 M HCl solution by some new diaminopropanenitrile compounds

The inhibition of the corrosion of mild steel 1 M HCl solution by some diamine compounds has been investigated in relation to the concentration of the inhibitor as well as the temperature using weight loss and electrochemical measurements. The effect of the temperature on the corrosion behavior with the addition of different concentrations of new diamine compounds (3-[2-(2-cyano-ethylamino)-methylamino]-propionitrile (P1); 3-[2-(2-cyano-ethylamino)-ethylamino]-propionitrile (P2), and 3-[6-(2-cyano-ethylamino)-hexylamino]-propionitrile (P3), respectively, was studied in the temperature range 40–80 °C. Polarization curves reveal that (P1, P2, and P3) are mixed type inhibitors. The inhibition efficiency of organic compounds is temperature independent, but increases with the inhibitor concentration. Adsorption of inhibitor on the carbon steel surface is found to obey the Langmuir adsorption isotherm. Some thermodynamic functions of dissolution and adsorption processes were also determined. On the other hand, and in order to determine the relationship between the molecular structure of these compounds and inhibition efficiency, quantum chemical parameters were calculated. The theoretically obtained results were found to be consistent with the experimental data.     

Adsorption and corrosion inhibitive properties of piperidine derivatives on mild steel in phosphoric acid medium

The present study describes the inhibition effect of 4-benzyl piperidine (P1), 1,6-bis(4-benzylpiperidine-1-carboxamide)hexane (P2) and bis(4-benzylpiperidine)thiuram disulfide (P3) towards the corrosion of mild steel in 5.5 M H₃PO₄ solution using weight loss measurements and polarization technique. The influence of inhibitor concentration and temperature on the inhibitory behavior of P2 and P3 was investigated. Meanwhile, the inhibition efficiency (IE) was found to depend on the molecule structure and the concentration of piperidine derivatives. The IE for 10^?3 M P2 and P2 in 5.5 M H₃PO₄ is around 90 %. Polarization studies clearly revealed that all the compounds used act as mixed-type inhibitors. Adsorption isotherms were fitted by the Langmuir isotherm. Adsorption energies ( $ \Updelta {\text{G}}^\circ_{\text{ads}} $ and $ \Updelta {\text{H}}^\circ_{\text{ads}} $ ) and kinetic parameters were evaluated. Significant correlations are obtained between inhibition efficiency with the calculated chemical indexes, indicating that the variation of inhibition with structure of the inhibitor may be explained in terms of electronic properties.     

Electroanalytical studies of the corrosion-protection properties of 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) on mild steel in 0.5?N sulfuric acid

Inhibition of the corrosion of mild steel in aerated 0.5?N H₂SO₄ solution by 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) was investigated by use of potentiodynamic polarization (Tafel), electrochemical impedance spectroscopy, adsorption, and surface morphological studies. The effects on the rate of corrosion of inhibitor concentration, temperature, extent of surface coverage, adsorption kinetics, and surface morphology were investigated. Inhibition efficiency increased markedly with increasing ATD concentration and decreased slightly with increasing temperature. The presence of ATD reduced the capacitance of the double layer and increased the charge-transfer resistance. Values of the activation energy (E _a) and of the thermodynamic data adsorption equilibrium constant (K _ads) and free energy of adsorption (??G _ads) were computed from the temperature dependence of the corrosion current. The inhibitor molecule first became adsorbed on the mild steel surface, obeying the Langmuir adsorption isotherm, and substantially reduced the rate of corrosion. Results of electroanalytical studies revealed that ATD acts as a mixed-type inhibitor.     

Reactivity and reaction pathways of alkylalkoxybenzene radical cations. Part 3. Effects of 2-alkyl substituents on the relative importance of ring-substitution over deprotonation of 2-alkyl-1,4-dimethoxybenzene radical cations

One-electron oxidation of 2-alkyl-1,4-dimethoxybenzenes 1a-f (2-alkyl=Me, Et, i-Pr, cy-C₃H₅CH₂, PhCH₂ and t-Bu) by 4-nitrobenzoyl peroxide 2 and pentaflurobenzoyl peroxide 3 was proved by the observation of great acceleration of decomposition of the peroxides at room temperature, the detection of the corresponding radical cations 1 ^+? a-f and product analysis. The product studies have disclosed that under the conditions employed (in acetonitrile at 40°C), the reaction pathways of the radical cations are greatly dependent on the nature of 2-alkyl substituents: Ring-4-nitrobenzoloxylation product at C ₅ and C ₆ were obtained exclusively in the reactions of the donors with aliphatic 2-alkyl substituents bearing at least one α-hydrogen atom, such as 1a, 1b, 1c and 1d; whereas in the case of 1e (with 2-benzyl group), both ring-substitution at C ₅ (4e) and C ₆ (5e) and deprotonation/4-nitrobenzoloxylation products 8e were isolated; from the donor without α-hydrogen atom, 1f, de-t-butylation products 12 and t-butyl 4-nitrobenzoate 13 were incorporated with ring-substitution at C ₅ (4f) and C ₆ (5f). Furthermore, the product distribution (4 over 5) is also affected by the bulkiness of 2-alkyl group. For all the electron-transfer reactions, large amounts of the benzoic acid (4-NO₂-C₆H₄COOH or C₆F₅COOH) were generated and trace amounts of de-methylation product (2-alkyl-1,4-benzoqinones 6) were also detected by ¹H NMR.     

Copper complexes of two isomeric NS2-macrocycles

Two isomeric NS₂-macrocycles incorporating a xylyl group at ortho (o -L) and meta (m -L) positions were employed and their copper complexes (1?C5) were prepared and structurally characterized. The copper(II) nitrate complexes [Cu(L)(NO₃)₂] (1: L = o -L, 2: L = m -L) for both ligands were isolated. In each case, the copper center is five-coordinated with a distorted square pyramidal geometry. Despite the overall geometrical similarity, 1 and 2 show the different ligand conformation due to the discriminated packing pattern. Reaction of o -L with copper(II) perchlorate afforded complex 3 containing two independent complex cations [Cu(o -L)(H₂O)(DMF)(ClO₄)]⁺ and [Cu(o -L)(H₂O)(DMF)]²⁺; the coordination geometry of the former is a distorted octahedron while the latter shows a distorted square pyramidal arrangement. In the reactions of copper(I) halides (I or Br), o -L gave a mononuclear complex [Cu(o-L)I] (4) with a distorted tetrahedral geometry, while m -L afforded a unique exodentate 2:1 (ligand-to-metal) complex [trans-Br₂Cu(m-L)₂] (5) adopting a trans-type square-planar arrangement.     

Theoretical Study of the Solvent Effect on the Methyltrioxorhenium/Hydrogen Peroxide System

The effect of solvent on the stability and reactivity of methyltrioxorhenium (MTO) for activation of hydrogen peroxide (H₂O₂) was investigated theoretically. The possible geometries for all Re complexes present in this system, MTO, monoperoxo complexes [A: MeReO₂(η ²–O₂) and A·H ₂ O: MeReO₂(η ²–O₂)(H₂O)], and bisperxo complexes [B: MeReO(η ²–O₂)₂ and B·H ₂ O: MeReO(η ²–O₂)₂(H₂O)] were calculated. Based on the theoretical calculations, species A lacks coordinated water while species B·H ₂ O definitely has water coordinated to the Re. The changes of thermodynamic parameters (ΔH and ΔG) for six reactions in the MTO/H₂O₂, system including formation of mono- and bisperoxo complexes, were determined.     

The electronic structure of 5-methylhexa-1,2,4-triene-1,3-diyl, the first representative of highly delocalized triplet ethynylvinylcarbenes, from ESR spectroscopy data and quantum chemical calculations

The ESR spectrum of the first representative of highly conjugated triplet ethynylvinylcarbenes, 5-methylhexa-1,2,4-triene-1,3-diyl (1), was recorded in solid argon matrix. The zero-field splitting (ZFS) parameters of carbene 1 (D = 0.5054±0.0006 cm^?1 and E = 0.0045±0.0002 cm^?1) determined from the experimental ESR spectrum are in between the corresponding parameters of ethynylcarbene C3H2 (2) and vinylcarbene C₃H₄ (3): D(3) < D(1) < D(2) and E(2) < E(1) < E(3). Quantum chemical calculations of the ZFS parameters of 1, 2, and 3 have been carried out for the first time using two DFT-based approaches, RODFT and UDFT. An analysis of the experimental and theoretical ZFS parameters shows that carbene 1 is characterized by a greater extent of delocalization of the spin density of unpaired electrons than carbenes 2 and 3. The characteristic structural fragments of carbene 1 possess the principal features of the electronic structure of both ethynylcarbene (2) and vinylcarbene (3), respectively. Magnetic spin-spin interactions are identical in carbenes 1 and 2. The dominant contribution to D in 1 and 2 results from the one-center spin-spin interactions on carbon atoms in the propynylidene group, which are subjected to strong spin polarization.     

Ionic Mobility in Glasses in the ZrF4-BiF3-MF Systems (M = Li,Na, K) as Probed by 7Li, 19F,and 23Na NMR

The ion mobility in new fluoride glasses (mol %) 45ZrF₄ · 25BiF₃ · 30MF (I) (M = Li, Na, K), (70 - x)ZrF₄ · xBiF₃ · 30LiF (II) (15 ≤ x ≤ 35), and 45ZrF₄ · (55-x)BiF₃ · xMF (III) (M = Li, Na; 10 ≤ x ≤ 30) has been studied by ⁷Li, ¹9F, and ²³Na NMR in the temperature range 250–500 K. The character of ion motion in bismuth fluorozirconate glasses I and III is determined by temperature and the nature and concentration of an alkali-metal cation. Major type of ion mobility in glasses I–III at temperature 400–440 K are local motions of fluorine-containing moieties and diffusion of lithium ions (except for the glass with x = 10). The factors responsible for diffusion in the fluoride sublattice of glasses I have been determined. Sodium ions in glasses I and III are not involved in ion transport.     

Syntheses, characterization and crystal structures of new mono- and bis-Schiff base compounds derived from 1,2,4-triazine and the silver(I) complexes containing mono-Schiff base ligands

Some new Schiff bases, (Z)-4-amino-3-((E)-(R-methoxybenzylidene)hydrazono)-6-methyl-3,4-dihydro-1,2,4-triazin-5(2H)-one (R?=?2 (L2), R?=?3 (L3) and R?=?4 (L4)), were synthesized by the condensation reactions of 4-amino-3-hydrazinyl-6-methyl-1,2,4-triazin-5(4H)-one (L1) and corresponding methoxybenzaldehyde in a molar ratio 1:1.5 in high yields. The reaction of L2 and L4 with an excess amount of the corresponding aldehydes gave the unsymmetrical bis-Schiff bases (E)-3-((E)-(R-methoxybenzylidene)hydrazono)-4-((E)-R-methoxybenzylideneamino)-6-methyl-3,4-dihydro-1,2,4-triazin-5(2H)-one (R?=?2 (L22) and R?=?4 (L44)), respectively. Furthermore, the reaction of L2?CL4 with silver(I) nitrate in a molar ratio 2:1 led to the silver(I)-complexes with the general formula [Ag(Lx)₂]NO₃ (Lx?=?L2 (2), L3 (3) and L4 (4)). All synthesized Schiff base compounds and complexes were characterized by a combination of IR-, ¹H-NMR spectroscopy, mass spectrometry and elemental analyses. In addition, the structures of L2, L4·CH₃CN, L22·CH₃OH and L44·CH₃OH and complexes 2 and 4 were determined by X-ray diffraction studies.     

Raman spectroscopy data on the phase transition of KO2 mixed with KOH on a glass fiber matrix

The composition of solid products of vacuum decomposition of K₂O₂ · 2H₂O₂ (I) on a glass fiber matrix was determined by Raman spectroscopy. The products were mainly mechanical mixtures of potassium superoxide KO₂ (II) with KOH · nH₂O (III) and, in some cases, with KOH (IV). The n value in III varies from sample to sample (most often, from 0.2 to 1). Component II is represented by the typical tetragonal phase (the ν(O-O) stretching maximum at 1146 ± 1 cm^?1). The transformation of the tetragonal phase of II into cubic phase upon sample irradiation with a focused laser beam was studied. The phase transition was initiated by increasing the power of monochromatic radiation (λ = 514.5 nm). The formation of the cubic phase was indicated by a sharp increase in the width of the ν(O-O) stretching mode. Reaching the threshold power facilitates warming up of the sample in the focusing point to ～120°C. In pure II, the phase transition is enantiotropic; when the laser radiation power drops to the initial minimal level, the tetragonal phase is formed again. When III or IV is present in the sample, this does not take place. Stabilization of the cubic phase of II is attributable to the chemical reaction with IV taking place at phase transition temperature to give a binary compound or a solid solution of the KO₂ · KOH type (V). The crystals of V correspond to the cubic system.     

Comparative investigation of the copper(II) complexes of (R)-, (S)- and (R,S)-1-phenyl-N,N-bis(pyridine-3-ylmethyl)ethanamine along with the related complex of (R,S)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine. Synthetic, magnetic, and structural studies

The interaction of the enantiopure (R)- and (S)-1-phenyl-N,N-bis(pyridine-3- ylmethyl)ethanamine ligands, R-L ¹ and S-L ¹ , with copper(II) chloride followed by addition of hexafluorophosphate resulted in the isolation of the corresponding enantiomeric complexes [Cu(R-L ¹ )Cl](PF₆) (1), [Cu(S-L ¹ )Cl](PF₆) (2) and [Cu(S-L ¹ )Cl](PF₆)??0.5Et₂O (3), in which dimerization occurs through two long Cu??????Cl interactions, the ??-chloro bridges being thus strongly asymmetric. The organic ligand is bound to the metal centre via its N₃-donor dipyridylmethylamine fragment in a planar fashion, such that each copper centre is in a square planar environment (or distorted square pyramidal with a long axial bond length if the additional interaction is considered). When R,S-L ¹ was employed in a parallel synthesis, the similar racemic complex [Cu(R,S-L ¹ )Cl](PF₆)??0.5MeOH (4) was obtained, in which the L ¹ ligands in each dimeric unit have opposite hands. In contrast to the complexes of L ¹ , the reaction of Cu(II) chloride with the related ligand, (R)-1-cyclohexyl-N,N-bis(pyridine-3-ylmethyl)ethanamine (R-L ² ), yielded the mononuclear complex [Cu(R,S-L ² )Cl₂] (5), displaying a distorted square pyramidal coordination geometry. The structure of this product along with its corresponding circular dichroism spectrum revealed that racemisation of the starting R-L ² ligand has occurred under the relatively mild (basic) conditions employed for the synthesis. A temperature-dependent magnetic studies of the complexes 1, 2 and 5 indicate that a week ferromagnetic interaction is operative in each dicopper core in 1 and 2 with 2J?=?1.2?cm^?1. On the other hand, a week antiferromagnetic intermolecular interaction is operative for 5.     

Copper(II), iron(III) and cobalt(III) complexes of the pendent-arm cyclam derivative 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane

The interaction of Cu(II), Fe(III) and Co(III) with 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane (L ³ ) incorporating a pendent amine group has led to isolation of the new octahedral complexes [Cu(HL ³ )(ClO₄)₂]Cl·H₂O (1), [Fe(L ³ )Cl](S₂O₆)·H₂O (2), [Co(L ³ )Cl](ClO₄)_1.5Cl_0.5·0.25H₂O (3), [Co(HL ³ )Cl₂](ClO₄)₂·H₂O (4) and [Co(L ³ )Cl]₂(S₂O₄)(ClO₄)₂ (5). In (1) the copper ion occupies the macrocyclic cavity of protonated (–NH₃ ⁺) L ³ which is present in its trans-III configuration; weakly bound ClO₄ ^? ligands occupy the axial positions. The X-ray structure of (2) showed that Fe(III) occupies the N₄-macrocyclic cavity of L ³ in a trans-III configuration, with the pendent amine group binding in an axial position. The remaining axial position is occupied by a Cl^? ligand. Chromatography of the product obtained from the reaction of Na₃[Co(CO₃)₃] with L ³ yielded three fractions. Fraction 1 yielded crystals (3) composed of three crystallographically independent species incorporating cations of type [Co(L ³ )Cl]²⁺ with very similar structures; in each case the macrocyclic ring nitrogens of L ³ are bound to the Co(III) in an asymmetric cis-fashion. Fraction 2 yielded the trans-III octahedral cationic complex (4) incorporating L ³ in its protonated form. The Co(III) complex (5) from fraction 3 shows a different coordination arrangement to the products from fractions 1 or 2. The macrocyclic ring coordinates in its trans-III form, but the axial sites in this case are occupied by the pendent-NH₂ group and a Cl^? ligand.     

Corrosion inhibition investigations of 3-acetylpyridine semicarbazone on carbon steel in hydrochloric acid medium

The corrosion inhibition efficiency of 3-acetylpyridine-semicarbazide (3APSC) on carbon steel (CS) in 1.0 M HCl solution has been investigated using weight loss measurements, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies. The results show that inhibition efficiency on metal increases with the inhibitor concentration. 3APSC exhibited marked inhibition towards carbon steel in HCl medium even at low concentrations. The adsorption of inhibitor on the surfaces of the corroding metal obeys the Langmiur isotherm and thermodynamic parameters (K _ads, ?G _ads ⁰ ) were calculated. Activation parameters of the corrosion process (E _a, ?H* and ?S*) were also calculated from the corrosion rates. Polarization studies revealed that 3APSC act as a mixed-type inhibitor. Surface analysis of the metal specimens was performed by scanning electron microscopy.     

A novel view of modelling interactions between synthetic and biological polymers via docking

Multipoint interactions between synthetic and natural polymers provide a promising platform for many topical applications, including therapeutic blockage of virus-specific targets. Docking may become a useful tool for modelling of such interactions. However, the rigid docking cannot be correctly applied to synthetic polymers with flexible chains. The application of flexible docking to these polymers as whole macromolecule ligands is also limited by too many possible conformations. We propose to solve this problem via stepwise flexible docking. Step 1 is docking of separate polymer components: (1) backbone units (BU), multi-repeated along the chain, and (2) side groups (SG) consisting of functionally active elements (SG _F ) and bridges (SG _B ) linking SG _F with BU. At this step, probable binding sites locations and binding energies for the components are scored. Step 2 is docking of component-integrating models: [BU] _m , SG = SG _F –SG _B , BU–SG, BU–BU(SG)–BU, BU(SG)–[BU] _m –BU(SG), and [BU _var (SG _var )] _m . Every modelling level yields new information, including how the linkage of various components influences on the ligand—target contacts positioning, orientation, and binding energy in step-by-step approximation to polymeric ligand motifs. Step 3 extrapolates the docking results to real-scale macromolecules. This approach has been demonstrated by studying the interactions between hetero-SG modified anionic polymers and the N-heptad repeat region tri-helix core of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41, the key mediator of HIV-1 fusion during virus entry. The docking results are compared to real polymeric compounds, acting as HIV-1 entry inhibitors in vitro. This study clarifies the optimal macromolecular design for the viral fusion inhibition and drug resistance prevention.     

Conformational space of tetrakis(2-naphthalenyl)ethene: a naphthologous AIE luminogen

The AIE luminogen tetrakis(2-naphthalenyl)ethene (2-NA ₄ E) was synthesized by Barton’s double extrusion diazo-thione coupling method from 2,2′-dinaphthyl thioketone and 2,2′-(diazomethylene)bisnaphthylene in 77 % yield. The structure of 2-NA ₄ E was confirmed by its ¹H NMR and ¹³C NMR spectra with full assignments. 2-NA ₄ E and its parent tetraphenylethene (Ph ₄ E) have been subjected to a comprehensive computational DFT study, in search of their conformational spaces. Seven conformers and two transition states of 2-NA ₄ E have been located. Four conformers and one transition state of Ph ₄ E have been located. The conformers of 2-NA ₄ E and Ph ₄ E are not overcrowded, as indicated by the contact distances in the fjord and cove regions. The relative free energies (ΔG ₂₉₈) of the six most stable conformers of 2-NA ₄ E are in the narrow range of 2.3 kJ/mol; they make comparable contributions (12–29 %) to the equilibrium mixture. The energy barriers for the diastereomerization D ₂-Z,Z,Z,Z $ \rightleftharpoons $ ? D ₂-E,E,E,E via the transition state C ₁-Z,E,E,Z and for the enantiomerization C ₂-Z,Z,E,E $ \rightleftharpoons $ ? C ₂-E,E,Z,Z via the transition state C _i -Z,E,Z,E are only 29.8 and 29.0 kJ/mol, respectively, indicating very rapid rates of diastereomerization and enantiomerization at room temperature. The values of naphthalenyl torsion angles and ethenic twist angles in 2-NA ₄ E are almost identical to those in the parent Ph ₄ E. The previously proposed “bulkiness” of the naphthalenyl substituents and the validity of the restriction of naphthalenyl rotation are challenged. The analysis of the AIE effect in 2-NA ₄ E should take into account the intermolecular homochiral and heterochiral interactions between the conformers.     

Synthese von (5,10)-(7,8)-Bisepoxiden aus α- und β-4-Phenyl-1,2,4-triazolin-3,5-dion-Addukten von Vitamin D3 und Röntgenstrukturanalyse eines der Benzoylderivate

Oxidation of the α- and β-4-phenyl-1,2,4-triazolin-3,5-dione adducts of vitamin D₃ (2 and1) withMCPBA yields two diastereomeric mixtures of the (5,10)-(7,8)-dioxiranes3 a,3 b,3 c and4 a,4 b respectively. The corresponding benzoates5 a,5 b,6 a and6 b were prepared and the X-ray crystal structure of5 b was determined. This analysis proved5 b to be the (5R, 1 OS)-(7R, 8R)-dioxirane of the β-resp. (6S)-4-phenyl-1,2,4-triazolin-3,5-dione adduct1 of vitamin D₃.     

Synthesis and characterization of glycol-modified vanadium(V) oxoisopropoxide and their oximato derivatives: sol–gel transformations of [VO(OPr i )3], [VO{OCH2CH2OCH2CH2O}{OPr i }] and [VO{OCH2CH2OCH2CH2O}{ON=C(CH3)(C4H3S-2)}] to vanadia

Reaction of [VO(OPr ⁱ )₃] (1) with [O(CH₂CH₂OH)₂] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH₂CH₂OCH₂CH₂O}{OPr ⁱ }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH₂CH₂OCH₂CH₂O}{ON=C(R)(Ar)}] (3–8) {where R=CH₃, Ar=C₄H₃O-2 (3), C₄H₃S-2 (4), C₅H₄N-2 (5); and when R=H, Ar=C₄H₃O-2 (6), C₄H₃S-2 (7), C₅H₄N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively.     

Construction and characterization of novel molecular architectures through coordination-driven self-assembly: rhomboid and overlapped double rhomboid

The potentially tridentate ligands 4-(6-(pyridin-4-yl)pyridin-2-yl)pyridine (4) and 3-(6-(pyridin-3-yl)-pyridin-2-yl)pyridine (5) have been prepared and characterized. From the self-assembly of 4 or 5 and 2,9-bis[trans-Pt(PEt₃)₂(NO₃)]phenanthrene (6), two supramolecular platinum-based macrocycles with rhomboid (7) and overlapped double rhomboid (8) structures have been constructed. Compounds 7 and 8 are formed in different shapes due to the different nitrogen positions (meta and para) of the ligands 4 and 5, respectively. Both supramolecules are characterized by multinuclear NMR and electrospray ionization mass spectroscopies.     

Further studies on the properties and effect of high energetic ionizing radiation on copper(II) complexes: 1H NMR,electronic absorption,ESR spectra and solid electrical conductivity

The effect of energetic γ-radiation on ¹H NMR, electronic absorption, ESR spectra, differential thermal analysis (DTA) and solid state dc electrical conductivity of the ligand N-phenyl-2-(2-(phenylamino)acetyl)hydrazine carbothioamide (H₂L) and its copper(II) complexes; Cu(HL)(OAc)H₂O, Cu(HL)BrH₂O and Cu(H₂L)₂(NO₃)₂?3H₂O before and after γ-irradiation (hereafter referred to as (B), (B ₁ ), (B ₂ ), (B ₃ ) and (A), (A ₁ ), (A ₂ ), (A ₃ ), respectively) has been studied. Electronic spectral bands of the complexes after irradiation exhibited some better resolved shapes with a remarkably higher absorbance, ESR spectrum of complex Cu(HL)BrH₂O (B ₂ ) before irradiation showed isotropic spectrum with g _iso = 2.075 however, after irradiation (A ₂ ) displayed axial ESR spectrum with g _∥ > g _⊥ > 2.0023 and d _(x2?y2) ground state. DTA of the compounds reveals that γ-irradiation induced generation of new peaks as well as changes in the peak intensities. Solid state dc electrical conductivity for complexes was investigated before and after γ-irradiation. Complexes were found to be semiconductors, the activation energies (E _a) were calculated for the complexes by using the Arrhenius plot.