Synthesis and characterization of some new 4,4′‐(1,4‐phenylene)dipyrimidine and 6,6′‐(1,4‐phenylene)‐di(pyridin‐2(1H)‐one) derivatives

A series of new 4,4′‐(1,4‐phenylene)dipyrimidines 5a–c, 8a–c , and 10a,b have been synthesized from the reaction of amidines 1a–c with the dienaminone 2 , bis‐chalcone 6 , or ylidenemalono‐ nitrile 9 . The reaction of malononitrile and ethyl cyanoacetate with 2 gave 6,6′‐(1,4‐phenylene)di(pyridin‐2(1H)‐ones) ( 15a,b ). The structures of the products were proved by elemental analyses, IR, MS, ¹H, and ¹³C NMR spectroscopy. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:507–512, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20150     

Bis-dioxomolybdenum (VI) oxalyldihydrazone complexes: Synthesis,characterization, DFT studies,catalytic epoxidation potential,molecular modeling and biological evaluations

Two cis-bis-dioxomolybdenum oxalylsalicylidenedihydrazone complexes (MoO₂L1 and MoO₂L2) were synthesized via the complexation of dioxomolybdenum (VI) acetylacetonate with oxalylsalicylidenedihydrazone (H₂L1) and p-sodium sulfonate oxalylsalicylidenedihydrazone (H₂L2) bis-Schiff base chelating ligands, respectively. The structures of the newly synthesized complexes were confirmed by ¹H- and ¹³C-NMR, IR, ultraviolet–visible and mass spectra, as well as elemental analyses (EA) and conductivity measurements. The spectrophotometric continuous variation method revealed the formation of 2: 1 (metal: ligand molar ratios). DFT studies were applied for the ligands and their Mo-chelates. Interestingly, the bis-MoO₂(VI) oxalyldihydrazone complexes showed remarkable catalytic sufficiency towards the selective (ep)oxidation of 1,2-cyclooctene, benzyl alcohol and thiophene using H₂O₂ or tert-butyl hydroperoxide (tBuOOH) at 85 °C. Under aqueous conditions, the MoO₂L2 (with p-sodium sulfonate substituent) exhibited superior that of the MoO₂L1 (without p-NaSO₃―group), highlighting the role of sodium sulfonate substituent in the catalytic progress of the Mo-chelate. The ligands (H₂L1 and H₂L2) and their corresponding Mo-complexes (MoO₂L1 and MoO₂L2) were assessed for their antitumor and antimicrobial activities. Furthermore, the antioxidant activity was also evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and superoxide dismutase (SOD) assays. The binding nature between the Mo-complexes and calf thymus DNA (ctDNA) was also studied within spectroscopic and hydrodynamic techniques.     

Dose distribution verification in intraoperative radiation therapy using an N-isopropyl acrylamide-based polymer gel dosimeter

The purpose of the current study was to verify the dose distribution of an Intrabeam-50 kV IORT system using polymer gel dosimetry technique. Results of dose distribution evaluation using NIPAM polymer gel dosimetry were compared with those measured using an ionization chamber and simulated using MCNPX code. Results showed the calculated gamma index was less than 1 with 2% dose-difference/2 mm distance-to-agreement for comparison between NIPAM and ionization chamber as well as between NIPAM and MCNPX simulation. It was concluded that the NIPAM polymer gel dosimetry is useful for verifying the dose distribution of low energy X-ray IORT technique.

     

Recent Trends in the Chemistry of 4-Amino-1,2,4-triazole-3-thiones

The synthesis and reactions of substituted 4-amino-1,2,4-triazole-5-thione derivatives as well as their biological activity are reviewed.     

Study of complex formation of 5,5′-(2E, 2′E)-2,2′-(ethane-1,2-diylidene)bis(hydrazine-1-yl-2-ylidene)bis(4-amino-4H-1,2,4-triazole-3-thiol) (HYT) macrocyclic ligand with Cd2+ cation in non-aqueous solution by spectroscopic and conductometric methods

In this paper the complexation reaction of the 5,5′-(2E,2′E)-2,2′-(ethane-1,2-diylidene)bis(hydrazine-1-yl-2-ylidene)bis(4-amino-4H-1,2,4-triazole-3-thiol) ligand (HYT) with Cd²⁺ education was studied in some binary mixtures of methanol (MeOH), n-propanol (PrOH) and dimethyl-formamide (DMF) at different temperatures using the conductometry and spectrophotometry. The stability constants of the complex was determined using a GENPLOT computer program. The conductance data and absorbance-mole ratio plots show that in all solvent systems, the stoichiometry of the complex formed between (HYT) and Cd²⁺ cation is 1: 1. The obtained results show that the stability of (HYT)-Cd complex is sensitive to the mixed solvents composition. The values of thermodynamic parameters (ΔG ^°, ΔH ^°, and ΔS ^°) for formation of (HYT)-Cd complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots. The results show that in most cases, the complex are enthalpy destabilized but entropy stabilized and the complex formation is affected by pH, time, temperature and the nature of the solvent.     

Effect of bromide salts on the acid hydrolysis of anti-bacterial hydrophilic Schiff base amino acid iron(II) complexes

Salt effects on the kinetics of acid hydrolysis of some novel hydrophilic iron(II) complexes have been investigated in aqueous medium. The ligands are derived from the condensation of amino acids (glycine, L-alanine, L-leucine, L-isoleucine, DL-methionine, DL-serine or L-phenylalanine) and sodium 2-hydroxybenzaldehyde-5-sulfonate. The reaction was studied under conditions of pseudo first order kinetics. The general rate equation was suggested as follows: rate = k _obs[complex], where k _obs = k ₂[H⁺]. The reaction rate decreases with an increase of the salt concentration.     

Salt effects on the reactivity of the base‐catalyzed hydrolysis of some novel low‐spin hydrophobic Fe(II)–amino acid azomethine chelates

Salt effects on the reactivity of base hydrolysis of Fe(II) chelates [naphthylideneisoleucinate (nili), naphthylideneleucinate (nli), naphthylideneserinate (nsi), salicylideneisoleucinate (sili), salicylideneleucinate (sli), salicylidenemethioninate (smi), and salicylidenetryptophanate (sti)] have been investigated in aqueous media containing alkali metal halides and tetra‐n‐butylammonium bromide (TBAB). NaCl and NaBr exhibited different reactivity trends from those of KBr and TBAB. The observed patterns vary markedly with complex hydrophobicity. Generally, the presence of the salt markedly enhances the rate compared to its absence. This behavior agrees with the anionic nature of the transient species. With increasing added NaCl and NaBr, the rate of the reaction decreases. The rate decreases and then increases on increasing the concentration of KBr and TBAB. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 592–601, 2003