Diarylamines with the neighboring pyridyl group: synthesis and modulation of the amine functionality via intramolecular H-bonding

New pyridyl-containing diarylamines were obtained via Cu-assisted reductive amination of the ortho-2-pyridylaryl boronic acids. Comparative analysis of the spectral and electrochemical data obtained for new diarylamines and their pyridyl-free counterparts revealed the intramolecular H-bond (IMHB) formation which significantly influences the properties of the amino group. The electron density at the N atom of the amino group is increased due to partial weakening of the N-H bond, although the BDE and activation energy for the H-atom abstraction is increased due to the chelating effect of two N atoms. The ortho-pyridyl-containing diarylamines are more prone to be oxidized as compared to their pyridyl-free counterparts; the shift in the oxidation potential values correlates with the strength of the intramolecular H-bonding which can be tuned by inserting substituents in the pyridyl or phenyl rings. The IMHB is reserved even in polar solvents having a significant H-acceptor ability (such as DMSO) but can be destroyed in methanol, testifying in favor of the dynamic nature of the H-bonding.

Novel Mannich Base Derivatives: Synthesis, Characterization, Antimicrobial and Antioxidant Activities

: In this study, 3-alkyl(aryl)-4-(4-ethylbenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones 2 were synthesized as explained in the literature. Then, the Schiff bases 2 were treated with morpholine/ N-methylpiperazine/ 3-methylpiperidine/ 4-piperidinecarboxamide in the presence of formaldehyde according to the Mannich reaction to synthesize novel Mannich bases 3, 4, 5, and 6 types, respectively. The structural analyses of twenty four compound which synthesized new, were characterized using proton/ carbon 13 nuclear magnetic resonance (1H/ 13C-NMR), Infrared (IR) spectoscopic techniques. In addition, the antimicrobial activity of the compounds was determined on six bacteria by using the agar well diffusion method.The most effective results against gram positive and negative bacteria were observed in 6(a-d) and 6f compounds. Also, the antioxidant capacities of the substances were investigated by three different methods (DPPH, reducing power, metal chelation). All compounds 3-6(a-f) showed metal chelating effect.

Enhanced Selective Removal of Cd(II) by an Amino-Functional Water-Retaining Agent Incorporating Nano Hydrous Manganese Oxide

An amino-functionalized water-retaining agent (PPM40-NH2) and a water-retaining agent lacking functionalization (PPM40) were prepared to investigate their selective Cd(II) removal properties. The affinity for Cd(II) was increased after introducing the amino functional group. The SFCd/Ca of PPM40-NH2 was 3–7 fold higher than that of PPM40 although the CCa was 100–1000 times higher than that of CCd. The chelating effect of –COOH and –NH2 in PPM40-NH2 corresponded well with the selective adsorption of Cd(II), as confirmed by simulations. A seed germination experiment demonstrated that PPM40-NH2 could act as a filter of heavy metals to supply “clean” water for the roots of the pakchoi plant. The leaching experiment indicated that PPM40-NH2 is an efficient in situ fixation agent for the remediation of agricultural soil contaminated with Cd(II) in the presence of high concentrations of Ca(II) salts.

Function Synergy of Cross-Linked Cationic PVA Polymer to AMPS-Type Fluid Loss Additive Used for Cement-Based Material

In this research, a kind of 2-acrylamido-2-methylpropanesulfonic acid sodium salt- (AMPS-Na-) type copolymer additive, the fluid loss additive (FLA), named as FLA A additive, was used for research. The performance of FLA A was tested and found to fail in the effective control of free water and to hinder the hydration process for delaying the breaking of the early hydration shell. The reason for it was the absorbed behavior and chelating effect of the AMPS-Na unit to Ca2+ hydrating cement particles. Thus, a cationic polyvinyl alcohol (PVA) polymer, modified by glyoxal and boric acid, was discovered due to its excellence in associating with the FLA A additive for controlling the free cement-based material water amount and preventing the chelating effect of FLA A chains on the surface of the cement-based material. Glyoxal/boric acid-modified polyvinyl alcohol, abbreviated as PVAGB or PVA-G-B, was with special molecular properties, i.e., positive ZETA (ζ) potential characteristics and cross-linked molecular structure. Due to competitive absorbed behavior of glyoxal-modified hydroxyl groups and free Ca2+ released by the hydration product, the chelating effect of AMPS-Na units to Ca2+ was weakened and the possibility of FLA A chains being absorbed to the surface of the cement-based material was decreased. Then, the formation of a complete fluid loss system was obtained; i.e., the fluid loss volume decreased to less than 50 mL at 30°C and 108 mL at 80°C with 0.2 percentage by weight of cement (%BWOC) of PVAGB and 0.50%BWOC (percentage by weight of cement) of FLA A. Besides, the hydration process of cement-based material was accelerated due to formation of more C-S-H gels in the early hydration period. As a result, the cement-based material not only showed no worse compressive-strength retrogression but also showed a stable 28-day compressive strength of 28 MPa.

Formation of iron(iii)–thiolate metallocyclophane using a ferrocene-based bis-isocyanide

Ferrocene-based iron–thiolate complexes are reported, and the kinetic product transforms to its corresponding thermodynamic product by the chelating effect of Fc(NC)2.