ε-Poly(L-lysine)-based Hydrogels with Fast-acting and Prolonged Antibacterial Activities

Bacterial infections and the associated morbidity and mortality due to bacterial pathogens in wounds and medical implants have been increasing as most of current coatings cannot fulfill all the requirements including excellent intrinsically antibacterial activity,low cytotoxicity, and favorable physical properties. Herein, we present a kind of antibacterial hydrogel based on ε-poly(L-lysine)(EPL)grafted carboxymethyl chitosan(CMC-g-EPL) as the inherently antibacterial matrix and the surplus EPL as highly efficient antimicrobial agent. Such hydrogels possess tunable swelling abilities with water absorption percentages of 800%–2000% and modulus varying from10 kPa to 100 kPa, and exhibit two-stage excellent antibacterial behavior. First, the free EPL can be released from the hydrogel network for quick and highly efficient bacteria killing with 99.99% of efficacy; second, the grafted EPL endows hydrogel matrix with prolonged intrinsically antibacterial activity, especially when most of free EPL is released from the hydrogel. Overall, we provide a new insight for preparing highly effective antibacterial hydrogels.     

Directed Aminomethylation of Pyrrole,Indole, and Carbazole with <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>,<Emphasis Type="Italic">N′</Emphasis>-Tetramethylmethanediamine

Catalytic aminomethylation of pyrrole and indole with N,N,N′,N′-tetramethylmethanediamine in the presence of 5 mol % of ZrOCl₂·8H₂O proceeds selectively at the positions 2, 5 of pyrrole and 1, 3 of indole. Carbazole under the same conditions affords 3-formyl-9-aminomethyl derivative. The reaction in the presence of 5 mol % of K₂CO₃ occurs as monoaminomethylation: for pyrrole at the position 2, for indole at the position 3, and for carbazole at the nitrogen atom of the substrate. Water-soluble 1,1′-(1H-pyrrole-2,5-diyl)bis(N,N-dimethylmethanamine) exhibits a fungistatic activity with respect to phytopathogenic fungi Rhizoctonia solani.     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

Complex formation of magnesium and calcium ions with trimethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>’,<Emphasis Type="Italic">N</Emphasis>’-tetraacetic acid

Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO₃) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K⁰, Δ_rG⁰, Δ_rH⁰, and Δ_rS⁰) of the studied equilibriums have been determined.     

1,3-Diamino-2-Hydroxypropane-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-Tetraacetic Acid: Crystal and Molecular Structures

The synthesis, IR spectroscopic study, and X-ray diffraction analysis (CIF file CCDC no. 1574078) are carried out for 1,3-diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid (I). The structural units of a crystal of compound I are (H_4.5HPdta)^0.5– anions, (H_5.5HPdta)^0.5+ cations, and molecules of water of crystallization joined by a branched network of hydrogen bonds: strong intermolecular O–H…O and intramolecular N–H…O bonds.     

Thermophysical properties of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimеthylacetamide mixtures with <Emphasis Type="Italic">n</Emphasis>-butanol

The refraction, dielectric, viscosity, density, data of the binary mixtures of N,N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature.     

Computer models of eutectic-type <Emphasis Type="Italic">T</Emphasis>–<Emphasis Type="Italic">x</Emphasis>–<Emphasis Type="Italic">y</Emphasis> diagrams with allotropy

Using the eutectic-type T–x–y diagram as an example, it can be represented the analysis of its geometrical construction dependence on the temperature of a component two polymorphous modifications which participate in mono- and invariant metatectic and invariant eutectic (eutectoid) transformations above or below (and within) binary eutectics temperature intervals and below a ternary eutectic temperature. Computer models for considered phase diagrams have been designed. Such models help to solve applied tasks like visualization, isopleths and isothermal sections decoding, mass balances calculation and evaluation of phase and conglomerate concentration in microstructure.     

SBR composites reinforced with <Emphasis Type="Italic">N</Emphasis>-isopropyl-<Emphasis Type="Italic">N</Emphasis>′-phenyl-<Emphasis Type="Italic">P</Emphasis>-phenylenediamine-modified clay

SBR compounds including the N-isopropyl-N’-phenyl-p-phenylenediamine-modified clay(organoclay) were prepared.Effects of modified clay and antioxidant(IPPD) contents on mechanical and rheological properties of SBR composites were studied.FTIR results confirmed that the clay was chemically modified by IPPD and changed into an organoclay.X-ray diffraction(XRD) results confirmed the increase in interlayer distance of the clay due to the insertion of IPPD.Rheological and cure characteristics of SBR compounds were determined using RPA(Rubber Process Analyzer) and rheometer.Scorch time and cure time of SBR compounds decreased with introduction of the organoclay.Mechanical properties and heat aging resistance of the SBR composites were improved significantly by incorporation of the organoclay.     

New heteroscorpionate lanthanide complexes for ring-opening polymerisation of <Emphasis Type="Italic">ε</Emphasis>-caprolactone and <Emphasis Type="Italic">rac</Emphasis>-lactide

Yttrium and lanthanum amido-complexes with bis(pyrazol-1-yl)acetates in their coordination spheres were studied as the catalysts in ε-caprolactone and lactide ring-opening polymerisation. A high molecular mass poly(ε-caprolactone) (PCL) was obtained in almost quantitative yield under mild conditions. rac-Lactide polymerisations were less efficient and required quite harsh experimental conditions to obtain atactic PLA samples with moderate yields. The average chain-length of PCL was dependent upon the choice of the metal centre and the presence of substituents on the pyrazole rings of the ancillary ligand. The ground-state geometries of the complexes and the first stages of ε-caprolactone polymerisation were computationally modelled by means of DFT calculations.     

<Emphasis Type="Italic">N</Emphasis>-arylsulfanyl-<Emphasis Type="Italic">N</Emphasis>-arylsulfonyl(acyl)-<Emphasis Type="Italic">N</Emphasis>′-phenylthiourea sodium salts

Reactions of N-arylsulfonyl(acyl)arenesulfenamide sodium salts with phenyl isothiocyanate afforded N-arylsulfanyl-N-arylsulfonyl(acyl)-N-phenylthioura sodium salts which were found to increase thermal stability of finely dispersed poly(vinyl chloride).Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 10, 2004, pp. 1532–1535.Original Russian Text Copyright © 2004 by Koval, Oleinik.     

Spectroscopic and electrical characterization of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">γ</Emphasis>-bisdiphenylene-<Emphasis Type="Italic">β</Emphasis>-phenylallyl radical as an organic semiconductor

The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1^?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1^? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1^? displays photocurrent and an electron mobility of 6.3 × 10^?7 cm² V^?1 s^?1 on a trially-fabricated organic field effect transistor.     

Preparation and crystal structure of bis(triethylene glycol-<Emphasis Type="Italic">O</Emphasis>,<Emphasis Type="Italic">O</Emphasis>′,<Emphasis Type="Italic">O</Emphasis>′’,<Emphasis Type="Italic">O</Emphasis>‴)manganese(II) dibromide

A new complex, bis(triethylene glycol-O,O′,O′’,O?)manganese(II) dibromide [Mn(TEG)₂]²⁺·2Br^?, was prepared. Its structure was studied by single crystal X-ray diffraction. The complex cation [Mn(TEG)₂]²⁺ is of the host-guest type with two TEG ligands (podands) as hosts. Both TEG ligands are disordered and tetradentate, with all the four oxygen atoms of each ligand participating in the coordination. The Mn²⁺ cation has coordination number 8, and its coordination polyhedron is a distorted bisdisphenoid (trigonal dodecahedron). The geometric parameters (bond lengths, bond and torsion angles) of the complex were determined relatively accurately. In the crystal structure, the ions form infinite thick layers by interionic hydrogen bonds O-H···Br^?.     

Synthesis of 20<Emphasis Type="Italic">S</Emphasis>-protopanaxadiol <Emphasis Type="Italic">β</Emphasis>-D-galactopyranosides

20S-Protopanaxadiol (3β,12β,20S-trihydroxydammar-24-ene) 3-, 12-, and 20-O-β-D-galactopyranosides were synthesized for the first time. Condensation of 12β-acetoxy-3β,20S-dihydroxydammar-24-ene (1) and 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosylbromide (α-acetobromogalactose) (2) under Koenigs–Knorr conditions with subsequent removal of the protecting groups resulted in regio- and stereoselective formation of 20S-protopanaxadiol 3-O-β-D-galactopyranoside, an analog of the natural ginsenoside Rh₂. Glycosylation of 12β,20S-dihydroxydammar-24-en-3-one (5) by 2 with subsequent treatment of the reaction products with NaBH₄ in isopropanol and deacetylation with NaOMe gave 20S-protopanaxadiol 12- and 20-O-β-Dgalactopyranosides.     

Synthesis and structure of the cobalt(II) coordination compounds with <Emphasis Type="Italic">N,N</Emphasis>-dimethyl-<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dimethylthiocarbamoylsulfenamide

The CoLX₂ complexes were obtained by the reaction of N,N-dimethyl-N′,N′-dimethylthio-carbamoylsulfenamide (L) with CoX₂ (X = Cl, Br, I, NCS). The complexes were investigated by elemental and X-ray analysis, IR, ¹H NMR, and electron spectroscopy, conductometry, magnetochemistry, thermogravimetry. It is found that these compounds are high-spin complexes of pseudotetraedral structure with bidentate coordination of L through the thione sulfur atom and sulfenamide nitrogen atom.     

Cyclization of the substituted <Emphasis Type="Italic">N</Emphasis>-(<Emphasis Type="Italic">Ortho</Emphasis>-cyclopropylphenyl)-<Emphasis Type="Italic">N′</Emphasis>-aryl ureas and thioureas in the gas phase and solution

Electron ionization (EI), chemical ionization (CI), tandem mass spectrometry, high-resolution measurements, and labeling studies as well as quantum chemical calculations were used to understand the behavior of the molecular radical cations (EI) and protonated molecules (CI) of substituted N-(ortho-cyclopropylphenyl)-N'-aryl ureas and N-(ortho-cyclopropylphenyl)-N'-aryl thioureas in a mass spectrometer. Fragmentation schemes and possible mechanisms of primary isomerization were proposed. According to the fragmentation pattern, formation of the corresponding benzoxazines and benzothiazines was considered as the major process of isomerization of the original M(+.) and MH(+), although some portions of these ions definitely transformed into other structures. The treatment of N-(ortho-cyclopropylphenyl)-N'-phenyl urea and N-(ortho-cyclopropylphenyl)-N'-phenylthiourea in solution with strong acids formed predicted 4-ethyl-N-phenyl-4H-3,1-benzoxazin-2-amin and 4-ethyl-N-phenyl-4H-3,1-benzothiazin-2-amine as principal products.     

<Emphasis Type="Italic">β</Emphasis>-Chloro-<Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated carbonyls as convenient precursors of highly substituted benzenes

The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques.     

Phase Diagrams of the <Emphasis Type="Italic">n</Emphasis>-Decane–<Emphasis Type="Italic">n</Emphasis>-Hexadecane–Cyclododecane, <Emphasis Type="Italic">n</Emphasis>-Decane–Cyclododecane,and <Emphasis Type="Italic">n</Emphasis>-Hexadecane–Cyclododecane Systems

The n-decane–n-hexadecane–cyclododecane, n-decane–cyclododecane, and n-hexadecane–cyclododecane systems are studied by means of low-temperature differential thermal analysis using a differential scanning heat flow calorimeter. It is noted that all studied systems belong to the eutectic type. It is concluded that in the n-decane–n-hexadecane–cyclododecane system, the eutectic composition contains 85.0 wt % n-С₁₀Н₂₂, 4.0 wt % n-С₁₆Н₃₄, and 11.0 wt % С₁₂Н₂₄. It has a melting point of ?35.0°C.