Common Diamines Research Articles

Cytotoxic Anti-Cancer Activity of Certain Thermotropic Liquid Crystalline Poly (Ester-Amides) Containing 2, 6-Bis (Benzylidene)Cyclohexanone Moiety in the Main Chain

Five thermotropic liquid crystalline poly(ester-amides) were synthesized by polycondensation method. The poly(ester-amides) were synthesized from varying dicarboxylic acids with a common diamine namely 4,4'-diaminobenzene and a common diol namely 2,6-bis(4-hydroxybenzylidene))cyclohexanone. For qualitative characterization, viscosity measurements and solubility data were used for these synthesized poly(ester-amides). The spectroscopic techniques such as FT-IR, 1H NMR, 13C NMR were performed to investigate the microstructural features of these synthesized poly(ester-amides). The thermal phase transition behavior of these poly(ester-amides) were studied by Differential Scanning Calorimetry (DSC) and Hot-stage Optical Polarized Microscopy (HOPM). The degree of crystallinity was assessed by X-ray diffraction (XRD) patterns. Scanning Electron Microscopic (SEM) technique was used to illustrate the morphology of these poly(ester-amides). The copolymer synthesized was subjected into in vitro anti-cancer activity studies against human breast cancer (MCF-7) cell line.
 Keywords: Bisbenzylidenecyclohexanone; poly(ester-amides); polycondensation; thermotropic liquid crystalline properties; cytotoxicity, anticancer.

Synthesis, Characterization and Applications of Certain New Poly (ester amides), Their Blend Nanofibers

Abstract A new series of four aromatic poly(ester amides) were synthesized by direct polycondensation from 2,5-pyridine dicarboxylic acid as common diacid and 4, 4’ - diamino diphenyl methane as common diamine with four different diols using diphenylchlorophosphate (DPCP) in pyridine medium. The resulting polymers were found to be soluble in highly polar solvents and sparingly soluble in nonpolar solvents. The synthesized poly(ester amides) were characterized by FT-IR, 1H and 13C NMR spectra which confirmed that the monomers are well incorporated in the main chain of the poly(ester amides). The thermal phase transition behaviour of these polymers was investigated by Differential Scanning Calorimetry (DSC). X-ray diffraction (XRD) studies were carried out to determine the crystallinity of the poly(esteramides). Antibacterial activity of the polymers was studied against some pathogenic bacteria by agar well diffusion method. Blend nanofibers of the polymers with PVC were prepared by electrospinning technique. Morphological studies of the nanofibers were carried out by using Scanning Electron Microscopy (SEM). The synthesized poly(ester amides) are expected to be potential candidates for novel biomedical applications.

Synthesis, Characterization and Photocrosslinkable Studies of Certain Thermotropic Liquid Crystalline Poly(ester-amides)

Five thermotropic liquid crystalline poly(ester-amides) were synthesized by polycondensation method using varying dicarboxylic acids with a common diamine namely 4,4-diaminodiphenyl and a common diol namely 2,6-bis(4-hydroxy-3-methoxybenzylidene)cyclohexanone (CHBV). The solubility data and viscosity measurements of these synthesized poly(ester-amides) were used for qualitative characterization. The spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR were performed for investigating micro structural features. By differential scanning calorimetry (DSC), the thermal phase transition behavior of these poly(ester-amides) was studied. Scanning electron microscopy (SEM) technique was used to investigate the morphology of these poly(ester-amides). By using UV-visible spectroscopic technique, the photocrosslinkability of these poly(ester-amides) were studied by irradiating these poly(ester-amides) under a 160 W medium pressure mercury lamp. SEM analysis of these UV irradiated poly(ester-amides) showed the changes in morphology. Thus, the poly(ester-amides) containing arylidene keto moiety in the main chain exhibited nematic mesophase and were photocrosslinked upon UV irradiation. X-ray diffraction (XRD) patterns of these poly(ester-amides) were taken to assess the degree of crystallinity.<div><br></div>

Graphene oxide composite membranes cross-linked with urea for enhanced desalting properties

Cross-linking reaction is an important method to prepared stable graphene oxide (GO) membrane, however, the cross-linking reaction with common diamine always induces the water flux decline and ion rejection decrease because GO is partly reduced to result in some oxygen functional groups lose and the cross-linking diamine was inserted to enlarge the free spacing of GO layers. Herein, GO was cross-linked with urea (UR) to show high water flux and good ion rejection. XPS results demonstrated that UR was chemically linked with GO sheets and cellulose acetate (CA) membrane support. In comparison with GO/CA membrane, the water contact angle increase of UR modified membrane (GO-UR/CA) is 10°, but the water contact angle increase of ethane diamine (EDA) modified GO membrane (GO-EDA/CA) achieved 40°, which resulted in GO-UR/CA membrane almost achieving the similar water permeation flux with the pristine GO/CA and the much lower water flux of GO-EDA/CA at same GO specific mass deposition. The “d” spacing of GO-UR/CA in wet state is about 9.7 nm, and GO-EDA/CA reaches a 0.95 nm “d” spacing, however, GO-UR/CA membrane yielded a best separation performance with the ion rejections reaching 21.6%, 26.8%, 63.2%, 73.5%, 81.9% for KCl, NaCl, CaCl2, MgSO4, and CuSO4, respectively. The reasons for that was the higher O content, the introduced the polar ketone groups and smaller free “empty” space in GO-UR/CA membrane. This finding may provide a new viewpoint to comprehend the mechanism of molecule and ions permeation in GO membrane.

Preparation and characterization of a composite nanofiltration membrane interfacially polymerized from cis,cis‐1,3,5‐triaminocyclohexane and trimesoyl chloride

ABSTRACTcis,cis‐1,3,5‐Triaminocyclohexane (TAC) was synthesized and used to prepare composite nanofiltration (NF) membranes by interfacial polymerization with trimesoyl chloride (TMC). The surface elemental composition, morphology, and hydrophilicity of the prepared NF membranes were characterized. The separation performances were examined with various salts and polyethylene glycol (PEG400, PEG600) solutions. The effects of preparation conditions were also systematically studied. The NF membrane was negatively charged and exhibited a salt rejection in the order Na2SO4 (98.2%) &gt; MgSO4 (90.8%) &gt; MgCl2 (84.5%) &gt; NaCl (54.6%). The water permeability was 1.56 L m−2 h−1 bar−1, and the molecular weight cutoff was 600 Da. The TAC/TMC membrane exhibited some characteristics that were different from the ones made from common diamines such as m‐phenylenediamine: (1) the surface was smoother, without a ridge‐and‐valley structure; (2) there were two kinds of crosslinking points in the polyamide chains; (3) the active layer was formed faster (only 5 seconds was required to reach a Na2SO4 rejection of 98%). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43511.

The inhibition of cell-free supernatant of Lactobacillus plantarum on production of putrescine and cadaverine by four amine-positive bacteria in vitro

Putrescine and cadaverine are common diamines in fermented food and represent a toxicological risk for consumer health. This work aimed to investigate the inhibitory effects of cell-free supernatant (CFS) and water bathed (100 °C, 10 min) cell-free supernatant (WCFS) from Lactobacillus plantarum on cell growth, diamine production, and the related decarboxylase activities of four amine-positive bacteria, namely, Enterobacter aerogenes, Enterobacter cloacae, Enterococcus faecium, and Enterococcus faecalis. Results showed that compared with Man Rogosa Sharpe (MRS) broth (control), both CFS and WCFS treatment significantly reduced the cell growth and diamine production of the four amine-positive bacteria, but only caused limited inhibition (less than 15%) on related decarboxylase activities from E. aerogenes and E. cloacae. Meanwhile, cell growth and related decarboxylase activities significantly declined when initial pH value decreased from 6.5 to 4.5. Furthermore, a significant positive relationship was found between diamine production and cell number of the four amine-positive bacteria. However, no significant relationship was observed between diamine production and related decarboxylase activities (except for E. aerogenes and E. cloacae in pH 6.5). These results indicate that the reduction in diamine accumulation by L. plantarum may mainly result from the inhibition of cell growth, but not from the inhibition of relevant decarboxylases.

Poly(ester imide)s Possessing Low CTE and Low Water Absorption (II). Effect of Substituents

The film properties of a variety of poly(ester imide)s (PEsIs) were evaluated for development of a novel high temperature base film in flexible printed circuit (FPC) boards. In this work, three types of PEsI systems were systematically prepared from the following combinations of monomers: (1) ester-containing tetracarboxylic dianhydrides: hydroquinone bis(trimellitate anhydride) (TAHQ), methyl-substituted TAHQ (M-TAHQ), and methoxy-substituted TAHQ (MeO-TAHQ) with common diamines such as p-phenylenediamine (PDA), (2) common tetracarboxylic dianhydrides such as pyromellitic dianhydride (PMDA) with ester-containing diamines: 4-aminophenyl-4′-aminophenylbenzoate (APAB) and methyl-substituted APAB (ATAB), and (3) the TAHQ series with the APAB series. The effects of the substituents on the PEsI film properties and polymerizability were also discussed in this work. The ester-containing monomers used in this work (TAHQ series and the APAB series) were all highly reactive and led to PEsAAs possessing high inherent viscosities ranging 1.09–9.33 dL/g. The incorporation of methyl and methoxy substituents into rigid TAHQ-based PEsI systems caused no significant decrease in Tg but allowed molecular motions above the Tgs. In some cases, these substituents, in particular, the methoxy group contributed to a significant decrease in water absorption without sacrificing other target properties. For practical FPC application, a flexible diamine was copolymerized into the highly esterified rigid PEsI systems derived from the TAHQ series with the APAB series. One of the PEsI copolymers obtained achieved excellent combined properties: a low CTE (17.8 ppm/K) completely consistent with that of copper foil as a conductive layer, considerably low water absorption (0.47 wt %), a high Tg exceeding 360 °C, and improved toughness (elongation at break > 40%).

Effects of monomer structure and imidization degree on mechanical properties and viscoelastic behavior of thermoplastic polyimide films

Two thermoplastic polyimides based on a common diamine (3,4′-ODA) were synthesized using different dianhydrides, namely ODPA and BPDA by a two step method. Molecular weight was controlled by using PA as an end capping agent. Effects of imidization degree on the mechanical properties and viscoelastic behavior of thermoplastic polyimide films were investigated. Film samples with varying degrees of imidization were characterized using FTIR, DMTA and tensile properties testing. It was found that two polyimides have different rates of imidization because of difference in monomer reactivity and molecular structure. It was observed that with an increase in imidization degree there was a decrease in thermoplastic response and a change in viscoelastic behavior from liquid-like to solid-like. With increase in imidization degree the tensile modulus and tensile strength of the films were increased, whereas elongation at break and tensile breaking energy were found to decrease after a certain imidization temperature.

Synthesis and characterization of new sulfonated polyimides as proton-exchange membranes for fuel cells

The synthesis and characterization of a series of new sulfonated polyimides are described. One-step high temperature polymerization method was used to prepare the sulfonated polyimide copolymers from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDSA), and other three common diamines, i.e., 4,4′-oxydianline (ODA), 4,4′-methylene dianiline (MDA), and 4,4′-(9-fluorenylidene)dianiline (FDA). The sulfonation degree of the copolymers was regulated through variation of the molar ratio of DSDSA to the common diamines. Flexible, transparent, and mechanically strong membranes were successfully obtained. The membranes were characterized with Fourier transform infrared spectra, thermogravimetric analysis, ion-exchange capacity, and proton conductivity measurements. These results showed that the membranes had good thermal stability and exhibited high conductivity at high relative humidity levels, especially in liquid water at 70 °C. At high temperatures of above 140 °C, the membranes displayed higher conductivities than Nafion ® membranes because of their high activation energies.

Reactions of plant copper/topaquinone amine oxidases with N6-aminoalkyl derivatives of adenine

Plant copper/topaquinone-containing amine oxidases (CAOs, EC 1.4.3.6) are enzymes oxidising various amines. Here we report a study on the reactions of CAOs from grass pea (Lathyrus sativus), lentil (Lens esculenta) and Euphorbia characias, a Mediterranean shrub, with N6-aminoalkyl adenines representing combined analogues of cytokinins and polyamines. The following compounds were synthesised: N6-(3-aminopropyl)adenine, N6-(4-aminobutyl)adenine, N6-(4-amino-trans-but-2-enyl)adenine, N6-(4-amino-cis-but-2-enyl)adenine and N6-(4-aminobut-2-ynyl)adenine. From these, N6-(4-aminobutyl)adenine and N6-(4-amino-trans-but-2-enyl)adenine were found to be substrates for all three enzymes (Km∼10−4 M). Absorption spectroscopy demonstrated such an interaction with the cofactor topaquinone, which is typical for common diamine substrates. However, only the former compound provided a regular reaction stoichiometry. Anaerobic absorption spectra of N6-(3-aminopropyl)adenine, N6-(4-amino-cis-but-2-enyl)adenine and N6-(4-aminobut-2-ynyl)adenine reactions revealed a similar kind of initial interaction, although the compounds finally inhibited the enzymes. Kinetic measurements allowed the determination of both inhibition type and strength; N6-(3-aminopropyl)adenine and N6-(4-amino-cis-but-2-enyl)adenine produced reversible inhibition (Ki∼10−5–10−4 M) whereas, N6-(4-aminobut-2-ynyl)adenine could be considered a powerful inactivator.

Putrescine Aminopropyltransferase Is Responsible for Biosynthesis of Spermidine, Spermine, and Multiple Uncommon Polyamines in Osmotic Stress-Tolerant Alfalfa.

The biosynthesis of polyamines from the diamine putrescine is not fully understood in higher plants. A putrescine aminopropyltransferase (PAPT) enzyme activity was characterized in alfalfa (Medicago sativa L.). This enzyme activity was highly specific for putrescine as the initial substrate and did not recognize another common diamine, 1,3-diaminopropane, or higher-molecular-weight polyamines such as spermidine and spermine as alternative initial substrates. The enzyme activity was inhibited by a general inhibitor of aminopropyltransferases, 5[prime]-methylthioadenosine, and by a specific inhibitor of PAPTs, cyclohexylammonium sulfate. The initial substrate specificity and inhibition characteristics of the enzyme activity suggested that it is a classical example of a PAPT. However, this enzyme activity yielded multiple polyamine products, which is uncharacteristic of PAPTs. The major reaction product of PAPT activity in alfalfa was spermidine. The next most abundant products of the enzyme reaction using putrescine as the initial substrate included the tetramines spermine and thermospermine. These two tetramines were distinguished by thin-layer chromatography to be distinct reaction products exhibiting differential rates of formation. In addition, the uncommon polyamines homocaldopentamine and homocaldohexamine were tentatively identified as minor enzymatic reaction products but only in extracts prepared from osmotic stresstolerant alfalfa cultivars. PAPT activity from alfalfa was highest in meristematic shoot tip and floral bud tissues and was not detected in older, nonmeristematic tissues. Product inhibition of the enzyme activity was observed after spermidine was added into the in vitro assay for alfalfa PAPT activity. A biosynthetic pathway is proposed that accounts for the characteristics of this PAPT activity and accommodates a novel scheme by which certain uncommon polyamines are produced in plants.

Polyamines in [formula omitted]: Presence of an unusually high, osmotically sensitive pool of 1,3-diaminopropane

High (15–25 mM) concentrations of 1,3-diaminopropane, a normally minor derivative of polyamine metabolism, have been observed in vegetative cells of Acanthamoeba castellanii . Trace amounts of a putative polyamine, which chromatographically behaved like norspermidine, were also found. The size of the intracellular pool of 1,3-diaminopropane was inversely related to the ambient osmolality and to the free amino acid levels during osmotic shock experiments. Due to its high concentration in A. castellanii , this diamine may be operative in ionic regulation during environmental stress. 1,3-diaminopropane may substitute for putrescine, a common diamine which was undetectable in A. castellanii .