Methylene Chain Length Research Articles

The High-Pressure Hexagonal Phase of Long Chain Dicarboxylic Acids in Water

Abstract The high pressure phase of several kinds of dicarboxylic acid (DCA) has been studied by X-ray diffraction up to 700 MPa and compared with the hexagonal phase of polyethylene (PE) under high pressure. Eicosanedioic acid (DCA-20) is the shortest DCA investigated that has the high pressure phase. The phase diagram of DCA-20 is determined. Water plays an essential role for the transition from the monoclinic to the hexagonal form; in the absence of water, the monoclinic form directly melts without passing through the hexagonal form. Low molecular weight PE treated by fuming nitric acid is a DCA with a long methylene chain and also has the hexagonal form only in the water as a pressure transmitting fluid. The mechanism of the transition is discussed in the light of hydration of the carboxyl groups on the crystal surface and flexibility of the molecule depending on the length of methylene chain.

Photoinduced Hydrogen Evolution with Viologen-Linked Porphyrins

Abstract Viologen-linked water-soluble porphyrins with different methylene chain lengths between porphyrin and viologen were synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH, viologen-linked porphyrin, and hydrogenase under steady-state irradiation.

Mobility of spin probes having an amide group in nylon films

The mobility of spin probes having an amide group in dried nylon films was investigated by means of an electron spin resonance (e.s.r.) technique. The results for 4-acetylamino-2,2,6,6-tetramethyl-1-piperidinyloxy (SPVII) and 4-benzoylamino-2,2,6,6-tetramethyl-1-piperidinyloxy (SPVIII) were compared with that for 4-(( p-phenylazobenzoyl)amino)-2,2,6,6-tetramethyl-1-piperidinyloxy (SPI) examined previously. The mobility of all the spin probes increased with increasing methylene chain length of the nylon, and a small effect of drawing was observed. The mobility of SPVII was a little lower than that of SPI, whereas SPVIII gave the same mobility as SPI. From this, it was concluded that the mobility of spin probes having an amide group was affected by interactions between the amide group of the probe molecules and the nylons rather than by the molecular volumes of the spin probes.

Mobility of Spin Probes in Quaternized Poly(4-vinylpyridine) Membranes

The mobility of nonionic and anionic spin probes in water-containing quaternized poly(4-vinylpyridine) membranes was investigated by means of an electron spin resonance (ESR) technique. Poly(4-vinylpyridine) was quaternized and crosslinked by dibromoalkane Br(CH2)nBr (n=4, 6, 8, 10), and the effects of the side alkyl chain length were studied. Three spin probes, 2,2,4,4-tetramethyl-1,2,3,4-tetrahydro-γ-carboline-3-oxyl (SPII), 2,2,6,6-tetramethyl-1-piperidinyloxy (SPIV), and sodium 2,2,5,5-tetramethyl-1-pyrrolidinyloxy-3-carboxylate (ASPI), were used. In the temperature region examined, the side methylene chain length had no effect on the mobility of SPII and SPIV, but a little effect for ASPI. This suggests that the ASPI can monitor the mobility of the side alkyl chain. In addition, the effects of water on the mobility of the spin probes were investigated. The mobility of the spin probes was much greater in the membrane containing 30 wt% water than in that containing 3 wt% water, and the polarity around the probes was larger in the former than in the latter membrane. From this, as pointed out in our previous papers on nylon 6/spin probe systems, the effects of water are divided into (1) the effects on the mobilities of the polymer chains and probe molecules, and (2) the effects on the microenvironment around the spin probes.

Effects of Hydrogen Bonds on the Mobility of Spin Probes in Nylon Films

To elucidate the effects of hydrogen bonds between polymer chains and small molecules on the mobility of small molecules, the mobilities of TEMPO (SPIV), TEMPOL containing a hydroxyl group (SPV), and TEMPONE containing a carbonyl group (SPVI) were investigated by means of electron spin resonance (ESR) measurements, and compared with the mobility of TEMPAMINE containing amino group (SPIII) examined previously. T50G, at which the extrema separation of ESR spectra becomes 5 mT (50 G) decreased in the order of SPVI>SPIII>SPV>SPIV, suggesting that the functional groups of the spin probes strongly affect the mobilities of the spin probes. For all the spin probes, T50G decreased with an increase in the methylene chain length of the nylon. However, the effects of drawing on the mobility were found only for SPIII. In the Arrhenius plots of rotational correlation times, one or two crossover points were defined. The crossover point at the lower temperature, Tn′, is considered to be the temperature at which the full rotation of a piperidine ring in the spin probes occurs, and that at the higher temperature, Tn, is presumed to be the temperature at which the rotational motion of the whole probe molecule becomes coupled with translational diffusion. For SPVI only, could Tn′ not be observed. The variation of the rotational behavior in the spin probes is due to the way in which hydrogen bonds form between their functional groups and the nylon chains. Such a variation was also found in the activation energies for rotation. The activation energy for rotation in the temperature region between Tn′ and Tn was greatly dependent on the structure of the spin probe.

Photoredox Properties of Viologen Linked Porphyrins

Abstract Viologen linked water-soluble porphyrins (ZnP(CnV)4) with different methylene chain lengths (n=2–5) between porphyrin and viologen were synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH–ZnP(CnV)4–hydrogenase under steady state irradiation.

Magnetic field effects on the fluorescence of intramolecular electron-donor-acceptor systems

The external magnetic field effects on the exciplex fluorescence of α-(4-dimethylaminophenyl)-ω-(9-phenanthryl)alkanes have been studied by photostationary, time-resolved, and magnetic field modulation fluorescence spectroscopy. The singlet-triplet degeneracy of the radical ion pair is suggested to occur at a methylene chain length of about ten.

Photoinduced Hydrogen Evolution with Viologen Linked Porphyrin in a Micellar System

Abstract Viologen linked porphyrins, ZnP(CnV)4, with various methylene chain lengths (n=2–5) between the porphyrin and the viologen have been synthesized. These compounds were applied to photoinduced hydrogen evolution in a system containing NADPH–ZnP(CnV)4–hydrogenase under steady state irradiation. On the addition of surfactant to the system, a remarkable rate increase of hydrogen evolution was observed in the case of ZnP(C5V)4.

Characterization of 1- O-alkyl-2-acetyl- sn-glycero-3-phosphocholine (AGEPC)-induced protein phosphorylation in rabbit platelets: Inhibitory effects of AGEPC analogs

1- O-Alkyl-2-acetyl- sn-glycero-3-phosphocholine (AGEPC) induced phosphorylation of two proteins having molecular masses of approximately 20- and 40-kDa in washed rabbit platelets in a concentration- and time-dependent manner. Sequential stimulation with AGEPC did not induce additional protein phosphorylation, supporting the concept of desensitization of the AGEPC receptors responsible for biological activity. AGEPC analogs 1- O-octadecyl-2-acetyl- sn-glycero-3-phosphoric acid-6′-trimethylammonium hexyl ester and 1- O-octadecyl-2-acetyl- sn-glycero-3-phosphoric acid-10′-trimethylammonium decyl ester (U66985 and U66982), containing polar head groups with methylene chain lengths of C6 and C10, did not cause protein phosphorylation, but they did inhibit the AGEPC-induced events. Thus protein phosphorylation is closely associated with the receptor-mediated stimulation of platelets and is a useful indicator of the signaling process initiated through the receptors. Other synthetic analogs of AGEPC such as rac-3-( N-n-octadecylcarbamoyloxy)-2-methoxypropyl 2-thiazolioethyl phosphate and 1-( N-n-pentadecylcarbamoyloxy)-2-methoxy- rac-glycero-3-phosphocholine (CV3988 and U68043) were also shown to be inhibitors of the AGEPC-induced protein phosphorylation. Inhibition by these analogs was specific for AGEPC since there was no observed effect of thrombin, ADP, 12- O-tetradecanoyl-phorbol 13-acetate (TPA) and arachidonic acid-induced changes. The extent of inhibition was dependent on the concentration of AGEPC and its analogs and did not change with time after the addition of AGEPC. In platelets incubated with AGEPC analogs before and simultaneously with the addition of AGEPC, protein phosphorylation was prevented; however, addition of AGEPC to platelets shortly before the addition of these analogs showed a high response. In experiments where platelets were previously incubated with AGEPC analogs and washed with buffer containing 0.5% bovine serum albumin, AGEPC-induced protein phosphorylation was recovered to a level of 80%. These observations support the conclusion that AGEPC stimulates platelets through its specific receptor, and that the AGEPC analogs bind to the AGEPC receptor and block that pathway sensitive to AGEPC stimulation but not because of the desensitization of its receptor. On the other hand, in platelets where phosphorylation of the 40-kDa protein was induced by a 2-min preincubation with 3 × 10 −10 M TPA, 5 × 10 −10 M AGEPC-induced serotonin release decreased by 51% compared to a control value. But the IC 50 value for U66985 (2 × 10 −8 M) with 5 × 10 −10 M AGEPC then was not affected by the pretreatment with TPA prior to the addition of U66985. These observations showed that the activation of protein kinase C pathway suppressed the AGEPC-induced secretion reaction but did not affect the mode of inhibitory action by the antagonists.

Cycloadditions in syntheses. Part XXIX Novel annelation method to pyridine and isoquinoline by photochemical means.

Intramolecular photoaddition reactions of 2-(ω-alkenyl)isoquinolin-1(2H)-ones and 1-(ω-alkenyl)pyridin-2(1H)-ones were examined, and the regioselectivity and dependence of these reactions on the length of methylene chain in the alkenyl group were clarified. By utilizing these reactions, a synthetic route to indolizine and quinolizine derivatives was elaborated. By an extension of this approach to the intermolecular reaction, 6-methoxy-3-methyl-1, 2-dihydrocyclobuta[b]pyridin-4(3H)-one was synthesized from 4, 6-dimethoxy-1-methylpyridin-2(1H)-one.

Flexible methylene chain length in crosslinked networks as a measure of the brittleness of γ-irradiated low density polyethylene sheet

Low density polyethylene (LDPE) sheets, untreated and pre-crosslinked by thermal reaction with dicumyl peroxide (DCP) in the molten state, have been γ-irradiated with doses up to 200 Mrad at room temperature in air. The elongation at break ( γ B ) of both materials was decreased by the irradiation. The radiation resistance of pre-crosslinked LDPE, as measured by the characteristic dose which leads to a 50% decrease in γ B , ( D 1 2 = 110 Mrad ) was 2·6 times greater than that of untreated LDPE ( D 1 2 = 42 Mrad ). The gel fraction (f g ) of untreated LDPE was increased by the irradiation, while that of pre-crosslinked LDPE with an initial f g value of 0·803 showed negligible change. The density (d p ) of both LDPEs increased and the weight swelling ratio (S w ) of the polymer network decreased with increasing radiation dose. The changes in these quantities for untreated LDPE were more rapid than for pre-crosslinked LDPE. The γ B value was universally correlated with both the d p and S w values, whether the samples were of untreated or pre-crosslinked LDPE. Characteristic values of d p and S w associated with a 50% decrease of residual γ B value for both LDPEs were obtained as 0·924 g/cm 3 and 4·3, respectively. The molar concentration of crosslinks (Φ) in the irradiated LDPE sheets was evaluated from the S w value by the use of Flory's theory. The flexible methylene chain length between two crosslink points, derived from the Φ value, was shown to be a universal molecular measure of the brittleness of irradiated LDPE sheets.

Formation of Molecular Membranes in Water from Ionene Oligomers and Related Amphiphiles

Ionenes were prepared by reaction of α,ω-dibromoalkanes and α,ω-bis(dimethylamino)alkanes at room temperature. The degree of polymerization as estimated from NMR data was 2 to 5. The oligomeric ammonium amphiphiles (ionenes) thus obtained gave molecular weights of 105 to 108 in water. Vesicles of the molecular membrane were formed by self-assembly of the C20 ionene. A related bis-ammonium amphiphile gave similar results. The introduction of symmetrical aromatic rings into the middle of the C20 chain did not change the general aggregation behavior. Differential scanning calorimetry indicated the presence of gel-to-liquid crystal phase transition in these cases. No membrane formation was observed when the methylene chain length was shorter (C10 and C12) or the two methylene portions were uneven in length (C20 and C16).

Molecular Design of Crown Ethers. 3. Extraction of Alkaline Earth and Heavy Metal Picrates with 14- to 17-Crown-5 and 17- to 22-Crown-6

Abstract The solvent extraction of alkaline earth and heavy metal picrates with a series of ring-contracted and ring-enlarged crown ethers has been carried out in order to reveal the effects of methylene-chain length upon cation-binding ability. Compared with the parent 3m-crown-m, the ring-contracted crown ethers and their sila analogues possess limited extractabilities, often as low as those for the corresponding glymes. On the other hand, the ring-enlarged crown ethers, in general, show gradual, but not drastic, decreases in extractability for most cations with increasing methylene-chain length. Interestingly, the extractabilities for Ag+, Tl+, and Ba2+ do not decrease monotonously with ring expansion; in particular 16-crown-5 is a better extractant for Ag+ than 15-crown-5 and even than 18-crown-6. These results are accounted for in terms of cavity size, conformation, and molecular symmetry of crown ethers. Effects of cation hydration upon extractability and the limitations of solvent extraction technique are also discussed.

Molecular design of crown ethers. 1. Effects of methylene chain length: 15- to 17-crown-5 and 18- to 22-crown-6

Synthese des ethers crown et evaluation de leur aptitude a former des cations par extraction par solvant des picrates alcalins aqueux. La stabilite des complexes cation-ether crown est gouvernee par la variation d'enthalpie

The effect of methylene chain length on the chromatographic behaviour of aminobonded silicas in high-performance thin layer chromatography

High-performance thin layer chromatography has been carried out on 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-γ-aminopropyltrimethoxysilane or trimethoxysilylpropyldiethylenetriamine-treated thin layer plates, the chromatographic properties of the amino-modified plates depends largely on the amino-methylene (alkylamino) chain length bonded to the surface of the silica gel.

Long‐chain phenols: XX. Synthesis of oxidative degradation products from the methylated component phenols ofAnacardium occidentale and other phenolic lipids: Confirmation of the structure of the parent phenols and of a related material

AbstractA general procedure for the determination of the first double bond position in the side‐chain of a phenolic lipid has been investigated and, in the first place, the phenols of natural cashew nut‐shell liquid (Anacardium occidentale) have been examined. An improved oxidative degradation procedure has been applied consisting of methylation by the phase transfer procedure, hydroxylation with performic acid and oxidation of the mixture of vicinal diols with periodic acid (Malaprade reaction) followed by reduction of the aldehyde fragments with sodium borohydride. The aromatic moieties from the 15∶1, 15∶2 and 15∶3 constituents of cardanol methyl ether, cardol dimethyl ether and dimethyl anacardate were shown to be 8‐(3‐methoxyphenyl)octan‐1‐ol, 8‐(3,5‐dimethoxyphenyl)octan‐1‐ol and 6‐(8‐hydroxyocyl)salicylate methyl ether, respectively. The first two octanols were identical to synthetic materials, thus confirming the 8‐position for the first double bond in the side‐chain of cardanol methyl ether and cardol dimethyl ether constituents. Methyl 6‐(8‐hydroxyoctyl)salicylate relationship in a series of synthetic reference materials of log (retention time) to the methylene chain length. The synthetic acids 8‐(3‐methoxyphenyl)octanoic acid, 8‐(3,5‐dimethoxyphenyl)octanoic acid and 6‐(7‐carboxyheptyl)salicylic acid methyl ether have been obtained pure for the first time and correspond to the oxidation products of the aromatic aldehyde fragments from the Malaprade reaction stage. The unsaturation in peladjauol, 17∶1‐bishomocardanol methyl ether, fromPentaspadon officinalis was confirmed to be at the 8‐position by the identity of the anilides of synthetic 8‐(3‐methoxyphenyl) octanoic acid and of the oxidative degradation product.

Bis-quaternary ammonium blockers as structural probes of the sarcoplasmic reticulum K+ channel.

A series of n-alkyl-bis-alpha,omega-trimethylammonium (bisQn) compounds was synthesized, and their ability to block K+ currents through a K+ channel from sarcoplasmic reticulum was studied. K+ channels were inserted into planar phospholipid membranes, and single-channel K+ currents were measured in the presence of the blocking cations. These bisQn compounds block K+ currents only from the side of the membrane opposite to the addition of SR vesicles (the trans side). The block is dependent on transmembrane voltage, and the effective valence of the block (a measure of this voltage dependence) varies with the methylene chain length. For short chains (bisQ2-bisQ5), the effective valence decreases with chain length from 1.1 to 0.65; it then remains constant at approximately 0.65 for bisQ5 to bisQ8; the effective valence abruptly increases to 1.2-1.3 for chains of nine carbons and longer. For the compounds of nine carbons and longer, the discrete nature of the block can be observed directly as 'flickering noise" on the open channel. The kinetics of the block were studied for these long-chain blockers. Both blocking and unblocking rates of the blockers vary with chain length, with the blocking rate showing the strongest variation--an increase of 2.8-fold per added methylene group. All of the voltage dependence of the binding equilibrium resides in the blocking rate, and none in the unblocking rate. The results imply that 65% of the voltage drop within the channel occurs over a distance of 6-7A, and that the short-chain blockers bind in a bent-over conformation with both charges deeply inside the channel.

Thermomechanical analysis of linear aromatic polyesters

AbstractThe thermomechanical properties of linear aromatic polyesters, studied using thermomechanical analysis techniques, have been related to the chemical structure and methylene chain length. An increase in the number of methylene groups, the use of an asymmetric diacid, or random copolymerization of the repeating units of these polyesters, resulted in a lower linear thermal expansion coefficient α, a lower Vicat softening temperature Ts, a lower heat deflection temperature Td, and a lower glass transition temperature Tg. With longer methylene sequence lengths, the influence of the methylene groups on the thermomechanical properties is predominant, the data are closer together. The values are generally highest for the terephthalate series and lowest for the copolymer series. Glass transition temperatures calculated from group contributions and measured experimentally agreed. The deflection temperatures approximated the glass transition temperatures and the Vicat softening points the melting temperatures.

Picosecond Laser Spectroscopy of Intramolecular Heteroexcimer Systems. Time-resolved Fluorescence Studies of p-(CH3)2NC6H4–(CH2)n–(9-Anthryl), p-(CH3)2NC6H4–(1-Pyrenyl) Systems and 9,9′-Bianthryl

Abstract In order to elucidate the details of elementary processes of photochemical charge transfer and heteroexcimer formation processes, and also in order to compare the obtained results with those of transient absorption spectral measurements, we have examined the following intramolecular heteroexcimer systems by means of ps time-resolved fluorescence measurements with a mode-locked Nd3+: YAG laser and a streak camera: p-(CH3)2–NC6H4–(CH2)n–(9-anthryl) (n=0, 1, 2, 3), p-(CH3)2NC6H4–(CH2)n-(1-pyrenyl) (n=1, 2, 3) and 9,9′-bianthryl. Effects of methylene chain length, solvent polarity and viscosity upon the intramolecular charge transfer processes have been clearly demonstrated. It is concluded that molecules with sandwich configuration in the ground state are not recognized in both n=3 compounds, and it takes a few ns for the heteroexcimer formation in hexane because of an extensive conformation change necessary to take sandwich configuration. Both conformation change and solvent reorientation are involved in the heteroexcimer formation processes in polar solvents, and heteroexcimer formation becomes faster with increase of solvent polarity and decrease of its viscosity. Moreover, two step conformation changes are observed in the case of the heteroexcimer formation of n=3 compounds in polar solvents, i.e. a heteroexcimer with loose structure is formed first, and then follows a structural change to the one of sandwich type. In acetonitrile, a strongly polar solvent, formation of heteroexcimer is very fast, occurring within the time-resolution of the picosecond apparatus.

ChemInform Abstract: THE STEREOCHEMISTRY OF OXOVANADIUM(IV) COMPLEXES DERIVED FROM SALICYLALDEHYDE AND POLYMETHYLENEDIAMINES

AbstractDie Strukturen der nach bekannter Methode oder durch äquimolare Umsetzung von Vanadyl(IV)‐sulfatdihydrat mit den Liganden in Gegenwart überschüssigen Triethylamins dargestellten Vanadyl‐Komplexe (I) werden anhand von IR‐ und elektronenspektroskopischen sowie magnetischen Daten diskutiert.