Effect Of Methylene Chain Length Research Articles

Amidoamine Oxide Surfactants as Low-Molecular-Weight Hydrogelators: Effect of Methylene Chain Length on Aggregate Structure and Rheological Behavior.

Rheology control is an important issue in many industrial products such as cosmetics and paints. Recently, low-molecular-weight compounds have attracted considerable attention as thickeners/gelators for various solvents; however, there is still a significant need for molecular design guidelines for industrial applications. Amidoamine oxides (AAOs), which are long-chain alkylamine oxides with three amide groups, are surfactants that act as hydrogelators. Here, we show the relationship between the length of methylene chains at four different locations of AAOs, the aggregate structure, the gelation temperature Tgel, and the viscoelasticity of the formed hydrogels. As seen from the results of electron microscopic observations, the aggregate structure (ribbon-like or rod-like) can be controlled by changing the length of methylene chain in the hydrophobic part, the length of methylene chain between the amide and amine oxide groups, and the lengths of methylene chains between amide groups. Furthermore, hydrogels consisting of rod-like aggregates showed significantly higher viscoelasticity than those consisting of ribbon-like aggregates. In other words, it was shown that the gel viscoelasticity could be controlled by changing the methylene chain lengths at four different locations of the AAO.

Effect of Methylene Chain Length on the Thermodynamic Properties, Ferroelastic Properties, and Molecular Dynamics of the Perovskite-type Layer Crystal [NH3(CH2) n NH3]MnCl4 (n = 2, 3, and 4).

The structures and phase transitions of [NH3(CH2)nNH3]MnCl4 (n = 2, 3, and 4) crystals were confirmed through X-ray diffraction and differential scanning calorimetry (DSC) experiments. Thermodynamic properties, ferroelastic properties, and molecular dynamics of three crystals were studied as a function of the number (n) of CH2 groups in the alkylene chains. The loss in molecular weight due to a decrease in n marked the onset of the partial thermal decomposition. The thermal decomposition temperature, Td, increased with increasing length of the CH2 chain. While the ferroelastic twin domain walls for n = 2 and 4 were in the same direction at all temperatures, the domain walls for n = 3 were rotated by 45°, and the direction of extinction in phase II was rotated by 45° with respect to phases I and III. The 1H and 13C MAS NMR spectra of the three crystals were recorded as a function of temperature. With increasing length of the CH2 chain, the 1H spin relaxation time decreased, indicating that molecular motions were activated. These results provide insights into the thermodynamic properties and structural dynamics of the [NH3(CH2)nNH3]MnCl4 crystals and are expected to facilitate their potential applications.

Effect of methylene chain length of perovskite-type layered [NH3(CH2) n NH3]ZnCl4 (n = 2, 3, and 4) crystals on thermodynamic properties, structural geometry, and molecular dynamics.

The structure of organic–inorganic perovskite [NH3(CH2)4NH3]ZnCl4 was determined; the lattice constants with monoclinic structure were determined to be a = 7.2527 Å, b = 8.1101 Å, c = 10.3842 Å, and β = 80.3436°. The crystal was almost thermally stable up to approximately 560 K. The endothermic peaks at 481 K and 506 K were assigned to the phase transition of the material. In addition, the structural characteristics and molecular dynamics of the cation were studied via magic angle spinning nuclear magnetic resonance experiments. Based on the results, the effects of the length of the CH2 group in the cation of the [NH3(CH2)nNH3]ZnCl4 (n = 2, 3, and 4) crystals were considered. Regardless of whether n was even or odd, the differences in the thermal and physical properties were minimal. Moreover, a difference in molecular motion relative to the length of the cation was observed only at high temperatures. These results provide useful information about the thermal stability and molecular dynamics of [NH3(CH2)nNH3]ZnCl4 crystals and are expected to facilitate potential applications of such compounds in supercapacitors, batteries, and fuel cells.

Structural Diversity of Mn(II) Complexes with Acetylene Dicarboxylate and Hexadentate Ancillary Ligands under Ambient Conditions: Effect of Methylene Chain Length on Coordination Architectures

For Mn(II)-adc (adc = acetylene dicarboxylate) chemistry, diversity of product formation is demonstrated with five similar hexadentate polypyridyl ancillary ligands differing in methylene chain lengths between the alkyl nitrogens, such as tpen (N,N,N′,N′-tetrakis-(2-pyridylmethyl)-1,2-diaminoethane), 1,2-tppn (N,N,N′,N′-tetrakis-(2-pyridylmethyl)-1,2-diaminopropane), tppn (N,N,N′,N′-tetrakis-(2-pyridylmethyl)-1,3-diaminopropane), tpbn (N,N′,N″,N‴-tetrakis-(2-pyridylmethyl)-1,4-diaminobutane), and tppen (N,N′,N″,N‴-tetrakis-(2-pyridylmethyl)-1,5-diaminopentane). Five new compounds, [Mn2(adc)2(tpbn)(H2O)2]·2(solvent)}n (solvent = H2O, 1a; solvent = CH3OH, 1b), [Mn2(tppn)(H2O)6](adc)2·3H2O (2), [Mn2(adc)(1,2-tppn)2](ClO4)2·2(solvent) (solvent = H2O, 3a; solvent = CH3CN, 3b), [Mn2(adc)(tpen)2](ClO4)2·2(solvent) (solvent = H2O, 4a; solvent = CH3CN, 4b), and {[Mn2(adc)(tppen)(H2O)4](adc)·4H2O}n (5), have been isolated in good yields from the self-assembly reactions of raw materials at ambient conditions and str...

A ‘magic bridge’: effect of methylene chain length on the photochemistry of radical cations produced from bifunctional X–(CH 2) n–Y molecules

The radical cations of aminoamides Me 2 N(CH 2 ) n C(O)NMe 2 and aminoethers Me 2 N(CH 2 ) n OMe reveal selective photoinduced intramolecular H transfer from methylene bridge at a specific chain length ( n = 3).

Click Polyester: Synthesis of Polyesters Containing Triazole Units in the Main Chain by Click Chemistry and Improved Thermal Property

A "click" polymerization of dialkynes that contain an ester linkages and diazides to has been performed to synthesize various polyesters, termed "click polyesters" with a high $\overline M _{\rm n}$ of 1.0 × 10(4) to 7.0 × 10(4) in an excellent yield. This polymerization accompanied a formation of 1,4-disubstituted triazoles in the polyester main chain by a Cu(I) catalyst. The triazole ring formation in the polyester main chain leads to improved thermal properties and enhancement of the even-odd effect of methylene chain length of the produced click polyesters. This report is the first report of the application of click chemistry to synthesize a series of polyesters under mild conditions.

Effects of amines on the polymerization of isoprene withsec-butyllithium catalyst

Polymerization of isoprene (IP) with alkyllithium (RLi) catalysts in the presence of amines such as triethylamine (TEA), 1,2-dipiperidinoethane (DPPE) and N,N,N',N'-tetramethyldiaminoalkanes [(CH 3 ) 2 N(CH 2 ) n N(CH 3 ) 2 where n=1, 2, 3, 4 and 6 (TMDAA)] has been studied. By adding the amines, the polymerization rate of IP was accelerated, and the contents of 3,4- and 1,2-units in the resulting polymers increased. The effects of methylene chain length of the TMDAA on the polymerization were examined. It was found that both the polymerization rates and the microstructure of the polymers depend on the methylene length of the TMDAA. The amines having 2 and 3 methylenes in (CH 3 ) 2 N(CH 2 ) n N(CH 3 ) 2 favoured production of the polymer consisting of predominantly 1,2- and 3,4-units. It was proposed that two types of active sites for the polymerization of IP were produced depending on the number n of the TMDAA. Two types of active species were confirmed to be produced with sec-BuLi in the presence of N,N,N',N'-tetramethylethylenediamine (TMEDA) depending on the TMEDA/sec-BuLi mole ratios.

Effect of methylene chain length on electron transfer and photocurrent generation using viologen-linked porphyrin monolayer modified ITO electrode

The increase of the electron transfer yield from the photoexcited porphyrin to viologen was achieved by forming a Langmuir-Blodgett (LB) film of viologen-linked porphyrin. Four kinds of porphyrin covalently linked to viologen (BuPC n V: n = 3,4,5,8) by methylene chain, in which the center-to-center distance between porphyrin and viologen is less than 1.7 nm, were synthesized, and the molecularly oriented films of BuPC n V ( n = 3,4,5,8) were prepared on indium tin oxide (ITO) electrodes using an LB technique. The effect of methylene chain length both on the quenching of the fluorescence from porphyrin by viologen and on the photocurrent generation was investigated. The fluorescence quenching by viologen increased with the decrease of the methylene chain length, showing that the electron transfer from the photoexcited porphyrin to viologen is easy to take place when the distance between porphyrin and viologen is shorter. Furthermore, the fluorescence was quenched more efficiently by viologen in the LB film compared with a methanol solution, indicating that the fluorescence is quenched both by the bonded viologen and by the neighboring viologen in the LB film of BuPC n V ( n = 3,4,5). Under visible light irradiation, a cathodic photocurrent was generated, which increased with the decrease of the methylene chain length owing to the increase of the electron transfer yield from the photoexcitted porphyrin to viologen. The orientation of BuPC n V ( n = 3,4,5,8) molecules on the ITO electrode was investigated by the effect of bias voltage and dioxygen concentration on the photocurrent. It was shown that the porphyrin moieties are attached to the surface of the ITO electrode and that the photocurrent is ascribable to the photoinduced charge separation in the BuPC n V ( n = 3,4,5) molecules.

Effect of methylene chain length in phospholipid moiety on blood compatibility of phospholipid polymers.

To investigate the effects of the methylene chain length between the phospholipid polar group and the backbone on blood compatibility of a phospholipid polymer, copolymers of omega-methacryloyloxyalkyl phosphorylcholine (MAPC) with n-butyl methacrylate (BMA) were synthesized. The methylene chains were ethylene (n = 2), tetramethylene (n = 4), and hexamethylene (n = 6). Every MAPC copolymer with an MAPC mole fraction in the range of 0.1-0.3 was soluble in ethanol but only swelled in water, and the equilibrium water fraction of the water-swollen MAPC copolymer membrane decreased with the length of the methylene chain. When a rabbit platelet-rich plasma was applied on the MAPC copolymer surface with an 0.1 MAPC mol fraction for 180 min, the number of adhered platelets depended on the length of the methylene chain in the MAPC moiety of the copolymer. The amount of phospholipid adsorbed on the MAPC copolymer from human plasma was larger than that on hydrophobic poly(BMA) and increased with the length of the methylene chain in the MAPC moiety. That is, the reduction of platelet adhesion corresponded to the increase in the amount of phospholipid adsorbed on the MAPC copolymer.

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.

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.