Tetra Ethylene Glycol Derivative Research Articles

Reversible end-to-end assembly of selectively functionalized gold nanorods by light-responsive arylazopyrazole-cyclodextrin interaction.

We propose a two-step ligand exchange for the selective end-functionalization of gold nanorods (AuNR) by thiolated cyclodextrin (CD) host molecules. As a result of the complete removal of the precursor capping agent cetyltrimethylammonium bromide (CTAB) by a tetraethylene glycol derivative, competitive binding to the host cavity was prevented, and reversible, light-responsive assembly and disassembly of the AuNR could be induced by host–guest interaction of CD on the nanorods and a photoswitchable arylazopyrazole cross-linker in aqueous solution. The end-to-end assembly of AuNR could be effectively controlled by irradiation with UV and visible light, respectively, over four cycles. By the introduction of AAP, previous disassembly limitations based on the photostationary states of azobenzenes could be solved. The combination photoresponsive interaction and selectively end-functionalized nanoparticles shows significant potential in the reversible self-assembly of inorganic–organic hybrid nanomaterials.

Low-cost tetra ethylene glycol derivatives in polymer blend electrolytes for dye-sensitized solar cells with high photovoltaic conversion efficiencies

The present study reports on a novel polymer blend electrolyte system comprised of poly(ethylene oxide), poly(vinylidene fluoride) and poly (methyl methacrylate) (PEO/PVdF/PMMA) with potassium iodide, iodine and novel and cost effective organic compounds such as 1-(2-(2-(2-(2-(benzoate)ethoxy)ethoxy)ethoxy)ethoxy) benzene (BEB) and 1-(2-(2-(2-(2-(1H-pyrazol-1-yl)ethoxy)ethoxy)ethoxy)ethyl)-1H-pyrazole (PEP) for dye-sensitized solar cell applications. The influence of the synthesized organic compounds on the ionic and photovoltaic characteristics of the electrolytes was studied. In specific, the PEO/PVdF/PMMA/KI/I2/PEP blend electrolyte exhibited high ionic conductivity of 6.3 × 10−4 S cm−1 and the corresponding DSSC demonstrated an enhanced conversion efficiency of 9%. The high photovoltaic conversion efficiency of the cell with the PEP-doped system can be attributed to the higher conductivities in the polymer electrolyte associated with the greater cross-linking and the increased I−/I3− transportation along the interaction of the tetra ethylene glycol derivative, salt and the polymer matrix.

Thermoresponsive Self-assembly and Conformational Changes of Amphiphilic Monodisperse Short Poly(ethylene glycol)s in Water

Abstract Physicochemical and supramolecular properties of monodisperse amphiphilic short poly(ethylene glycol)s (PEGs) bearing a phenyl group at the one end are studied to investigate the effects of substitution and length of the PEG unit on these properties. It was found that the aromatic substitution encourages these molecules to adopt gauche conformation at the neighboring ethylene units of PEGs and that the octaethylene glycol derivative revealed more PEG-like thermal response of aggregation than the tetraethylene glycol derivative.

ChemInform Abstract: Cyclic Di[(o-polyethyleneglycoxy)phenyl]amine: New Members in the Crown Ether Family.

Abstract The synthesis of cyclic ethers based on polyethyleneglycol chains grafted on di(o-hydroxyphenyl)amine is described. The starting diarylamine is obtained from a melted salt procedure and coupled to the tosylated tri-, tetra- and pentaethyleneglycol. The X-ray crystal structure of the tetraethyleneglycol derivative was determined. For the triethyleneglycol compound, alkylation of the nitrogen atom with 5-bromomethyl-5′-methyl-2,2′-bipyridine (excess or 1 equiv.) led either to the quaternary ammonium salt or to the tertiary amine derivatives, respectively. The latter reacted with [Re(CO)5Cl] to give the corresponding Re(I) complex in a facial configuration.

Synthesis and complexation characteristics of phenanthroline and bipyridine diols

Neocuproine (2,9-dimethyl-1,10-phenanthroline) 1 was converted to achiral and chiral tetradentate phenanthroline diols 3a-c by addition to benzophenone, adamantanone and camphor, respectively. Analogously 6,6'-dimethyl-2,2'-bipyridine 2 was converted to diol 7a on base- induced addition to benzophenone. Reactions with benzophenone and adamantanone proceeded smoothly although small amounts of mono adducts were also formed. Functionalization of 1 with (R)-camphor failed under the standard conditions. However, conversion of the lithio derivative 5 to the cerium chloride derivative 6 and subsequent reaction with (R)-camphor led to the phenanthroline diol 3c. Complexes of the diols 3 and 7 with zinc and copper were prepared. X- ray analysis of the zinc complex 20 of diol 7a revealed a five coordinate zinc ion that is firmly embedded in the ligand. X-ray analysis of the Cu(acac)2 complex 21 of diol 7a unexpectedly revealed this to be an acetate bridged di-copper species. This copper complex forms on recrystallization from ethyl acetate. The initial acac-complex apparently hydrolyses the ethyl acetate to provide the bridging acetate found in the di-copper complex 21. From 4,7-dichloro- 2,9-dimethyl-1,10-phenanthroline 13 a doubly armed derivative 18 was prepared by substitution with two tetraethylene glycol arms followed by suitable derivatisation. A bridged derivative 19 was prepared by ring closure with an amine of the ditosylated tetraethylene glycol derivative. Attempts to prepare copper complexes of 18 and 19 were inconclusive.

Silicon-modified surfactants and wetting: V. The spreading behaviour of trimethylsilane surfactants on energetically different solid surfaces

The spreading behaviour of defined trimethylsilane-based surfactants of general formula (CH3)3Si(CH2)6(OCH2CH2)nOCH3, n = 2–6, on five different solid surfaces at 21 °C has been investigated. Compounds bearing short diethylene and triethylene glycol hydrophiles do not spread. For the longer-chained tetraethylene to hexaethylene glycol derivatives, the ability to spread depends on the surface energy. Rapid spreading is restricted to the slightly polar surface of 40 mN m−1 surface energy. Lower or higher surface energies considerably reduce the spreading rates. The phase behaviour of the solutions substantially influences the spreading process. The dispersed systems of the tetraethylene glycol derivative spread constantly over long time intervals. The dispersions of the pentaethylene glycol analogue are very close to the temperature for a transition into the one-phase state. A retardation of the spreading process occurs after a few seconds. Micellar solutions of the hexaethylene glycol derivative either spread very slowly or stop spreading after a few seconds. The largest spreading areas and highest initial spreading rates were found for the 0.1 wt% solutions. Copyright © 1999 John Wiley & Sons, Ltd.

Silicon‐modified surfactants and wetting: II. Temperature‐dependent spreading behaviour of oligoethylene glycol derivatives of heptamethyltrisiloxane

The temperature-dependent spreading performance of defined trisiloxane surfactants of the general formula [(CH3)3SiO]2CH3Si-­(CH2)3(OCH2CH2)3–9OCH3 and Silwet L77 on a trimethylsilylated silicon-wafer surface has been investigated. At 6 °C the tetraethylene glycol derivative showed the highest initial spreading rate. At 40 °C the octaethylene glycol derivative was the fastest spreader. It is shown that spreading behaviour and phase behaviour are closely related. The highest initial spreading rates were found for solutions in the two-phase state (2Φ) closely above the liquid–liquid insolubility boundary. Copyright © 1999 John Wiley & Sons, Ltd.

Silicon-modified surfactants and wetting: II. Temperature-dependent spreading behaviour of oligoethylene glycol derivatives of heptamethyltrisiloxane

The temperature-dependent spreading performance of defined trisiloxane surfactants of the general formula [(CH3)3SiO]2CH3Si-­(CH2)3(OCH2CH2)3–9OCH3 and Silwet L77 on a trimethylsilylated silicon-wafer surface has been investigated. At 6 °C the tetraethylene glycol derivative showed the highest initial spreading rate. At 40 °C the octaethylene glycol derivative was the fastest spreader. It is shown that spreading behaviour and phase behaviour are closely related. The highest initial spreading rates were found for solutions in the two-phase state (2Φ) closely above the liquid–liquid insolubility boundary. Copyright © 1999 John Wiley & Sons, Ltd.

Synthesis of a propargyl alcohol having a C 60 cage, its transformation into C 60 derivatives with polar functional groups, and the solubility measurements

The reactions of fullerene C 60 with lithium acetylide derived from silylated propargyl alcohol and quenching either with trifluoroacetic acid or iodomethane afforded the corresponding adduct at the 6-6 bond of C 60, i. e., the 1-(3-siloxy-1-propynyl)-1,2-dihydro[60]fullerene ( 3) or the 1-(3-siloxy-1-propynyl)-2-methyl-1,2-dihydro[60]fullerene ( 4), both in 56% yield. In order to obtain C 60 derivatives having solubility in water or in other polar organic solvents, the propargyl alcohol derived from 4 was allowed to react with succinic anhydride and with diglycolic anhydride to give the corresponding carboxylic acids 6 and 7 having ester groups. In the same manner, the reaction of C 60 with tetraethylene glycol derivative of propargyl alcohol afforded the corresponding tetraethylene glycol monoether derivative of C 60 ( 10). The solubility of the newly obtained C 60 derivatives in common organic solvents and in aqueous organic solvents was determined.

Complexation of acyclic ligands having two terminal quinoline units with alkali metal cations

Abstract Acyclic multidentate ligands consisting of an oligooxyethylene chain (di-, tri-, tetra-, and penta-) and two terminal rigid quinaldate end groups were newly prepared and their complexation properties with alkali metal cations were estimated by the solvent extraction method to indicate a better affinity for K+. Among them, the tetraethylene glycol derivative showed the highest K+ binding on about the same level as 18-crown-6. Their conformations in solution and in the solid state were examined by using 1H- and 13C-NMR spectroscopy and X-ray crystal analyses, respectively. The better binding of K+ in comparison with the corresponding glymes or analogues having the same donor sites was reasonably explained by considering the effective co-ordination of the carbonyl oxygen of the ester groups and the parallel π-stacking interaction between two quinaldate surfaces.