Biomaterial Database

Neutron reflectivity study of alkylated azacrown ether at the air-liquid and the liquid-liquid interfaces. 2009

A Zarbakhsh, and J R P Webster, and K Wojciechowski

School of Biological & Chemical Sciences, Queen Mary, University of London, Walter Basent Building, Mile End Road, London E1 4NS, UK. a.zarbakhsh@qmul.ac.uk

We report the neutron reflectometry study of partially deuterated di-hexadecyl-diaza-18-crown-6 ether (d-ACE-16) at the air-water and the oil-water interfaces. At the air-water interface, the thickness of the monolayer is smaller than that for a fully stretched d-ACE-16 molecule, suggesting a tilt of the alkyl chains with respect to the normal. At the oil-water interface, the same molecules were found to form a more diffuse layer distribution stretching across both sides of the interface. On the oil side, the molecules are densely packed within a thickness of 17 A, the hydrophilic part of the molecule with the azacrown ether ring being immersed in the adjacent aqueous side of the interface. The latter consists of a thick 38 A layer comprising staggered, loosely adsorbed d-ACE-16 molecules. With increasing spread amount, the adsorbed layer density increases at the oil side until saturation at ca. 2.25 x 10(-6) mol m(-2), above which the layer collapses.

UI	MeSH Term	Description	Entries
D009821	Oils	Unctuous combustible substances that are liquid or easily liquefiable on warming, and are soluble in ether but insoluble in water. Such substances, depending on their origin, are classified as animal, mineral, or vegetable oils. Depending on their behavior on heating, they are volatile or fixed. (Dorland, 28th ed)
D003903	Deuterium	The stable isotope of hydrogen. It has one neutron and one proton in the nucleus.	Deuterons,Hydrogen-2,Hydrogen 2
D000327	Adsorption	The adhesion of gases, liquids, or dissolved solids onto a surface. It includes adsorptive phenomena of bacteria and viruses onto surfaces as well. ABSORPTION into the substance may follow but not necessarily.	Adsorptions
D000388	Air	The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.
D000478	Alkylation	The covalent bonding of an alkyl group to an organic compound. It can occur by a simple addition reaction or by substitution of another functional group.	Alkylations
D013499	Surface Properties	Characteristics or attributes of the outer boundaries of objects, including molecules.	Properties, Surface,Property, Surface,Surface Property
D014867	Water	A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Hydrogen Oxide
D043844	Crown Ethers	Macrocyclic polyethers with the repeating unit of (-CH2-CH2-O)n where n is greater than 2 and some oxygens may be replaced by nitrogen, sulfur or phosphorus. These compounds are useful for coordinating CATIONS. The nomenclature uses a prefix to indicate the size of the ring and a suffix for the number of heteroatoms.	Aza-Oxa Crown Ethers,Crown Ether,Cryptands,Cryptate,Cryptates,Oxa-Thia Crown Ethers,Aza Oxa Crown Ethers,Crown Ethers, Aza-Oxa,Crown Ethers, Oxa-Thia,Ether, Crown,Ethers, Aza-Oxa Crown,Ethers, Crown,Ethers, Oxa-Thia Crown,Oxa Thia Crown Ethers
D033363	Neutron Diffraction	The scattering of NEUTRONS by matter, especially crystals, with accompanying variation in intensity due to interference effects. It is useful in CRYSTALLOGRAPHY and POWDER DIFFRACTION.	Diffraction, Neutron,Diffractions, Neutron,Neutron Diffractions