- Nanoparticles with Near-Infrared Emission Enhanced by Pillararene-Based Molecular Recognition in Water
-
Here we report the unprecedented preparation of nanoparticles with near-infrared (NIR) emission enhanced by host-guest complexation between a water-soluble pillar[5]arene (WP5) and a cyanostilbene derivative (1) in water. Amphiphilic 1 self-assembles in water to form nanoribbons with relatively weak NIR emission at low concentrations. However, after addition of equimolar WP5, these nanoribbons transform into nanoparticles with stronger NIR emission due to the formation of a supramolecular amphiphile and host-guest complexation-enhanced aggregation. These nanoparticles show pH responsiveness, and collapse after treatment with acid. More importantly, these nanoparticles can be used in living cell imaging.
- Shi, Bingbing,Jie, Kecheng,Zhou, Yujuan,Zhou, Jiong,Xia, Danyu,Huang, Feihe
-
-
Read Online
- Odd-even effect and unusual behavior of dodecyl-substituted analogue observed in the crystal structure of alkyltrimethylammonium-[Ni(dmit) 2]- salts
-
A series of [Ni(dmit)2]- (dmit: 1,3-dithiole-2- thione-4,5-dithiolato) salts of alkyltrimethylammonium (Cn: n represents the alkyl chain length; n = 3 and 518) have been prepared and analyzed by X-ray structural analysis. All complex salts have been found to be composed of alternate sheets of [Ni(dmit)2]- anions and sheets of cations with a pronounced interdigitation of the alkyl chains. However, molecular arrangement differed between (C3)[Ni(dmit)2] and other (Cn)[Ni(dmit)2] (n = 518). Adjacent cations were aligned along the long axis of [Ni(dmit)2]- anion in C3 complex salt, while in others (C5-C18 complex salts), they were aligned toward the short axis. Such a difference in arrangement arose from correlativity between the lengths of the long axis of cation and anion, namely CLCA. Furthermore, relative orientation between the alkyl chain of cation and [Ni(dmit)2]- anion differed between the odd- and even-numbered cations for C10-C18. Whereas the plane of alkyl chain for odd-numbered cation was normal to the plane of [Ni(dmit)2]- anion, that of even-numbered cation was parallel. It was also found that C12 analog behaved like odd-numbered cations. However, in C12 salt, the end methyl group of the dodecyl group adopted unusual end-gauche conformation.
- Dai, Kotaro,Nomoto, Kuniharu,Ueno, Shinji,Tomono, Kazuaki,Miyamura, Kazuo
-
experimental part
p. 312 - 319
(2011/05/13)
-
- USE OF QUATERNARY AMMONIUM COMPOUNDS AS SPECIFIC BLOCKERS OF TRANSPORT THROUGH AQUAPORIN, COMPOSITIONS COMPRISING THE COMPOUNDS AND METHOD OF SELECTING THE COMPOUNDS
-
The present invention relates to the use of quaternary ammonium compounds for the preparation of a composition for specifically blocking transport through a particular type of aquaporin. The invention further relates to compositions comprising such quaternary ammonium compounds for use in various applications.
- -
-
Page/Page column 17-18
(2008/06/13)
-
- Effect of Cationic Surfactants on the Conformational Transition of Poly(methacrylic acid)
-
The interaction between poly(methacrylic acid) and alkyltrimethylammonium bromide, CnTAB, cationic surfactants has been investigated in aqueous solutions of pH 8, by use of the photophysics of pyrene and its derivatives.Photophysical studies of these fluorescent probes, both steady-state and pulsed laser studies, show that a conformational transition of PMA is induced by CnTAB.The surfactant induces a coiling up of PMA chains at pH 8, which takes place via a cooperative process.This effect takes places when the concentration of CnTAB is above a critical aggregate concentration, CAC.The CAC is 1 or 2 orders of magnitude less than the cmc of the corresponding micelle.There is a significant effect of surfactant chain length and PMA concentration on the CAC, which provides information on the nature of the CAC and the mechanism of the PMA transition.A model is suggested for the aggregation of PMA-C10TAB based on experimental data.Studies show that the aggregate consists of about 100 C10TAB molecules and 1 coiled polymer chain.
- Chu, Deh-ying,Thomas, J. K.
-
p. 6270 - 6276
(2007/10/02)
-
- Photoprocesses on Colloidal Clay Systems. 2. Quenching Studies and the Effect of Surfactants on the Luminescent Properties of Pyrene and Pyrene Derivatives Adsorbed on Clay Colloids
-
The cationic fluorescent probe trimethylammonium bromide (PN+) is adsorbed by the colloidal particles of the clay minerals montmorillonite and kaolin.The emission spectrum, polarization of fluorescence measurements, and transient fluorescence decay characteristics of PN+ are used to study the nature of its adsorbed state.Quaternary ammonium surfactants of varying hydrocarbon chain length cause a rearrangement of the PN+ molecules on the surface and decrease its interaction with the mineral surface.Quenching studies with nonionic andcationic molecules indicate that diffusion on the surface of montmorillonite is reduced below that observed in aqueous solution while the apparent rates obtained with kaolin particles are increased.Montmorillonite particles with a surfactant bilayer surrounding their surfaces are formed by the addition of an excess amount of surfactant to the colloid.The emission spectrum and the steady-state quenching studies yield information on the location of pyrene on these particles, as well as on the nature of the colloidal particles.
- DellaGuardia, R. A.,Thomas, J. K.
-
p. 3550 - 3557
(2007/10/02)
-
