6 research outputs found
NMR Spectroscopic Study of the Complexation Behaviors of Deuterated Cyclodextrins and [60]Fullerene
Cyclodextrins (CDxs) have been selectively deuterated using a Ru/C-catalyzed HāD exchange reaction in D<sub>2</sub>O. The structures of the deuterated CDxs barely changed and their <sup>1</sup>H NMR spectra became very simple, which made it possible for the deuterated CDxs to be applied to the analysis of CDx complexes. Furthermore, the deuterated CDxs allowed for the existence of the equilibrium between free and complexed CDx to be confirmed, even at rt
Synthesis and Properties of [7]Helicene-like Compounds Fused with a Fluorene Unit
[7]ĀHelicene-like
compounds with a fluorene unit were successfully
synthesized using a platinum-catalyzed double cyclization reaction.
Crystal structures and photophysical properties of these compounds
were also studied. In particular, they were found to exhibit a high
fluorescence quantum yield and a relatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminescence
(CPL) for small molecules
Time-Resolved Observation of Chiral-Index-Selective Wrapping on Single-Walled Carbon Nanotube with Non-Aromatic Polysilane
In the present paper, we ascertain two novel findings
on chiral-index-selective
binding/separating of single-walled carbon nanotubes (SWNTs) with
a nonaromatic polymer, polyĀ(dialkylsilane) (PSi). PSi is a typical
Ļ-conjugated polymer, composed of alkyl side chains attached
to the silicon (Si)-catenated main chain. First, PSiās with
linear alkyl side chains showed significant diameter-selective wrapping
for SWNTs with ca. 0.9 nm in diameter, resulting in the selective
separation of (7,6) and (9,4) SWNTs. Its driving force was demonstrated
to be cooperative CHāĻ interactions among the alkyl side
chains of PSiās and the curved graphene of SWNTs. Second, the
dynamic wrapping behavior of PSiās onto SWNTs was elucidated
with time-resolved UV spectroscopy. Highly anisotropic UV absorption
of PSi along the Si main chain was utilized as a āchromophoric
indicatorā to monitor the global/local conformations, which
enabled us to track kinetic structural changes of PSiās on
SWNTs. Consequently, we concluded that upon wrapping, flexible/helical
PSi with an average dihedral angle (Ļ) of 145Ā° and Kuhnās
segment length (Ī»<sup>ā1</sup>) of 2.6 nm interconverted
to the more stiffer/planar conformation with 170Ā° and Ī»<sup>ā1</sup> of 7.4 nm. Furthermore, through kinetic analyses
of the time-course UV spectra, we discovered the fact that PSiās
involve three distinct structural changes during wrapping. That is,
(i) the very fast adsorption of several segments within dead time
of mixing (<30 ms), following (ii) the gradual adsorption of loosely
wrapped segments with the half-maximum values (Ļ<sub>1</sub>) of 31.4 ms, and (iii) the slow rearrangement of the entire chains
with Ļ<sub>2</sub> of 123.1 ms, coupling with elongation of
the segment lengths. The present results may be useful for rational
design of polymers toward chiral-index-selective binding/separating
of desired (<i>n</i>,<i>m</i>) SWNTs
[70]Fullerenes Assist the Formation of Phospholipid Bicelles at Low Lipid Concentrations
The
incorporation of neutral [70]Āfullerenes (C<sub>70</sub>) led to bicelle
formation in a relatively low lipid concentration range from neutral
lipid mixtures (DMPC/DHPC). Furthermore, C<sub>70</sub> addition resulted
in the formation of large bicelles with a radius of ca. 100 nm, in
contrast to C<sub>70</sub>-free bicelles that were formed from anionic
lipid mixtures (DMPC/DHPC/DMPG). The stabilization of these bicelles
was attributed to C<sub>70</sub> incorporation into the membranes
Facile Synthetic Route to Highly Luminescent Sila[7]helicene
A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules
Facile Synthetic Route to Highly Luminescent Sila[7]helicene
A facile synthetic route to dimethylsila[7]helicene by using a Lewis acid catalyzed double-cyclization reaction for construction of the twisted two phenanthrene moieties is described. Sila[7]helicene exhibited a high fluorescence quantum yield and a realatively large <i>g</i> value (dissymmetric factor) of circularly polarized luminencence (CPL) for small molecules