10 research outputs found
Modified Synthesis and Supramolecular Polymerization of Rim-to-Rim Connected Bisresorcinarenes
The acid-catalyzed condensation reaction of resorcinol and bisdimethoxyacetals gave rise to rim-to-rim connected bisresorcinarenes in good yields. In the presence of ethanol, the homoditopic bisresorcinarenes assembled to form supramolecular polymers via hydrogen bonding interactions. The fibrous morphologies of the supramolecular polymers were confirmed by atomic force microscopy and scanning electron microscopy
Modified Synthesis and Supramolecular Polymerization of Rim-to-Rim Connected Bisresorcinarenes
The acid-catalyzed condensation reaction of resorcinol and bisdimethoxyacetals gave rise to rim-to-rim connected bisresorcinarenes in good yields. In the presence of ethanol, the homoditopic bisresorcinarenes assembled to form supramolecular polymers via hydrogen bonding interactions. The fibrous morphologies of the supramolecular polymers were confirmed by atomic force microscopy and scanning electron microscopy
Synthesis and Structure of Feet-to-Feet Connected Bisresorcinarenes
Bisresorcinarenes <b>1a</b>–<b>d</b> were obtained
in excellent yields, and <b>1e</b> was finally obtained in 50%
yield. X-ray diffraction analysis showed that <b>1a</b> and <b>1b</b> adopted helical conformations, whereas the two resorcinarenes
of <b>1c</b>–<b>e</b> were in parallel orientations
in which the clefts of the aliphatic chains entrapped one or two solvent
molecules. The conformational study revealed that the helix interconversion
between the (<i>P</i>)- and (<i>M</i>)-helical
conformers depended on the length of the aliphatic chains. <b>1a</b> had the largest energetic barrier to helix interconversion, while
in <b>1b</b>, its more flexible aliphatic chains lowered its
energetic barriers. The <i>P</i>/<i>M</i> interconversion
of <b>1a</b> was coupled with the clockwise/anticlockwise interconversion
of the interannular hydrogen bonding of the two resorcinarenes. The
large negative entropic contributions indicate that the transition
state is most likely more ordered than the ground states, suggesting
that the transition state is most likely symmetric and is solvated
by water molecules. Calculations at the M06-2<i>X</i>/6-31GÂ(d,p)
level revealed that the more stable (<i>P</i>)-conformation
has clockwise interannular hydrogen bonding between the two resorcinarenes
Cooperative Self-Assembly of Carbazole Derivatives Driven by Multiple Dipole–Dipole Interactions
Carbazole
possessing phenylisoxazoles self-assembled in a cooperative
manner in decalin. X-ray crystal structure analysis revealed that
the isoxazole dipoles align in a head-to-tail fashion. DFT calculations
suggested that the linear array of dipoles induced the polarization
of each dipole, leading to an increase in dipole–dipole interactions.
This dipole polarization resulted in cooperative assembly
Induced-Dipole-Directed, Cooperative Self-Assembly of a Benzotrithiophene
A benzotrithiophene derivative possessing
phenylisoxazoles self-assembled
to form stacks. The molecule isodesmically self-assembled in chloroform,
whereas it self-assembled in a cooperative fashion in decalin and
in methylcyclohexane. Thermodynamic studies based on isodesmic, van
der Schoot, and Goldstein–Stryer mathematical models revealed
that the self-assembly processes are enthalpically driven and entropically
opposed. An enthalpy–entropy compensation plot indicates that
the assembly processes in chloroform, decalin, and methylcyclohexane
are closely related. The enthalpic gains in less-polar solvents are
greater than those in more-polar solvents, resulting in the formation
of large assemblies in decalin and in methylcyclohexane. The formation
of large assemblies leads to cooperative assemblies. The elongation
process is enthalpically more favored than the nucleation process,
which drives the cooperativity of the self-assembly. DFT calculations
suggested that a hexameric assembly is more stable than tetrameric
or dimeric assemblies. Cooperative self-assemblies based on intermolecular
interactions other than hydrogen bonding have rarely been reported.
It is demonstrated herein that van der Waals interactions, including
induced dipole–dipole interactions, can drive the cooperative
assembly of planar π-conjugated molecules
Baseline characteristics of the study population.
<p><i>P</i> values were calculated with Student’s t-test* and Fisher’s exact test**. SS, severe sepsis/septic shock; ICU, intensive care unit; SOFA, sequential organ failure assessment; APACHE II, the acute physiology and chronic health evaluation; ICH, intracerebral hemorrhage; CI, cerebral infarction; CPAOA, cardiopulmonary arrest on arrival; SD, standard deviation.</p
IRGM(+313) mRNA expression of whole blood with LPS challenge in healthy volunteers.
<p><i>P</i> = 0.019 with Mann-Whitney U test ((CC+CT) v TT).</p><p>RQ, relative quantification; ΔRQ, (post-stimulation)-(pre-stimulation with LPS).</p
Tests of association between IRGM(+313) genotype and severe sepsis death in the combined cohort.
<p><i>P</i> values were calculated with correlation/trend test.</p
Comparison of mortality between different genotype categories for SNP at IRGM(+313) (rs10065172).
<p>(a) The discovery cohort (<i>P</i> = 0.043, recessive model of the correlation/trend test; TT v (CC+CT) in the 125 SS patients). (b) The multi-center validation cohort (<i>P</i> = 0.037, recessive model the correlation/trend test; TT v (CC+CT) in the 271 SS patients). (c) The combined cohort (<i>P</i> = 0.004, recessive model the correlation/trend test; TT v (CC+CT) in the 396 SS patients). SS, severe sepsis/septic shock.</p