Five new compounds, based on diketopyrrolopyrrole (DPP) and phenylene thiophene (PT) moieties, were synthesized to investigate the effect of structural variations on solid state properties, such as single-crystal structures, optical absorption, energy levels, thermal phase transitions, film morphology, and hole mobility. The molecular structures were modified by means of (i) backbone length by changing the number of thiophenes on both sides of DPP, (ii) alkyl substitution (n-hexyl or ethylhexyl) on DPP, and (iii) the presence of an n-hexyl group at the end of the molecular backbone. These DPP-based oligophenylenethiophenes were systematically characterized by UV−visible spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), cyclic voltammetry (CV), ultraviolet photoelectron spectroscopy (UPS), atomic force microscopy (AFM), and hole-only diodes. Single-crystal structures were provided to probe insight into structure−property relationships at a molecule level resolution. This work demonstrates the significance of alkyl substitution as well as backbone length in tuning material's solid-state properties.
Geometry-relaxed ab initio calculations of acetic anhydride at interalia B3LYP/6-31G**, B3LYP/cc-pvtz,
and MP2/6-31G** level revealed a mixture of nonplanar (sp,sp) and (sp,ac) energy minima, connected to
one another via low-energy rotation barriers, thereby allowing for extensive large-amplitude motions. This
model provided the geometrical constraints and force fields necessary to perform the joint analysis of gas-phase electron diffraction and infrared data. The large-amplitude motion is described, using pseudoconformers
at 20° intervals around the axes of rotation. It led to a dynamic model consisting of eight pseudoconformers
of lowest energy connected to the two local minima ((sp,ac) and nonplanar (sp,sp)) by fixed differences in
torsion angles. The main structural parameters were refined using the electron diffraction method and an
experimental “conformer” ratio of nonplanar (sp,sp)/(sp,ac) = 37(±15)%:63(±15)% was obtained, in close
agreement with the quantum chemical results. The model of acetic anhydride is self-consistent, reproduces
the IR frequencies, with a root-mean-square deviation of about 10 cm-1, and results in an improved frequency
assignment. Assisted by MP2/6-31G**-based IR band intensities, the model also explains the following
experimental spectral peculiarities: (i) the relatively large number of bands with a small intensity and (ii) the
changes in band intensities, band shape, and doublet behavior when going from the gas phase to the liquid
and to solutions of different polarity.
BackgroundDiabetes is the most common metabolic disease with many chronic complications, and cognitive disorders are one of the common complications in patients with diabetes. Previous studies have showed that autophagy played important roles in the progression of metabolic syndrome, diabetes and other diseases. So we investigated whether aged diabetic mice are prone to be associated with the cognitive and affective disorders and whether Beclin-1-mediated autophagy might be involved in thepahological process.MethodsHigh-fat diet/streptozotocin (STZ) injection-induced diabetic C57 mice were adopted in this study. Cognitive disorders were detected by Morris water maze and fear conditional test. Affective disorders were detected by tail suspension test and forced swimming test. Magnetic resonance imaging was applied to observe changes of morphology and metabolism in the brain. The 18 F-fluorodeoxyglucose positron emission tomography (FDG-PET) was used to assess metabolism changes in the brain of aged diabetic mice. Autophagy were evaluated by Beclin- 1, LC3II/I and P62, which were detected by western blot analysis and observed by electron microscopy.Results1. Compared with control group, diabetes mice showed significantly decreasing abilities in spatial memory and conditioned fear memory (all P < 0.05), and increasing tendency of depression (P < 0.05). 2. MRI showed that the majority of elderly diabetic mice were associated with multiple cerebral small vessel disease. Some even showed hippocampal atrophy, ventricular dilatation and leukoaraiosis. 3. FDG-PET-CT discovered that the glucose metabolism in the amygdala and hippocampus was significantly decreased compared with normal aged mice (P < 0.05). 4. Electron microscopy found that, although autophagy bodies was not widespread, and there was no significant difference between the two groups, yet compared with normal aged mice, apparent cell edema, myelinated tow reduction and intracellular lipofuscin augmentation existed in elderly diabetic mice brain. 5. The level of p62 was increased in the STZ-induced diabetic mice hippocampus and striatum, and beclin1 protein expression were significantly decreased in diabetic mice hippocampus compared with normal aged mice (P < 0.05). There was a upward trend of the ratio of LC3II/I in hippocampus, cortex and striatum, but no statistically difference between the two groups.ConclusionCompared with normal aged mice, diabetic aged mice were apt to cerebral small vessel disease and associated with cognitive and affective disorders, which may be related to the significantly reduced glucose metabolism in hippocampus and amygdala. Beclin1 mediated autophagy in hippocampus probably played an important role in cognitive and affective disorders of STZ-induced aged diabetic mice.
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