Important Effects of Lithium Carbonate on Stoichiometry and Property of the Inclusion Complexes of Polypropylene Glycol and β-Cyclodextrin

Hot Electrons at Solid-Liquid Interfaces: A Large Chemoelectric Effect during the Catalytic Decomposition of Hydrogen Peroxide

The study of energy and charge transfer during chemical reactions on metals is of great importance for understanding the phenomena involved in heterogeneous catalysis. Despite extensive studies, very little is known about the nature of hot electrons generated at solid-liquid interfaces. Herein, we report remarkable results showing the detection of hot electrons as a chemicurrent generated at the solid-liquid interface during decomposition of hydrogen peroxide (H2 O2 ) catalyzed on Schottky nanodiodes. The chemicurrent reflects the activity of the catalytic reaction and the state of the catalyst in real time. We show that the chemicurrent yield can reach values up to 10(-1) electrons/O2 molecule, which is notably higher than that for solid-gas reactions on similar nanodiodes.

Characterization of supramolecular gels based on β-cyclodextrin and polyethyleneglycol and their potential use for topical drug delivery

Novel gels were prepared by blending β-cyclodextrin and polyethyleneglycol (PEG) in the presence of K2CO3. The objective of this study was thus to characterize the gels using rheology, modulated temperature differential scanning calorimetry (MTDSC), turbidity measurements, and hot stage microscopy, and then investigate the potential use of the gel for topical drug delivery. Two types of supramolecular gels, GelL and GelH were prepared at a low temperature (below 50 °C) and at a high temperature (above 70 °C), respectively. Both gels were thermo-reversible. Upon heating, GelL could turn to GelH. Nevertheless, upon cooling, GelH that was more stable than GelL precipitated and GelL could not be reformed. GelL may form through simple complexation of polyethyleneglycol (PEG) with β-cyclodextrin in the presence of K2CO3. However, GelH may form a specific complex or a pseudopolyrotaxane gel. For pharmaceutical application, GelL was investigated instead of GelH because the forming temperature of this gel was close to the human body temperature. The interactions among diclofenac sodium (DS), a model drug, and the components of the gel were examined using FTIR. These interactions may include ionic attraction and hydrogen bonds between the carboxylate groups of DS and the hydroxyl groups of PEG or β-cyclodextrin and probably also the inclusion of the aromatic ring of DS into the cavity of β-cyclodextrin. Furthermore, the release and permeation of diclofenac from GelL were significantly greater than those from a commercial gel. Therefore, GelL may be useful for the topical delivery of drugs.

Complex from ionic β-cyclodextrin polyrotaxane and sodium tetraphenylthiophenesulfonate: restricted molecular rotation and aggregation-enhanced emission

Because restricted intramolecular rotation (RIR) is the main mechanism responsible for the aggregation-enhanced emission (AEE), we thus used a rigid polyrotaxane to impose effective RIR for an water-soluble and AEE-active luminogen of TPS.

Rigid Jeffamine-included polyrotaxane as hydrogen-bond template for salicylideneazine with aggregation-enhanced emission

A Jeffamine-included polyrotaxane (JCD) was used as rigid template to impose effective rotational restriction on the AIE-active luminogen of 1,2-bis(2,4-dihydroxybenzylidene)hydrazine (CN₄OH).

Leveling effects of ammonium salts on thermal stabilities of polyethylene glycols

In this work, the thermal stabilities of a series of polyethylene glycols (PEG 4000, 6000 and 10000) were investigated after compositing with different kinds of inorganic salts, such as ammonium molybdate tetrahydrate (AMT), NH4VO3, (NH4)2SO4, NH4NO3, Na2SO4, Na2MoO4. It was first observed that all the ammonium salts exerted leveling effects for the thermal stabilities of the PEGs. In other words, the presence of the ammonium salts caused the occurrence of the maximum decomposition rates of the PEGs with the same repeat sequence but different chain lengths at almost the same temperatures. Leveling effects were defined by three parameters: leveling spans, leveling degrees and dispersion degrees of leveling. Further experiments revealed that leveling effects also occur in similar types of polymers: polypropylene glycols (PPG 2000, 3000 and 4000). A series of independent experiments including Fourier transformation infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, time-of-flight mass spectrometry, conductivity and field-emission scanning electron microscopy were performed to explore the origin of leveling effects. We consider that the interaction between inorganic ions and polymer molecules and the Hofmeister effect of ions in solution are two important factors affecting the stability of salt–polymer composites, because they can contribute to decrease the interaction between the polymer chains, leading to changes in the conformation and pyrolysis mode of polymers. We believe that the finding of leveling effects would be significant for both basic and applied research of soft matter.