High-quality γ-Ga2O3 nanospheres (diameter, 130 nm) were successfully synthesized by direct conversion of a precursor complex of Ga3+ ions and tartrate ions (L2−) in water. The addition of even a small amount of L2− ions can efficiently suppress the hydrolysis of Ga3+ ions to GaOOH. This synthetic method is new and has great advantages of simplicity, organic solvent-free processing and high efficiency. The γ-Ga2O3 nanospheres which consist of primary nanoparticles with a diameter of about 10 nm show an extremely high specific surface area (83.7 m2 g−1), thereby possessing improved solar-blind detection performance (e.g., light current, 1.83 μA; light–dark ratio, 2.29 × 103 and photocurrent fluctuation, <0.5%) relative to reported results elsewhere.

This report describes the facile solvothermal synthesis of highly monodispersed nickel microspheres with surfaces uniformly covered by nickel dots. Synthesis parameters including reaction times and reagent concentrations significantly influence the microspheric particle characteristics. The novelty of the synthetic method in this work is twofold: first, the controlled synthesis of Ni metallic microspheres using ethylene glycol as the precursor of a reductant and urea as the origin of OH− has never been reported. Second, there are few studies on the construction of Ni microspheres covered by uniform Ni dots using a one-step solvothermal method. Importantly, the as-prepared Ni microspheres show an improved ability to remove Cd2+ ions even at high concentrations in water and a unique adsorption isotherm having an increasing adsorption capacity for Cd2+ ions. The presence of Ni dots was considered to play an important role in the onset of the adsorption process. We believe that this work opens up new and possibly exciting opportunities in the field of adsorption of heavy metal ions.

One-, two- and three-dimensional nanostructures of copper molybdenum oxide hydroxide were successfully constructed by a simple approach through a pH-dependent dimensional transformation of ammonium copper molybdate. Thin nanoplates of copper molybdate, which were obtained by sintering the two-dimensional nanobelts of copper molybdenum oxide hydroxide, exhibited remarkably high reversible lithium storage capacity, good rate capability and excellent cycling stability.

Herein we report the first example of the creation of Bi/BiOBr square microflowers with square nanopetals by a one-pot solvothermal process using ethylene glycol as both a solvent and a source of the reductant simultaneously. The square microflower material exhibited good photoelectric response and extremely high photodegradation efficiency for rhodamine B. We believe that this study represents an important advance regarding Bi-based inorganic materials.

A novel metallo-supramolecular micelle PF–SDS–SM was formed at room temperature through the self-assembly of potassium ferrioxalate and sodium dodecyl sulphate. This leads to a new reaction pattern which is not yet fully understood, accompanied by the creation of hollow elongated square microtubular iron oxalate dihydrate during a hydrothermal process.

Highly monodisperse CuS microflowers with uniform size and shape were successfully constructed by a simple one-pot solvothermal approach assisted by EDA and PVP. When used as photocatalysts, the as-obtained CuS materials exhibited excellent photocatalytic activity and good selectivity for the degradation of organic contamination in waters.

A new route to produce Ru-based nanocomposites with mixed valence states of ruthenium is reported in this paper via a solid-phase sintering process. Precursor particles were prepared by an intimate mixing of RuCl3 and native β-cyclodextrin (β-CD) with a molar ratio of 1:1, followed by a sintering process at various temperatures ranging from 573 to 1173 K in ambient atmosphere. The so-obtained composite nanomaterials have been characterized by X-ray diffraction and notably the results show that an adjustment of the temperature enabled us to obtain Ru-based nanoparticles with controllable compositions. The surface-enhanced Raman scattering performances of the obtained nanomaterials have been analyzed using Rhodamine 6G (R6G) as the Raman probe. Their magnetic behaviors have been investigated as a function of the field strengths. The present work provides a significant advance in the development of both transformation in valence states of transition metals and in situ nanocomposites of metal/metal oxide combinations.

Face-raised Co3O4 octahedral crystals were successfully constructed through a carbon-assisted method using cellulose as carbon resource and used for a catalyst for selective oxidation of alcohols. The face-raised Co3O4 octahedra are about 200 nm in edge length and assembled to microtubes with a length of ca. 10 μm and a width of 2–3 μm. Our analysis showed that the thermal decomposition and carbonization of cellulose has contributed to the generation of the octahedral structure and the assembled process. Moreover, compared with normal Co3O4 octahedra, the face-raised Co3O4 octahedral crystals have higher remanence and saturation magnetization, which is attributed to their more uniform small grain sizes. In particular, the face-raised Co3O4 octahedra gave both higher activity and higher selectivity than the normal Co3O4 octahedra in the catalytic oxidation reactions of alcohols. More importantly, after eight cycles, the face-raised Co3O4 octahedral crystals still exhibited considerably high catalytic activity, suggesting promising applications in heterocatalysis.

Well-ordered NiO nanoflowers were successfully constructed by sintering flower-like nickel ethylene glycol nanocrystals derived from the thermal decomposition of rod-like nickel tartrate. We found that the NiO nanoflowers have a high adsorption selectivity to organic dyes and a strong adsorption capacity to toxic heavy metal ions in water owing to their porous structure.

The present work provides a novel route for forming one-dimensional (1D) gallium (Ga) nanoribbon materials with a host molecule calix[6]arene (CA-6) as a template by a facile, one-step and low temperature chemical bath method. Field-emission scanning electron microscopy and transmission electron microscopy showed that the uniform 1D Ga nanoribbon material (Ga-a) can be constructed only in the presence of CA-6, and the formation of ribbon structures is highly dependent on doping ratios and deposition times. Our data indicate that the unusual effect of CA-6 is due to a combination of two factors: a high density of OH groups in the outer surface of its cavity and an appropriate cavity diameter. Especially, the uniform 1D Ga nanoribbon material exhibits a distinct electronic structure and very rare magnetic behaviour when compared to those 3D Ga materials obtained by means of other host molecules: calix[4]arene, γ-cyclodextrin and 18-crown-6. For example, of all the Ga materials, the uniform 1D nanoribbon material has the lowest electron density of Ga core levels in light of X-ray photoelectron spectroscopy analysis. This result suggests that there is a stronger molecule–atom interaction between Ga atoms and CA-6 molecules compared with those in other host–guest systems. More importantly, the uniform 1D Ga nanoribbon material exhibits a magnetic transformation from a diamagnetic to a paramagnetic state under the influence of an applied field, which is completely different from those of all the 3D Ga materials and all the irregular Ga nanoribbon materials. Such a transformation is novel in metals and particularly useful in the chemistry of materials since it allows dramatic modifications of magnetic properties of metal nanocrystals. Finally, a strong surface-enhanced Raman scattering of the uniform 1D Ga nanoribbon material has been observed for organic molecules adsorbed on their surface. Taken together, we believe this work opens a new channel for development of 1D metal-based nanomaterials.

The thermal pyrolysis behaviour of a complex of β-cyclodextrin (CD) and potassium ferrioxalate (PF) was analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Two rare inorganic ions: CO22+ and O4+, neither of which was found in the cases of free β-CD and PF, were synchronously observed during the decomposition of the complex. Our observations led to proposed formation mechanisms of the ions, in which the structural transformation of a metastable intermediate ion (C2H4O3+) was employed to qualitatively explain our data. Besides this, the formation, structure and magnetic properties of the complex were evaluated carefully. First, XPS analysis indicates a decrease of electron densities of Fe(III) ions in the presence of β-CD. We think that this is due to an effect of the noncovalent complexation between PF and β-CD. This gives an indication on the effect of second sphere coordination of β-CD on the electronic structure of the Fe(III) in the first coordination sphere. Second, structural changes in stacking modes and morphologies provide further support for the noncovalent complexation. For example, the surface feature of the complex gives us an impression that both β-CD and PF are evenly dispersed with each other. Also, the complex presents a uniform sponge-like porous nanostructure with diameters of less than 50 nm. This seems to be an important reason for those changes that occurred in the thermal analysis. Finally, the result of magnetic experiments implies that the coordination compound PF upon complexation with β-CD will experience a gradual decrease in magnetization with the increase of magnetic fields. These observations have significant implications for a better understanding of the importance of the construction and deconstruction of a second sphere coordination in modifying the physical properties of an σ-coordination compound.

The present study revealed a surprising valence transformation of copper (Cu) in the sintering process of mixtures of copper chloride dihydrate (CuCl2·2H2O) with β-cyclodextrin (β-CD) in ambient atmosphere. Such a transformation in Cu valence states can be modulated by changing the initial molar ratio (IMR) of CuCl2·2H2O to β-CD in the mixtures. Firstly, as the value of IMR decreased, the content of cuprous chloride (CuCl) decreased, while the content of cupric oxide (CuO) increased gradually. That is to say, there is an unambiguous IMR-dependence of the contents of CuCl and CuO formed. However, such a controllable valence transformation from Cu(II) to Cu(I) to Cu(II) did not happen in nitrogen atmosphere. Secondly, the in situ composite of CuCl and CuO produced a highly ordered structure of self-assembled nanowires, intertwined, with a diameter of 30 to 50 nm. Furthermore, electronic structural analysis provided direct evidence that the Cu–Cl and Cu–O bonds in this composite material were simultaneously impaired by self-assembled growth. Finally, we noticed that the photoluminescence property of CuCl was regulated through the formation of composites with CuO. In addition, this in situ composite synthesis technique was used to modify the magnetic property of CuO. Furthermore, the anomalous ferromagnetic behaviour of the CuO nanocrystal was observed and explained. In short, this work not only demonstrates a flexible and easily controllable valence transformation of Cu, but also provides a novel approach for constructing inorganic nanocomposite materials. We believe that the implications of these findings are important and make significant contributions to the development of inorganic chemistry and material science.

A series of α-Fe2O3 crystalline materials with fascinating polyhedral morphologies, such as octahedral, cuboctahedral and truncated cubic structures, were prepared through a novel solid-phase sintering process. Our results demonstrated that the structural transformations among the polyhedra were easily controlled by the sintering times. This suggested that the Wulff polyhedra transformation could occur in a hexagonal crystal system. Furthermore, we found that the magnetic properties of the α-Fe2O3 crystals were associated with their size and shape.

A variety of α-MoO3 nanostructures, including 1D nanobelts, 2D nanolayers and 3D nanoparticles, were prepared via three methods: sintering AMT, sintering aggregates of AMT with PEGs, and oxidating MoO2. Our results suggested that the surface structures of the α-MoO3 crystals obtained can be controlled by preparation conditions, including sintering temperatures, sintering times and starting materials. Several rough rules were given to explain the influence of the preparation conditions. Also, this work provided a paradigm for the structural regulation of α-MoO3 crystals from 3D to 1D to 2D. Furthermore, the electron structures, photoluminescence performances and photocatalytic properties of the α-MoO3 crystals were investigated. It was found that they were highly dependent on surface features of the α-MoO3 crystals. For instance, the binding energies of Mo 3d3/2 and Mo 3d5/2 increased corresponding to a decrease in surface area of particles, induced by a structural transformation from 3D to 2D. Also, their photoluminescence intensity was greatly enhanced compared to that of commercial α-MoO3. More importantly, fascinating photocatalytic properties of the as-obtained α-MoO3 crystals were also associated with their morphologies and surface areas, for example, the smaller nanoparticles and larger surface areas of the catalysts and the higher photodegradation percentage of methylene blue. Interestingly, the photocatalytic efficiency of all the as-obtained α-MoO3 crystals was much better than commercial α-MoO3. A possible photocatalytic degradation mechanism was proposed. Overall, these results not only enhance our understanding of the relationship between structures and properties of inorganic nanomaterials but also could be potentially useful for new crystal design and growth of inorganic nanomaterials.

The present work is devoted to an attempt to understand the effect of an inorganic salt such as ferric trichloride (FeCl3) on the carbonization and degradation of carbohydrates such as β-cyclodextrin (CD), amylose, and cellulose. Our data revealed two important observations. First, the presence of FeCl3 led to the occurrence of a low carbonization temperature of 373 K. This is a rare phenomenon, in which carbonization improvement is present even if a small amount of FeCl3 was added. Experimental results had provided evidence for the fact that a redox process was started during the low-temperature carbonization of β-CD, causing the reduction of FeCl3 to ferrous chloride (FeCl2) by carbon materials formed in the carbonization process in air. However, the reduction process of FeCl3 produced the in situ composite nanomaterial of Fe–FeCl2 combination in nitrogen. Second, a molecule–ion interaction emerged between FeCl3 and the carbohydrates in aqueous solution, resulting in a more effective degradation of the carbohydrates. Moreover, our results demonstrated that FeCl3 played the role of a catalyst during the degradation of the carbohydrates in solution. We believe that the current work not only has a significant potential application in disposal of waste carbohydrates but also could be helpful in many fields such as environmental protection, biomass energy development, and inorganic composite nanomaterials.

The first part of the study is devoted to the comparison between the doping effect of urea (a small molecule) and polyethylene glycol (PEG, a long-chain polymer) on the physical property of metallic gallium (Ga). The physical properties of the Ga composited in the two materials, Ga/urea and Ga/PEG, were investigated by scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, differential scanning calorimetry, superconducting quantum interference device, and surface-enhanced Raman scattering spectra and compared with our previous results for the effect of macrocyclic hosts (e.g., cyclodextrins, calixarenes) on the physical modification of metallic Ga. Our data provide new direct evidence that the modification of physical properties of Ga is highly dependent on the nature of dopants used. For example, the addition of a small amount of urea causes a fundamental change in the crystallization behavior of Ga, and the presence of PEG results in the occurrence of a weak paramagnetism of Ga at high fields, both of which are completely different from the effect of other dopants. The other part of the study is devoted to demonstrating whether there is a significant difference in the oxidation process of metallic Ga and its composites. Our result gives a strong positive answer to the question. β- and γ-gallium oxide nanocrystals were obtained by sintering the Ga/urea composite at different temperatures and exhibited distinctive photoluminescence and photocatalysis properties. These results gave a strong impression that the introduction of different dopants leads metallic Ga to generate different features in microstructure, physical property, and especially chemical reactivity. We believe that the findings of this study have important implications for the development of inorganic materials.

An adduct behaviour of ammonium molybdate tetrahydarte (AMT) with polytetrafluoroethylene (PTFE) resulted in three significant benefits: (a) a much lower degradation temperature (ΔTm, 82 K) of the PTFE in the adduct and a much lower final residual mass (ΔRM, 39%) of the adduct compared to the theoretical prediction, (b) the formation of MoO3 and MoO2 nanoparticles, and (c) the shuttle-shaped MoO2 nanoparticles coated with graphite exhibits superior soft magnetic property. The much earlier degradation suggested that there was a strong mutual effect between AMT and PTFE. The much lower residual mass implied that the intervention of a chemical reaction was responsible for the effect in nitrogen. Actually, Raman spectra revealed that the adducted PTFE was degraded into a graphite structure at this atmosphere, and the presence of the graphite layer led to the reduction of AMT into shuttle-shaped MoO2 nanoparticles at 837 K to a complete extent. Controlled sintering measurements in air indicated that the AMT in the presence of PTFE produced α-MoO3 nanoparticles, instead of MoO2. Further, our results indicated that the MoO3 nanoparticles obtained had a positive response to the heterogeneous catalytic oxidation of thiophene in the presence of hydrogen peroxide. We believe that the present work is not only of relevance for applications in the degradation of polymer materials, but also will attract the attention of many groups studying the preparation and magnetic properties of transition metal oxide nanoparticles and their practical application in heterogeneous catalytic reactions.

The present work supports a novel paradigm in which the surface structure and stacking behavior of metallic gallium (Ga) were significantly influenced by the preparation process in the presence of organic small molecules (ethanol, acetone, dichloromethane, and diethyl ether). The extent of the effect strongly depends on the polarity of the molecules. Especially, a series of new atom–molecule aggregates consisting of metallic Ga and macrocyclic hosts (cyclodextrins, CDs) were prepared and characterized by various techniques. A comprehensive comparative analysis between free metallic Ga and the Ga samples obtained provides important and at present rare information on the modification in structure, phase transition, and magnetic property of Ga driven by atom–molecule interactions. First, there is a notable difference in microstructure and electronic structure between the different types of Ga samples. Second, differential scanning calorimetry analysis gives us a complete picture (such as the occurrence of a series of metastable phases of Ga in the presence of CDs) that has allowed us to consider that Ga atoms were protected by the shielding effect provided by the cavities of CDs. Third, the metallic Ga distributed in the aggregates exhibits very interesting magnetic property compared to free metallic Ga, such as the uniform zero-field-cooled and field-cooled magnetization processes, the enhanced responses in magnetization to temperature and applied field, and the fundamental change in shape of magnetic hysteresis loops. These significant changes in structural transformation and physical property of Ga provide a novel insight into the understanding of atom–molecule interactions between metallic atoms and organic molecules.

The present work was devoted to an experimental investigation of the molecule-ion interaction between copper chloride (CuCl2) and β-cyclodextrin (CD) and its effect on the electrostatic interaction between Cu2+ and Cl− ions. Our results gave an explicit description of the mutual effect between the interactions. First, the molecular arrangement and surface feature of β-CD experienced a fundamental structural change after interaction with Cu2+ and Cl− ions, which was ascribed to a good separation of Cu2+ from Cl− ions in β-CD matrix. Second, arguments based on electronic structural analysis provided a direct indication of the change in charge density distributions of Cu2+ and Cl− ions in the presence of β-CD. Third, the actual occurrence of a second signal in the course of water release at a higher temperature suggested that the Cu2+ ions were trapped in the form of hydrates in the crystal interstice of β-CD molecules. Fourth, comparison of the mass spectra indicated that the thermal decomposition of β-CD in the presence of CuCl2 produced a series of interesting molecular ions: C3H2OH+, C4H3OH+, C5H4OH+, and C7H6OH+. We consider that this study is helpful in providing a new approach to the evaluation of the extent of the mutual effect between an inorganic salt and an organic molecule.

The present work revealed the presence of the molecule−ion interaction between ethylenediaminetetraacetic acid disodium salt (Na2H2EDTA) and β-cyclodextrin (CD) on the basis of observable changes in crystal patterns and thermal behaviors before and after interaction. Results from electric conductivity measurements confirmed this presence and showed that the extent of the molecule−ion interaction was associated with the concentration of β-CD. More importantly, the molecule−ion interaction led to a decreased coordination interaction of Na2H2EDTA and copper chloride, and this decrease exhibited a concentration dependence of β-CD. Similar phenomena were also observed in the case of several analogs of Na2H2EDTA by UV−vis spectroscopy. A possible explanation was proposed on the basis of the hypothesis that there was a competitive relationship between the molecule−ion interaction and the coordination interaction. Further, nuclear magnetic resonance measurements provided important information on the difference in interaction modes of β-CD with H2EDTA2− and [Cu(EDTA)]2−. We are of the opinion that the results would provide a significant bridge between coordination chemistry and supramolecular chemistry and help us further understand factors related to different interactions in multicomponent systems.

In this study, we try to answer a fundamental question: what is the consequence of the noncovalent interaction between a polymer and a coordination compound? Here, polyethylene glycol (PEG-4000, PEG-b) and copper complex of ethylenediaminetetraacetic acid (H2CuY) were employed to solve this problem. A novel adduct (CEP) between H2CuY and PEG-b was prepared. Our results indicated several interesting findings. First, the introduction of H2CuY had no effect on the stacking structure of PEG-b but led to a large change in surface structure of the polymer. Second, there was a significant difference (117 K) in the maximum degradation temperature between the PEG and the CEP, suggesting that the noncovalent interaction can drastically improve the thermal stability of the PEG. Third, sintering experiments showed that H2CuY and CEP produced completely different decomposition products. The former formed Cu crystals in nitrogen and CuO in air, but the latter generated Cu and CuCl crystals with good crystallinity, respectively. Finally, three independent measurements: viscosity, conductivity and nuclear magnetic resonance in solution, provided useful information and insights from both sides of the noncovalent interaction. Probable interaction mechanisms and interaction sites were proposed. We consider that the current research could create the foundation for a new understanding of how the noncovalent adduct interaction between a metallic complex and a polymer relates to the change in physical and chemical properties of the adducted components.

This study reveals that the noncovalent complexation between β-CD and Cu(HMTA)2+ makes a positive contribution to the coordination interaction between Cu2+ and HMTA in a tricomponent system. Besides, mono- and binuclear complexes: [β-CD·Cu]+ and [Cu·β-CD·Cu]+ were observed under the condition of ESI-MS.

The present work reveals a significant influence of lithium carbonate (Li2CO3) on stoichiometry, yield, spectral property, and thermal behavior of the inclusion complex formed by polypropylene glycol (PPG) and β-cyclodextrin (CD). First, the presence of Li2CO3 in aqueous solution leads to the formation of an inclusion complex PPG−(β-CD)6, which is completely different from that precipitated from pure water. This finding is supported by the result of a similar experiment in the case of lithium chloride, demonstrating that the self-assembling behavior of PPG, a flexible oligomer, and β-CD, a rigid oligomer, in solution can be mediated by additions of the lithium salts. Second, powder X-ray diffraction patterns indicate that the lithium salts in solution play a considerable role in fabricating three-dimensional structures of the complex. Third, the difference in stoichiometry and microstructure of the complexes precipitated from different media is reflected by the difference of their thermal properties. Finally, the results of viscosity, surface tension, and conductivity measurements provide positive support on the effect of the lithium salts on the physical property of PPG solution. Taken together, these observations provide a novel framework for understanding functions of inorganic salts in designing and constructing supramolecules.

In this paper, the difference in thermal degradation behavior between polypropylene glycol (PPG) and its complex of β-cyclodextrin was carefully compared by a gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) as well as in situ Fourier transformation infrared spectroscopy and thermogravimetric (TG) analyses. The present data revealed a very interesting phenomenon that there was a variation in the order of thermal stability of PPG and its complex between the conditions of TG and GC-TOF-MS. In addition, the relative abundances of released fragments in the inclusion complex were changed with different programmed temperatures in GC-TOF-MS measurements. We believe that this work will provide a better understanding on the degradation behavior of polypseudorotaxanes.Graphical abstract:Figure options.

A tricomponent aggregate PPG−Fc−β-CD formed by polypropylene glycol (PPG), ferrocene (Fc), and β-cyclodextrin (β-CD) was obtained and characterized by a series of physical methods, such as 1H nuclear magnetic resonance, flame atomic absorption spectrometry, high performance liquid chromatography, UV−vis absorption spectroscopy, thermogravimetry, and gas chromatography coupled to time-of-flight mass spectrometry. First, the tricomponent aggregate exhibited a component ratio of 1:28:32 (PPG/Fc/β-CD) in the solid state, and showed a completely different order in thermal stability when compared with β-CD: under a nitrogen atmosphere, β-CD > PPG−Fc−β-CD, and in a vacuum, PPG−Fc−β-CD > β-CD. Second, the appearance of two peculiar points p and q at the end of TG curve of the aggregate gave a strong impression that the degradation rate further increased after the sharp decomposition of the aggregate reached point p and the amount present in the residual fraction at point q about 780.0 K was lower than 1%, both of which were rather different from those reported previously. This finding implied that the molecular assembly resulting from the binding interaction among Fc, PPG, and β-CD induced more efficiently the degradation of each of them. Third, an interesting phenomenon was found that the order of thermal release of the three assembled components in PPG−Fc−β-CD was Fc > β-CD > PPG. Results of this study provide some insight into an initial attempt to construct a supramolecule among a polymer, a coordination compound, and an organic compound.

A novel molecule−ion adduct of ammonium molybdate tetrahydarte (AMT) with β-cyclodextrin (CD) was prepared in this work. Significant differences in spectral properties between AMT and the adduct AMT−β-CD were observed by a series of experimental probes, such as powder X-ray diffraction, Fourier transformation infrared spectroscopy, and Raman spectroscopy. Field emission scanning electron microscopy showed that, although the crystal growth of AMT−β-CD was dominated by the molecular stacking of AMT, the size and morphology of the adduct were rather different from those seen in free AMT. The difference in stacking forms was attributed to the contribution of the molecule−ion interaction between AMT and β-CD. A drastic improvement in thermal stability of AMT and β-CD after adduct formation was observed by thermogravimetry analysis, which was confirmed by controlled sintering measurements. This revealed that the adduct interaction between them played an important role in mediating the thermal decomposition process of the adducted components. Furthermore, our results indicated that AMT and its adduct had a different performance in the catalytic desulfurization of thiophene and its derivatives. The fact that the catalytic efficiency of AMT was decreased after adduct formation implied there was a complexation between AMT and β-CD. Besides, several unusual molecular ions—NH3+, NH2+, and NH+—were simultaneously found with gas chromatography coupled to time-of-flight mass spectrometry of free AMT.

In this paper, the inclusion complexation between host and guest in cyclodextrin (CD) chemistry is carefully compared with the coordination interaction between central ion (Mx+) and ligands in coordination chemistry. In view of the importance of the concept of the coordination number (CN) of Mx+ in coordination compounds, the inclusion number (IN) is first defined to evaluate the nature of inclusion complexation between host and guest in CD supramolecular inclusion complexes. The similarities and differences between CN and IN are also discussed. The changes of the number and forms of water molecules both in CD hydrates and in CD crystal inclusion complex hydrates are reviewed. Moreover, this paper emphasizes the distinction between the two forms of CD-guest inclusion phenomenon, i.e., inclusion complexation and encapsulation interaction. Furthermore, the present work indicates that though chemical stoichiometric ratio can be used to characterize the inclusion phenomena, IN can better reveal the essence of inclusion phenomena in cyclodextrin chemistry.

An interesting paradigm in which the conformation of glucopyranose of β-CD in the presence of Li2CO3 is transformed into both an aromatic structure, such as the heterocyclic compound C6H6O+ with a prominent relative abundance (RA) and the tropylium ions C3H3+, C5H5+, and C7H7+ at comparatively low temperatures, and a linear structure such as C18H30O+ and C4H10O3+ is reported in the present work. The efficient transformation (higher RA, lower temperature) from a sugar structure to an aromatic structure is ascribed to the contribution of the molecule−ion interaction between β-CD and Li2CO3. Such a transformation is significant because it provides new insight into the link between supramolecular chemistry and other fields such as organic synthesis, biomineralization, environmental protection, and energy utilization.

In the present work, the influence of molecule−ion interactions on the precipitation−dissolution equilibrium of a typical inorganic drug, lithium carbonate (Li2CO3), in water and on the chiral recognition behaviors and binding abilities of α-, β-, γ-, and heptakis(2,6-di-O-methyl)-β-cyclodextrin (CD) to d- and l-tryptophan (Trp) was investigated. Our results revealed that the solubility of Li2CO3 was increased to a large extent and the phase solubility diagram of Li2CO3 belonged to the AN type. This finding provided a new insight into the link between molecule−ion interactions and precipitation−dissolution equilibriums of poorly dissolving inorganic salts. Furthermore, despite having a negative effect on the isomer recognition behaviors, the molecule−ion interaction between CDs and Li2CO3 effectively increased the binding abilities of these CDs to both d- and l-Trp synchronously. The observation gave an important implication that buffer solutions consisting of inorganic salts are used with caution in molecular recognition fields between host and guest or between acceptor and donor. Further analyses confirmed the interaction among Li2CO3, β-CD, and l-Trp using an electrospray ionization mass spectrum.

The thermal decomposition behavior of survived β-cyclodextrin in its inclusion complex of clove oil is investigated by nonisothermal thermogravimetry (TG) analysis at the heating rates of 5.0, 10.0, 15.0, 20.0 and 25.0 K min−1. The TG profiles based on mass loss as a function of temperature show a clear trend of increased thermal decomposition temperature with increased heating rate. Gas chromatography coupled to time-of-flight mass spectrometry (GC-TOF-MS) with a programmed temperature heating treatment is performed to experimentally investigate the relationship between procedural decomposition temperature and fragment composition of the sample. The results on the basis of fragment analysis explain the different mass loss of the sample corresponding to different temperatures on the gradient hot stage.

How does a complexed organic guest change its thermal stability during the heating process? How does the guest release influence the decomposition behavior of the complexed host? To answer these questions, in-situ Fourier transform infrared spectroscopy and gas chromatography coupled to time-of-flight mass spectrometry with programmed temperature were employed in the present work. The careful comparisons among the thermal decomposition behaviors of free β-cyclodextrin (β-CD) and its inclusion complexes of ethylenediamine and diethylenetriamine indicated that the release of the amines was not a simple physical process without the rupture of chemical bonds but was instead a complex process together with the fragments from complexed β-CD. In short, the release and decomposition of the complexed amines drove the decomposition of the complexed β-CD in their respective inclusion complexes. It was found that the thermal decomposition behavior of the complexed β-CD was influenced by the complexed amines dependent on the nature of the amines, and at the same time, β-CD had, to a certain extent, changed the temperature of the phase-change, release, and decomposition of organic amines by the formation of inclusion complexes with them.

The present work revealed there was a conceptual difference in the thermal decomposition behaviors between the complexed β-cyclodextrin (CD) in an inclusion system and the β-CD complex of guest. The thermal decomposition behaviors of the solid inclusion complexes of β-CD with ethylenediamine (Eda), diethylenetriamine (Dta) and triethylamine (Tea) were investigated using nonisothermal thermogravimetry (TG) analysis based on weight loss as a function of temperature. In view of TG profiles, a consecutive mechanism describing the formation and thermal decomposition of the three solid supermolecules of β-CD was presented. Heating rate has very different effects on the thermal decomposition behaviors of these complexes. The faster the heating rate is, the higher the melting-decomposition point of the complexed β-CD in an inclusion system is, and on the whole the bigger the rate constant (k) of the thermal decomposition reaction of the complexed β-CD is. The thermal decomposition process of the complexed β-CD for each inclusion system is determined to be simple first-order reaction using Ozawa method. The apparent activation energies (Ea) and frequency factors (A) of the thermal decomposition reactions of the complexed β-CD molecules have been also calculated. It is found that when the decomposition reaction of the complexed β-CD encountered a large value of Ea, such as that in Dta–β-CD system, an apparent compensation effect of A on Ea can provide enough energy to conquer the reaction barrier in prompting the k value of thermal decomposition reaction of the complexed β-CD according to Arrhenius equation.

An adduct behaviour of ammonium molybdate tetrahydarte (AMT) with polytetrafluoroethylene (PTFE) resulted in three significant benefits: (a) a much lower degradation temperature (ΔTm, 82 K) of the PTFE in the adduct and a much lower final residual mass (ΔRM, 39%) of the adduct compared to the theoretical prediction, (b) the formation of MoO3 and MoO2 nanoparticles, and (c) the shuttle-shaped MoO2 nanoparticles coated with graphite exhibits superior soft magnetic property. The much earlier degradation suggested that there was a strong mutual effect between AMT and PTFE. The much lower residual mass implied that the intervention of a chemical reaction was responsible for the effect in nitrogen. Actually, Raman spectra revealed that the adducted PTFE was degraded into a graphite structure at this atmosphere, and the presence of the graphite layer led to the reduction of AMT into shuttle-shaped MoO2 nanoparticles at 837 K to a complete extent. Controlled sintering measurements in air indicated that the AMT in the presence of PTFE produced α-MoO3 nanoparticles, instead of MoO2. Further, our results indicated that the MoO3 nanoparticles obtained had a positive response to the heterogeneous catalytic oxidation of thiophene in the presence of hydrogen peroxide. We believe that the present work is not only of relevance for applications in the degradation of polymer materials, but also will attract the attention of many groups studying the preparation and magnetic properties of transition metal oxide nanoparticles and their practical application in heterogeneous catalytic reactions.

Well-ordered NiO nanoflowers were successfully constructed by sintering flower-like nickel ethylene glycol nanocrystals derived from the thermal decomposition of rod-like nickel tartrate. We found that the NiO nanoflowers have a high adsorption selectivity to organic dyes and a strong adsorption capacity to toxic heavy metal ions in water owing to their porous structure.

High-quality γ-Ga2O3 nanospheres (diameter, 130 nm) were successfully synthesized by direct conversion of a precursor complex of Ga3+ ions and tartrate ions (L2−) in water. The addition of even a small amount of L2− ions can efficiently suppress the hydrolysis of Ga3+ ions to GaOOH. This synthetic method is new and has great advantages of simplicity, organic solvent-free processing and high efficiency. The γ-Ga2O3 nanospheres which consist of primary nanoparticles with a diameter of about 10 nm show an extremely high specific surface area (83.7 m2 g−1), thereby possessing improved solar-blind detection performance (e.g., light current, 1.83 μA; light–dark ratio, 2.29 × 103 and photocurrent fluctuation, <0.5%) relative to reported results elsewhere.

The present work provides a novel route for forming one-dimensional (1D) gallium (Ga) nanoribbon materials with a host molecule calix[6]arene (CA-6) as a template by a facile, one-step and low temperature chemical bath method. Field-emission scanning electron microscopy and transmission electron microscopy showed that the uniform 1D Ga nanoribbon material (Ga-a) can be constructed only in the presence of CA-6, and the formation of ribbon structures is highly dependent on doping ratios and deposition times. Our data indicate that the unusual effect of CA-6 is due to a combination of two factors: a high density of OH groups in the outer surface of its cavity and an appropriate cavity diameter. Especially, the uniform 1D Ga nanoribbon material exhibits a distinct electronic structure and very rare magnetic behaviour when compared to those 3D Ga materials obtained by means of other host molecules: calix[4]arene, γ-cyclodextrin and 18-crown-6. For example, of all the Ga materials, the uniform 1D nanoribbon material has the lowest electron density of Ga core levels in light of X-ray photoelectron spectroscopy analysis. This result suggests that there is a stronger molecule–atom interaction between Ga atoms and CA-6 molecules compared with those in other host–guest systems. More importantly, the uniform 1D Ga nanoribbon material exhibits a magnetic transformation from a diamagnetic to a paramagnetic state under the influence of an applied field, which is completely different from those of all the 3D Ga materials and all the irregular Ga nanoribbon materials. Such a transformation is novel in metals and particularly useful in the chemistry of materials since it allows dramatic modifications of magnetic properties of metal nanocrystals. Finally, a strong surface-enhanced Raman scattering of the uniform 1D Ga nanoribbon material has been observed for organic molecules adsorbed on their surface. Taken together, we believe this work opens a new channel for development of 1D metal-based nanomaterials.

Highly monodisperse CuS microflowers with uniform size and shape were successfully constructed by a simple one-pot solvothermal approach assisted by EDA and PVP. When used as photocatalysts, the as-obtained CuS materials exhibited excellent photocatalytic activity and good selectivity for the degradation of organic contamination in waters.

In this study, we try to answer a fundamental question: what is the consequence of the noncovalent interaction between a polymer and a coordination compound? Here, polyethylene glycol (PEG-4000, PEG-b) and copper complex of ethylenediaminetetraacetic acid (H2CuY) were employed to solve this problem. A novel adduct (CEP) between H2CuY and PEG-b was prepared. Our results indicated several interesting findings. First, the introduction of H2CuY had no effect on the stacking structure of PEG-b but led to a large change in surface structure of the polymer. Second, there was a significant difference (117 K) in the maximum degradation temperature between the PEG and the CEP, suggesting that the noncovalent interaction can drastically improve the thermal stability of the PEG. Third, sintering experiments showed that H2CuY and CEP produced completely different decomposition products. The former formed Cu crystals in nitrogen and CuO in air, but the latter generated Cu and CuCl crystals with good crystallinity, respectively. Finally, three independent measurements: viscosity, conductivity and nuclear magnetic resonance in solution, provided useful information and insights from both sides of the noncovalent interaction. Probable interaction mechanisms and interaction sites were proposed. We consider that the current research could create the foundation for a new understanding of how the noncovalent adduct interaction between a metallic complex and a polymer relates to the change in physical and chemical properties of the adducted components.

The present study revealed a surprising valence transformation of copper (Cu) in the sintering process of mixtures of copper chloride dihydrate (CuCl2·2H2O) with β-cyclodextrin (β-CD) in ambient atmosphere. Such a transformation in Cu valence states can be modulated by changing the initial molar ratio (IMR) of CuCl2·2H2O to β-CD in the mixtures. Firstly, as the value of IMR decreased, the content of cuprous chloride (CuCl) decreased, while the content of cupric oxide (CuO) increased gradually. That is to say, there is an unambiguous IMR-dependence of the contents of CuCl and CuO formed. However, such a controllable valence transformation from Cu(II) to Cu(I) to Cu(II) did not happen in nitrogen atmosphere. Secondly, the in situ composite of CuCl and CuO produced a highly ordered structure of self-assembled nanowires, intertwined, with a diameter of 30 to 50 nm. Furthermore, electronic structural analysis provided direct evidence that the Cu–Cl and Cu–O bonds in this composite material were simultaneously impaired by self-assembled growth. Finally, we noticed that the photoluminescence property of CuCl was regulated through the formation of composites with CuO. In addition, this in situ composite synthesis technique was used to modify the magnetic property of CuO. Furthermore, the anomalous ferromagnetic behaviour of the CuO nanocrystal was observed and explained. In short, this work not only demonstrates a flexible and easily controllable valence transformation of Cu, but also provides a novel approach for constructing inorganic nanocomposite materials. We believe that the implications of these findings are important and make significant contributions to the development of inorganic chemistry and material science.

The thermal pyrolysis behaviour of a complex of β-cyclodextrin (CD) and potassium ferrioxalate (PF) was analyzed using gas chromatography coupled to time-of-flight mass spectrometry. Two rare inorganic ions: CO22+ and O4+, neither of which was found in the cases of free β-CD and PF, were synchronously observed during the decomposition of the complex. Our observations led to proposed formation mechanisms of the ions, in which the structural transformation of a metastable intermediate ion (C2H4O3+) was employed to qualitatively explain our data. Besides this, the formation, structure and magnetic properties of the complex were evaluated carefully. First, XPS analysis indicates a decrease of electron densities of Fe(III) ions in the presence of β-CD. We think that this is due to an effect of the noncovalent complexation between PF and β-CD. This gives an indication on the effect of second sphere coordination of β-CD on the electronic structure of the Fe(III) in the first coordination sphere. Second, structural changes in stacking modes and morphologies provide further support for the noncovalent complexation. For example, the surface feature of the complex gives us an impression that both β-CD and PF are evenly dispersed with each other. Also, the complex presents a uniform sponge-like porous nanostructure with diameters of less than 50 nm. This seems to be an important reason for those changes that occurred in the thermal analysis. Finally, the result of magnetic experiments implies that the coordination compound PF upon complexation with β-CD will experience a gradual decrease in magnetization with the increase of magnetic fields. These observations have significant implications for a better understanding of the importance of the construction and deconstruction of a second sphere coordination in modifying the physical properties of an σ-coordination compound.

One-, two- and three-dimensional nanostructures of copper molybdenum oxide hydroxide were successfully constructed by a simple approach through a pH-dependent dimensional transformation of ammonium copper molybdate. Thin nanoplates of copper molybdate, which were obtained by sintering the two-dimensional nanobelts of copper molybdenum oxide hydroxide, exhibited remarkably high reversible lithium storage capacity, good rate capability and excellent cycling stability.

This report describes the facile solvothermal synthesis of highly monodispersed nickel microspheres with surfaces uniformly covered by nickel dots. Synthesis parameters including reaction times and reagent concentrations significantly influence the microspheric particle characteristics. The novelty of the synthetic method in this work is twofold: first, the controlled synthesis of Ni metallic microspheres using ethylene glycol as the precursor of a reductant and urea as the origin of OH− has never been reported. Second, there are few studies on the construction of Ni microspheres covered by uniform Ni dots using a one-step solvothermal method. Importantly, the as-prepared Ni microspheres show an improved ability to remove Cd2+ ions even at high concentrations in water and a unique adsorption isotherm having an increasing adsorption capacity for Cd2+ ions. The presence of Ni dots was considered to play an important role in the onset of the adsorption process. We believe that this work opens up new and possibly exciting opportunities in the field of adsorption of heavy metal ions.