Complexation Thermodynamics of Cyclodextrins.

Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).

A review of electrolyte materials and compositions for electrochemical supercapacitors

Yuming Yang,†,§ Qiang Zhao,‡,§ Wei Feng,† and Fuyou Li*,† †Department of Chemistry and State Key Laboratory of Molecular Engineering of Polymers and Institutes of Biomedical Sciences, Fudan University, Shanghai 200433, P. R. China ‡Key Laboratory for Organic Electronics and Information Displays (KLOEID) and Institute of Advanced Materials (IAM), Nanjing University of Posts and Telecommunications, Nanjing 210046, P. R. China.

Luminescent chemodosimeters for bioimaging.

The Stability of Cyclodextrin Complexes in Solution.

NMR Studies of Cyclodextrins and Cyclodextrin Complexes

A wide variety of macrocyclic ligands able to interact with cations, anions, and neutral species are known. These have been isolated from natural resources or are the result of the synthetic developments which have taken place in the last 30 years.1a,b Among the latter, calixarenes (products of the baseinduced condensation of p-substituted phenols and formaldehyde) and their derivatives have received considerable attention in recent years. The chemistry of calixarenes has been extensively discussed in several books2a-c and review articles.2d-g There are several reasons for the current widespread interest in calixarenes. An important one is the remarkably simple way (single-step procedure) used for the synthesis of the parent compounds. In addition, lower and upper rim functionalization of these macrocycles has resulted in a massive expansion in the range of derivatives available.2e,g Within this context, calix(4)arenes are of particular interest. Several conformers (cone, partial cone, 1,2 alternate, and 1,3 alternate) have been isolated. A great deal of efforts have been directed toward calix(4)arene derivatives in “cone” conformation. Their particular molecular architecture with well-defined hydrophobic and hydrophilic regions makes these compounds suitable hosts for neutral and ionic species. Calixarenes are potential building blocks for the design of novel supramolecular systems. This is exemplified in the synthesis of calixarenes bridged across the lower and upper rim or indeed coupled between themselves or to other macrocycles.2g-i Calixarenes have found a wide range of applications. A good account on the industrial uses of these macrocycles prior to 1992 has been given by Perrin and Harris.2j However in the past few years several internationally significant patents have been published.2k-u These patents center mostly on the potential use of calixarenes to sequester metal ions and neutral species, although the ultimate use is fairly broad. The remarkable growth of the field of calixarene chemistry has been greatly motivated by the interest in finding derivatives able to enter into selective complexation with neutral or ionic species. A quantitative measure of the strength of interaction between two chemical species (macrocycle and guest) in a given solvent is provided by the stability constant. Therefore, the role of experimental thermodynamics in understanding the factors contributing to complex stability and selectivity is important and must not be underestimated. It should be explicity stated that the derivation of accurate thermodynamic data requires knowledge of the speciation in the systems under study. A significant point arising from this statement is that a high level of scrutiny and detail regarding the behavior of chemical species in a given medium is required in thermodynamic studies related to solution processes. It is only on the bases of accurate experimental data that the 2495 Chem. Rev. 1998, 98, 2495−2525

Thermodynamics of Calixarene Chemistry.

Turning the volume down on heavy metals using tuned diatomite. A review of diatomite and modified diatomite for the extraction of heavy metals from water.

The solubility of 27 1:1 electrolytes in 1,2-dichloroethane and 25 1:1 electrolytes in 1,1-dichloroethane has been determined. Combination of the solubility values with association constants, and correction for activity coefficients by the extended Debye–Huckel theory, yields standard free energies of solution of the ionic species (M++ X–). From like data in water, free energies of transfer from water to the dichloroethanes have been calculated and have been split into single-ion values through the assumption that ΔGt°(Ph4P+, Ph4As+)=ΔGt°(Ph4B–). It is shown that the free energy of anions (Cl–, Br–, I– and ClO4–) in the dichloroethanes is much higher in value than in water and in dipolar approtic solvents (DMSO, DMF and MeCN). The free energy of most cations (Na+, K+, Rb+, Cs+, Me4N+, Et4N+, Pr4N+ and Bu4N+) is also higher in value in the dichloroethanes than in the dipolar approtic solvents. Both anions and cations are invariably higher in free energy by ∼1 kcal mol–1 in 1,1-dichloroethane than in 1,2-dichloroethane. It is concluded that the (Ph4P+, Ph4As+)=(Ph4B–) assumption yields single-ion free energies of transfer to or from the dichloroethanes that are chemically reasonable.

Solubility of electrolytes in 1,2-dichloroethane and 1,1-dichloroethane, and derived free energies of transfer

The interaction of lower rim calix(4)arene derivatives containing ester (1) and ketone (2) functional groups and bivalent (alkaline-earth, transition- and heavy-metal) cations has been investigated in various solvents (methanol, N,N-dimethylformamide, acetonitrile, and benzonitrile). Thus, 1 H NMR studies in CD 3 -OD, C 3 D 7 NO, and CD 3 CN show that the interaction of these ligands with bivalent cations (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Hg 2+ , Pb 2+ , Cd 2+ ) is only observed in CD 3 CN. These findings are corroborated by conductance measurements in these solvents including benzonitrile, where changes upon the addition of the appropriate ligand (1 or 2) to the metal-ion salt only occur in acetonitrile. Thus, in this solvent, plots of molar conductance against the ligand/metal cation ratio reveal the formation of 1:1 complexes between these ligands and bivalent cations. Four metal-ion complex salts resulting from the interaction of 1 and 2 with cadmium and lead, respectively, were isolated and characterized by X-ray crystallography. All four structures show an acetonitrile molecule sitting in the hydrophobic cavity of the ligand. The mode of interaction of the neutral guest in the cadmium(II) complexes differs from each other and from that found in the lead(II) complexes and provides evidence of the versatile behavior of acetonitrile in binding processes involving calix(4)arene derivatives. The thermodynamics of complexation of these ligands and bivalent cations in acetonitrile is reported. Thus, the selective behavior of 1 and 2 for bivalent cations is for the first time demonstrated. The role of acetonitrile in the complexation process in solution is discussed on the basis of 1 H NMR and X-ray crystallographic studies. It is suggested that the complexation of 1 and 2 with bivalent cations is likely to involve the ligand-solvent adducts rather than the free ligand. Plots of complexation Gibbs energies against the corresponding data for cation hydration show a selectivity peak which is explained in terms of the predominant role played by cation desolvation and ligand binding energy in complex formation involving metal cations and macrocycles in solution. A similar peak is found in terms of enthalpy suggesting that for most cations (except Mg 2+ ) the selectivity is enthalpically controlled. The ligand effect on the complexation process is quantitatively assessed. Final conclusions are given highlighting the role of the solvent in complexation processes involving calix(4)arene derivatives and metal cations.

Selective interaction of lower rim calix[4]arene derivatives and bivalent cations in solution. Crystallographic evidence of the versatile behavior of acetonitrile in lead(II) and cadmium(II) complexes.

Angela F. Danil de Namor

Papers

Thermodynamics of Calixarene Chemistry.

Turning the volume down on heavy metals using tuned diatomite. A review of diatomite and modified diatomite for the extraction of heavy metals from water.

Solubility of electrolytes in 1,2-dichloroethane and 1,1-dichloroethane, and derived free energies of transfer

Selective interaction of lower rim calix[4]arene derivatives and bivalent cations in solution. Crystallographic evidence of the versatile behavior of acetonitrile in lead(II) and cadmium(II) complexes.

Host properties of cyclodextrins towards anion constituents of antigenic determinants. A thermodynamic study in water and in N,N-dimethylformamide