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Geometries of benzene complexes with C6F5X, C6H5X, and CF3X (X is I, Br, Cl, and F) were optimized, and their interaction energies were evaluated. The CCSD(T) interaction energies at the basis set limit (Eint) of C6F5X (X is I, Br, Cl, and F) with benzene were −3.24, −2.88, −2.31, and −0.92 kcal mol-1. Eint of C6H5X (X is I, Br, and Cl) with benzene were −2.31, −1.97, and −1.48 kcal mol-1. The fluorination of halobenzenes slightly enhances the attraction. Eint of CF3X (X is I, Br, Cl, and F) with benzene (−3.11, −2.74, −2.22, and −0.71 kcal mol-1) were very close to Eint of corresponding C6F5X with benzene. In contrast to the halogen bond of iodine and bromine with pyridine (n-type halogen bond acceptor) where the main cause of the attraction is the electrostatic interactions, that of halogen bond with benzene (p-type acceptor) is dispersion interaction. In the halogen bonds with p-type acceptors (halogen−π interactions), the electrostatic interactions and induction interactions are small. The overall orbital-orbital interactions are repulsive. The directionality of halogen bonds with p-type acceptors is very weak, owing to the weak electrostatic interactions, in contrast to the strong directionality of the halogen bonds with n-type acceptors and hydrogen bonds. [ABSTRACT FROM AUTHOR]

Electrospraying is an electrochemical technique in which fine droplets are generated in the balance of electrostatic repulsion and surface tension. In this paper, we applied electrospray in the liquid phase in a new reactor system in which positively and negatively charged fine droplets collided with each other between two electrospray nozzles submerged in a solvent. When the hydrolysis of alkylchlorosilanes was carried out using this reactor, not only did the reaction rates increase, but also, the product distribution changed: the kinetically favored cyclotrimer was predominantly formed over the thermodynamically favored cyclotetramer. The yield of cyclotrimer increased with an increase in the voltage between the needles. Since the droplet size decreases with an increase in the applied voltage, the result suggests that the formed cyclotrimer could diffuse into the solvent before it was converted to the thermodynamically favored cyclotetramer. [ABSTRACT FROM AUTHOR]

Thermodynamics of the formation of coordination polymers (CPs) or metal-organic frameworks (MOFs) has not been focused on, whereas many CPs or MOFs have been synthesized in a solution. With a view of separating Nd3+ and Dy3+ in an aqueous solution, we demonstrate that crystallization of the CPs of Nd3+ and Dy3+ based on dibutyl phosphoric acid (Hdbp) can be thermodynamically described; crystallization yields of [Ln(dbp)3] (Ln = Nd or Dy) complex are predicted well using a simple calculation, which takes the apparent solubility products (Kspa) for [Ln(dbp)3] and the acid dissociation constant of Hdbp into account. The Kspa values of [Nd(dbp)3] and [Dy(dbp)3] are experimentally determined to be (1.3 ± 0.1) × 10-14 and (2.9 ± 0.4) × 10-18 M4, respectively, at 20 °C. The ratio of these Kspa values, that is, ca. 4500, is significantly larger than the ratio of the solubility products for inorganic salts of Nd3+ and Dy3+. Therefore, Nd3+ and Dy3+ are selectively crystallized in an aqueous solution via the formation of CPs. Under optimized conditions, Dy3+ crystallization is preferable, whereas Nd3+ remains in the solution phase, where the ratio of the Dy molar content to the total metal content (i.e., Nd + Dy) in the crystal is higher than 0.9. The use of acids, such as HCl or HNO3, has no practical impact on the separation in an aqueous solution. [ABSTRACT FROM AUTHOR]

Coordination polymers can be attractive ion exchange materials because of their crystallinity and semiflexibility, which are rather opposing properties, and play integral and synergistic roles in introducing unique ion-exchange behavior. In this paper, Ln3+/Ce3+ exchange (Ln3+ = Nd3+, Gd3+, Dy3+, or Lu3+) in a coordination polymer, [Ce(dehp)3], based on di(2-ethylhexyl)phosphoric acid (Hdehp) is studied by distribution coefficient measurements, ion-exchange isotherms, Kielland plot analysis, and morphology observation. The ion-exchange selectivity is in the order Nd3+ < Gd3+ < Dy3+ < Lu3+ when a small amount of Ln3+ is loaded, but Lu3+ ≈ Nd3+ < Gd3+ ≈ Dy3+ for a high loading ratio. The Kielland plot suggests that a steric effect is involved in the reactions, which becomes stronger in the order of Nd3+/Ce3+ < Gd3+/Ce3+ < Dy3+/Ce3+ < Lu3+/Ce3+ for exchange systems. This trend is attributable to the differences in the ionic sizes between an incoming Ln3+ and original Ce3+. Scanning electron microscopy observations reveal the generation of a new phase via the Ln3+/Ce3+ exchange. Such a phenomena results from solid–solid transformation, rather than dissolution–recrystallization. The small steric strain in the Nd3+/Ce3+ system leads to the formation of a Nd3+-and-Ce3+ solid-solution, whereas the morphological change is possibly restrained by the strong strain caused by loaded Ln3+ with an ionic size significantly smaller than the original Ce3+. [ABSTRACT FROM AUTHOR]