Alkylated, naphthalimide-containing ionic compounds with rich thermotropic behaviour and nonlinear optical response

Chemical functionalization of π-conjugated units plays a key role in fine tuning their supramolecular organizations and functions. Herein, five 1,8-naphthalimide derivatives were prepared where the naphthalimide moiety was attached to...

Synthesis and Comprehensive Study of Quaternary-Ammonium-Based Sorbents for Natural Gas Sweetening

The present study provides a solvent-free organic synthesis of quaternary ammonium salts: bis(2-hydroxyethyl)dimethylammonium taurate ([BHEDMA][Tau]) and bis(2-hydroxyethyl)dimethylammonium acetate ([BHEDMA][OAc]). These ionic compounds are promising materials for carbon dioxide capture processes, as mono sorbents, supplemental components in the conventional process of chemical absorption, and in the combined membrane approach for improving sorption efficiency. The synthesized compounds were characterized by 1H NMR and FT-IR spectroscopies and elemental analysis. Afterward, the sorption properties of the compounds were evaluated using the inverse gas chromatography (IGC) method, and their thermodynamic parameters were calculated in the temperature range of 303.15–333.15 K. The enthalpy change (∆sH) was less than 80 kJ·mol−1, indicated by the physical nature of sorption and also proved by FT-IR. Henry’s law constant in regard to carbon dioxide at 303.15 K was equal to 4.76 MPa for [BHEDMA][Tau], being almost 2.5 lower than for [BHEDMA][OAc] (11.55 MPa). The calculated carbon dioxide sorption capacity for [BHEDMA][Tau] and [BHEDMA][OAc] amounted to 0.58 and 0.30 mmol·g−1, respectively. The obtained parameters are comparable with the known solid sorbents and ionic liquids used for CO2 capture. However, the synthesized compounds, combining the advantages of both alkanolamines and ionic liquids, contain no fluorine in their structure and thus match the principles of environmental care.

Ionic and Enzymatic Multiple-Crosslinked Nanogels for Drug Delivery

Both ionic and enzymatic crosslink are efficient strategies for constructing network materials of high biocompatibility. Here chitosan was modified firstly and then crosslinked by these two methods for complementary advantages. The preparation methods and ionic crosslinkers can regulate the size and uniformity of the multiple-crosslinked nanogels. The multiple-crosslinked nanogels with the smallest size and the best uniformity was selected for the drug delivery. The drug-loading content and encapsulation efficiency were up to 35.01 and 66.82%, respectively. Their release behaviours are correlated with the pH value and the drug dosage. In general, the lower pH value and the lower drug dosage promoted the drug release. With the assistance of several kinetic models, it is found that drug diffusion plays a preponderant role in drug release, while polymer relaxation has a subtle effect. The multiple-crosslink resulting from ionic compounds and enzymes may provide a new perspective on developing novel biocompatible materials.

Solution Chemistry

Solution Chemistry discusses the solution process, properties of solutions, saturated solutions and solubility, and factors affecting the solubility of solutes. Several quantitative measures of concentration are explained: percent by mass, parts per million, molarity, molality, normality and mole fraction. A systematic method of solving solubility problems is reviewed and several illustrative examples provided. Solubility is described as an equilibrium process with emphasis on the effect of temperature and pressure on the solubility of solute. The relationship between solubility and temperature for ionic compounds is illustrated by solubility curves. Henry’s law, which expresses the relationship between the pressure of a gas and its solubility, is discussed.

Solubility and Complex-Ion Equilibria

Solubility and Complex-Ion Equilibria broadens the previous chapter’s coverage of equilibria to include aqueous systems containing two or more solutes of slightly soluble ionic compounds and the formation of metal complexes in solution. Solubility equilibria which allow quantitative predictions of how much of a compound will dissolve under given conditions are covered. The meaning of the solubility product constant (K sp) and how to calculate it from molar solubility values is presented. Also discussed is determination of molar solubility from K sp. Calculations demonstrate how to predict the formation of a precipitate by comparing the ion product or solubility quotient (Q) with K sp. Formation constants of complex ions and calculations involving complex ion equilibria are explained.

Oxidation and Reduction Reactions

Oxidation and Reduction Reactions deals with chemical reactions involving electron transfer. It begins with oxidation numbers and their applications in naming complex molecular or ionic compounds. Rules for assigning oxidation numbers and how to calculate the oxidation number of any atom in a compound or ion are described. Extensive coverage is given to oxidizing and reducing agents, including how to identify them in a given process. Half-cell reactions are defined. Balancing redox equations with the oxidation number method and the half-reaction method are emphasized. The chapter concludes with an overview of oxidation-reduction titration and calculations based on redox titration analysis.

Oxidoborates Templated by Cationic Nickel(II) Complexes and Self-Assembled from B(OH)3

Several oxidoborates, self-assembled from B(OH)3 and templated by cationic Ni(II) coordination compounds, were synthesized by crystallization from aqueous solution. These include the ionic compounds trans-[Ni(NH3)4(H2O)2][B4O5(OH)4].H2O (1), s-[Ni(dien)2][B5O6(OH)4]2 (dien = N-(2-aminoethyl)-1,2-ethanediamine (2), trans-[Ni(dmen)2(H2O)2] [B5O6(OH)4]2.2H2O (dmen = N,N-dimethyl-1,2-diaminoethane) (3), [Ni(HEen)2][B5O6(OH)4]2 (HEen = N-(2-hydroxyethyl)-1,2-diaminoethane) (4), [Ni(AEN)][B5O6(OH)4].H2O (AEN = 1-(3-azapropyl) -2,4-dimethyl-1,5,8-triazaocta-2,4-dienato(1-)) (5), trans-[Ni(dach)2(H2O)2][Ni(dach)2] [B7O9(OH)5]2.4H2O (dach = 1,2-diaminocyclohexane) (6), and the neutral species trans-[Ni(en)(H2O)2{B6O7(OH)6}].H2O (7) (en = 1,2-diaminoethane), and [Ni(dmen)(H2O){B6O7(OH)6}].5H2O (8). Compounds 1–8 were characterized by single-crystal XRD studies and by IR spectroscopy and 2, 4–7 were also characterized by thermal (TGA/DSC) methods and powder XDR studies. The solid-state structures of all compounds show extensive stabilizing H-bond interactions, important for their formation, and also display a range of gross structural features: 1 has an insular tetraborate(2-) anion, 2–5 have insular pentaborate(1-) anions, 6 has an insular heptaborate(2-) anion (‘O+’ isomer), whilst 7 and 8 have hexaborate(2-) anions directly coordinated to their Ni(II) centers, as bidentate or tridentate ligands, respectively. The Ni(II) centers are either octahedral (1–4, 7, 8) or square-planar (5), and compound 6 has both octahedral and square-planar metal geometries present within the structure as a double salt. Magnetic susceptibility measurements were undertaken on all compounds.