10-Methyl-9-(phenoxycarbonyl)acridinium trifluoromethanesulfonates bearing alkyl substituents at the benzene ring were synthesized, purified, and identified. In the reaction with OOH(-) in basic aqueous media, the cations of the compounds investigated were converted to electronically excited 10-methyl-9-acridinone, whose relaxation was accompanied by chemiluminescence (CL). The kinetic constants of CL decay, relative efficiencies of light emission, chemiluminescence quantum yields, and resistance toward alkaline hydrolysis were determined experimentally under various conditions. The mechanism of CL generation is considered on the basis of thermodynamic and kinetic parameters of the reaction steps predicted at the DFT level of theory. The chemiluminescence efficiency is the result of competition of the electrophilic center at C(9) between nucleophilic substitution by OOH(-) or OH(-) and the ability of the intermediates thus formed to decompose to electronically excited 10-methyl-9-acridinone. Identification of stable and intermediate reaction products corroborated the suggested reaction scheme. The results obtained, particularly the dependency of the "usefulness" parameter, which takes into account the CL quantum yield and the susceptibility to hydrolysis, on the cavity volume of the entity removed during oxidation, form a convenient framework within which to rationally design chemiluminescent 10-methyl-9-(phenoxycarbonyl)acridinium cations.

In this work, ionic liquids (ILs) are proposed as candidates for extractive removal of 2-phenylethanol (PEA) (well-known rose-like aroma compound) from its aqueous solutions. Four ILs based on different cations, namely, 1-hexyl-1-methylpyrrolidinium, 1-hexyl-1,4-diaza [2.2.2]­bicyclooctanium, 1-(2-methoxyethyl)-3-methylimidazolium, and 1-(2-methoxyethyl)-1-methylpyrrolidinium, and bis­(trifluoromethylsulfonyl)­imide anion were under study. Thermodynamic data at ambient pressure are presented for pure ILs (including temperature-dependent density data and thermal characterization with DSC) as well as for binary systems {IL + water} and ternary systems {IL + PEA + water}. For the binary systems, (liquid + liquid) equilibrium phase diagrams were determined in temperature range T = (280–370) K. For ternary systems, (liquid + liquid) equilibrium was investigated at T = 308.15 K. An impact of the cation structure on the studied properties is established. The data obtained are discussed in terms of the selectivity and distribution ratio of separation of PEA from water. Modeling of the measured properties with two modern chemical engineering thermodynamic tools, namely, nonrandom two liquid (NRTL) model and perturbed-chain statistical associating fluid theory (PC-SAFT), is demonstrated. The NRTL model is applied in a purely correlative fashion in the case of both binary and ternary systems. In turn, the predictive capacity of the PC-SAFT is tested for ternary (liquid + liquid) equilibrium using the combining rules corrections transferred from binary data.

Diflavonol is a molecule that can exist in neutral or anionic form and in several tautomeric forms in ground and excited states. Absorption and emission spectroscopy combined with theoretical calculations have shown that only one tautomer of neutral diflavonol exists in the ground state, but two exist in the excited state. In the latter case, one is the tautomer originating from the ground state tautomer, which exists in strongly protic solvents, the other is the phototautomer occurring in weakly protic or aprotic solvents as a result of the intramolecular transfer of one proton. The OH groups present in diflavonol and involved in weak intramolecular hydrogen bonds exhibit a proton-donating ability reflected by the experimental values of acidity constants or theoretical enthalpies and free energies of proton detachment. The electronically excited molecule is a relatively strong acid when it loses one proton. With increasing basicity of the medium, monoanionic and dianionic forms occur which exhibit spectral characteristics and an emission ability different from those of neutral diflavonol. These interesting features of diflavonol open up possibilities for the analytical use of the compound and its application as a spectral probe sensitive to the properties of liquid phases.

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The 9-cyano-10-methylacridinium cation possesses an electrophilic center at the carbon atom in position (9) susceptible to the addition of anions. The addition of OOH(-) to this cation--in weakly acidic, neutral, or alkaline media--initiates processes leading to the formation of electronically excited 10-methyl-9-acridinone, which deactivates by light emission. The effect of changes in reactant concentrations and pH on emission decay with time, as well as other features of the accompanying chemiluminescence, were established. Calculations carried out at the semiempirical and density functional theory level demonstrated that initial addition of OOH(-) and subsequent processes lead either to the elimination of OCNH (in weakly acidic and neutral media) or OCN(-) (in alkaline media) and that their exothermicity is sufficiently high to generate electronically excited 10-methyl-9-acridinone. On the other hand, primary addition of OH(-) to C(9) in alkaline media initiates the conversion of the cation to the nonexcited 10-methyl-9-acridinone. This relatively rapid process influences to a substantial extent the intensity of the chemiluminescence. The prospects for the analytical application of 9-cyano-10-methylacridinium salts are briefly outlined.

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