42982-87-6Relevant articles and documents
Quaternary salts of alkaloids
Makarevich,Gubin
, p. 473 - 476 (2006)
New biologically active quaternary salts of the alkaloids ajmaline, quinine, hyoscyamine, codeine, and strychnine were synthesized. So-called separable conformers were observed among the ajmaline derivatives.
Modulation of charge transfer by: N -alkylation to control photoluminescence energy and quantum yield
Turley, Andrew T.,Danos, Andrew,Prlj, Antonio,Monkman, Andrew P.,Curchod, Basile F. E.,McGonigal, Paul R.,Etherington, Marc K.
, p. 6990 - 6995 (2020)
Charge transfer in organic fluorophores is a fundamental photophysical process that can be either beneficial, e.g., facilitating thermally activated delayed fluorescence, or detrimental, e.g., mediating emission quenching. N-Alkylation is shown to provide straightforward synthetic control of the charge transfer, emission energy and quantum yield of amine chromophores. We demonstrate this concept using quinine as a model. N-Alkylation causes changes in its emission that mirror those caused by changes in pH (i.e., protonation). Unlike protonation, however, alkylation of quinine's two N sites is performed in a stepwise manner to give kinetically stable species. This kinetic stability allows us to isolate and characterize an N-alkylated analogue of an 'unnatural' protonation state that is quaternized selectively at the less basic site, which is inaccessible using acid. These materials expose (i) the through-space charge-transfer excited state of quinine and (ii) the associated loss pathway, while (iii) developing a simple salt that outperforms quinine sulfate as a quantum yield standard. This N-alkylation approach can be applied broadly in the discovery of emissive materials by tuning charge-transfer states.
Quinine based ionic liquids: A tonic for base instability
McNeice, Peter,Vallana, Federico M.F.,Coles, Simon J.,Horton, Peter N.,Marr, Patricia C.,Seddon, Kenneth R.,Marr, Andrew C.
, (2019/11/26)
Six basic ionic liquids were synthesised from the natural molecule quinine, including one room temperature ionic liquid. The thermal properties were studied and the basicity analysed by Hammett measurements. The properties are discussed in relation to the crystal structure of one of the salts, [C4Qn][NTf2] (2c) and electron density models generated using Spartan. The ionic liquids were shown to catalyse the Knoevenagel condensation of Malononitrile and Benzaldehyde.
Synthesis and characterization of chiral ionic liquids based on quinine, L-proline and L-valine for enantiomeric recognition
Sintra, Tania E.,Gantman, Mikhail G.,Ventura, Sónia P.M.,Coutinho, Jo?o A.P.,Wasserscheid, Peter,Schulz, Peter S.
, p. 410 - 416 (2019/03/28)
The separation of enantiomers remains a major challenge for the pharmaceutical industry. In this work, eight chiral ionic liquids (CILs) directly derived from the ‘chiral pool’ were synthesized and characterized in order to develop enantioselective systems, for the chiral resolution. According to their chiral cations, three different groups of CILs were prepared, namely based on quinine, L-proline and L-valine, and their enantiomeric recognition ability evaluated. For that purpose the diastereomeric interactions between a racemic mixture of Mosher's acid sodium salt and each CIL were studied using 19F NMR spectroscopy. The remarkable chemical shift dispersion induced by some CILs demonstrates their potential application in chiral resolution. Additionally the optical rotation, thermophysical properties and ecotoxicity against the marine bacteria Aliivibrio fischeri of these chiral ionic liquids were addressed.
