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Imine formation in aqueous solution of kanamycin A with pyridoxal 5'-phosphate and other aldehydes was studied by potentiometry, NMR spectroscopy and computational chemistry. It was found that imines are formed with yields near 100 % at pH 7 in equimolar reactant ratio. In order to identify the kanamycin amino groups involved in the reaction, a NMR spectroscopic study was conducted. The structures of possible imines formed between kanamycin and FURAN or PLP were optimized by molecular mechanics with the OPLS-2005 force field. The 1H NMR spectra were calculated at the DFT-GIAO B3LYP/6-31G(d) level of theory for all structures and compared with the experimentally observed spectra. From these results a probable structure of the imines was proposed. The results obtained in this work show that kanamycin has the ability to form imine derivatives in high yields due to its anion recognition properties. Copyright © 2012 John Wiley & Sons, Ltd.

Nine mononuclear diorganotin(IV) dithiocarbamate complexes 1–9 with 19-, 20- and 21-membered macrocyclic structures were synthesized from dimethyl, di-n-butyl, and diphenyltin(IV) dichloride and three bis-dithiocarbamate ligands derived from secondary bis-amines having aromatic spacer groups. All compounds were characterized by elemental analysis, mass spectrometry, and spectroscopic methods (IR and 1H, 13C, and 119Sn NMR). Additionally, quantum chemical DFT calculations were performed for the dimethyltin(IV) derivatives in order to model the molecular structures. For one compound series the NMR spectra showed a concentration-dependent behavior in solution, which was analyzed in detail and permitted to postulate the existence of an equilibrium with the corresponding [2+2] macrocycles.