Determination of enantiomeric excess of leucine and valine by X-ray powder diffraction

Two amino acids, leucine and valine, were studied by X-ray powder diffraction (XRPD). The linear correlations between intensity of racemate (decrease) or enantiomer (increase) and enantiomeric excesses were observed in each case

Supplementary data for the article: Adhikary, J.; Chakraborty, A.; Dasgupta, S.; Chattopadhyay, S. K.; Kruszynski, R.; Trzesowska-Kruszynska, A.; Stepanović, S.; Gruden-Pavlović, M.; Swart, M.; Das, D. Unique Mononuclear Mn II Complexes of an End-off Compartmental Schiff Base Ligand: Experimental and Theoretical Studies on Their Bio-Relevant Catalytic Promiscuity. Dalton Transactions 2016, 45 (31), 12409–12422. https://doi.org/10.1039/c6dt00625f

Supplementary material: [https://doi.org/10.1039/c6dt00625f]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2294

Unique mononuclear Mn-II complexes of an end-off compartmental Schiff base ligand: experimental and theoretical studies on their bio-relevant catalytic promiscuity

Three new mononuclear manganese(II) complexes, namely [Mn(HL)(2)]center dot 2ClO(4) (1), [Mn(HL)(N(CN)(2)) (H2O)(2)]center dot ClO4 (2) and [Mn(HL)(SCN)(2)] (3) [LH = 4-tert-butyl-2,6-bis-[(2-pyridin-2-yl-ethylimino)-methyl]-phenol], have been synthesized and structurally characterized. An "end-off" compartmental ligand (LH) possesses two symmetrical compartments with N2O binding sites but accommodates only one manganese atom instead of two due to the protonation of the imine nitrogen of one compartment. Although all three complexes are mononuclear, complex 1 is unique as it has a 1 : 2 metal to ligand stoichiometry. The catalytic promiscuity of complexes 1-3 in terms of two different bio-relevant catalytic activities namely catecholase and phenoxazinone synthase has been thoroughly investigated. EPR and cyclic voltametric studies reveal that radical formation rather than metal centered redox participation is responsible for their catecholase-like and phenoxazinone synthase-like catalytic activity. A computational approach suggests that imine bond bound radical generation rather than phenoxo radical formation is most likely responsible for the oxidizing properties of the complexes.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3657

On construction of lead coordination polymers derived from <i>N</i>′-(2-hydroxybenzylidene)nicotinohydrazide via covalent and non-covalent interactions

<div><p>Lead(II) and lead(IV) coordination polymers with <i>N</i>′-(2-hydroxybenzylidene)nicotinohydrazide have been synthesized from lead(II) salts, and subsequently characterized by solid-state UV‒Vis‒IR spectroscopy, thermal analysis, and powder and single-crystal X-ray diffraction techniques. The compounds crystallize in the same space group but differ in the oxidation state of lead, composition, conformation of the organic ligand, its charge, and tautomeric form. The coordination network is propagated by the hydrazone anion in the lead(II) metal-organic framework <i>catena</i>-[(<i>μ</i>₂-<i>N</i>-((2-oxidophenyl)methylidene)pyridine-3-carbohydrazonoato-<i>N</i>:<i>N</i>′,<i>O</i>,<i>O</i>′)-lead(II) (<b>1</b>) and by nitrate in a one-dimensional lead(IV) coordination polymer <i>catena</i>-(<i>μ</i>₂-nitrato-O,O)-(nitrato-O,O′)-(salicylaldehydeisonicotinoylhydrazonato-N,N′,O)-lead(IV) nitrate (<b>2</b>). The formation of metal-organic framework of <b>1</b> is affected by Pb···<i>π</i> interactions.</p></div

Solvent-Free and Catalysis-Free Approach to the Solid State in Situ Growth of Crystalline Isoniazid Hydrazones

The isonicotinoylhydrazones and their coordination compounds have antibacterial, antifungal, antitubercular, antitumor, and anticonvulsant activities. A typical method employed in the preparation of isonicotinoylhydrazones involves the usage of the volatile organic solvents during the condensation reaction between isonicotinic acid hydrazide and carbonyl compounds. It has been shown that the solvent-free technique can be applied to obtain crystalline compounds. Reaction of isoniazid with carbonyl compound under solvent-free conditions results in microcrystalline solid state isonicotinoylhydrazones. The influence of solvent effect on the mechanism of condensation reaction was evaluated and the most significant intermediates and transition states, in the gas phase and in the presence of water and methanol were resolved. The solvent has positive effect on the reaction mechanism, but the organic solvent is unnecessary during the synthesis of crystalline isonicotinoylhydrazones derived from aldehydes. Mixing solid/liquid reactants together without additional solvent reduce the time of reaction and can be used to obtain microcrystalline compounds, which are synthesized for example to evaluate biological properties

Solvent-Free and Catalysis-Free Approach to the Solid State in Situ Growth of Crystalline Isoniazid Hydrazones

The isonicotinoylhydrazones and their coordination compounds have antibacterial, antifungal, antitubercular, antitumor, and anticonvulsant activities. A typical method employed in the preparation of isonicotinoylhydrazones involves the usage of the volatile organic solvents during the condensation reaction between isonicotinic acid hydrazide and carbonyl compounds. It has been shown that the solvent-free technique can be applied to obtain crystalline compounds. Reaction of isoniazid with carbonyl compound under solvent-free conditions results in microcrystalline solid state isonicotinoylhydrazones. The influence of solvent effect on the mechanism of condensation reaction was evaluated and the most significant intermediates and transition states, in the gas phase and in the presence of water and methanol were resolved. The solvent has positive effect on the reaction mechanism, but the organic solvent is unnecessary during the synthesis of crystalline isonicotinoylhydrazones derived from aldehydes. Mixing solid/liquid reactants together without additional solvent reduce the time of reaction and can be used to obtain microcrystalline compounds, which are synthesized for example to evaluate biological properties

Copper(II) 2,2-Bis(Hydroxymethyl)Propionate Coordination Compounds with Hexamethylenetetramine: From Mononuclear Complex to One-Dimensional Coordination Polymer

Three new copper coordination compounds derived from 2,2-bis(hydroxymethyl)propionic acid (dmpa) and hexamethylenetetramine (hmta) were obtained and their crystal structures were determined. The stoichiometry of the reagents applied in the syntheses reflects the metal to ligand molar ratio in the formed solid products. Due to the multiple coordination modes of the used ligands, wide structural diversity was achieved among synthesized compounds, i.e., mononuclear [Cu(dmp)2(hmta)2(H2O)] (1), dinuclear [Cu2(dmp)4(hmta)2] (2), and 1D coordination polymer [Cu2(dmp)4(hmta)]n (3). Their supramolecular structures are governed by O—H•••O and O—H•••N hydrogen bonds. The compounds were characterized in terms of absorption (UV-Vis and IR) and thermal properties. The relationships between structural features and properties were discussed in detail. Owing to discrepancies in the coordination mode of a dmp ligand, bidentate chelating in 1, and bidentate bridging in 2 and 3, there is a noticeable change in the position of the bands corresponding to the stretching vibrations of the carboxylate group in the IR spectra. The differences in the structures of the compounds are also reflected in the nature and position of the UV-Vis absorption maxima, which are located at lower wavelengths for 1