Clustering of biphenyl oxamide ions by chiral recognition.

Gels created by self-assembly of small organic molecules are dynamic soft materials that have unique properties and demanding characterization. Four chiral gelators, with two valinol- or leucinoloxamido arms attached to the 2,2'-positions of the proatropisomeric biphenyl group were chosen to show that the electrospray ionization mass spectrometry (ESI-MS) could be used to differentiate the gelation feature of the chiral compounds 1-4 and also to shed light on the gelation processes. By inspecting the gelation of several solvents, we showed that 1 (R, R) proved to be the most efficient gelator, forming the largest observable assemblies in the gas phase. The strong intermolecular H-bonds hold single-charged assemblies consisting of up to five monomer units detectable by ESI MS. Enantiomer 1 (R, R) is a good gelator due to favorable intramolecular interactions that remain preserved in the gas phase. Compound 3 (meso) does not have gelator properties and detected signals of larger assemblies in the gas phase. So, the detected signals correlate with the conformations of the studied compounds. MS could be used to elucidate the preferential type of noncovalent interaction due to the chiral recognition. The study paves a novel way to investigate the influence of chirality on the molecular assembly and consequently macroscopic properties and functions of materials.

Counting the truxillines-11 or more, the question is now.

Truxillines are a group of tropane alkaloids present in coca leaves that are formed by photochemical dimerization of cinnamoylcocaine(s). Proportion of different truxilline forms present in cocaine serves as its geographical, manufacture, and storage "fingerprint"; thus, the quantitative determination of truxilline content represents one of the powerful methods of analysis and characterization of cocaine samples. Contrary to the statements repeatedly presented in the literature, namely, that there exist exactly 11 truxillines and that every single truxilline is diastereomer of any other, here we show that, in fact, a total of 15 truxillines exist, which can be divided in two structurally isomeric groups-five mutually diastereomeric truxillates and 10 mutually diastereomeric truxinates.

Supramolecular ionogels prepared with bis(amino alcohol)oxamides as gelators: ionic transport and mechanical properties.

Supramolecular ionogels composed of an ionic liquid (IL) immobilized in a network of self-assembled low-molecular weight molecules have been attracting considerable interest due to their applicability as smart electrolytes for various electrochemical applications. Despite considerable scientific effort in this field, the design of a mechanically and thermally stable yet highly conductive supramolecular ionogels still remains a challenge. In this article, we report on a series of novel ionogels of three ILs containing different cations (imidazolium/pyrrolidinium) and anions (tetrafluoroborate/bis(trifluoromethylsulfonyl)imide) prepared using (S,S)-bis(amino alcohol)oxamides as gelators. The gelation behaviour of the oxamide compound depends strongly on the structural features of amino alcohol substituents. Among them, (S,S)-bis(valinol)oxamide (capable of gelling all three ILs) and (S,S)-bis(phenylalaninol)oxamide (capable of gelling ILs based on bis(trifluoromethylsulfonyl)imide with a concentration as low as ≈0.2 wt%) are highly efficient. All investigated supramolecular ionogels retain the high ionic conductivity and ion diffusion coefficients of their parent IL, even for high gelator concentrations. Further, at low temperatures we observe an enhancement of the ionic conductivity in ionogels of (i) 1-butyl-3-methylimidazolium tetrafluoroborate which can be attributed to specific interactions between ionic species and gelator molecules and (ii) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide due to inhibited crystallization. In contrast to ionic transport, mechanical strength of the ionogels shows a wider variation depending on the type and concentration of the oxamide gelator. Among all the ionogels, that of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide prepared with 1 wt% (S,S)-bis(phenylalaninol)oxamide exhibits the best performance: optical transparency, stability over a wide temperature range, high conductivity and high mechanical strength. The results presented here reveal the versatile nature of bis(amino alcohol)oxamides as gelators and their high potential for preparing functionalized IL-based materials.

Correction: Supramolecular ionogels prepared with bis(amino alcohol)oxamides as gelators: ionic transport and mechanical properties.

[This corrects the article DOI: 10.1039/D0RA01249A.].

Mechanochemical Catalytic Transfer Hydrogenation of Aromatic Nitro Derivatives.

Mechanochemical ball milling catalytic transfer hydrogenation (CTH) of aromatic nitro compounds using readily available and cheap ammonium formate as the hydrogen source is demonstrated as a simple, facile and clean approach for the synthesis of substituted anilines and selected pharmaceutically relevant compounds. The scope of mechanochemical CTH is broad, as the reduction conditions tolerate various functionalities, for example nitro, amino, hydroxy, carbonyl, amide, urea, amino acid and heterocyclic. The presented methodology was also successfully integrated with other types of chemical reactions previously carried out mechanochemically, such as amide bond formation by coupling amines with acyl chlorides or anhydrides and click-type coupling reactions between amines and iso(thio)cyanates. In this way, we showed that active pharmaceutical ingredients Procainamide and Paracetamol could be synthesized from the respective nitro-precursors on milligram and gram scale in excellent isolated yields.

One-pot mechanosynthesis of aromatic amides and dipeptides from carboxylic acids and amines.

Environmentally friendly one-pot synthesis of amides, bis-amides and dipeptides by mechanochemical carbodiimide-mediated coupling of carboxylic acids and amines is described; high reaction yields and simple aqueous work-up allow for the clean, practical and fast preparation of a variety of compounds containing the amide bond from readily accessible reagents.

N-(4-Methyl-benz-yl)-3-nitro-anilinium chloride.

The cation of the title compound, C(14)H(15)N(2)O(2) (+)·Cl(-), comprises two almost ideally planar systems, 3-nitro-phenyl (r.m.s. deviation = 0.0117 Å) and 4-methyl-phenyl (r.m.s. deviation = 0.238 Å), separated by the central C-N bond, and with their mean planes inclined to one another by 61.36 (5)°. In the crystal, hydrogen-bonded chains running along [001] are generated by connecting neighbouring mol-ecules via N-H⋯Cl hydrogen bonds and consolidated by C-H⋯Cl and C-H⋯O inter-actions. Within these chains, fused R(2) (1)(6) and R(3) (2)(10) ring motifs are formed. Parallel chains are further linked into a two-dimensional network parallel to (100) via C-H⋯O inter-actions.

N-(4-Methyl-benz-yl)-3-nitro-aniline.

In the title compound, C(14)H(14)N(2)O(2), the angle between the mean plane of the N-methyl-3-nitro-aniline system (r.m.s. deviation = 0.0185 Å) and the p-tolyl unit is 89.79 (4)°. In the crystal, hydrogen-bonded chains running along [10-1] are generated by the linking of neighbouring mol-ecules via N-H⋯O and C-H⋯O hydrogen bonds involving the 3-nitro-aniline systems and forming R(2) (2)(8) motifs.

N-Benzyl-3-nitro-aniline.

The mol-ecule of the title compound, C(13)H(12)N(2)O(2), has a bent conformation with a torsion angle about the central C-N bond of 72.55 (19)°. In the crystal, the mol-ecules are connected via classical N-H⋯O and non-classical C-H⋯O hydrogen bonds into chains along [10[Formula: see text]]. The dihedral angle between the ring planes is 86.0 (6)°.

Dicyclo-hexyl-ammonium 2-methoxy-benzoate.

The asymmetric unit of the title compound, C(12)H(24)N(+)·C(8)H(7)O(3) (-), contains one dicyclo-hexyl-ammonium cation and one 2-methoxy-benzoate anion. Two cations and two anions are linked together to form a four-ion cluster through a set of N-H⋯O hydrogen bonds. Weak C-H⋯O hydrogen bonds connect the clusters into chains that are stacked along the crystallographic c axis.

Propane-2,2-diyl di-p-phenyl-ene dibenzoate.

The V-shaped propeller-like mol-ecule of the title compound, C(29)H(24)O(4), does not exhibit crystallographic twofold symmetry as the two benzene rings are twisted asymmetrically with respect to both the central propyl plane and the benzo-yloxy groups [4.6 (2), 43.6 (2)° and 45.07 (8), 69.50 (8)°]. In the crystal structure, centrosymmetrically related mol-ecules form a dimer through C-H⋯π inter-molecular inter-actions.