Effect of Aromatic System Expansion on Crystal Structures of 1,2,5-Thia- and 1,2,5-Selenadiazoles and Their Quaternary Salts: Synthesis, Structure, and Spectroscopic Properties.

Rational manipulation of secondary bonding interactions is a crucial factor in the construction of new chalcogenadiazole-based materials. This article reports detailed experimental studies on phenanthro[9,10-][1,2,5]chalcogenadiazolium and 2,1,3-benzochalcogenadiazolium salts and their precursors. The compounds were synthesized, characterized employing NMR and UV-Vis spectroscopy.

Helicity discrimination in N,N'-dibenzoyl-1,2,3,4,7,8,9,10-octahydro-1,10-phenanthrolines and their thiono- and selenocarbonyl analogues by inclusion complexation with chiral diols.

X-ray crystallographic analysis of the title compounds revealed that they assume a folded helical conformation of an approximate C2 symmetry in the solid state. Dithioamide 5b, diselenoamide 5c and monoselenoamide 5d were resolved to enantiomers by inclusion crystallization with optically active diols (TADDOLs). The absolute configuration of the guest molecules in the complexes 5b·6a, 5c·6a and 5d·6a was assigned as P.

Helicity discrimination in diaryl dichalcogenides generated by inclusion complexation with chiral hosts.

Inclusion complexation of diaryl dichalcogenides with either cholic acid or chiral diols results in their helicity discrimination and an induction of optical activity that can be detected by solid-state CD measurements.

Enantiomeric resolution of N,N'-dimethyldithiodianthranilide through diastereomeric silver(I) complex. Circular dichroism spectra, racemization barrier, and molecular self-assembly.

Planar chiral N,N'-dimethyldithiodianthranilide (2b) was resolved to enantiomers through a diasteromeric complex with easily accessible silver(I) (1S)-camphorosulfonate (3). The (-)-2b enantiomer was assigned the R absolute configuration from the X-ray crystal structure of the silver complex. The compound is configurationally stable and its racemization occurs through boat-to-boat ring inversion (DeltaG(double dagger) = 36.

Conformational properties, chiroptical spectra, and molecular self-assembly of 2,3-piperazinodiones and their dithiono analogues.

A family of chiral cyclic oxamides was prepared by the condensation of optically active 1,2-diamines with diethyl oxalate. Thionation of the products with Lawesson's reagent afforded a series of chiral 2,3-piperazinedithiones. Molecular geometries of the title compounds were studied with the use of quantum mechanical DFT calculations and were compared to the X-ray crystallographic results.

Supramolecular structures of bis-thionooxalamic acid esters derived from (+/-)-cyclohexane-1,2-diamine and (+/-)-1,2-diphenylethylenediamine.

The bis-thionooxalamic acid esters trans-(+/-)-diethyl N,N'-(cyclohexane-1,2-diyl)bis(2-thiooxamate), C14H22N2O4S2, and (+/-)-N,N'-diethyl (1,2-diphenylethane-1,2-diyl)bis(2-thiooxamate), C22H24N2O4S2, both consist of conformationally flexible molecules which adopt similar conformations with approximate C2 rotational symmetry. The thioamide and ester parts of the thiooxamate group are significantly twisted along the central C-C bond, with the S=C-C=O torsion angles in the range 30.94 (19)-44.

N,N'-Bis(2-pyridyl)benzene-1,2-diamine.

Hindered rotation about the partial double C-N bonds between the amine and pyridine moieties in the title molecule, C16H14N4, results in two different conformations of the N-aryl-2-aminopyridine units. One, assuming an E conformation, is involved in a pair of N-H..

Planar chiral dianthranilide and dithiodianthranilide molecules: optical resolution, chiroptical spectra, and molecular self-assembly.

Planar chiral dianthranilide (1) was resolved to enantiomers with use of (-)-(1S,4R)-camphanoyl chloride as a chiral derivatizing agent. The (+)-1 enantiomer was assigned the S absolute configuration from the X-ray crystal structure of its N,N'-dicamphanoyl derivative. Optical resolution of dithionodianthranilide (2) was accomplished by inclusion crystallization with (R,R)-1,2-diaminocyclohexane, and the X-ray structure of the corresponding adduct revealed the (-)-2stereoisomer has the R configuration.

2,4,6-Trimethylbenzamide.

The crystal structure of the title compound, C(10)H(13)NO, displays an infinite one-dimensional network composed of primary amide molecules connected by N-H...

Creation of hydrogen bonded 1D networks by co-crystallization of N,N'-bis(2-pyridyl)aryldiamines with dicarboxylic acids.

The preparation and crystal structures of fourteen complexes of N,N'-bis(2-pyridyl)aryldiamines with dicarboxylic acids and two complexes with squaric acid are reported. The recognition between the carboxylic acids and the 2-aminopyridine units occurs through the formation of the cyclic R(2)2 (8) hydrogen bond motif, whereas squaric acid creates the analogous R(2)2 (9) motif. In the 1:1 complexes the cyclic motifs generate infinite hydrogen-bonded 1D networks with the alternating component molecules.

Hydrogen-bonded one-dimensional networks in 1:1 complexes of N,N'-bis(2-pyridyl)aryldiamines with anilic acid.

The 1:1 complexes N,N'-bis(2-pyridyl)benzene-1,4-diamine-anilic acid (2,5-dihydroxy-1,4-benzoquinone) (1/1), C(16)H(14)N(4).C(6)H(4)O(4), (I), and N,N'-bis(2-pyridyl)biphenyl-4,4'-diamine-anilic acid (1/1), C(22)H(18)N(4).C(6)H(4)O(4), (II), have been prepared and their solid-state structures investigated.

(S)-trans-cyclohexane-1,2-dicarboximide.

The molecule of the title compound, C(8)H(11)NO(2), contains a strained bicyclic system with a significantly twisted imide chromophore. The five-membered ring fragment containing the imide function is strongly puckered and adopts a half-chair conformation. The six-membered ring has a slightly distorted chair conformation.

Enantioselective Inclusion Complexation of N-Nitrosopiperidines by Steroidal Bile Acids.

N-nitrosamines, whose chirality is solely due to hindered rotation about the N-N bond, are enantioselectively enclathrated by the crystal host matrices of cholic or deoxycholic acid, as evidenced by X-ray crystallography (see structure in picture) and CD spectra.

Structure, Conformation, and Stereodynamics of N-Nitroso-2,4-diaryl-3-azabicyclo[3.3.1]nonanes and N-Nitroso-2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-ones(1).

The variable temperature (1)H, (13)C, and (19)F NMR spectra were measured for the title N-nitrosamines. The observed unusually low N-N rotation barriers (12-15 kcal/mol) result from a significant deviation of the nitrosamino system from planarity. A pyramidal character of the amino nitrogen was confirmed by the X-ray crystal structures of two compounds and by bathochromic shifts of the n-pi absorption bands in the UV spectra.