The 2:1 cocrystal of benzamide and pentafluorobenzoic acid.
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Biomedical subjects
Tadeusz Połoński
Publications and source records attributed to Tadeusz Połoński.
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. A slow boat-to-boat ring inversion (DeltaG(++) = 24.1 +/- 0.1 kcal mol(-1)) causes racemization of (+)-1 in solution as manifested by a gradual decrease of the CD spectrum whereas, (-)-2 is configurationally stable at these conditions. The analysis of the CD spectra of the title compounds showed that the n-pi* Cotton effect signs are determined by the helicity of the skewed benzamide and thiobenzamide chromophores. The solid-state structures of the racemic and homochiral forms of 1 and 2 show different self-assembly patterns: the racemate (+/-)-1 prefers the cyclic R(2)(2)(8) hydrogen bond motif, whereas the crystalline DMSO solvates of (+/-)-1 and (+)-1 consist of 1D homochiral hydrogen-bonded assemblies generated by the C(6) motif. In the case of dithionolactams (+/-)-2 and (-)-2 two types of 1D networks were observed: in the racemate they are generated by the centrosymmetric R(2)(2)(8) and R(2)(2)(12) hydrogen bond motifs, whereas the molecules in the homochiral crystals are connected solely with use of the strongly nonplanar R(2)(2)(8) motif.
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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...N hydrogen bonds that generate a centrosymmetric R2(2)(8) motif. The second, adopting a Z conformation, is not engaged in any hydrogen bonding and is flattened, the dihedral angle between the benzene and pyridine rings being 12.07 (7) degrees. This conformation is stabilized by an intramolecular C-H...N interaction [C...N = 2.9126 (19) A, H...N = 2.31 A and C-H...N = 120 degrees ].
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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...O[double bond]C hydrogen bonds involving the anti NH amide H atoms, thus generating a C(4) motif. This network is additionally stabilized by a weak N-H...pi interaction between the syn-oriented amide H atom and the aromatic ring of a neighbouring molecule. The distance between the H atom and the ring centroid is 2.50 A. The amide group and the aryl moiety are nearly perpendicular, forming an intramolecular dihedral angle of 84.69 (6) degrees.
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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. These networks are further organised into densely packed layers assembled through weaker C-H...O interactions. Analysis of the intermolecular interactions in these complexes led us to the synthesis of N,N'-bis(2-pyridyl)-2,2'-oxybis(aminobenzene) (5) which acts as a tritopic receptor of the carboxylic group and forms exclusively 2:1 complexes with dicarboxylic acids.
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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. The component molecules of these complexes are connected via conventional N-H.O and O-H.N hydrogen bonds, leading to the formation of an infinite one-dimensional network generated by the cyclic motif R(2)(2)(9). The anilic acid molecules in both crystal structures lie around inversion centres and the observed bond lengths are typical for the neutral molecule. Nevertheless, the pyridine C-N-C angles [120.9 (2) and 120.13 (17) degrees for complexes (I) and (II), respectively] point to a partial H-atom transfer from anilic aicd to the bispyridylamine, and hence to H-atom disorder in the OHN bridge. The bispyridylamine molecules of (I) and (II) also lie around inversion centres and exhibit disorder of their central phenyl rings over two positions.
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(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. The molecules are joined by strong N-H.O and weak C-H.O hydrogen bonds into infinite chains.
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