Short Cl Research Articles

Bis[2,4-dichloro-6-(ethyl-imino-meth-yl)phenolato-κN,O]nickel(II).

In the title compound, [Ni(C9H8Cl2NO)2], the NiII ion lies on an inversion centre and is coordinated in a slightly distorted square-planar geometry by an N and an O atom from two symmetry-related bidentate 2,4-dichloro-6-(ethyl­imino­meth­yl)phenolate ligands. In the crystal structure, there are short Cl⋯Cl distances of 3.506 (1) and 3.350 (1) Å.

(E)-1-(2,4-Dichlorophenyl)-3-(1,3-diphenyl-1H-pyrazol-4-yl)prop-2-en-1-one

In the title mol­ecule, C24H16Cl2N2O, the dihedral angles between the pyrazole ring and its N- and C-bonded phenyl rings are 7.06 (10) and 53.15 (10)°, respectively. The dihedral angle between the two pendant rings is 52.32 (10)°. The mol­ecule exists in a trans conformation with respect to the acyclic C=C bond. In the crystal, inversion dimers occur in which each mol­ecule is linked to the other by two C—H⋯O hydrogen bonds to the same acceptor O atom. There are also short Cl⋯Cl contacts [3.3492 (9) Å] and C—H⋯π inter­actions.

5-Chloro-1,3-dimethyl-1H-pyrazole-4-carbaldehyde

In the title compound, C6H7ClN2O, the mol­ecules are situated on mirror planes, so H atoms of two methyl groups were treated as rotationally disordered over two orientations each. The crystal packing exhibits weak inter­molecular C—H⋯O inter­actions and short Cl⋯N contacts of 3.046 (2) Å.

{4-[(2,4-Dichlorobenzoyloxy)methyl]-1-phenyl-1H-1,2,3-triazol-5-yl}methyl 2,4-dichlorobenzoate

In the title molecule, C24H15Cl4N3O4, the triazole ring makes dihedral angles of 72.02 (12), 81.60 (12) and 73.82 (11)°, respectively, with the adjacent phenyl ring and the two dichloro­benzene rings. In the crystal, a weak C—H⋯N inter­action, a short Cl⋯Cl contact [3.307 (2) Å] and a π–π stacking inter­action [centroid–centroid distance = 3.568 (4) Å] are observed. An intra­molecular C—H⋯O inter­action is also present.

2,3-Dichloro-pyridine.

The complete mol­ecule of the title compound, C5H3Cl2N, is generated by crystallographic twofold symmetry, which forces the pyridine N atom and the opposite C—H group to be statistically disordered. In the crystal, weak aromatic π–π stacking [centroid–centroid separation = 3.805 (4) Å and slippage = 1.704 Å] leads to [100] stacks of mol­ecules. Short Cl⋯Cl contacts [3.334 (3) Å] are also observed.

2,6-Dichloro-3-nitropyridine

The asymmetric unit of the title compound, C5H2Cl2N2O2, consists of two crystallographically independent mol­ecules. The pyridine ring in each mol­ecule is essentially planar, with maximum deviations of 0.004 (4) and 0.007 (4) Å. Short Cl⋯O [3.09 (3) and 3.13 (4) Å] and Cl⋯Cl [3.38 (12) Å] contacts were observed. No significant inter­molecular inter­actions were observed in the crystal packing.

Supramolecular structures constructed by 3-(2-amino-6-chloropyrimidin-4-yl)-1,1-dimethylprop-2-yn-1-ol monohydrate and 3-[2-amino-6-(3-hydroxy-3,3-dimethylprop-1-yn-1-yl)pyrimidin-4-yl]-1,1-dimethylprop-2-yn-1-ol

The molecule of 3-(2-amino-6-chloropyrimidin-4-yl)-1,1-dimethylprop-2-yn-1-ol monohydrate, C(9)H(10)ClN(3)O·H(2)O, (I), shows a very polarized molecular-electronic structure, while the polarization is slight for 3-[2-amino-6-(3-hydroxy-3,3-dimethylprop-1-yn-1-yl)pyrimidin-4-yl]-1,1-dimethylprop-2-yn-1-ol, C(14)H(17)N(3)O(2), (II). In the supramolecular structure of (I), a combination of hard N-H···N hydrogen bonds and soft C-H···N hydrogen bonds creates a molecular column. Aromatic π-π stackings between the pyrimidine rings stabilize the column with perpendicular and centroid-centroid distances of 3.283 (3) and 3.588 (1) Å, respectively. Short Cl···Cl contacts further link neighbouring molecular columns, creating a hydrophilic tube in which water molecules are fixed by various hydrogen bonds. In the packing of (II), a one-dimensional molecular chain is formed through several contacts involving hard N-H···O(N) and O-H···O(N) and soft C-H···O hydrogen bonds. Interchain O-H···O hydrogen bonds link the chains giving a two-dimensional stepped network. It is anticipated that study of the influence of hydrogen bonding on the patterns of base pairing and molecular packing in aminopyrimidine structures will shed significant light on nucleic acid structures as well as their functions.

2-[(E)-(2,4-Dichlorobenzylidene)amino]isoindoline-1,3-dione

In the title compound, C15H8Cl2N2O2, the mol­ecule adopts an E configuration about the central C=N double bond. The isoindoline ring is essentially planar, with a maximum deviation of 0.019 (2) Å. The dihedral angle between the isoindoline ring and the dichloro-substituted benzene ring is 6.54 (9)°. An intra­molecular C—H⋯O hydrogen bond occurs. A short Cl⋯Cl contact of 3.4027 (9) Å is present in the crystal structure. The crystal packing is further stabilized by weak C—H⋯π inter­actions.

2-(4-Chlorophenyl)-2-oxoethyl 2-methoxybenzoate

In the title compound, C16H13ClO4, the two benzene rings make a dihedral angle of 86.38 (8)°. In the crystal, inter­molecular C—H⋯O hydrogen bonds link the mol­ecules to form columns along the a axis. The mol­ecules are also stabilized by a π–π stacking inter­action, with a centroid–centroid distance of 3.7793 (10) Å between the inversion-related benzene rings.

Calcium-induced Folding of Intrinsically Disordered Repeat-in-Toxin (RTX) Motifs via Changes of Protein Charges and Oligomerization States

Ligand-induced disorder-to-order transition plays a key role in the biological functions of many proteins that contain intrinsically disordered regions. This trait is exhibited by so-called RTX (repeat-in-toxin) motifs found in many virulence factors secreted by numerous gram-negative pathogenic bacteria: RTX proteins are natively disordered in the absence of calcium but fold upon calcium binding. The adenylate cyclase toxin (CyaA) produced by Bordetella pertussis, the causative agent of whooping cough, contains ∼40 RTX motifs organized in five successive blocks separated by non-RTX flanking regions. This RTX domain mediates toxin binding to its eukaryotic cell receptor. We previously showed that the last block of the RTX domain, block V, which is critical for CyaA toxicity, exhibits the hallmarks of intrinsically disordered proteins in the absence of calcium. Moreover, the C-terminal flanking region of CyaA block V is required for its calcium-induced folding. Here, we describe a comprehensive analysis of the hydrodynamic and electrophoretic properties of several block V RTX polypeptides that differ in the presence and/or length of the flanking regions. Our results indicate that the length of the C-terminal flanking region not only controls the calcium-induced folding but also the calcium-induced multimerization of the RTX polypeptides. Moreover, we showed that calcium binding is accompanied by a strong reduction of the net charge of the RTX polypeptides. These data indicate that the disorder-to-order transition in RTX proteins is controlled by a calcium-induced change of the polypeptide charges and stabilized by multimerization.

3-Chloropyridin-2-amine

In the title compound, C5H5ClN2, a by-product in the synthesis of ethyl 2-(3-chloro­pyridin-2-yl)-5-oxopyrazolidine-3-carboxyl­ate, the amine groups form inter­molecular hydrogen-bonding associations with pyridine N-atom acceptors, giving centrosymmetric cyclic dimers. Short inter­molecular Cl⋯Cl inter­actions [3.278 (3) Å] also occur.

Charge Density Analysis of Heterohalogen (Cl···F) and Homohalogen (F···F) Intermolecular Interactions in Molecular Crystals: Importance of the Extent of Polarizability

Experimental charge density distribution in 2-chloro-4-fluorobenzoic acid and 4-fluorobenzamide has been carried out using high resolution X-ray diffraction data collected at 100 K using Hansen-Coppens multipolar formalism of electron density. These compounds display short Cl···F and F···F interactions, respectively. The experimental results are compared with the theoretical charge densities using theoretical structure factors obtained from periodic quantum calculation at the B3LYP/6-31G** level. The topological features were derived from Bader’s “atoms in molecules” (AIM) approach. Intermolecular Cl···F interaction in 2-chloro-4-fluorobenzoic acid is attractive in nature (type II interaction) while the nature of F···F interactions in 4-fluorobenzamide shows indication of a minor decrease in repulsion (type I interaction), though the extent of polarization on the fluorine atom is arguably small.

(E)-1-(4-Chlorobenzylidene)thiosemicarbazide

In the crystal of the title compound, C8H8ClN3S, mol­ecules are connected by N—H⋯S hydrogen bonds into strips parallel to the (112) planes and running along [10]. One of the amino H atoms is not involved in a classical hydrogen bond. In addition, there is a rather short inter­molecular Cl⋯S distance of 3.3814 (5) Å.

Nature of Cl···Cl Intermolecular Interactions via Experimental and Theoretical Charge Density Analysis: Correlation of Polar Flattening Effects with Geometry

The experimental charge density distribution in three compounds, 2-chloro-3-quinolinyl methanol, 2-chloro-3-hydroxypyridine, and 2-chloro-3-chloromethyl-8-methylquinoline, has been obtained using high-resolution X-ray diffraction data collected at 100 K based on the aspherical multipole modeling of electron density. These compounds represent type I (cis), type I (trans), and type II geometries, respectively, as defined for short Cl···Cl interactions. The experimental results are compared with the theoretical charge densities using theoretical structure factors obtained from a periodic quantum calculation at the B3LYP/6-31G** level. The topological features derived from the Bader's theory of atoms in molecules (AIM) approach unequivocally suggest that both cis and trans type I geometries show decreased repulsion, whereas type II geometry is attractive based on the nature of polar flattening of the electron density around the Cl atom.

2,3-Dibromo-1,3-bis(4-chlorophenyl)propan-1-one

In the title compound, C15H10Br2Cl2O, the terminal benzene rings make a dihedral angle of 31.1 (2)° with each other. In the crystal, mol­ecules are stacked along the a axis and consolidated by C—H⋯π inter­actions. Short Cl⋯Cl [3.1140 (17) Å] and Br⋯Cl [3.4565 (13) Å] contacts are observed.

Isopropyl 4-chloro-3,5-dinitrobenzoate

In the title compound, C10H9ClN2O6, the two nitro groups and the ester group are oriented with respect to the benzene ring at dihedral angles of 49.42 (13)/87.61 (13) and 9.10 (10)°, respectively. In the crystal structure, a weak C—H⋯O inter­action is present. A short Cl⋯O contact of 2.972 (2) Å is also observed in the crystal structure.

4-Amino-3,5-dichlorobenzenesulfonamide

In the title compound, C6H6Cl2N2O2S, the O atoms of the sulfonamide group lie on one side of the benzene ring and the amino group lies on the opposite side. An inter­molecular N—H⋯Cl inter­action occurs. In the crystal, adjacent mol­ecules are linked by N—H⋯O hydrogen bonds, forming a three-dimensional structure with supporting π–π stacking inter­actions [centroid–centroid distance = 3.7903 (12) Å]. A short Cl⋯Cl contact [3.3177 (10) Å] also occurs.

4,5,6,7-Tetra-chloro-N-(2-fluoro-phen-yl)phthalimide.

In the title compound, C14H4Cl4FNO2, the benzene ring and the phthalimide plane are nearly planar, the maximum deviations being 0.005 (2) and 0.010 (2) Å, respectively, but the mol­ecule as a whole is not planar: the dihedral angle between the two planar ring systems is 68.06 (10)°. A short Cl⋯O contact of 2.914 (2) Å exists in the crystal structure.

N2-(4-Chlorobenzylidene)-4-nitrobenzene-1,2-diamine

In the title compound, C13H10ClN3O2, the dihedral angle between the two benzene rings is 3.61 (6)°. In the crystal structure, mol­ecules are linked by weak inter­molecular C—H⋯O hydrogen bonds, forming layers parallel to the bc plane. Short inter­molecular Cl⋯Cl contacts [3.491 (1) Å] are also observed.

4,5,6,7-Tetra-chloro-2-(2,2,2-trifluoro-eth-yl)isoindoline-1,3-dione.

In the title compound, C10H2Cl4F3NO2, the isoindoline ring system is almostplanar, the maximum atomic deviation being 0.064 (2) Å. The C—C bond of the ethyl­ene group is twisted with respect to the isoindoline plane by a dihedral angle of 59.58 (12)°. In the crystal, weak inter­molecular C—H⋯F hydrogen bonding links the mol­ecules into supra­molecular chains running along the a axis. A short inter­molecular Cl⋯O contact of 2.950 (3) Å is also observed.