Effect of nucleants in photothermally assisted crystallization.

Laser-induced crystallization is emerging as a promising technique to crystallize biomolecules like amino acids and proteins. The use of external materials as nucleants and novel seeding methods open new paths for protein crystallization. We report here the results of experiments that explore the effect of nucleants on laser-based crystallization of microlitre droplets of small molecules, amino acids, and proteins. The role of parameters like solute concentration, droplet volume, type and size of the nucleant, and laser power, are systematically investigated. In addition to crystallization of standard molecules like NaCl, KCl, and glycine, we demonstrate the crystallization of negatively (l-histidine), and positively (l-aspartic acid) charged amino acids and lysozyme protein. Single crystal X-ray diffraction and Raman spectroscopy studies unequivocally indicate that the nucleants do not alter the molecular structure of glycine, hydrogen bonding patterns, and packing. Localized vaporization of the solvent near the nucleant due to photothermal heating has enabled us to achieve rapid crystallization - within 3 s - at laser intensities of 0.1 MW cm-2, significantly lower than those reported earlier, with both saturated and unsaturated solutions. The outcome of the current experiments may be of utility in tackling various crystallization problems during the formation of crystals large enough to perform X-ray crystallography.

Synthesis, anticancer, structural, and computational docking studies of 3-benzylchroman-4-one derivatives.

A series of 3-Benzylchroman-4-ones were synthesized and screened for anticancer activity by MTT assay. The compounds were evaluated against two cancerous cell lines BT549 (human breast carcinoma), HeLa (human cervical carcinoma), and one noncancerous cell line vero (normal kidney epithelial cells). 3b was found to be the most active molecule against BT549 cells (IC50 = 20.1 µM) and 3h against HeLa cells (IC50 = 20.45 µM). 3b also exhibited moderate activity against HeLa cells (IC50 = 42.8 µM). The molecular structures of 3h and 3i were solved by single crystal X-ray crystallographic technique. Additionally, the molecular docking studies between the tumour suppressor protein p53 with the lead compound 3h, which exhibited better anticancer activity against HeLa cells was examined.

N'-Benzyl-idene-2-chloro-N-(4-chloro-phen-yl)acetohydrazide.

In the title compound, C15H12Cl2N2O, the atoms not making up the chloro-benzene ring are approximately coplanar (r.m.s. deviation = 0.073 Å). The dihedral angle between these 13 atoms and the chloro-benzene ring is 67.37 (10)°. The C=O and Csp (2)-Cl groups are almost eclipsed [Cl-C-C=O = -6.5 (3)°]. In the crystal, C(6) chains linked by C-H⋯O hydrogen bonds result in [100] chains.

(1Z)-1-(1-Benzo-furan-2-yl)ethanone oxime.

The title compound, C10H9NO2, is almost planar (r.m.s. deviation for the non-H atoms = 0.027 Å) and the conformation across the C=N bond is syn. Further, the O atom of the benzo-furan ring is syn to the CH3 group in the side chain. In the crystal, mol-ecules are linked into C(3) chains propagating in [010] by O-H⋯N hydrogen bonds.

Bis(2-bromo-benz-yl) ether.

In the title compound, C14H12Br2O, the dihedral angle between the aromatic rings is 2.7 (3)° and the Br atoms lie on the same side of the mol-ecule. No inter-molecular inter-actions occur in the crystal beyond van der Waals contacts.

2-Nitro-benzyl methane-sulfonate.

In the title compound, C8H9NO5S, the dihedral angle between the benzene ring and the nitro group is 5.86 (15)° and the C-C-O-S group adopts an anti conformation [torsion angle = -168.44 (15)°]. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, generating a three-dimensional network.

4-(4-Methyl-phen-yl)-2-(prop-2-yn-1-yl)phthalazin-1(2H)-one.

In the title compound, C18H14N2O, the dihedral angle between the methyl-phenyl ring and the phthalazone ring system (r.m.s. deviation = 0.034 Å) is 53.93 (9)°. In the crystal, mol-ecules are connected by C-H⋯O hydrogen bonds, forming chains along [101]. The chains are linked by π-π inter-actions [centroid-centroid distance 3.6990 (12) Å], forming layers parallel to (10-1).

(E)-N'-[4-(Di-methyl-amino)-benzyl-idene]-2-(4-methyl-phen-oxy)acetohydrazide.

In the title compound, C18H21N3O2, the dihedral angle between the benzene rings is 68.85 (11)°. In the crystal, the mol-ecules are linked by C-H⋯O and N-H⋯O hydrogen bonds, as well as weak C-H⋯π contacts, forming a three-dimensional supra-molecular architecture.

6,7-Dimeth-oxy-2,4-di-phenyl-quinoline.

In the title structure of the title compound, C23H19NO2, two conformationally similar mol-ecules (A and B) comprise the asymmetric unit. The dihedral angle between phenyl rings bridged by the quinoline moiety are 76.25 (8)° in mol-ecule A and 70.39 (9)° in mol-ecule B. In the crystal, the independent mol-ecules are connected by C-H⋯O hydrogen bonds and the resulting dimeric aggregates are linked by π-π [inter-centroid distance = 3.7370 (8) Å] and C-H⋯π inter-actions, forming a three-dimensional architecture.

1-[5-Methyl-1-(4-nitro-phen-yl)-1H-1,2,3-triazol-4-yl]ethanone.

The asymmetric unit of the title compound, C11H10N4O3, contains two independent mol-ecules in which the benzene rings make dihedral angles of 38.3 (2) and 87.1 (2)° with respect to the triazole rings. In the crystal, the mol-ecules are linked by C-H⋯O hydrogen bonds, forming chains along [021]. Further, weak C-O⋯π [3.865 (5) Å, 83.8 (3)°] and N-O⋯π [3.275 (5) and 3.240 (6) Å, 141.8 (4) and 102.8 (3)°] inter-actions are observed.

4-[Amino-(3-methyl-phen-yl)methyl-idene]-2-(3-methyl-phen-yl)-1H-imidazol-5(4H)-one ethanol hemisolvate.

In the title compound, C(18)H(17)N(3)O·0.5C(2)H(5)OH, the dihedral angles between the central imidazole rings and the pendant benzene rings are 42.06 (15) and 2.01 (16)° in one asymmetric mol-ecule and 47.91 (15) and 7.31 (14)° in the other. An intra-molecular N-H⋯O hydrogen bond occurs in each imidazole mol-ecule. In the crystal, the components are connected by O-H⋯N, N-H⋯O, C-H⋯O and N-H⋯N hydrogen bonds. Weak aromatic π-π inter-actions also occur [shortest centroid-centroid distance = 3.684 (3) Å].

5-[(4-Benzyl-1H-1,2,3-triazol-1-yl)meth-yl]-5H-dibenzo[b,f]azepine.

In the title compound, C24H20N4, the azepine ring adopts a boat conformation and the dihedral angle between the benzene rings fused to it is 57.95 (8)°. The bond-angle sum at the azepine N atom is 346.6°, indicating a significant deviation from planarity. The triazole ring subtends a dihedral angle of 71.45 (10)° with the terminal phenyl group. A weak intra-molecular C-H⋯Na (a = azepine) inter-action occurs, which closes an S(6) ring.

1-{3-(4-Methyl-phen-yl)-5-[5-(2-nitro-phen-yl)furan-2-yl]-4,5-di-hydro-1H-pyrazol-1-yl}ethanone.

In the title compound, C22H19N3O4, the dihedral angle between the furan and pyrazole rings is 82.73 (19)° while the dihedral angles between the furan and pyrazole rings and their attached benzene rings are 31.93 (18) and 1.88 (18)°, respectively. In the crystal, inversion dimers linked by pairs of C-H⋯O hydrogen bonds generate R 2 (2)(16) loops. In addition, weak C-H⋯π and aromatic π-π stacking [minimum centroid-centroid distance = 3.5374 (17) Å] inter-actions are observed.

4-Chloro-2-(2-chloro-benzoyl)phenol.

In the title mol-ecule, C13H8Cl2O2, the dihedral angle between the benzene rings is 74.53 (9)°. An intra-molecular O-H⋯O hydrogen bond leading to a S(6) ring is observed. In the crystal, the mol-ecules are connected into a three-dimensional network by C-H⋯O and π-π [inter-centroid distance = 3.6254 (10) Å] inter-actions.

1-(3-Oxo-3-phenyl-prop-yl)piperidinium chloride.

In the title salt, C14H20NO(+)·Cl(-), the piperidine ring adopts a chair conformation. In the crystal, the cations and anions are linked by classical N-H⋯Cl hydrogen bond and weak C-H⋯Cl and C-H⋯O hydrogen bonds; the C-H⋯O hydrogen bonds exhibit R 2 (2)(14) ring motifs while the C-H⋯Cl hydrogen bonds link the mol-ecules into chains along the a-axis direction. π-π stacking is observed between parallel phenyl rings of adjacent cations, the centroid-centroid distance being 3.8164 (15) Å.

4-(4,5-Diphenyl-1H-imidazol-2-yl)-N,N-di-methyl-aniline.

The asymmetric unit of the title compound, C23H21N3, consists of two symmetry-independent and conformationally different mol-ecules [the comparable dihedral angles between the imidazole ring and the three benzene rings being 38.5 (2)/61.5 (3)/3.37 (17) and 45.8 (2)/36.01 (19)/46.94 (17)°]. In the crystal, inter-molecular imidazole N-H⋯N hydrogen-bonding inter-actions give a one-dimensional chain extending along [101].

5-(Prop-2-yn-1-yl)-5H-dibenzo[b,f]azepine: ortho-rhom-bic polymorph.

In the title ortho-rhom-bic polymorph (space group Iba2), C17H13N, the dihedral angle between the benzene rings is 55.99 (10)° and the azepine ring adopts a boat conformation. In the crystal, mol-ecules are linked by C-H⋯π contacts. The previously-reported polymorph [Yousuf et al. (2012 ▶). Acta Cryst. E68, o1101] crystallizes in the monoclinic system (space group P21/c) with two mol-ecules in the asymmetric unit.

4-[5-(4-Benzoyl-oxyphen-yl)-1,2,4-oxa-diazol-3-yl]phenyl benzoate.

In the title compound, C28H18N2O5, the dihedral angle between the terminal benzoate rings is 20.67 (12)°. The central oxadiazole ring is almost coplanar with its two benzene ring substituents, making dihedral angles of 4.80 (16) and 5.82 (16)°. In the crystal, pairs of C-H⋯O hydrogen bonds form inversion dimers with R 2 (2)(40) ring motifs. The structure also features C-H⋯O, C-H⋯π and π-π inter-actions [centroid-centroid separation = 3.695 (4) Å].

A triclinic polymorph of (E)-2-(4-iso-butyl-phen-yl)-N'-[1-(4-nitro-phen-yl)ethyl-idene]propano-hydrazide.

The asymmetric unit of the triclinic polymorph of the title compound, C21H25N3O3, consists of two mol-ecules, whereas for the monoclinic polymorph Z' = 1 [Fun et al. (2009 ▶). Acta Cryst. E65, o445]. The two mol-ecules exhibit an E configuration with respect to the C=N bond. The mol-ecules are linked into dimers by N-H⋯O and C-H⋯O hydrogen bonds forming R 2 (2)(8) ring motifs. In addition, π-π inter-actions occur between nitro-phenyl groups [minimum centroid-centroid distance 3.940 (2) Å], stacking the molecules along the ac plane.

Methyl 4-(tri-fluoro-meth-yl)-1H-pyrrole-3-carboxyl-ate.

In the title compound, C7H6F3NO2, all the non-H atoms except for one of the F atoms lie on a crystallographic mirror plane. In the crystal, the mol-ecules are linked into inversion dimers by pairs of C-H⋯F inter-actions, forming R 2 (2)(10) loops. These dimers are connected into C(6) chains along [001] through N-H⋯O hydrogen bonds. Aromatic π-π stacking inter-actions [centroid-centroid separation = 3.8416 (10) A°] connect the mol-ecules into a three-dimensional network.