Crystal structure and Hirshfeld surface analysis of poly[[di-µ3-glycine-lithium] perchlorate].

In the title salt, {[Li(C2H5NO2)2]ClO4} n , the Li+ cation is coordinated by four carboxyl-ate oxygen atoms of the glycine mol-ecules with a distorted tetra-hedral geometry. The glycine exists in a zwitterionic form with protonated amino and deprotonated carboxyl-ate groups. In the crystalline state, the title salt is primarily stabilized by inter-molecular N-H⋯O and Cα-H⋯O inter-actions which inter-connect various units. Hirshfeld surface analysis indicates that the inter-molecular H⋯O/O⋯H inter-actions are the most important contributors to the crystal packing.

Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium bromide 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate.

In the title mol-ecular salt, C9H12NO4+·Br-·C9H11NO4, one of the dopa mol-ecules is in the cationic form in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged, while the second dopa mol-ecule is in the zwitterion form. The Br- anion occupies a special position and is located on a twofold rotation axis. The two dopa mol-ecules are inter-connected by short O-H⋯O hydrogen bonds. In the crystal, the various units are linked by O-H⋯O, N-H⋯Br and N-H⋯O hydrogen bonds, forming a three-dimensional framework. The title compound was refined as an inversion twin with an absolute structure parameter of 0.023 (8).

Crystal structure and Hirshfeld surface analysis of 1-carb-oxy-2-(3,4-di-hydroxy-phen-yl)ethan-1-aminium chloride 2-ammonio-3-(3,4-di-hydroxy-phen-yl)propano-ate: a new polymorph of l-dopa HCl and isotypic with its bromide counterpart.

The title mol-ecular salt, C9H12NO4+·Cl-·C9H11NO4, is isotypic with that of the bromide counterpart [Kathiravan et al. (2016 ▸). Acta Cryst. E72, 1544-1548]. The title salt is a second monoclinic polymorph of the l-dopa HCl structure reported earlier in the monoclinic space group P21 [Jandacek & Earle (1971 ▸). Acta Cryst. B27, 841-845; Mostad & Rømming (1974 ▸). Acta Chemica Scand. B28, 1161-1168]. In the title compound, monoclinic space group I2, one of the dopa mol-ecules has a positive charge with a protonated α-amino group and the α-carb-oxy-lic acid group uncharged, while the second dopa mol-ecule has a neutral charge, the α-amino group is protonated and the α-carb-oxy-lic acid is deprotonated. In the previously reported form, a single dopa mol-ecule is observed in which the α-amino group is protonated and the α-carb-oxy-lic acid group is uncharged. The invariant and variations of various types of inter-molecular inter-actions present in these two forms of dopa HCl structures are discussed with the aid of two-dimensional fingerprint plots.

Crystal structure of poly[[µ2-di-aqua-di-aqua-µ2-l-proline-κ(2) O:O'-strontium] dibromide].

In the title coordination polymer, {[Sr(C5H9NO2)(H2O)4]Br2} n , the proline mol-ecule exists in a zwitterionic form with one of the ring C atoms disordered over two sites [site-occupancy factors = 0.57 (6):0.43 (6)]. The Sr(II) ion is nine-coordinated by six water O atoms, two monodentate and two µ2-bridging, and three carboxyl-ate O atoms of the proline ligands, with two bridging [Sr-O range = 2.524 (4)-2.800 (5) Å]. In the crystal, there is no direct inter-action between the proline mol-ecules. However, the proline and water mol-ecules associate with the bromide counter-anions through a number of inter-molecular O-H⋯Br and N-H⋯Br hydrogen-bonding inter-actions, giving a three-dimensional supra-molecular structure.

Crystal structure of catena-poly[[[tri-aqua-strontium]-di-µ2-glycinato] dibromide].

In the title coordination polymer, {[Sr(C2H5NO2)2(H2O)3]Br2} n , the Sr(2+) ion and one of the water mol-ecules are located on twofold rotation axes. The alkaline earth ion is nine-coordinated by three water O atoms and six O atoms of the carboxyl-ate groups of four glycine ligands, two in a chelating mode and two in a monodentate mode. The glycine mol-ecule exists in a zwitterionic form and bridges the cations into chains parallel to [001]. The Br(-) counter-anions are located between the chains. Inter-molecular hydrogen bonds are formed between the amino and carboxyl-ate groups of neighbouring glycine ligands, generating a head-to-tail sequence. Adjacent head-to-tail sequences are further inter-connected by inter-molecular N-H⋯Br hydrogen-bonding inter-actions into sheets parallel to (100). O-H⋯Br and O-H⋯O hydrogen bonds involving the coordinating water mol-ecules are also present, consolidating the three-dimensional hydrogen-bonding network.

(E)-N'-(4-Chlorobenzylidene)-, (E)-N'-(4-bromobenzylidene)- and (E)-N'-[4-(diethylamino)benzylidene]- derivatives of 4-hydroxybenzohydrazide.

The 4-chloro- [C(14)H(11)ClN(2)O(2), (I)], 4-bromo- [C(14)H(10)BrN(2)O(2), (II)] and 4-diethylamino- [C(18)H(21)N(3)O(2), (III)] derivatives of benzylidene-4-hydroxybenzohydrazide, all crystallize in the same space group (P2(1)/c), (I) and (II) also being isomorphous. In all three compounds, the conformation about the C=N bond is E. The molecules of (I) and (II) are relatively planar, with dihedral angles between the two benzene rings of 5.75 (12) and 9.81 (17)°, respectively. In (III), however, the same angle is 77.27 (9)°. In the crystal structures of (I) and (II), two-dimensional slab-like networks extending in the a and c directions are formed via N-H···O and O-H···O hydrogen bonds. The molecules stack head-to-tail via π-π interactions involving the aromatic rings [centroid-centroid distance = 3.7622 (14) Å in (I) and 3.8021 (19) Å in (II)]. In (III), undulating two-dimensional networks extending in the b and c directions are formed via N-H···O and O-H···O hydrogen bonds. The molecules stack head-to-head via π-π interactions involving inversion-related benzene rings [centroid-centroid distances = 3.6977 (12) and 3.8368 (11) Å].

Dichloridobis(4-fluoro-aniline-κN)zinc.

In the title compound, [ZnCl(2)(C(6)H(6)FN)(2)], the Zn(II) atom has a slightly distorted tetra-hedral geometry, being coordinated by the N atoms of two 4-fluoro-aniline mol-ecules and the two Cl(-) anions. The two benzene rings are almost perpendicular to one another, making a dihedral angle of 89.96 (13)°. In the crystal, mol-ecules are linked via pairs of N-H⋯Cl hydrogen bonds, forming chains propagating along the b axis. These chains are in turn linked via a second pair of N-H⋯Cl hydrogen bonds, forming a two-dimensional network parallel to the ab plane. The title compound crystallizes in the space group Pca2(1) and exhibits weak second harmonic generation (SHG) properties.

N,N'-Bis(4-chloro-benzyl-idene)-3,3'-dimeth-oxy-biphenyl-4,4'-diamine.

The title compound, C(28)H(22)Cl(2)N(2)O(2), crystallized with two independent mol-ecules (A and B) in the asymmetric unit. The two mol-ecules differ essentially in the orientation of the outer aromatic rings. These dihedral angles are 56.07 (13) and 27.62 (15) Šfor mol-ecules A and B, respectively. In the crystal, A mol-ecules are related as centrosymmetric pairs through a weak π-π inter-action [centroid-centroid distance = 3.6959 (15) Å]. There are also a number of inter-molecular C-H⋯O, C-H⋯N and C-H⋯π inter-actions present.