Synthesis, characterization and biological activity of Cu(II), Zn(II) and Re(I) complexes derived from S-benzyldithiocarbazate and 3-acetylcoumarin.

Cu(II), Zn(II) and Re(I) complexes have been synthesized with the Schiff base, N'-[1-(2-oxo-2H-chromen-3-yl)-ethylidene]-hydrazinecarbodithioic acid benzyl ester (SBCM-H) which was prepared by condensation of S-benzyldithiocarbazate and 3-acetylcoumarin. The metal complexes were characterized on the basis of various physico-chemical and spectroscopic techniques including elemental analysis and electrochemical studies, and FT-IR, UV-Vis, NMR, EPR and mass spectroscopy. The Schiff base was found to behave as a bidentate ligand coordinating with Cu(II) and Zn(II) in the thiolate form with 1:2 metal to ligand stoichiometry. Crystals suitable for X-ray diffractometry (XRD) were obtained from the reaction of ReCl(CO)5 with SBCM-H forming a centrosymmetric dimeric complex Re2L2(CO)6 linked by Re-S-Re bridges, where S is the thiolate sulfur of the N,S-bidentate ligand. This Re(I) complex is the first metal carbonyl complex with a bidentate dithiocarbazate ligand to have been characterized by XRD. Cytotoxicity assays revealed enhancement of the bioactivity of SBCM-H upon complexation. Both Cu(II) and Re(I) complexes are found to be active against human breast adenocarcinoma cancer cell lines MDA-MB-231 and MCF-7. TOC diagram.

Conjugation of a new series of dithiocarbazate Schiff base Copper(II) complexes with vectors selected to enhance antibacterial activity.

A new series of six Schiff bases derived from S-methyldithiocarbazate (SMDTC) and S-benzyldithiocarbazate (SBDTC) with methyl levulinate (SMML, SBML), levulinic acid (SMLA, SBLA), and 4-carboxybenzaldehyde (SM4CB, SB4CB) were reacted with copper(II), producing complexes of general formula ML2 (M = Cu(II), L = ligand). All compounds were characterized using established physicochemical and spectroscopic methods. Crystal structures were determined for three Schiff bases (SMML, SBML, SBLA) and two Cu(II) complexes (Cu(SMML)2 and Cu(SMLA)2). In order to provide more insight into the behavior of the complexes in solution, electron paramagnetic resonance (EPR) and electrochemical experiments were performed. The parent ligands and their respective copper(II) complexes exhibited moderate antibacterial activity against both Gram-negative and Gram-positive bacteria. The most active ligand (SB4CB) and its analogous S-methyl derivative (SM4CB) were conjugated with various vector moieties: polyarginines (R1, R4, R9, and RW9), oligoethylene glycol (OEG), and an efflux pump blocker, phenylalanine-arginine-ß-naphthylamide (PAßN). Nonaarginine (R9) derivatives showed the most encouraging synergistic effects upon conjugation and complexation with copper ion including enhanced water solubility, bacteria cell membrane permeability, and bioactivity. These Cu(II)-R9 derivatives display remarkable antibacterial activity against a wide spectrum of bacteria and, in particular, are highly efficacious against Staphylococcus aureus with minimum inhibitory concentration (MIC) values of 0.5-1 µM. This pioneer study clearly indicates that the conjugation of cell-penetrating peptides (CPPs) to dithiocarbazate compounds greatly enhances their therapeutic potential.

Crystal structure of 2-{[2-(3-phenyl-allyl-idene)hydrazin-1-yl]thio-carbonyl-sulfanylmeth-yl}pyridinium chloride.

In the title salt of an S-substituted di-thio-carbazate, C16H16N3S2 (+)·Cl(-), the dihedral angles between the almost planar (r.m.s deviation = 0.005 Å) central CN2S2 residue and the terminal pyridinium and phenyl rings are 80.09 (11) and 3.82 (11)°, respectively, indicating the cation has an L-shape; the amine H and thione S atoms are syn. The conformation about each of the imine [1.376 (3) Å] and ethene [1.333 (4) Å] bonds is E. The shortened C-C bond [1.444 (4) Å] linking the double bonds is consistent with conjugation in this part of the mol-ecule. In the crystal, supra-molecular layers with a jagged topology are formed by charged-assisted amine-H⋯Cl(-) and pyridinium-N(+)-H⋯Cl(-) hydrogen bonds. The layers stack along the a axis with no specific directional inter-actions between them.

Benzyl N-[(Z)-(1-methyl-2-sulfanyl-propyl-idene)amino]-carbamodithio-ate.

The title compound, C(12)H(16)N(2)S(3), was obtained by the condensation reaction of S-benzyl dithio-carbazate and 3-mercaptobutan-2-one. The phenyl ring and thiol (SH) group are approximately perpendicular [S-C-C-C and N-C-C-S torsion angles = 67.8 (3) and 116.9 (2)°, respectively] to the rest of the mol-ecule. In the crystal, mol-ecules are linked by weak S-H⋯S and N-H⋯S hydrogen bonds, π-π inter-actions between the benzene rings [centroid-centroid distance = 3.823 (2) Å] and C-H⋯π inter-actions.

(Pyridin-4-yl)methyl N'-(3-phenyl-allyl-idene)hydrazinecarbodithio-ate.

In the title compound, C(16)H(15)N(3)S(2), the central C(2)N(2)S(2) residue is planar (r.m.s. deviation = 0.045 Å) and the pyridyl and benzene rings are inclined and approximately coplanar to this plane, respectively [dihedral angles = 72.85 (9) and 10.73 (9)°], so that, overall, the mol-ecule adopts an L-shape. The conformation about each of the N=C [1.290 (3) Å] and C=C [1.340 (3) Å] bonds is E. Supra-molecular chains along [1-10] are stabilized by N-H⋯N(pyridine) hydrogen bonding and these are connected into a double layer that stacks along the c-axis direction by C-H⋯π(pyridine) inter-actions.

2,2-Dibenzyl-hydrazin-1-ium chloride.

In the title salt, C14H17N2(+)·Cl(-), the central N atom is pyramidal (sum of bond angles = 330.9°) and there is a near orthogonal relationship between the benzene rings [dihedral angle = 89.95 (10)°]. The crystal packing features N-H⋯Cl hydrogen bonds, which lead to a supra-molecular undulating ribbon along the a axis comprising edge-shared eight-membered {⋯HNH⋯Cl}2 synthons. The chains are connected into layers in the ab plane by C-H⋯π inter-actions.

{S-Benzyl 3-[(6-methyl-pyridin-2-yl)-methyl-idene]dithio-carbazato}nickel(II) monohydrate.

The structure of the title compound, [Ni(C(15)H(14)N(3)S(2))(2)]·H(2)O, has one mol-ecule in the asymmetric unit, along with a solvent water mol-ecule. The two different Schiff base moieties coordinate to the central Ni(II) ion as tridentate N,N',S-chelating ligands, creating a six-coordinate distorted octa-hedral environment [the smallest angle being 77.43 (7)° and the widest angle being 169.99 (7)°]. The mean planes of the two ligands are nearly orthogonal to each other with an angle of 89.53 (6)°. The packing of the complex is supported by O-H⋯N and O-H⋯S hydrogen bonding between the solvent water mol-ecule and the uncoordinated N and S atoms of neighbouring ligands.

Bis{S-benzyl 3-[(phen-yl)(pyridin-2-yl)methyl-idene]dithio-carbazato}zinc acetonitrile monosolvate.

In the title compound, [Zn(C(20)H(16)N(3)S(2))(2)]·CH(3)CN, two different Schiff base moieties coordinate to the central Zn(II) ion as tridentate N,N',S-chelating ligands, creating a distorted octa-hedral environment [the smallest angle being 73.24 (6)° and the widest angle being 155.73 (7)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 83.65 (5)°. The crystal packing is consolidated by weak C-H⋯N hydrogen-bonding inter-actions.

{S-Benzyl 3-[(6-methyl-pyridin-2-yl-κN)methyl-idene]dithio-carbazato-κ(2)N(3),S}zinc.

The title compound, [Zn(C(15)H(14)N(3)S(2))(2)], contains two chemically equivalent Schiff base anions that are coordinated to the Zn(II) ion as tridentate N,N',S-chelating ligands, creating a distorted octa-hedral environment [the smallest angle being 75.40 (6)° and the widest angle being 162.87 (6)°], with the two S atoms in cis positions. The dihedral angle between the mean planes of the two coordinating ligands is 85.65 (5)°. Weak C-H⋯S hydrogen bonds are also observed.

Bis{S-benzyl 3-[(6-methyl-pyridin-2-yl)methyl-idene]dithio-carbazato}nickel(II).

The asymmetric unit of the title compound, [Ni(C(15)H(14)N(3)S(2))(2)], consists of two independent mol-ecules with similar configurations. Each Ni(2+) cation is coordinated in a cis-mode by two tridentate N,N',S-chelating Schiff base ligands, creating a distorted octa-hedron [the smallest angle being 77.57 (7)° and the widest being 168.97 (7)° for one mol-ecule, and 78.04 (7) and 167.55 (7)° for the second mol-ecule]. The dihedral angle between the mean coordination planes of the two ligands is 86.76 (7)° for one and 89.99 (7)° for the second mol-ecule. π-π inter-actions between neighbouring pyridine rings with plane-to-plane distances of 3.540 (1) and 3.704 (1) Šare observed.

2-Cyclo-hexyl-idene-N-methyl-hydrazine-carbothio-amide.

The title compound C(8)H(15)N(3)S has two mol-ecules in the asymmetric unit in which cis-trans isomerism is exhibited around the N(NH)C=S bonds. The cyclo-hexyl rings in both mol-ecules adopt a chair conformation. In the crystal, N-H⋯S hydrogen bonding produces dimers, which are inter-connected through further N-H⋯S hydrogen bonds, forming chains along the b-axis direction.

Benzyl 3-(2-methyl-phen-yl)dithio-carbazate.

In the title compound, C(15)H(16)N(2)S(2), the central C(2)N(2)S(2) unit is essentially planar (r.m.s. deviation = 0.047 Å) and forms dihedral angles of 68.26 (4) and 65.99 (4)° with the phenyl and benzene rings, respectively, indicating a twisted mol-ecule. Supra-molecular chains with a step topology and propagating along [100] feature in the crystal packing, mediated through N-H⋯S hydrogen bonds. The chains are consolidated into a three-dimensional architecture by C-H⋯π inter-actions.

1-{(E)-[4-(4-Meth-oxy-phen-yl)butan-2-yl-idene]amino}-3-methyl-thio-urea.

Two independent mol-ecules comprise the asymmetric unit of the title compound, C(13)H(19)N(3)OS, which differ in the conformations of the residues linking the thio-urea and the terminal benzene ring, as manifested in the C(m)-C(m)-C(a)-C(a) torsion angles [78.03 (16) and -93.64 (16)°, respectively; m = methyl-ene and a = aromatic]. The dihedral angles [84.40 (4) and 88.28 (5)°] formed between the thio-urea residue and the benzene ring indicate an almost orthogonal relationship. In each thio-urea residue, the N-H hydrogen atoms are anti, and the terminal N-H hydrogen atom forms an intra-molecular N-H⋯N hydrogen bond with the imine-N atom. In each case, the conformation about the imine C=N double bond [1.2812 (17) and 1.2801 (17) Å] is E. In the crystal, the mol-ecules are connected by N-H⋯S hydrogen bonds and these are connected into four mol-ecule aggregates via N-H⋯O hydrogen bonds, which are assembled into a two-dimensional array parallel to (011) via C-H⋯π and π-π inter-actions [ring centroid-centroid distance = 3.8344 (9) Å].

Bis{benzyl 2-[4-(4-meth-oxy-phen-yl)butan-2-yl-idene]hydrazinecarbodithio-ato-κ(2)N(2),S}nickel(II).

The complete mol-ecule of the title complex, [Ni(C(19)H(21)N(2)OS(2))(2)], is generated by the application of twofold symmetry. The Ni(II) atom is N,S-chelated by two hydrazinecarbodithio-ate ligands, which provide an N(2)S(2) donor set that defines a distorted square-planar geometry, the S atoms being approximately cis. The conformation of the chelate ring is an envelope with the Ni(II) atom being the flap atom. The dihedral angle between the least-squares planes through the chelate rings = 30.10 (6)°. Supra-molecular chains propagated by glide symmetry along the c axis and mediated by C-H⋯N contacts feature in the crystal packing.

N'-[Bis(benzyl-sulfan-yl)methyl-idene]benzohydrazide.

In the title hydrazonodithio-ate, C(21)H(19)N(3)OS(2), the amide group is twisted out of the plane through the S(2)C=N atoms: the C-N-N-C torsion angle is 139.71 (13)°. The pyridine ring forms dihedral angles of 52.96 (8) and 86.46 (8)° with the phenyl rings, and the latter are approximately orthogonal [dihedral angle = 76.42 (9)°]. Supra-molecular chains sustained by N-H⋯O hydrogen bonds and propagated by glide symmetry along the c axis are found in the crystal structure. The chains are consolidated into a three-dimensional architecture by C-H⋯O and C-H⋯N inter-actions.

1-Methyl-2-({[(2-methyl-phen-yl)meth-yl]disulfan-yl}meth-yl)benzene.

In the title disulfide, C(16)H(18)S(2), the mol-ecule is twisted about the central S-S bond [the C-S-S-C torsion angle = 93.24 (7)°] and the dihedral angle between the benzene rings is 72.84 (7)°, indicating an almost orthogonal relationship; the methyl groups are orientated to the same side of the mol-ecule. The crystal packing features C-H⋯.π inter-actions which consolidate a three-dimensional architecture.

(E)-[({[(3-Methyl-phen-yl)meth-yl]sulfan-yl}methane-thio-yl)amino](1-phenyl-pentyl-idene)amine.

In the structure of the title compound, C(20)H(24)N(2)S(2), the central CN(2)S(2) atoms are planar (r.m.s. deviation = 0.0205 Å) but both benzene rings are twisted out of this plane forming dihedral angles of 23.03 (6) and 84.75 (4)° (tol-yl); the n-butyl group occupies a position normal to the plane [N-C-C-C torsion angle = -84.33 (16)°]. The conformation of the imine bond [1.2888 (18) Å] is E. The syn arrangement of the thione S and amino H atoms enables the formation of N-H⋯S hydrogen bonds between centrosymmetrically related mol-ecules. These lead to eight-membered {⋯HNC=S}(2) synthons which are further stabilized by proximate C-H⋯S interactions. The resulting dimeric aggregates are connected into a supra-molecular chain along the c axis by C-H⋯π(tol-yl) inter-actions.

1-{(E)-[4-(4-Hy-droxy-phen-yl)butan-2-yl-idene]amino}-3-phenyl-thio-urea: crystal structure, Hirshfeld surface analysis and computational study.

The title thio-urea derivative, C17H19N3OS, adopts a U-shaped conformation with the dihedral angle between the terminal aromatic rings being 73.64 (5)°. The major twist in the mol-ecule occurs about the ethane bond with the Ci-Ce-Ce-Cb torsion angle being -78.12 (18)°; i = imine, e = ethane and b = benzene. The configuration about the imine bond is E, the N-bound H atoms lie on opposite sides of the mol-ecule and an intra-molecular amine-N-H⋯N(imine) hydrogen bond is evident. In the mol-ecular packing, hydroxyl-O-H⋯S(thione) and amine-N-H⋯O hydrogen bonding feature within a linear, supra-molecular chain. The chains are connected into a layer in the ab plane by a combination of methyl-ene-C-H⋯S(thione), methyl-ene-C-H⋯O(hydrox-yl), methyl-C-H⋯π(phen-yl) and phenyl-C-H⋯π(hy-droxy-benzene) inter-actions. The layers stack without directional inter-actions between them. The analysis of the calculated Hirshfeld surface highlights the presence of weak methyl-C-H⋯O(hydrox-yl) and H⋯H inter-actions in the inter-layer region. Computational chemistry indicates that dispersion energy is the major contributor to the overall stabilization of the mol-ecular packing.

Bis{N'-[3-(4-nitro-phen-yl)-1-phenyl-prop-2-en-1-yl-idene]-N-phenyl-carbamimido-thio-ato}zinc(II): crystal structure, Hirshfeld surface analysis and computational study.

The title zinc bis-(thio-semicarbazone) complex, [Zn(C22H17N4O2S)2], comprises two N,S-donor anions, leading to a distorted tetra-hedral N2S2 donor set. The resultant five-membered chelate rings are nearly planar and form a dihedral angle of 73.28 (3)°. The configurations about the endocyclic- and exocyclic-imine bonds are Z and E, respectively, and that about the ethyl-ene bond is E. The major differences in the conformations of the ligands are seen in the dihedral angles between the chelate ring and nitro-benzene rings [40.48 (6) cf. 13.18 (4)°] and the N-bound phenyl and nitro-benzene ring [43.23 (8) and 22.64 (4)°]. In the crystal, a linear supra-molecular chain along the b-axis direction features amine-N-H⋯O(nitro) hydrogen bonding. The chains assemble along the 21-screw axis through a combination of phenyl-C-H⋯O(nitro) and π(chelate ring)-π(phen-yl) contacts. The double chains are linked into a three-dimensional architecture through phenyl-C-H⋯O(nitro) and nitro-O⋯π(phen-yl) inter-actions.

2-[(1E)-[(Z)-2-({[(1Z)-[(E)-2-[(2-Hy-droxy-phen-yl)methyl-idene]hydrazin-1-yl-idene]({[(4-methyl-phen-yl)meth-yl]sulfan-yl})meth-yl]disulfan-yl}({[(4-methyl-phen-yl)meth-yl]sulfan-yl})methyl-idene)hydrazin-1-yl-idene]meth-yl]phenol: crystal structure, Hirshfeld surface analysis and computational study.

The complete mol-ecule of the title hydrazine carbodi-thio-ate derivative, C32H30N4O2S4, is generated by a crystallographic twofold axis that bis-ects the di-sulfide bond. The mol-ecule is twisted about this bond with the C-S-S-C torsion angle of 90.70 (8)° indicating an orthogonal relationship between the symmetry-related halves of the mol-ecule. The conformation about the imine bond [1.282 (2) Å] is E and there is limited delocalization of π-electron density over the CN2C residue as there is a twist about the N-N bond [C-N-N-C torsion angle = -166.57 (15)°]. An intra-molecular hydroxyl-O-H⋯N(imine) hydrogen bond closes an S(6) loop. In the crystal, methyl-ene-C-H⋯π(tol-yl) contacts assemble mol-ecules into a supra-molecular layer propagating in the ab plane: the layers stack without directional inter-actions between them. The analysis of the calculated Hirshfeld surfaces confirm the importance of H⋯H contacts, which contribute 46.7% of all contacts followed by H⋯C/C⋯H contacts [25.5%] reflecting, in part, the C-H⋯π(tol-yl) contacts. The calculation of the inter-action energies confirm the importance of the dispersion term and the influence of the stabilizing H⋯H contacts in the inter-layer region.