Design of three-component essential oil extract mixture from Cymbopogon flexuosus, Carum carvi, and Acorus calamus with enhanced antioxidant activity.

The development of novel antioxidant compounds with high efficacy and low toxicity is of utmost importance in the medicine and food industries. Moreover, with increasing concerns about the safety of synthetic components, scientists are beginning to search for natural sources of antioxidants, especially essential oils (EOs). The combination of EOs may produce a higher scavenging profile than a single oil due to better chemical diversity in the mixture. Therefore, this exploratory study aims to assess the antioxidant activity of three EOs extracted from Cymbopogon flexuosus, Carum carvi, and Acorus calamus in individual and combined forms using the augmented-simplex design methodology. The in vitro antioxidant assays were performed using DPPH and ABTS radical scavenging approaches. The results of the Chromatography Gas-Mass spectrometry (CG-MS) characterization showed that citral (29.62%) and niral (27.32%) are the main components for C. flexuosus, while D-carvone (62.09%) and D-limonene (29.58%) are the most dominant substances in C. carvi. By contrast, ß-asarone (69.11%) was identified as the principal component of A. calamus (30.2%). The individual EO exhibits variable scavenging activities against ABTS and DPPH radicals. These effects were enhanced through the mixture of the three EOs. The optimal antioxidant formulation consisted of 20% C. flexuosus, 53% C. carvi, and 27% A. calamus for DPPHIC50. Whereas 17% C. flexuosus, 43% C. carvi, and 40% A. calamus is the best combination leading to the highest scavenging activity against ABTS radical. These findings suggest a new research avenue for EOs combinations to be developed as novel natural formulations useful in food and biopharmaceutical products.

[(Z)-N-(3-Fluoro-phen-yl)-O-methyl-thio-carbamato-κS](tri-phenyl-phosphane-κP)gold(I): crystal structure, Hirshfeld surface analysis and computational study.

The title phosphanegold(I) thiol-ate, C26H22AuFNOPS or [Au(C8H7FNOS)(C18H15P)], has the AuI centre coordinated by phosphane-P [2.2494 (8) Å] and thiol-ate-S [2.3007 (8) Å] atoms to define a close to linear geometry [P-Au-S = 176.10 (3)°]. The thiol-ate ligand is orientated so that the meth-oxy-O atom is directed towards the Au atom, forming an Au⋯O close contact of 2.986 (2) Å. In the crystal, a variety of inter-molecular contacts are discerned with fluoro-benzene-C-H⋯O(meth-oxy) and phenyl-C-H⋯F inter-actions leading to dimeric aggregates. These are assembled into a three-dimensional architecture by phenyl-C-H⋯S(thiol-ate) and phenyl-C-H⋯π(fluorobenzene, phen-yl) inter-actions. Accordingly, the analysis of the calculated Hirshfeld surface shows 30.8% of all contacts are of the type C⋯H/H⋯C but this is less than the H⋯H contacts, at 44.9%. Other significant contributions to the surface come from H⋯F/F⋯H [8.1%], H⋯S/S⋯H [6.9%] and H⋯O/O⋯H [3.2%] contacts. Two major stabilization energies have contributions from the phenyl-C-H⋯π(fluoro-benzene) and fluoro-benzene-C-H⋯C(imine) inter-actions (-37.2 kcal mol-1), and from the fluoro-benzene-C-H⋯F and phenyl-C-H⋯O inter-actions (-34.9 kcal mol-1), the latter leading to the dimeric aggregate.

4-[(1E)-({[(Benzyl-sulfan-yl)methane-thio-yl]amino}-imino)-meth-yl]benzene-1,3-diol chloro-form hemisolvate: crystal structure, Hirshfeld surface analysis and computational study.

The title hydrazine carbodi-thio-ate chloro-form hemisolvate, 2C15H14N2O2S2·CHCl3, comprises two independent hydrazine carbodi-thio-ate mol-ecules, A and B, and a chloro-form mol-ecule; the latter is statistically disordered about its mol-ecular threefold axis. The common features of the organic mol-ecules include an almost planar, central CN2S2 chromophore [r.m.s. deviation = 0.0203 Š(A) and 0.0080 Š(B)], an E configuration about the imine bond and an intra-molecular hydroxyl-O-H⋯N(imine) hydrogen bond. The major conformational difference between the mol-ecules is seen in the relative dispositions of the phenyl rings as indicated by the values of the dihedral angles between the central plane and phenyl ring of 71.21 (6)° (A) and 54.73 (7)° (B). Finally, a difference is seen in the disposition of the outer hydroxyl-H atoms, having opposite relative orientations. In the calculated gas-phase structure, the entire mol-ecule is planar with the exception of the perpendicular phenyl ring. In the mol-ecular packing, the A and B mol-ecules assemble into a two-mol-ecule aggregate via N-H⋯S hydrogen bonds and eight-membered {⋯HNCS}2 synthons. The dimeric assemblies are connected into supra-molecular chains via hydroxyl-O-H⋯O(hydrox-yl) hydrogen bonds and these are linked into a double-chain through hy-droxy-O-H⋯π(phen-yl) inter-actions. The double-chains are connected into a three-dimensional architecture through phenyl-C-H⋯O(hydrox-yl) and phenyl-C-H⋯π(phen-yl) inter-actions. The overall assembly defines columns along the a-axis direction in which reside the chloro-form mol-ecules, which are stabilized by chloro-form-methine-C-H⋯S(thione) and phenyl-C-H⋯Cl contacts. The analysis of the calculated Hirshfeld surfaces, non-covalent inter-action plots and inter-action energies confirm the importance of the above-mentioned inter-actions, but also of cooperative, non-standard inter-actions such as π(benzene)⋯π(hydrogen-bond-mediated-ring) contacts.

2,2'-(Disulfanedi-yl)di-benzoic acid N,N-di-methyl-formamide monosolvate: crystal structure, Hirshfeld surface analysis and computational study.

The title 1:1 solvate, C14H10O4S2·C3H7NO, features a twisted mol-ecule of 2,2'-di-thiodi-benzoic acid (DTBA), with the central C-S-S-C torsion angle being -88.57 (6)°, and a mol-ecule of di-methyl-formamide (DMF). The carb-oxy-lic acid groups are, respectively, close to co-planar and twisted with respect to the benzene rings to which they are connected as seen in the CO2/C6 torsion angles of 1.03 (19) and 7.4 (2)°. Intra-molecular, hypervalent S←O inter-actions are noted [S⋯O = 2.6140 (9) and 2.6827 (9) Å]. In the crystal, four-mol-ecule aggregates are formed via DTBA-O-H⋯O(DMF) and DTBA-O-H⋯O(DTBA) hydrogen bonding, the latter via an eight-membered {⋯OHCO}2 homosynthon. These are linked into supra-molecular layers parallel to (011) via benzene-C-H⋯O(DTBA) and DTBA-C=O⋯π(benzene) inter-actions, with the connections between these, giving rise to a three-dimensional architecture, being of the type benzene-C-H⋯π(benzene). An analysis of the calculated Hirshfeld surfaces indicates, in addition to the aforementioned inter-molecular contacts, the presence of stabilizing inter-actions between a benzene ring and a quasi-π-system defined by O-H⋯O hydrogen bonds between a DTBA dimer, i.e. the eight-membered {⋯OCOH}2 ring system, and between a benzene ring and a quasi-π(OCOH⋯OCH) system arising from the DTBA-O-H⋯O(DMF) hydrogen bond. The inter-centroid separations are 3.65 and 3.49 Å, respectively.

Crystal structure, Hirshfeld surface analysis and computational study of the 1:2 co-crystal formed between N,N'-bis-[(pyridin-4-yl)meth-yl]ethanedi-amide and 3-chloro-benzoic acid.

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises a half-mol-ecule of oxalamide (4 LH2), being located about a centre of inversion, and a mol-ecule of3-chloro-benzoic acid (3-ClBA) in a general position. From symmetry, the 4 LH2 mol-ecule has a (+)anti-periplanar conformation with the 4-pyridyl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angle between the core and pyridyl ring being 74.69 (11)°; intra-molecular amide-N-H⋯O(amide) hydrogen bonds are noted. The 3-ClBA mol-ecule exhibits a small twist as seen in the C6/CO2 dihedral angle of 8.731 (12)°. In the mol-ecular packing, three-mol-ecule aggregates are formed via carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonding. These are connected into a supra-molecular tape along [111] through amide-N-H⋯O(carbon-yl) hydrogen bonding. Additional points of contact between mol-ecules include pyridyl and benzoic acid-C-H⋯O(amide), methyl-ene-C-H⋯O(carbon-yl) and C-Cl⋯π(pyrid-yl) inter-actions so a three-dimensional architecture results. The contributions to the calculated Hirshfeld surface are dominated by H⋯H (28.5%), H⋯O/O⋯H (23.2%), H⋯C/C⋯H (23.3%), H⋯Cl/Cl⋯H (10.0%) and C⋯Cl/C⋯Cl (6.2%) contacts. Computational chemistry confirms the C-Cl⋯π inter-action is weak, and the importance of both electrostatic and dispersion terms in sustaining the mol-ecular packing despite the strong electrostatic term provided by the carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonds.

2-[Carbamo-thio-yl(2-hy-droxy-eth-yl)amino]-ethyl benzoate: crystal structure, Hirshfeld surface analysis and computational study.

The title di-substituted thio-urea, C12H16N2O3S, has the hy-droxy-lethyl and ethyl benzoate substituents bound to the same amine-N atom, and is twisted, having a (+)syn-clinal conformation with the Namine-C-C-O(hydroxyl, carbon-yl) torsion angles of 49.39 (13) and 59.09 (12)°, respectively; the dihedral angle between the almost planar CN2S core and the pendent benzene ring is 69.26 (4)°. In the crystal, supra-molecular layers propagating in the ac plane are formed via a combination of hydroxyl-O-H⋯S(thione), amine-N-H⋯O(hydroxyl, carbon-yl) hydrogen-bonds. The layers stack along the b axis with inter-digitation of the benzene rings allowing the formation of π-π stacking [inter-centroid separation = 3.8722 (7) Å] and parallel C=O⋯π inter-actions. A computational chemistry study shows the conventional hydrogen bonding in the crystal leads to significant electrostatic stabilization but dispersion terms are also apparent, notably through the inter-actions involving the benzene residue.

3,3-Bis(2-hy-droxy-eth-yl)-1-(4-nitro-benzo-yl)thio-urea: crystal structure, Hirshfeld surface analysis and computational study.

In the title compound, C12H15N3O5S, a tris-ubstituted thio-urea derivative, the central CN2S chromophore is almost planar (r.m.s. deviation = 0.018 Å) and the pendant hy-droxy-ethyl groups lie to either side of this plane. While to a first approximation the thione-S and carbonyl-O atoms lie to the same side of the mol-ecule, the S-C-N-C torsion angle of -47.8 (2)° indicates a considerable twist. As one of the hy-droxy-ethyl groups is orientated towards the thio-amide residue, an intra-molecular N-H⋯O hydrogen bond is formed which leads to an S(7) loop. A further twist in the mol-ecule is indicated by the dihedral angle of 65.87 (7)° between the planes through the CN2S chromophore and the 4-nitro-benzene ring. There is a close match between the experimental and gas-phase, geometry-optimized (DFT) mol-ecular structures. In the crystal, O-H⋯O and O-H⋯S hydrogen bonds give rise to supra-molecular layers propagating in the ab plane. The connections between layers to consolidate the three-dimensional architecture are of the type C-H⋯O, C-H⋯S and nitro-O⋯π. The nature of the supra-molecular association has been further analysed by a study of the calculated Hirshfeld surfaces, non-covalent inter-action plots and computational chemistry, all of which point to the significant influence and energy of stabilization provided by the conventional hydrogen bonds.

Crystal structure, Hirshfeld surface analysis and computational study of the 1:2 co-crystal formed between N,N'-bis-(pyridin-4-ylmeth-yl)ethane-diamide and 4-chloro-benzoic acid.

The asymmetric unit of the title 1:2 co-crystal, C14H14N4O2·2C7H5ClO2, comprises two half mol-ecules of oxalamide (4 LH2), as each is disposed about a centre of inversion, and two mol-ecules of 4-chloro-benzoic acid (CBA), each in general positions. Each 4 LH2 mol-ecule has a (+)anti-periplanar conformation with the pyridin-4-yl residues lying to either side of the central, planar C2N2O2 chromophore with the dihedral angles between the respective central core and the pyridyl rings being 68.65 (3) and 86.25 (3)°, respectively, representing the major difference between the independent 4 LH2 mol-ecules. The anti conformation of the carbonyl groups enables the formation of intra-molecular amide-N-H⋯O(amide) hydrogen bonds, each completing an S(5) loop. The two independent CBA mol-ecules are similar and exhibit C6/CO2 dihedral angles of 8.06 (10) and 17.24 (8)°, indicating twisted conformations. In the crystal, two independent, three-mol-ecule aggregates are formed via carb-oxy-lic acid-O-H⋯N(pyrid-yl) hydrogen bonding. These are connected into a supra-molecular tape propagating parallel to [100] through amide-N-H⋯O(amide) hydrogen bonding between the independent aggregates and ten-membered {⋯HNC2O}2 synthons. The tapes assemble into a three-dimensional architecture through pyridyl- and methyl-ene-C-H⋯O(carbon-yl) and CBA-C-H⋯O(amide) inter-actions. As revealed by a more detailed analysis of the mol-ecular packing by calculating the Hirshfeld surfaces and computational chemistry, are the presence of attractive and dispersive Cl⋯C=O inter-actions which provide inter-action energies approximately one-quarter of those provided by the amide-N-H⋯O(amide) hydrogen bonding sustaining the supra-molecular tape.

N,N'-Bis(pyridin-3-ylmeth-yl)ethanedi-amide monohydrate: crystal structure, Hirshfeld surface analysis and computational study.

The mol-ecular structure of the title bis-pyridyl substituted di-amide hydrate, C14H14N4O2·H2O, features a central C2N2O2 residue (r.m.s. deviation = 0.0205 Å) linked at each end to 3-pyridyl rings through methyl-ene groups. The pyridyl rings lie to the same side of the plane, i.e. have a syn-periplanar relationship, and form dihedral angles of 59.71 (6) and 68.42 (6)° with the central plane. An almost orthogonal relationship between the pyridyl rings is indicated by the dihedral angle between them [87.86 (5)°]. Owing to an anti disposition between the carbonyl-O atoms in the core, two intra-molecular amide-N-H⋯O(carbon-yl) hydrogen bonds are formed, each closing an S(5) loop. Supra-molecular tapes are formed in the crystal via amide-N-H⋯O(carbon-yl) hydrogen bonds and ten-membered {⋯HNC2O}2 synthons. Two symmetry-related tapes are linked by a helical chain of hydrogen-bonded water mol-ecules via water-O-H⋯N(pyrid-yl) hydrogen bonds. The resulting aggregate is parallel to the b-axis direction. Links between these, via methyl-ene-C-H⋯O(water) and methyl-ene-C-H⋯π(pyrid-yl) inter-actions, give rise to a layer parallel to (10); the layers stack without directional inter-actions between them. The analysis of the Hirshfeld surfaces point to the importance of the specified hydrogen-bonding inter-actions, and to the significant influence of the water mol-ecule of crystallization upon the mol-ecular packing. The analysis also indicates the contribution of methyl-ene-C-H⋯O(carbon-yl) and pyridyl-C-H⋯C(carbon-yl) contacts to the stability of the inter-layer region. The calculated inter-action energies are consistent with importance of significant electrostatic attractions in the crystal.

The 1:2 co-crystal formed between N,N'-bis(pyridin-4-ylmeth-yl)ethanedi-amide and benzoic acid: crystal structure, Hirshfeld surface analysis and computational study.

The crystal and mol-ecular structures of the title 1:2 co-crystal, C14H14N4O2·2C7H6O2, are described. The oxalamide mol-ecule has a (+)-anti-periplanar conformation with the 4-pyridyl residues lying to either side of the central, almost planar C2N2O2 chromophore (r.m.s. deviation = 0.0555 Å). The benzoic acid mol-ecules have equivalent, close to planar conformations [C6/CO2 dihedral angle = 6.33 (14) and 3.43 (10)°]. The formation of hy-droxy-O-H⋯N(pyrid-yl) hydrogen bonds between the benzoic acid mol-ecules and the pyridyl residues of the di-amide leads to a three-mol-ecule aggregate. Centrosymmetrically related aggregates assemble into a six-mol-ecule aggregate via amide-N-H⋯O(amide) hydrogen bonds through a 10-membered {⋯HNC2O}2 synthon. These are linked into a supra-molecular tape via amide-N-H⋯O(carbon-yl) hydrogen bonds and 22-membered {⋯HOCO⋯NC4NH}2 synthons. The contacts between tapes to consolidate the three-dimensional architecture are of the type methyl-ene-C-H⋯O(amide) and pyridyl-C-H⋯O(carbon-yl). These inter-actions are largely electrostatic in nature. Additional non-covalent contacts are identified from an analysis of the calculated Hirshfeld surfaces.

Synthesis, characterization and evaluation of antidengue activity of enantiomeric Schiff bases derived from S-substituted dithiocarbazate.

A series of Schiff bases have been successfully synthesized through the acid-catalyzed condensation of S-substituted dithiocarbazates and three enantiomerically pure monoterpenes, (1 R )-(+)-camphor, (1 S )-(-)-camphor, (1 R )-(-)-camphorquinone, (1 S )-(+)-camphorquinone, ( R )-(-)-carvone and ( S )-(+)-carvone. Spectroscopic results revealed that the Schiff bases containing camphor or carvone likely adopted an E -configuration along the characteristic imine bond while those containing camphorquinone assumed a Z -configuration. The antidengue potential of these compounds was evaluated based on DENV 2 caused cytopathic effect (CPE) reduction-based in vitro evaluation. The compounds were validated through secondary foci forming unit reduction assay (FFURA). Compounds were also tested for their cytotoxicity against Vero cells. The compounds showed variable degrees of antiviral activity with the camphor compounds displaying the highest antidengue potential. The enantiomers of the compounds behaved almost similarly during the antiviral evaluation.

3,3-Bis(2-hy-droxy-eth-yl)-1-(4-methyl-benzoyl)thio-urea: crystal structure, Hirshfeld surface analysis and computational study.

In the title tri-substituted thio-urea derivative, C13H18N2O3S, the thione-S and carbonyl-O atoms lie, to a first approximation, to the same side of the mol-ecule [the S-C-N-C torsion angle is -49.3 (2)°]. The CN2S plane is almost planar (r.m.s. deviation = 0.018 Å) with the hy-droxy-ethyl groups lying to either side of this plane. One hy-droxy-ethyl group is orientated towards the thio-amide functionality enabling the formation of an intra-molecular N-H⋯O hydrogen bond leading to an S(7) loop. The dihedral angle [72.12 (9)°] between the planes through the CN2S atoms and the 4-tolyl ring indicates the mol-ecule is twisted. The experimental mol-ecular structure is close to the gas-phase, geometry-optimized structure calculated by DFT methods. In the mol-ecular packing, hydroxyl-O-H⋯O(hydrox-yl) and hydroxyl-O-H⋯S(thione) hydrogen bonds lead to the formation of a supra-molecular layer in the ab plane; no directional inter-actions are found between layers. The influence of the specified supra-molecular inter-actions is apparent in the calculated Hirshfeld surfaces and these are shown to be attractive in non-covalent inter-action plots; the inter-action energies point to the important stabilization provided by directional O-H⋯O hydrogen bonds.

N,N'-Bis(pyridin-4-ylmeth-yl)oxalamide benzene monosolvate: crystal structure, Hirshfeld surface analysis and computational study.

The asymmetric unit of the title 1:1 solvate, C14H14N4O2·C6H6 [systematic name of the oxalamide mol-ecule: N,N'-bis-(pyridin-4-ylmeth-yl)ethanedi-amide], comprises a half mol-ecule of each constituent as each is disposed about a centre of inversion. In the oxalamide mol-ecule, the central C2N2O2 atoms are planar (r.m.s. deviation = 0.0006 Å). An intra-molecular amide-N-H⋯O(amide) hydrogen bond is evident, which gives rise to an S(5) loop. Overall, the mol-ecule adopts an anti-periplanar disposition of the pyridyl rings, and an orthogonal relationship is evident between the central plane and each terminal pyridyl ring [dihedral angle = 86.89 (3)°]. In the crystal, supra-molecular layers parallel to (10) are generated owing the formation of amide-N-H⋯N(pyrid-yl) hydrogen bonds. The layers stack encompassing benzene mol-ecules which provide the links between layers via methyl-ene-C-H⋯π(benzene) and benzene-C-H⋯π(pyrid-yl) inter-actions. The specified contacts are indicated in an analysis of the calculated Hirshfeld surfaces. The energy of stabilization provided by the conventional hydrogen bonding (approximately 40 kJ mol-1; electrostatic forces) is just over double that by the C-H⋯π contacts (dispersion forces).

A 1:1:1 co-crystal solvate comprising 2,2'-di-thiodi-benzoic acid, 2-chloro-benzoic acid and N,N-di-methyl-formamide: crystal structure, Hirshfeld surface analysis and computational study.

The asymmetric unit of the three-component title compound, 2,2'-di-thiodi-benzoic acid-2-chloro-benzoic acid-N,N-di-methyl-formamide (1/1/1), C14H10O4S2·C7H5ClO2·C3H7NO, contains a mol-ecule each of 2,2'-di-thiodi-benzoic acid (DTBA), 2-chloro-benzoic acid (2CBA) and di-methyl-formamide (DMF). The DTBA mol-ecule is twisted [the C-S-S-C torsion angle is 88.37 (17)°] and each carb-oxy-lic group is slightly twisted from the benzene ring to which it is connected [CO2/C6 dihedral angles = 7.6 (3) and 12.5 (3)°]. A small twist is evident in the mol-ecule of 2CBA [CO2/C6 dihedral angle = 4.4 (4)°]. In the crystal, the three mol-ecules are connected by hydrogen bonds with the two carb-oxy-lic acid residues derived from DTBA and 2CBA forming a non-symmetric eight-membered {⋯HOCO}2 synthon, and the second carb-oxy-lic acid of DTBA linked to the DMF mol-ecule via a seven-membered {⋯HOCO⋯HCO} heterosynthon. The three-mol-ecule aggregates are connected into a supra-molecular chain along the a axis via DTBA-C-H⋯O(hydroxyl-2CBA), 2CBA-C-H⋯O(hydroxyl-DTBA) and DTBA-C-H⋯S(DTBA) inter-actions. Supra-molecular layers in the ab plane are formed as the chains are linked via DMF-C-H⋯S(DTBA) contacts, and these inter-digitate along the c-axis direction without specific points of contact between them. A Hirshfeld surface analysis points to additional but, weak contacts to stabilize the three-dimensional architecture: DTBA-C=O⋯H(phenyl-DTBA), 2CBA-Cl⋯H(phenyl-DTBA), as well as a π-π contact between the delocalized eight-membered {⋯HOC=O}2 carb-oxy-lic dimer and the phenyl ring of 2CBA. The latter was confirmed by electrostatic potential (ESP) mapping.

Utilizing Hirshfeld surface calculations, non-covalent inter-action (NCI) plots and the calculation of inter-action energies in the analysis of mol-ecular packing.

The analysis of atom-to-atom and/or residue-to-residue contacts remains a favoured mode of analysing the mol-ecular packing in crystals. In this contribution, additional tools are highlighted as methods for analysis in order to complement the 'crystallographer's tool', PLATON [Spek (2009). Acta Cryst. D65, 148-155]. Thus, a brief outline of the procedures and what can be learned by using Crystal Explorer [Spackman & Jayatilaka (2009). CrystEngComm 11, 19-23] is presented. Attention is then directed towards evaluating the nature, i.e. attractive/weakly attractive/repulsive, of specific contacts employing NCIPLOT [Johnson et al. (2010). J. Am. Chem. Soc. 132, 6498-6506]. This is complemented by a discussion of the calculation of energy frameworks utilizing the latest version of Crystal Explorer. All the mentioned programs are free of charge and straightforward to use. More importantly, they complement each other to give a more complete picture of how mol-ecules assemble in mol-ecular crystals.

A 1:2 co-crystal of 2,2'-di-thiodi-benzoic acid and benzoic acid: crystal structure, Hirshfeld surface analysis and computational study.

The asymmetric unit of the title 1:2 co-crystal, C14H10O4S2·2C7H6O2, comprises half a mol-ecule of di-thiodi-benzoic acid [systematic name: 2-[(2-carb-oxy-phen-yl)disulfan-yl]benzoic acid, DTBA], as the mol-ecule is located about a twofold axis of symmetry, and a mol-ecule of benzoic acid (BA). The DTBA mol-ecule is twisted about the di-sulfide bond [the C-S-S-C torsion angle is -83.19 (8)°] resulting in a near perpendicular relationship between the benzene rings [dihedral angle = 71.19 (4)°]. The carb-oxy-lic acid group is almost co-planar with the benzene ring to which it is bonded [dihedral angle = 4.82 (12)°]. A similar near co-planar relationship pertains for the BA mol-ecule [dihedral angle = 3.65 (15)°]. Three-mol-ecule aggregates are formed in the crystal whereby two BA mol-ecules are connected to a DTBA mol-ecule via hy-droxy-O-H⋯O(hydroxy) hydrogen bonds and eight-membered {⋯HOC=O}2 synthons. These are connected into a supra-molecular layer in the ab plane through C-H⋯O inter-actions. The inter-actions between layers to consolidate the three-dimensional architecture are π-π stacking inter-actions between DTBA and BA rings [inter-centroid separation = 3.8093 (10) Å] and parallel DTBA-hy-droxy-O⋯π(BA) contacts [O⋯ring centroid separation = 3.9049 (14) Å]. The importance of the specified inter-actions as well as other weaker contacts, e.g. π-π and C-H⋯S, are indicated in the analysis of the calculated Hirshfeld surface and inter-action energies.

A 1:2 co-crystal of 2,2'-thiodi-benzoic acid and tri-phenyl-phosphane oxide: crystal structure, Hirshfeld surface analysis and computational study.

The asymmetric unit of the title co-crystal, 2,2'-thiodi-benzoic acid-tri-phenyl-phosphane oxide (1/2), C14H10O4S·2C18H15OP, comprises two mol-ecules of 2,2'-thiodi-benzoic acid [TDBA; systematic name: 2-[(2-carb-oxy-phen-yl)sulfan-yl]benzoic acid] and four mol-ecules of tri-phenyl-phosphane oxide [TPPO; systematic name: (di-phenyl-phosphor-yl)benzene]. The two TDBA mol-ecules are twisted about their di-sulfide bonds and exhibit dihedral angles of 74.40 (5) and 72.58 (5)° between the planes through the two SC6H4 residues. The carb-oxy-lic acid groups are tilted out of the planes of the rings to which they are attached forming a range of CO2/C6 dihedral angles of 19.87 (6)-60.43 (8)°. Minor conformational changes are exhibited in the TPPO mol-ecules with the range of dihedral angles between phenyl rings being -2.1 (1) to -62.8 (1)°. In the mol-ecular packing, each TDBA acid mol-ecule bridges two TPPO mol-ecules via hy-droxy-O-H⋯O(oxide) hydrogen bonds to form two three-mol-ecule aggregates. These are connected into a three-dimensional architecture by TPPO-C-H⋯O(oxide, carbon-yl) and TDBA-C-H⋯(oxide, carbon-yl) inter-actions. The importance of H⋯H, O⋯H/H⋯O and C⋯H/H⋯C contacts to the calculated Hirshfeld surfaces has been demonstrated. In terms of individual mol-ecules, O⋯H/H⋯O contacts are more important for the TDBA (ca 28%) than for the TPPO mol-ecules (ca 13%), as expected from the chemical composition of these species. Computational chemistry indicates the four independent hy-droxy-O-H⋯O(oxide) hydrogen bonds in the crystal impart about the same energy (ca 52 kJ mol-1), with DTBA-phenyl-C-H⋯O(oxide) inter-actions being next most stabilizing (ca 40 kJ mol-1).

A cinnamaldehyde Schiff base of S-(4-methyl-benz-yl) di-thio-carbazate: crystal structure, Hirshfeld surface analysis and computational study.

The title di-thio-carbazate ester (I), C18H18N2S2 [systematic name: (E)-4-methyl-benzyl 2-[(E)-3-phenyl-allyl-idene]hydrazinecarbodi-thio-ate, comprises an almost planar central CN2S2 residue [r.m.s. deviation = 0.0131 Å]. The methyl-ene(tolyl-4) group forms a dihedral angle of 72.25 (4)° with the best plane through the remaining non-hydrogen atoms [r.m.s. deviation = 0.0586 Å] so the mol-ecule approximates mirror symmetry with the 4-tolyl group bis-ected by the plane. The configuration about both double bonds in the N-N=C-C=C chain is E; the chain has an all trans conformation. In the crystal, eight-membered centrosymmetric thio-amide synthons, {⋯HNCS}2, are formed via N-H⋯S(thione) hydrogen bonds. Connections between the dimers via C-H⋯π inter-actions lead to a three-dimensional architecture. A Hirshfeld surface analysis shows that (I) possesses an inter-action profile similar to that of a closely related analogue with an S-bound benzyl substituent, (II). Computational chemistry indicates the dimeric species of (II) connected via N-H⋯S hydrogen bonds is about 0.94 kcal mol-1 more stable than that in (I).

fac-Aceto-nitrile-tricarbon-yl(di-methyl-carbamodi-thio-ato-κ2S,S')rhenium(I): crystal structure and Hirshfeld surface analysis.

The title compound, [Re(C3H6NS2)(C2H3N)(CO)3], features an octa-hedrally coordinated ReI atom within a C3NS2 donor set defined by three carbonyl ligands in a facial arrangement, an aceto-nitrile N atom and two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. In the crystal, di-thio-carbamate-methyl-H⋯O(carbon-yl) inter-actions lead to supra-molecular chains along [36-1]; both di-thio-carbamate S atoms participate in intra-molecular methyl-H⋯S inter-actions. Further but weaker aceto-nitrile-C-H⋯O(carbonyl) inter-actions assemble mol-ecules in the ab plane. The nature of the supra-molecular assembly was also probed by a Hirshfeld surface analysis. Despite their weak nature, the C-H⋯O contacts are predominant on the Hirshfeld surface and, indeed, on those of related [Re(CO)3(C3H6NS2)L] structures.

[N,N-Bis(2-hy-droxy-eth-yl)di-thio-carbamato-κ2S,S']bis-(tri-phenyl-phosphane-κP)copper(I) chloro-form monosolvate: crystal structure, Hirshfeld surface analysis and solution NMR measurements.

The title compound, [Cu(C5H5NO2S2)(C18H15P)2]·CHCl3, features a tetra-hedrally coordinated CuI atom within a P2S2 donor set defined by two phosphane P atoms and by two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. Both intra- and inter-molecular hy-droxy-O-H⋯O(hydroxy) hydrogen bonding is observed: the former closes an eight-membered {⋯HOC2NC2O} ring, whereas the latter connects centrosymmetrically related mol-ecules into dimeric aggregates via eight-membered {⋯H-O⋯H-O}2 synthons. The complex mol-ecules are arranged to form channels along the c axis in which reside the chloro-form mol-ecules, being connected by Cl⋯π(arene) and short S⋯Cl [3.3488 (9) Å] inter-actions. The inter-molecular inter-actions have been investigated further by Hirshfeld surface analysis, which shows the conventional hydrogen bonding to be very localized with the main contributors to the surface, at nearly 60%, being H⋯H contacts. Solution NMR studies indicate that whilst the same basic mol-ecular structure is retained in solution, the tri-phenyl-phosphane ligands are highly labile, exchanging rapidly with free Ph3P at room temperature.