Classical Hydrogen Bonds Research Articles

Nine Supramolecular Adducts of 4-dimethylaminopyridine and Carboxylic acids Assembled by Classical Hydrogen Bonds and Other Noncovalent Intermolecular Interactions

Cocrystallization of the widely available 4-dimethylaminopyridine, with a series of carboxylic acids gave nine molecular adducts 4-dimethylaminopyridinium trifluoroacetate (1), 4-dimethylaminopyridinium glycolate glycolic acid (2), 4-dimethylaminopyridinium 2-furoate dihydrate (3), tri(4-dimethylaminopyridinium) tri(o-chlorobenzoate) tetrahydrate (4), 4-dimethylaminopyridinium 4-bromobenzoate 4-bromobenzoic acid (5), 4-dimethylaminopyridinium 4-formylbenzoate 4-formylbenzoic acid (6), 4-dimethylaminopyridinium 2,4-dichlorobenzoate (7), 4-dimethylaminopyridinium 2-aminobenzoate 2-aminobenzoic acid (8) and bis(4-dimethylaminopyridinium) 5-nitroisophthalate 5-nitroisophthalic acid methanol solvate (9). The nine adducts have been characterised by X-ray diffraction, IR and elemental analysis, the melting points were also reported. Their structural and supramolecular aspects are fully analyzed.The result reveals that among the nine investigated crystals only the ring Ns in the 4-dimethylaminopyridine moieties are protonated when the carboxylic acids are deprotonated. The crystal packing is interpreted by the strong charge-assisted N-H⋯O hydrogen bond between the NH+ and the deprotonated acidic groups. Except the N-H⋯O hydrogen bonds, the charge assisted or neutral O-H···O hydrogen bonds were also found at 2-6, 8 and 9. The COOH···COO−synthon has been at 2, 5-6 and 8-9.Further analysis of the crystal packing indicated that a different family of additional CH-O/CH2-O/CH3-O, F-F, Br-Br, CH-Cl, CH3-Cl, CH-π/CH3-π, C-H···Cπ, C-π, Cl-O, O-C, O-π and π-π contacts contribute to the stabilization and expansion of the total high-dimensional (2D-3D) framework structures. For the synergism of the various nonbonding contacts there created homo/hetero supramolecular synthons or both.

Structural diversity among some dialkyltin(IV) benzoate and related derivatives.

The molecular structures of five diorganotin(IV) carboxylates, (I)-(V), can be categorized into two main well-known structural types for such Sn complexes. One is the mononuclear dialkytin(IV) carboxylates with an [R2Sn(LH)2]-type skew-trapezoidal bipyramid, where the alkyl ligands are in pseudo-axial positions and the O atoms from two asymmetrically coordinated bidentate carboxylate ligands are in the equatorial plane. This structure type is adopted by dibutylbis{(E)-2-hydroxy-5-[(3-methylphenyl)diazenyl]benzoato}tin(IV) cyclohexane hemisolvate, [Sn(C4H9)2(C14H11N2O3)2]·0.5C6H12, (I), dibenzylbis{(E)-5-[(4-bromophenyl)diazenyl]-2-hydroxybenzoato}tin(IV), [Sn(C7H7)2(C13H8BrN2O3)2], (II), and aquadibenzylbis(4-{(E)-[(Z)-4-hydroxypent-3-en-2-ylidene]amino}benzoato)tin(IV) benzene disolvate, [Sn(C7H7)2(C12H12NO3)2(H2O)]·2C6H6, (III), although the latter has an additional water ligand to give a distorted pentagonal bipyramidal coordination geometry in which the carboxylate groups are more symmetrically coordinated to the Sn atom than in (I) and (II). The other structure motif is that of the tetranuclear bis(dicarboxylatotetraorganodistannoxanes), {[R2Sn(LH)]2O}2, which contain an Sn4O2 core decorated with four bridging carboxylate ligands, plus two alkyl ligands at each SnIV centre. The complexes octabutyltetrakis{μ-(E)-4-[(4-hydroxy-3,5-dimethylphenyl)diazenyl]benzoato}di-μ3-oxido-tetratin(IV) ethanol disolvate, [Sn4(C4H9)8(C15H13N2O3)4O2]·2C2H6O, (IV), and octabutyltetrakis{(E)-3-[(2-hydroxybenzylidene)amino]propanoato}di-μ3-oxido-tetratin(IV), [Sn4(C4H9)8(C10H10NO3)4O2], (V), display this motif. The structures obtained correlate with the 1:1 and 1:2 stoichiometric ratios of the dialkyltin(IV) and carboxylic acid starting materials in the syntheses. The supramolecular structures arising from consideration of secondary Sn...O interactions and/or classic hydrogen bonds include discrete molecules for (V), centrosymmetric dimers for (I), extended chains for (II) and (III), and sheets for (IV).

The crystal structures, Hirshfeld surface analyses and energy frameworks of 8-{1-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperidin-4-yl}-2-meth-oxy-quinoline and 8-{4-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperazin-1-yl}-2-meth-oxy-quinoline.

The title compounds, 8-{1-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperidin-4-yl}-2-meth-oxy-quinoline, C27H30N2O (I), and 8-{4-[3-(cyclo-pent-1-en-1-yl)benz-yl]piperazin-1-yl}-2-meth-oxy-quinoline, C26H29N3O (II), differ only in the nature of the central six-membered ring: piperidine in I and piperazine in II. They are isoelectronic (CH cf. N) and isotypic; they both crystallize in the triclinic space group P with very similar unit-cell parameters. Both mol-ecules have a curved shape and very similar conformations. In the biaryl group, the phenyl ring is inclined to the cyclo-pentene mean plane (r.m.s. deviations = 0.089 Å for I and 0.082 Å for II) by 15.83 (9) and 13.82 (6)° in I and II, respectively, and by 67.68 (6) and 69.47 (10)°, respectively, to the mean plane of the quinoline moiety (r.m.s. deviations = 0.034 Å for I and 0.038 Å for II). The piperazine ring in I and the piperidine ring in II have chair conformations. In the crystals of both compounds, mol-ecules are linked by C-H⋯π inter-actions, forming chains in I and ribbons in II, both propagating along the b-axis direction. The principal contributions to the overall Hirshfeld surfaces involve H⋯H contacts at 67.5 and 65.9% for I and II, respectively. The major contribution to the inter-molecular inter-actions in the crystals is from dispersion forces (E dis), reflecting the absence of classical hydrogen bonds.

Preparation, spectral characterization and single crystal analysis of bromo derivative of 2-acetyl-1-naphthol

Present work deals with the synthesis of the 1-(4-bromo-1-hydroxynaphthalen-2-yl)ethan-1-one 3 from 2-acetyl-1-naphthol 2 using Br 2 /AcOH (20%) as brominating agent. The structure compound 3 was confirmed on the basis of spectral study such as FTIR, 1 H NMR, 13 C NMR and GCMS. The crystal structure of 4-bromo-2-acetyl-1-naphthol was also confirmed by the X-ray single-crystal diffractometry analysis and revealed the unit cell parameters, packing style. The single crystal has been grown by slow evaporation method at ambient temperature. The crystal size for compound 3 was found to be 0.150 × 0.120 × 0.100 mm3 . The crystal has grown with monoclinic crystal system with Z value of four and space group symmetry was P21/c. The unit cell parameters and angles were a; 7.3584 Å, b; 17.772 Å, c; 8.357 Å, α; 90°, β; 108.711°, √; 90°. The crystal structure of 3 is stabilized via one strong classical hydrogen bond interaction and two weak intermolecular hydrogen bonding. The observed average bond lengths of C C, C H, C O, C Br and O H bonds were 1.410, 0.941, 1.289, 1.899 and 0.80 Å respectively. Single crystal packing view of 1-(4-bromo-1-hydroxynaphthalen-2-yl)ethan-1-one

Crystal structure of five solid forms from isonicotinamide and carboxylic acids assembled by classical hydrogen bonds and other noncovalent interactions

Cocrystallization of the commonly available isonicotinamide, with a series of carboxylic acids gave a total of five new anhydrous and hydrous multicomponent solid forms: (isonicotinamide)2: (suberic acid) [(L)2 · (H2sub), H2sub = suberic acid] (1), (isonicotinamide)2: (α-ketoglutaric acid): H2O [(HL+)2 · (kga2−) · H2O, kga2− = α-ketoglutarate] (2), (isonicotinamide): (1,2-phenylenediacetic acid) [(L) · (H2pda), H2pda = 1,2-phenylenediacetic acid] (3), (isonicotinamide): (4-nitrophthalic acid) [(HL+) · (Hnpta−), Hnpta− = 4-nitrohydrogenphthalate] (4) and (isonicotinamide)4: (butane-1,2,3,4-tetracarboxylic acid) [(L)4 · (H4bta), H4bta = butane-1,2,3,4-tetracarboxylic acid] (5). The five solid forms have been characterised by XRD, IR and EA and their melting points were also reported. Their structural and supramolecular aspects are fully analyzed.The result shows that 2 and 4 are organic salts with only the aryl N in L protonated, 1, 3 and 5 are co-crystals. The crystal packing is interpreted by the strong N-H···O, O-H···N and O-H···O hydrogen bonds. The carboxamide dimers were existed in all solid forms by a pair of N-H···O hydrogen bonds. Further inspection of the crystal packing told that a different set of additional CH-O/CH2-O, CH-N, O-C, O-O, O-N, O-π and π-π associations contribute to the stabilization and expansion of the total high-dimensional (2D-3D) structures. For the delicate balance of the various weak nonbonding interactions these structures adopted homo/hetero supramolecular synthons or both and the common R21(7) and R22(8) graph sets have been observed in all solid forms due to the interplay of hydrogen bonds and non-covalent associations.

Cobalt(II) complexes with small variations in the heterocycle ligand, crystal structure and DFT calculations

Novel mononuclear cobalt(II) complexes, [Co(mbipy)(H2O)(η2-NO3)(η-NO3)] (1), [Co(dmbipy)(H2O)(η2-NO3)(η-NO3)] (2) and [Co(dmphen)(H2O)(η2-NO3)(η-NO3)] (3) were synthesized by the reactions of Co(NO3)2·6H2O with bipyridine and phenanthroline derivatives (mbipy = 6-methyl-2,2́-bypiridine; dmbipy = 6,6́-dimethyl-2,2́-bypiridine and dmphen = 2,9-dimethyl-1,10-phenanthroline). The complexes were identified by elemental analysis, IR, UV–Vis spectroscopy and X-ray crystallography. In the molecular structure of the three complexes, the coordination geometry around Co(II) is distorted octahedral in a [CoN2O4] system. The crystal structure was stabilized with a network of OH···O and (CH···O classical hydrogen bond interactions as well as π-π interactions between the pyridine rings in 2 and 3. Furthermore, the density functional theory (DFT) calculations have been performed. Good consistency was observed between the calculated results and the experimental structure, in gas phase and aqua phase. DFT approach was used to interpreter the optical characterization. The electronic properties of the complexes were also calculated and compared. The origin of the intermolecular OH···O hydrogen bond in 3D structure of the complexes was explored by MEP.

Local potential energy density model (LPE): Applications and limitations to quantify intra/intermolecular interactions

In our previous work, we developed the local potential energy density model, LPE, based on the electrostatic force and QTAIM topological data with a high linearity with the supramolecular binding energy, SME, for the classical hydrogen bonds. In this work, we extended the investigation to other inter/intramolecular interactions. The LPE presented a high linearity with SME when excluding interactions of an ion with π-bonded groups or polar molecule. Due to this linearity, it is possible to obtain the SME of nearly all inter/intramolecular interaction from LPE values. The energy decomposition analysis from SAPT-DFT and LMOEDA showed that dispersion and electrostatic components are important to LPE, while polarization component impairs it. The LPE cannot be used for ions interacting with dipole or dipole or ion interacting with π-bonded systems). In addition, the absolute difference between the numerical values of LPE and SME is very small as in the case of our previous work.

Structural and spectral characterization of Cu(II) complexes of N(4)-substituted thiosemicarbazones derived from 2-hydroxyacetophenone: Crystal structure of a dinuclear Cu(II) complex

Copper(II) complexes of 2-hydroxyacetophenone-N(4)-cyclohexylthiosemicarbazone (H2L1) and 2-hydroxyacetophenone-N(4)-phenylthiosemicarbazone (H2L2) have been synthesized and characterized by different physicochemical techniques like magnetic studies and electronic, infrared and EPR spectral studies. [(CuL1)2] (1) is a dinuclear complex having four coordination around copper(II) with distorted square planar geometry. The two individual dinuclear complexes are interconnected through two bifurcated classical hydrogen bond interactions producing a sheet-like structure along b axis. [(CuL2)2]·1/2H2O (2) also has a dimeric structure. The thiosemicarbazones bind to the metal as dianionic ONS donor ligand in all the complexes, except in the complexes [Cu(HL1)Cl]·2H2O (3), [Cu(HL1)Br]·4H2O (4) and [Cu(HL1)NO3]·C2H5OH(H2O) (5), where the ligand moieties are coordinated as monoanionic (HL¯) ones. Complexes [CuL1dmbipy] (6), [CuL2dmbipy]·3H2O (7), [CuL2bipy]·H2O (8) and [CuL2phen]·2C2H5OH (9) are heterocyclic base adducts. The synthesis and characterization of monomeric and dimeric Cu(II) complexes with 2-hydroxyacetophenone-N(4)-cyclohexyl/phenyl substituted ONS donor ligands is described. It also reports the crystal structure of a novel binuclear Cu(II) complex with oxygen bridging and its interesting coordination. This compound [CuL1]2 is a rare example of copper(II)-thiosemicarbazone complex with oxygen bridging structure.

Ruthenium(IV) Complexes as Potential Inhibitors of Bacterial Biofilm Formation.

With increasing antimicrobial resistance there is an urgent need for new strategies to control harmful biofilms. In this study, we have investigated the possibility of utilizing ruthenium(IV) complexes (H3O)2(HL1)2[RuCl6]·2Cl·2EtOH (1) and [RuCl4(CH3CN)2](L32)·H2O (2) (where L1-2-hydroxymethylbenzimadazole, L32-1,4-dihydroquinoxaline-2,3-dione) as effective inhibitors for biofilms formation. The biological activities of the compounds were explored using E. coli, S. aureus, P. aeruginosa PAO1, and P. aeruginosa LES B58. The new chloride ruthenium complexes were characterized by single-crystal X-ray diffraction analysis, Hirshfeld surface analysis, FT-IR, UV-Vis, magnetic and electrochemical (CV, DPV) measurements, and solution conductivity. In the obtained complexes, the ruthenium(IV) ions possess an octahedral environment. The intermolecular classical and rare weak hydrogen bonds, and π···π stacking interactions significantly contribute to structure stabilization, leading to the formation of a supramolecular assembly. The microbiological tests have shown complex 1 exhibited a slightly higher anti-biofilm activity than that of compound 2. Interestingly, electrochemical studies have allowed us to determine the relationship between the oxidizing properties of complexes and their biological activity. Probably the mechanism of action of 1 and 2 is associated with generating a cellular response similar to oxidative stress in bacterial cells.

Synthesis, crystal structure and docking studies of tetracyclic 10-iodo-1,2-dihydroisoquinolino[2,1-b][1,2,4]benzothiadiazine 12,12-dioxide and its precursors.

The title compound, 10-iodo-1,2-dihydroisoquinolino[2,1-b][1,2,4]benzothiadiazine 12,12-dioxide, C15H11IN2O2S (8), was synthesized via the metal-free intramolecular N-iodosuccinimide (NIS)-mediated radical oxidative sp3-C-H aminative cyclization of 2-(2'-aminobenzenesulfonyl)-1,3,4-trihydroisoquinoline, C15H16N2O2S (7). The amino adduct 7 was prepared via a two-step reaction, starting from the condensation of 2-nitrobenzenesulfonyl chloride (4) with 1,2,3,4-tetrahydroisoquinoline (5), to afford 2-(2'-nitrobenzenesulfonyl)-1,3,4-trihydroisoquinoline, C15H14N2O4S (6), in 82% yield. The catalytic hydrogenation of 6 with hydrogen gas, in the presence of 10% palladium-on-charcoal catalyst, furnished 7. Products 6-8 were characterized by their melting points, IR and NMR (1H and 13C) spectroscopy, and single-crystal X-ray diffraction. The three compounds crystallized in the monoclinic space group, with 7 exhibiting classical intramolecular hydrogen bonds of 2.16 and 2.26 Å. All three crystal structures exhibit centrosymmetric pairs of intermolecular C-H...π(ring) and/or π-π stacking interactions. The docking studies of molecules 6, 7 and 8 with deoxyribonucleic acid (PDB id: 1ZEW) revealed minor-groove binding behaviours without intercalation, with 7 presenting the most favourable global energy of the three molecules. Nonetheless, molecule 8 interacted strongly with the DNA macromolecule, with an attractive van der Waals energy of -15.53 kcal mol-1.

Structural studies on two new phosphoramides with the same [OC4H8N]P(O) segment by means of single-crystal X-ray diffraction, Hirshfeld surface analysis and 3D energy framework approach

Two new phosphoramides containing the same [OC4H8N]P(O) segment (bearing the substituent morpholine) accompanied by different [C(O)NH]P(O)[N]2 (phosphoric triamide, 1) and [N]P(O)[O]2 (amidophosphoric acid ester, 2) skeletons are investigated by single crystal X-ray diffraction and completed by FT-IR and 1H, 13C, 31P NMR spectroscopy. Structures 1 and 2 crystallize in the triclinic space group P1¯ and the monoclinic space group I2/a, respectively, both with one independent molecule in the asymmetric unit. The crystal structure of 1 is stabilized via a classical hydrogen bond interaction N—H…OP as a dimer pattern extending into a 3D network by non-classical C—H…F, C—H…Cl and C—H…O weak hydrogen bond interactions, while, the crystal packing of 2 is mostly dominated by the non-classical hydrogen bond interaction (C―H…)3OP. A precise exploration of the intermolecular interactions by using different analysis tools including three-dimensional (3D) Hirshfeld surfaces, 2D fingerprint plots, enrichment ratios, and 3D energy frameworks shows that the attractive X―H…OP (X = N or C) hydrogen bond interactions on the Hirshfeld surfaces are quite enriched and thus accepted as favoured contacts. Based on the interaction energy analysis, a dominant electrostatic nature is found for the classical hydrogen bond interaction N―H…OP in 1, while the non-classical (C―H…)3OP hydrogen bond interaction in 2 shows both electrostatic and dispersion components. Furthermore, an interesting outcome of the obtained results is that the stability of both phosphoramide structures, in the presence (for 1) or absence (for 2) of a classical (strong) interaction, is given by pseudo-similar intermolecular connectivities with the contribution of the PO group as an suitable H atom acceptor site.

Effect of substitutions on the geometry and intramolecular hydrogen bond strength in meta-benziporphodimethenes: A new porphyrin analogue

A new class of compound meta-benziporphodimethene, that has low synthetic yield yet extensive applications in metal ion sensing and cell-imaging, has been explored here. The present work is aimed to investigate the effect of substituents at sp2 and sp3meso carbons, on the geometry and energy of these molecules. The substitution at these positions affects the inner geometry (cavity size) and the classical hydrogen bond strengths. The hydrogen bond strength has been estimated using molecular tailoring-based approach using density functional theory. Theoretical studies showed that on increasing the bulkiness of sp3meso positions, the puckered structure undergoes better conventional hydrogen bonding. It is also concluded that electron-withdrawing groups at sp2meso phenyl stabilize the molecule more than electron-donating ones. This study is useful for perceiving the factors regulating the cavity size in meta-benziporphodimethene analogs that can further enhance the ease in metalation of these moieties.

Crystal structure and Hirshfeld surface analysis of 4-{2,2-di-chloro-1-[(E)-2-(4-methyl-phen-yl)diazen-1-yl]ethen-yl}-N,N-di-methyl-aniline.

In the tile compound, C17H17Cl2N3, the dihedral angle between the benzene rings is 62.73 (9)°. In the crystal, there are no classical hydrogen bonds. Mol-ecules are linked by a pair of C-Cl⋯π inter-actions, forming an inversion dimer. A short inter-molecular HL⋯HL contact [Cl⋯Cl = 3.2555 (9) Å] links the dimers, forming a ribbon along the c-axis direction. The Hirshfeld surface analysis and two-dimensional fingerprint plots reveal that the most important contributions for the crystal packing are from H⋯H (45.4%), Cl⋯H/H⋯Cl (21.0%) and C⋯H/H⋯C (19.0%) contacts.

Crystal Structure of Dacarbazine, Metoclopramide, and Acetylcholine Pentacyanopropenides

The crystal structures of new salt forms of the known nitrogen-containing pharmaceuticals (dacarbazine, metoclopramide, and acetylcholine) in which 1,1,2,3,3-pentacyanopropenide anion acts as a counterion are analyzed by X-ray diffraction. It is found that in the crystals of studied salts with dacarbazine (in the form of a monohydrate) and metoclopramide, the mentioned anion plays the role of a structure-forming spacer, linking with more than one cation by classical hydrogen bonds. The types of cation and anion localization in the studied salts are revealed. They are: layered in the crystals with dacarbazine, stacked with the cation and anion alternation in the crystals with metoclopramide, and anion columns surrounded by cations in the crystals with acetylcholine. The tendency of the pentacyanopropenide anion to disordering in the crystals of metoclopramide and acetylcholine salts is detected.

Local potential energy: A novel QTAIM tool to quantify the binding energy of classical hydrogen bonds

We developed the local potential energy, LPE, model based on the electrostatic force (the unique fundamental force for chemical bonds) whose equation uses QTAIM topological data. The effectiveness of the LPE was evaluated with other well-known methods (supramolecular binding enthapy, SAPT-DFT, LMOEDA and IQA) by analyzing the hydrogen bond energy for a set of organic and inorganic molecules. The LPE has the second highest linearity with the supramolecular binding enthalpy (R2 = 0.9808) and the highest precision (RMSD = 1.60 kcal mol−1). In addition, LPE has the advantage to give individual binding energy values when the complex has more than one hydrogen bond.

Crystal structure of atazanavir, C38H52N6O7

The crystal structure of atazanavir has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Atazanavir crystallizes in space group P21 (#4) with a = 15.33545(7), b = 5.90396(3), c = 21.56949(13) Å, β = 96.2923(4)°, V = 1941.134(11) Å3, and Z = 2. Despite being labeled as “atazanavir sulfate”, the commercial reagent sample consisted of atazanavir free base. The structure consists of an array of extended-conformation molecules parallel to the ac-plane. Although the atazanavir molecule contains only four classical hydrogen bond donors, hydrogen bonding is, surprisingly, important to the crystal energy. Both intra- and intermolecular hydrogen bonds are significant. The hydroxyl group forms bifurcated intramolecular hydrogen bonds to a carbonyl oxygen atom and an amide nitrogen. Several amide nitrogens act as donors to the hydroxyl group and carbonyl oxygen atoms. An amide nitrogen acts as a donor to another amide nitrogen. Several methyl, methylene, methyne, and phenyl hydrogens participate in hydrogen bonds to carbonyl oxygens, an amide nitrogen, and the pyridine nitrogen. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1426.

Phenylalanine476 mutation of pullulanase from Bacillus subtilis str. 168 improves the starch substrate utilization by weakening the product β-cyclodextrin inhibition

Since β-cyclodextrin (β-CD) was the competitive inhibitor of pullulanase, substrate utilization and product inhibition were a conflict in β-CD production when using pullulanase for debranching to release more convertible substrate. Here, a phenylalanine complexed with cyclodextrin ligand via classic hydrophobic interaction and hydrogen bond in the crystal structure of pullulanase and absolutely conserved in all homologous, was selected to study its contribution in inhibition and to get mutants with lower affinity to β-CD. Mutants were generated by substituting phenylalanine with tyrosine, valine, histidine, cysteine, aspartic acid or alanine. Enzyme activity assay and ITC data proved that F476 mutants successfully reduced the protein affinity to β-CD. Although circular dichroism spectra and fluorescence spectroscopy results showed F476 mutation affected the secondary structure and microenvironment of pullulanase, mutants F476C and F476H retained relatively higher enzyme activity and significantly decreased affinity to β-CD. The conversion rate of starch into β-CD increased by 6.0% and 6.6%, when adding F476C or F476H in the production process.

Crystal structure of ethyl 2-(5-amino-1-benzene-sulfonyl-3-oxo-2,3-di-hydro-1H-pyrazol-2-yl)acetate.

In the title compound, C13H15N3O5S, the two rings face each other in a 'V' form at the S atom, with one N-H⋯O=S and one C-H⋯O=S contact from the pyrazolyl substituents to the sulfonyl group. Two classical hydrogen bonds from the amine group, one of the form N-H⋯O=S and one N-H⋯O=Coxo, link the mol-ecules to form layers parallel to the bc plane.

Packing Polymorphism on the Example of 5-Hydroxy-1-(4-Methylbenzyl)-3-Chloro-4-[(4-Chlorophenyl)Sulfanyl]-1,5-Dihydro-2H-Pyrrol-2-One: A Crystallographic, Thermochemical, and Spectroscopic Study

Two packing polymorphs of 5-hydroxy-1-(4-methylbenzyl)-3-chloro-4-[(4-chlorophenyl)sulfanyl]-1,5-dihydro-2H-pyrrol-2-one are studied by single-crystal and powder X-ray diffraction, IR spectroscopy, and differential scanning calorimetry. Classical hydrogen bonds and CL…O interactions have the fundamental importance for the formation of the supramolecular motif that is identical in both modifications. The difference relates to the packing of 2D layers which is “parallel” in the triclinic modification and of the “herringbone” type in the monoclinic modification. It is shown that close similarity between structural organizations of crystal lattices, which is typical of packing polymorphs, can be accompanied by significant differences between their energies as well as by a high potential barrier upon the transition from the metastable polymorph to its stable form.

Combining Chirality and Hydrogen Bonding in Methylated Ethylenedithio-Tetrathiafulvalene Primary Diamide Precursors and Radical Cation Salts

Methyl-and dimethyl-ethylenedithio-tetrathiafulvalene ortho-diamide donors Me-EDT-TTF(CONH2)2 (1a) and DM-EDT-TTF(CONH2)2 (1b) have been prepared by the direct reaction of the corresponding diester precursors with aqueous ammonia solutions. The neutral (rac)-1a, (S)-1a and (S,S)-1b donors have been characterized by single crystal X-ray diffraction. In the three compounds, which crystallized in the non-centrosymmetric monoclinic space-group P21, the amide groups are disordered, yet they form the classical intramolecular hydrogen bond for such ortho-diamide motif. Electrocrystallization experiments afforded the mixed valence radical cation salts [(S,S)-1b]2XO4 and [(R,R)-1b]2XO4 (X = Cl, Re) containing four independent donors in the asymmetric unit, with the positive charge localized essentially on two donors while the two others are neutral. The topology of the organic layer is of '-type. Single crystal resistivity measurements show semiconducting behavior for [(S,S)-1b]2ClO4 and [(R,R)-1b]2ReO4, with a room temperature conductivity of 5 10-5 S cm-1 and activation energies Ea ≈ 3000 K. Tight-binding band structure calculations of extended Huckel type in combination with DFT calculations are in agreement with the semiconducting behavior and suggest a localized Mott type semiconductor rather than a band gap semiconductor.