Facile hydrothermal bio-synthesis of cellulose acetate templated CuS nanorods like fibres: antibacterial, cytotoxicity effects and DNA cleavage properties against A549 lung cancer cells

In this research, the hydrothermal method was used for synthesising cellulose acetate (CA) templated nanorods like CuS fibres using vegetable extract (Brassica oleracea var. italica). These extracts act as a reducing agent in the presence of CA. Surprisingly, when the same reaction was carried out in the absence of CA and broccoli extract, structural morphology disappeared and was found as agglomerated. In the presence of cellulose templated extract mediated CuS has revealed as nanorods like fibres and was confirmed by field emission scanning electron microscope analysis. Their crystallinity property of CuS nanoparticles (NPs) and cellulose templated biosynthesised CuS NPs was analysed and compared using X-ray diffraction technique. The biological activities of the obtained product were examined for antibacterial assessment against two bacterial strains that include two-gram negative strains (E.Coli and S. aureus). The nanostructured product found to exhibit excellent antibacterial agent against all the strains. Biosynthesised nanostructure showed its efficacy against A549 lung cancer cells which might attribute to a larger surface to volume ratio of nanorods like fibres. The authors observation suggest that CuS nanorods like fibres can significantly reduce the cell growth with IC₅₀ value of 31.2 μg/ml.

Atropisomerism in 3-arylthiazolidine-2-thiones. A combined dynamic NMR and dynamic HPLC study

Sterically hindered 3-arylthiazolidine-2-thiones were prepared by a solvent-free reaction with arylisothiocyanates and 1,4-dithiane-2,5-diol. Atropisomerism was observed in two compounds (3 and 4, aryl = 1-naphthyl and 2-methylnaphth-1-yl), whose rotational energy barriers were measured using dynamic NMR and dynamic HPLC. The experimental analyses were supported by DFT calculations. Thermally stable atropisomers were obtained by dehydration of compounds 3 and 4 and the absolute configuration of the atropisomers of compound 6 was determined by theoretical simulation of the ECD and VCD spectra.

Spectroscopic investigations, molecular interactions, and molecular docking studies on the potential inhibitor "thiophene-2-carboxylicacid"

Thiophene derivatives have been focused in the past decades due to their remarkable biological and pharmacological activities. In connection with that the conformational stability, spectroscopic characterization, molecular (inter- and intra-) interactions, and molecular docking studies on thiophene-2-carboxylicacid have been performed in this work by experimental FT-IR and theoretical quantum chemical computations. Experimentally recorded FT-IR spectrum in the region 4000-400 cm(-1) has been compared with the scaled theoretical spectrum and the spectral peaks have been assigned on the basis of potential energy distribution results obtained from MOLVIB program package. The conformational stability of monomer and dimer conformers has been examined. The presence of inter- and intramolecular interactions in the monomer and dimer conformers have been explained by natural bond orbital analysis. The UV-Vis spectra of the sample in different solvents have been simulated and solvent effects were predicted by polarisable continuum model with TD-DFT/B3LYP/6-31+G(d,p) method. To test the biological activity of the sample, molecular docking (ligand-protein) simulations have been performed using SWISSDOCK web server. The full fitness (FF) score and binding affinity values revealed that thiophene-2-carboxylicacid can act as potential inhibitor against inflammation.

Anti-infective potential of caffeic acid and epicatechin 3-gallate isolated from methanol extract of Euphorbia hirta (L.) against Pseudomonas aeruginosa

Euphorbia hirta (L.) plant is traditionally used in Malaysia for the treatment of gastrointestinal, bronchial and respiratory ailments caused by nosocomial infectious agents. Bioactivity-guided fractionation of the methanol extract of the aerial parts of E. hirta and analysis using high-performance liquid chromatography have led to the isolation of two antibacterial compounds. These compounds were identified as caffeic acid (CA) and (-)-epicatechin 3-gallate (ECG) based on spectroscopic analyses and comparison with previously published data. Using broth microdilution method, both ECG and CA had demonstrated significant minimum inhibitory concentration of 15.6 and 31.3 μg/mL respectively, against Pseudomonas aeruginosa. Time-kill assessment of ECG and CA displayed bactericidal effect on P. aeruginosa cells.

Rotational isomers, spectroscopic (FT-IR, FT-Raman) studies and quantum chemical calculations on 2,4,6-tris(dimethylaminomethyl) phenol

In this work, the spectroscopic characterization of 2,4,6-tris(dimethylaminomethyl) phenol; a novel promoter factor for DNA has been studied primarily. The FT-IR (4000-400 cm(-1)) and FT-Raman (3500-100 cm(-1)) spectra have been recorded on the solid phase of the title molecule. The spectroscopic signature of the title molecule has been found by comparing experimental FT-IR, FT-Raman spectra with the theoretical IR and Raman spectra of the stable isomer geometry at density functional theory (DFT) method with 6-311++G(d,p) basis set. Further, the vibrational assignments were performed on the basis of potential energy distribution (PED). The natural atomic orbital and natural population analysis performed in this study ensures us to know about the delocalization of charge and electron density of atoms within the molecule. Analysis of natural bond orbitals (NBOs) and HOMO-LUMO energy gap of the compound provides information about its chemical stability and intramolecular charge transfer properties. In addition, the reacting electrophilic and nucleophilic sites of the molecule were predicted with the help of molecular electrostatic potential (MEP) surface analysis. Moreover, the intensity of molecular vibrations at different temperatures were examined by applying thermo-chemical analysis. To investigate the solvent effect, the polarizable continuum model was used and the allowed transitions between various HOMO and LUMO levels were found.

Ethyl 3-(4-chloro-benzo-yl)-1-(4-chloro-benz-yl)-4-(4-chloro-phen-yl)-2,2-dioxo-3,4,6,7,8,8a-hexa-hydro-1H-pyrrolo-[2,1-c][1,4]thia-zine-1-carboxyl-ate

In the title compound, C30H28Cl3NO5S, the pyrrolidine ring adopts an envelope conformation (with the N atom as the flap) and the thia-zine ring is in a distorted chair conformation. The mol-ecular structure shows three intra-molecular C-H⋯O inter-actions leading to self-associated ring S(6) and two S(7) motifs. In the crystal, the molecules are linked by C-H⋯O and C-H⋯Cl inter-actions. Two R 2 (2)(10) and one R 2 (2)(16) centrosymmetrically related ring motifs are observed in the unit cell and they are connected through C(6) and C(11) chain motifs extending along the b and c axes, respectively.

Vibrational (FT-IR and FT-Raman) spectra and quantum chemical studies on the molecular orbital calculations, chemical reactivity and thermodynamic parameters of 2-chloro-5-(trifluoromethyl) aniline

In this work, the vibrational characteristics of 2-chloro-5-(trifluoromethyl) aniline have been investigated and both the experimental and theoretical vibrational data indicate the presence of various functional groups within the title molecule. The influence of chlorine substituent on the vibrational wavenumbers of a molecule in comparison with aniline and trifluoromethyl aniline has been discussed in detail. The density functional theoretical (DFT) computations were performed at the B3LYP/6-31++G(3df,3pd)/6-31G(3df,3pd) levels to derive the optimized geometry, vibrational wavenumbers with IR and Raman intensities. Furthermore, the molecular orbital calculations such as; natural bond orbitals (NBOs) and HOMO-LUMO energy gap and mapped molecular electrostatic potential (MEP) surfaces were also performed with the same level of DFT. The temperature dependence thermodynamic parameters of a molecule were illustrated on the basis of their correlation graphs. The detailed interpretation of the vibrational spectra has been carried out with the aid of potential energy distribution (PED) results obtained from MOLVIB program. The delocalization of electron density in various constituents of the molecule has been discussed with the aid of NBO and HOMO-LUMO energy gap analysis.

Isomorphous methyl- and chloro-substituted small heterocyclic analogues obeying the chlorine-methyl (Cl-Me) exchange rule

The two new isomorphous structures [3-methyl-4-(4-methylphenyl)-1-phenyl-6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridin-5-yl](thiophen-2-yl)methanone, C26H18F3N3OS, (I), and [4-(4-chlorophenyl)-3-methyl-1-phenyl-6-trifluoromethyl-1H-pyrazolo[3,4-b]pyridin-5-yl](thiophen-2-yl)methanone, C25H15ClF3N3OS, (II), are shown to obey the chlorine-methyl exchange rule. Both structures show extensive disorder, treatment of which greatly improves the quality of the description of the structures. In addition, it is worth noting that the presence of extensive disorder may make it difficult to detect the isomorphism automatically during data-mining procedures (such as searches of the Cambridge Structural Database).

5-Benzoyl-2-(1H-indol-3-yl)-4-[4-(propan-2-yl)phenyl]-4,5-dihydrofuran-3-carbonitrile

In the title compound, C₂₉H₂₄N₂O₂, the hydrofuran ring is twisted with puckering parameters Q = 0.1553 (16) Å and ϕ = 305.0 (6)°. In the crystal, the graph-set motifs of the inter­action pattern are an R₂²(16) motif involving dimers through N—H⋯N hydrogen bonds across centres of inversion and a C(6) motif through C—H⋯O hydrogen-bond between glide-related mol­ecules. Together, these generate [101] ladder-like chains.

Spin-spin and spin-orbit interactions in nanographene fragments: a quantum chemistry approach

The relativistic behavior of graphene structures, starting from the fundamental building blocks--the poly-aromatic hydrocarbons (PAHs) along with other PAH nanographenes--is studied to quantify any associated intrinsic magnetism in the triplet (T) state and subsequently in the ground singlet (S) state with account of possible S-T mixture induced by spin-orbit coupling (SOC). We employ a first principle quantum chemical-based approach and density functional theory (DFT) for a systematic treatment of the spin-Hamiltonian by considering both the spin-orbit and spin-spin interactions as dependent on different numbers of benzene rings. We assess these relativistic spin-coupling phenomena in terms of splitting parameters which cause magnetic anisotropy in absence of external perturbations. Possible routes for changes in the couplings in terms of doping and defects are also simulated and discussed. Accounting for the artificial character of the broken-symmetry solutions for strong spin polarization of the so-called "singlet open-shell" ground state in zigzag graphene nanoribbons predicted by spin-unrestricted DFT approaches, we interpolate results from more sophisticated methods for the S-T gaps and spin-orbit coupling (SOC) integrals and find that these spin interactions become weak as function of size and increasing decoupling of electrons at the edges. This leads to reduced electron spin-spin interaction and hence almost negligible intrinsic magnetism in the carbon-based PAHs and carbon nanographene fragments. Our results are in agreement with the fact that direct experimental evidence of edge magnetism in pristine graphene has been reported so far. We support the notion that magnetism in graphene only can be ascribed to structural defects or impurities.

(±)-trans-5-Benzoyl-4-(3-bromophenyl)-2-(1H-indol-3-yl)-4,5-dihydrofuran-3-carbonitrile

The furan ring in the title compound, C₂₆H₁₇BrN₂O₂, adopts a twisted envelope conformation. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O inter­action which generates an S(6) ring motif. The crystal packing is stabilized by N—H⋯O and C—H⋯Br inter­actions, generating an R₂²(16) ring motif and a C(12) linear chain motif, respectively. Weak C—H⋯π bonding is also observed.

Vibrational spectroscopic studies, molecular orbital calculations and chemical reactivity of 6-nitro-m-toluic acid

The potential energy surface scan for the selected dihedral angle of 6-nitro-m-toluic acid (NTA) has been performed to identify stable conformer. The optimized structure parameters and vibrational wavenumbers of stable conformer have been predicted by density functional B3LYP method with 6-311++G(d,p) basis set. The formation of dimer species through carboxylic acid group of the title molecule has also been discussed. The theoretical dimer geometries have been compared with that of monomer and the variations of bond lengths and bond angles upon dimerization were also discussed. Natural bond orbital (NBO) analysis has been performed on both monomer and dimer geometries. The significant changes in occupancies and the energies of bonding and anti-bonding orbitals upon dimerization have been explained in detail. The predicted frontier molecular orbital energies at B3LYP/6-311++G(d,p) method set show that charge transfer occurs within the molecule. The nucleophilic and electrophilic sites obtained from the molecular electrostatic potential (MEP) surface were compared with their derived fitting point charges. The vibrational wavenumbers of NTA affected profusely by the nitro group substitution in comparison to the toluic acid have been interpreted in this work.

(±)-trans-5-Benzoyl-2-(1H-indol-3-yl)-4-phenyl-4,5-dihydro-furan-3-carbonitrile

The furan ring in the title compound, C(26)H(18)N(2)O(2), is twisted about the C(H)-C(H) bond. The mol-ecular structure is stabilized by an intra-molecular C-H⋯O inter-action, which generates an S(6) ring motif. The presence of N-H⋯N hydrogen bonds leads to inversion dimers, which are stabilized in the crystal packing by C-H⋯O and C-H⋯π inter-actions, forming layers that stack along the a axis.

5-Benzoyl-2-(1H-indol-3-yl)-4-(4-methylphenyl)-4,5-dihydrofuran-3-carbonitrile

The furan ring in the title compound, C₂₇H₂₀N₂O₂, adopts a twisted conformation about the sp³—sp³ bond. The mol­ecular structure is stabilized by an intra­molecular C—H⋯O inter­action which generates an S(6) ring motif. The crystal packing is stabilized by N—H⋯O and C—H⋯O inter­actions generating centrosymmetric R₂²(18) and C(6) chain motifs, respectively. A weak C—H⋯π inter­action is also observed.

Poly[μ(3)-β-alanine-aqua-μ(4)-sulfato-dilithium]

The title compound, [Li(2)(SO(4))(C(3)H(7)NO(2))(H(2)O)](n), is a coordination polymer in which the β-alanine residues remain in the zwitterionic form. The crystal structure consists of corrugated sheets of [LiO(4)] and [SO(4)] tetra-hedra parallel to (010) with the β-alanine mol-ecules located between the sheets. The two independent Li(+) cations are four-coordinated by O atoms in a distorted tetra-hedral geometry. The crystal structure is formed by stacking of alternate organic and inorganic layers along the a axis. The crystal structure is further stabilized by N-H⋯O hydrogen bonds.

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied.

Diethyl 1-benzyl-2,2-dioxo-4-phenyl-3,4,6,7,8,8a-hexahydro-1H-pyrrolo[2,1-c][1,4]thiazine-1,3-dicarboxylate

In the title compound, C₂₆H₃₁NO₆S, the five-membered pyrrolidine ring adopts an envelope conformation and the six-membered thia­zine ring is in a distorted chair conformation. The crystal packing is stabilized through an inter­molecular C—H⋯O inter­action, generating inversion-related R₂²(10) ring motifs.

Interfacial dynamic adsorption and structure of molecular layers of peptide surfactants

Short peptide surfactants have recently emerged as a new class of amphiphiles, with tremendous potential in improving surface biocompatibility and mediating interfacial DNA immobilization. To establish their basic interfacial adsorption properties, cationic peptide surfactants V(m)K(n) have been studied by combining the measurements of spectroscopic ellipsometry (SE), neutron reflection (NR) and atomic force microscopy (AFM). Our results showed that changes in peptide structure, concentration, solution pH and ionic strength all affected their interfacial assembly. Increases in m and decreases in n reduced the critical aggregation concentration (CAC), but increased the amount of adsorption, showing the strong influence of the amphiphilic balance between hydrophilic and hydrophobic moieties. While the surface adsorbed amount increased with time and peptide concentration, an increase in ionic strength decreased peptide adsorption due to surface charge neutralization. Changes in solution pH did not affect the equilibrium surface adsorbed amount on the weakly negative SiO(2) surface, but did alter the adsorption dynamics. Neutron reflection revealed that V(6)K readily formed a bilayer structure of 35 A thickness at the interface, with the main part of the V(6) fragments being packed back-to-back to form a 15 A hydrophobic core and the two outer K regions being incorporated with a minor amount of V fragments forming the headgroup layers of 9 A each. AFM imaging revealed a sheet-like membrane structure incorporating defects of holes but the thicknesses probed by AFM were consistent with neutron reflection. It was demonstrated that the V(6)K peptide bilayer was effective for immobilization of DNA. The amount of DNA immobilized followed approximate 1:1 charge neutralization between the outer leaf peptide sublayer and the negatively charged DNA.

2-(2,4-Dichlorophenyl)-9-phenyl-2,3-dihydrothieno[3,2-b]quinoline

In the title compound, C₂₃H₁₅Cl₂NS, the quinoline system is almost planar [r.m.s. deviation = 0.013 (2) Å]. The phenyl group is disordered over two positions with site occupancies of 0.55 and 0.45, and is oriented in a nearly perpendicular configuration to the quinoline ring [the dihedral angles between the quinoline ring and the major and minor disordered components of the phenyl ring are 81.8 (2) and 71.6 (2)°, respectively]. The dihydro­thiene ring adopts an envelope conformation. The dihedral angle between the chloro­phenyl ring and the quinoline system is 79.32 (1)°. In the crystal weak C—H⋯π inter­actions occur.

2,10-Dihydroxy-13-methyl-13-azatetracyclo[9.3.1.02,10.03,8]pentadeca-3(8),4,6-triene-9,15-dione

In the title compound, C15H15NO4, then-methylpiperidone ring adopts a chair conformation and both five-membered rings adopt a twist conformation. An intramolecular O—H...O hydrogen bond is observed. Inversion-related molecules are linked intoR22(10) dimers by pairs of O—H...O hydrogen bonds. The crystal structure is further stabilized by C—H...O hydrogen bonds.

13-Hydroxy-4,16-dimethyl-4,16-diazapentacyclo[12.3.1.01,5.05,13.07,12]octadeca-7(12),8,10-triene-6,18-dione

In the title compound, C₁₈H₂₀N₂O₃, the N-methyl­piperidone ring adopts a chair conformation. The pyrrolidine ring and the five-membered cyclo­pentane rings adopt envelope conformations. The five-membered ring of the ninhydrin system adopts an envelope conformation with the central C atom deviating by 0.217 (1)Å from the mean plane through the other atoms. The mol­ecular packing is characterized by inter­molecular C—H⋯O and intra­molecular C—H⋯O and O—H⋯N inter­actions.

The Small Ribozymes: Common and Diverse Features Observed through the FRET Lens

The hammerhead, hairpin, HDV, VS and glmS ribozymes are the five known, naturally occurring catalytic RNAs classified as the "small ribozymes". They share common reaction chemistry in cleaving their own backbone by phosphodiester transfer, but are diverse in their secondary and tertiary structures, indicating that Nature has found at least five independent solutions to a common chemical task. Fluorescence resonance energy transfer (FRET) has been extensively used to detect conformational changes in these ribozymes and dissect their reaction pathways. Common and diverse features are beginning to emerge that, by extension, highlight general biophysical properties of non-protein coding RNAs.

1-Benzyl-4',5'-diphenyl-piperidine-3-spiro-3'-pyrrolidine-2'-spiro-3''-indoline-4,2''-dione

The asymmetric unit of the title compound, C₃₄H₃₁N₃O₂, consists of two independent mol­ecules which differ slightly in the orientations of the phenyl rings with respect to the pyrrolidine ring. In both mol­ecules, the piperidin-4-one ring adopts a chair conformation, whereas the pyrrolidine ring adopts an envelope conformation in one of the mol­ecules and a twisted conformation in the other. An intra­molecular C—H⋯O hydrogen bond is observed. The crystal packing is stabilized by inter­molecular N—H⋯O hydrogen bonds and C—H⋯π inter­actions.

Candidate cell and matrix interaction domains on the collagen fibril, the predominant protein of vertebrates

Type I collagen, the predominant protein of vertebrates, polymerizes with type III and V collagens and non-collagenous molecules into large cable-like fibrils, yet how the fibril interacts with cells and other binding partners remains poorly understood. To help reveal insights into the collagen structure-function relationship, a data base was assembled including hundreds of type I collagen ligand binding sites and mutations on a two-dimensional model of the fibril. Visual examination of the distribution of functional sites, and statistical analysis of mutation distributions on the fibril suggest it is organized into two domains. The "cell interaction domain" is proposed to regulate dynamic aspects of collagen biology, including integrin-mediated cell interactions and fibril remodeling. The "matrix interaction domain" may assume a structural role, mediating collagen cross-linking, proteoglycan interactions, and tissue mineralization. Molecular modeling was used to superimpose the positions of functional sites and mutations from the two-dimensional fibril map onto a three-dimensional x-ray diffraction structure of the collagen microfibril in situ, indicating the existence of domains in the native fibril. Sequence searches revealed that major fibril domain elements are conserved in type I collagens through evolution and in the type II/XI collagen fibril predominant in cartilage. Moreover, the fibril domain model provides potential insights into the genotype-phenotype relationship for several classes of human connective tissue diseases, mechanisms of integrin clustering by fibrils, the polarity of fibril assembly, heterotypic fibril function, and connective tissue pathology in diabetes and aging.

3-[(E)-4-Methoxy-benzyl-idene]-1-methyl-piperidin-4-one

The piperidone ring of the title compound, C(14)H(17)NO(2), adopts a half-chair conformation. The crystal packing is stabilized by inter-molecular C-H⋯O inter-actions, which generate a C(8) chain running along the b axis.

3-[(E)-2,4-Dichloro-benzyl-idene]-1-methyl-piperidin-4-one

The piperidine ring of the title compound, C₁₃H₁₃Cl₂NO, adopts an envelope conformation. Inter­molecular C—H⋯O inter­actions link the mol­ecules into a C(7) chain running along the b axis.

3-(4-Chloro-phen-yl)-7-methyl-4-(4-methyl-phen-yl)-1-oxa-2,7-diaza-spiro-[4.5]dec-2-en-10-one

In the title compound, C₂₁H₂₁ClN₂O₂, the dihydro­isoxazole ring adopts an envelope conformation and the piperidinone ring is in a chair conformation. The dihedral angle between the two benzene rings is 84.2 (1)°. The crystal used was an inversion twin.

(1R,4R,5R)-1,3,4-Triphenyl-7-[(R)-1-phenyl-ethyl]-2-oxa-3,7-diaza-spiro-[4.5]decan-10-one

In the title compound, C₃₃H₃₂N₂O₂, the polysubstituted piperidine ring adopts a chair conformation. The isoxazolidine ring is in an envelope conformation. In the crystal structure, intra- and inter­molecular C—H⋯π inter­actions involving the phenyl rings are observed.

1'-Methyl-4'-(1-naphth-yl)-3''-(1-naphthyl-methyl-ene)acenaphthene-1-spiro-2'-pyrrolidine-3'-spiro-1''-cyclo-hexane-2,2''-dione

In the title compound, C(42)H(33)NO(2), the six-membered cyclo-hexa-none ring adopts a slightly distorted chair conformation and the five-membered pyrrolidine ring is in an envelope conformation. The mol-ecular structure features four intra-molecular C-H⋯O inter-actions and an intra-molecular C-H⋯π inter-action. Furthermore, the crystal packing is stabilized by an inter-molecular C-H⋯O and three inter-molecular C-H⋯π inter-actions.

(5S,6S,10R)-10-(2,4-Dichloro-phen-yl)-14-[(E)-(2,4-dichloro-phen-yl)methyl-idene]-3,9-diphenyl-12-[(R)-1-phenyl-ethyl]-1,4,7-trioxa-2,8,12-triaza-dispiro-[4.0.4.4]tetra-deca-2,8-diene

The asymmetric unit of the title compound, C(41)H(31)Cl(4)N(3)O(3), contains two independent mol-ecules with almost identical geometries. The piperidine ring adopts a chair conformation in both mol-ecules, and the dihydro-isoxazole rings adopt envelope conformations. The crystal structure is stabilized by C-H⋯N hydrogen bonds and C-H⋯π inter-actions.

1'-Methylcyclooctane-1-spiro-3'-pyrrolidine-2'-spiro-3''-indoline-2,2''-dione and 1,1'-dimethylpiperidine-3-spiro-3'-pyrrolidine-2'-spiro-3''-indoline-2'',4-dione

In both title compounds, C(19)H(24)N(2)O(2), (I), and C(17)H(21)N(3)O(2), (II), respectively, there are two molecules in the asymmetric unit and the pyrrolidine rings adopt envelope conformations. The conformations of the cyclooctane [in (I)] and 1-methylpiperidone [in (II)] rings are boat-chair and chair, respectively. The indolin-2-one group is almost perpendicular to the pyrrolidine ring. Intermolecular C-H...O, N-H...O and N-H...N interactions provide stability to the structures.

(R)-3,5-Bis[(E)-benzylidene]-1-(1-phenylethyl)piperidin-4-one, 3,5-bis[(E)-4-chlorobenzylidene]-1-[(R)-1-phenylethyl]piperidin-4-one and 3,5-bis[(E)-2-chlorobenzylidene]-1-[(R)-1-phenylethyl]piperidin-4-one

Polysubstituted piperidones, viz. the title compounds, C(27)H(25)NO, (I), C(27)H(23)Cl(2)NO, (II), and C(27)H(23)Cl(2)NO, (III), adopt sofa conformations. The molecular packing in (I) and (II) is a result of van der Waals interactions, whereas in (III), a C-H...O interaction is also found.

Surface-induced unfolding of human lactoferrin

We have determined the structural conformations of human lactoferrin adsorbed at the air/water interface by neutron reflectivity (NR) and its solution structure by small angle neutron scattering (SANS). The neutron reflectivity measurements revealed a strong structural unfolding of the molecule when adsorbed at the interface from a pH 7 phosphate buffer solution (PBS with a total ionic strength at 4.5 mM) over a wide concentration range. Two distinct regions, a top dense layer of 15-20 angstroms on the air side and a bottom diffuse layer of some 50 angstroms into the aqueous subphase, characterized the unfolded interfacial layer. At a concentration around 1 g dm(-3), close to the physiological concentration of lactoferrin in biological fluids, the adsorbed amount was 5.5 x 10(-8) mol m(-2) in the absence of NaCl, but the addition of 0.3 M NaCl reduced protein adsorption to 3.5 x 10(-8) mol m(-2). Although the polypeptide distributions at the interface remained similar, quantitative analysis showed that the addition of NaCl reduced the layer thickness. Parallel measurements of lactoferrin adsorption in D2O instead of null reflecting water confirmed the unfolded structure at the interface. Furthermore, the D2O data indicated that the polypeptide in the top layer was predominantly protruded out of water, consistent with it being hydrophobic. In contrast, the scattering intensity profiles from SANS were well described by a cylindrical model with a diameter of 47 angstroms and a length of 105 angstroms in the presence of 0.3 M NaCl, indicating a retention of the globular framework in the bulk solution. In the absence of NaCl but with the same amount of phosphate buffer, the length of the cylinder increased to some 190 angstroms and the diameter remained constant. The length increase is indicative of changes in distance and orientation between the bilobal monomers due to the change in charge interactions. The results thus demonstrate that the surface structural unfolding was caused by the exposure of the protein molecule to the unsymmetrical energetic balance following surface adsorption.

Stereoselective synthesis and stereochemistry of r-2-alkoxycarbonyl-c-3-o-substituted phenyl-1,4-thiazane 1,1-dioxides

r-2-Alkoxycarbonyl-c-3-aryl-1,4-thiazane 1,1-dioxides were obtained as the stereoselective product, when the aldehyde used was o-substituted benzaldehyde while the p-substituted benzaldehydes gave a trans product. The relative configuration of the adjacent alkoxycarbonyl and aryl groups was assigned from the vicinal coupling constant, 3J = 10.6 Hz in the trans isomer and 3.2 Hz in the cis isomer, and from the multiplicity pattern, i.e., a doublet for the H-2 proton of the trans isomer and a triplet for the H-2 proton of the cis isomer. The unusual, large long-range coupling (4J = 2.8 Hz) because of the "W" arrangement between H-2e and H-6e across the ring type was very useful for confirming the cis configuration and chair conformation of the isomer. The various 1H and 13C NMR assignments were made with the help of 1H–1H COSY, 1H–13C COSY, HMBC, and NOESY spectral analyses.Key words: 1H and 13C NMR, 1H–1H COSY, 1H–13C COSY, HMBC, NOESY, stereoselectivity, 1,4-thiazane.

A(1,3)-strain mediated epimerization of 2e,3e,5e,6e-tetraarylpiperidin-4-one oximes

A series of tri- and tetraarylpiperidin-4-one oximes were synthesized from 2e,3e,6e-tri- and 2e,3e,5e,6e-tetraarylpiperidin-4-ones, respectively. In the case of the latter compounds, oximation is accompanied by epimerization at C-5 to avoid the A(1,3)-strain between the oxime OH group and the 5e-aryl ring of the initially formed oxime resulting in 2e,3e,5a,6e-tetraarylpiperidin-4-one oximes. 1H, 13C and 2D NMR spectroscopic data were employed to characterize and investigate the stereochemistry of these compounds.