Fluoride Anions: Unexploited but Effective Halogen Bond Acceptors

Due to their high electron density, fluoride anions can be considered the most effective halogen bond (HaB) acceptors among the halides. However, under common experimental conditions, F- uncommonly acts as HaB acceptor, expectedly as it is present in hydrated form. Herein we report that under specific crystallization conditions a hydrogen bond-free F- functioning as donor of electron density can be obtained, with the formed HaBs constituting the driving force of the observed crystal packings. Computations confirm the strength of these HaBs compared to analogous interactions involving other halides.

Elucidation of dominant energy metabolic pathways of methane, sulphur and nitrogen in respect to mangrove-degradation for climate change mitigation

Mangroves play a key role in ecosystem balancing and climate change mitigation. It acts as a source and sink of methane (CH₄), a major greenhouse gas responsible for climate change. Energy metabolic pathways of methane production (methanogenesis) and oxidation (methanotrophy) are directly driven by sulphur (S) and nitrogen (N) metabolism and salinity in coastal wetlands. To investigate, how mangrove-degradations, affect the source-sink behaviour of CH₄; the pathways of CH₄, S and N were studied through whole-genome metagenomic approach. Soil samples were collected from degraded and undisturbed mangrove systems in Sundarban, India. Structural and functional microbial diversities (KEGG pathways) of CH₄, S and N metabolism were analysed and correlated with labile carbon pools and physico-chemical properties of soil. Overall, the acetoclastic pathway of methanogenesis was dominant. However, the relative proportion of conversion of CO₂ to CH₄ was more in degraded mangroves. Methane oxidation was higher in undisturbed mangroves and the serine pathway was dominant. After serine, the ribulose monophosphate pathway of CH₄ oxidation was dominant in degraded mangrove, while the xylulose monophosphate pathway was dominant in undisturbed site as it is more tolerant to salinity and higher pH. The assimilatory pathway (AMP) of S-metabolism was dominant in both systems. But in AMP pathway, adenosine triphosphate sulfurylase enzyme reads were higher in degraded mangrove, while NADPH-sulfite reductase abundance was higher in undisturbed mangrove due to higher salinity, and pH. In N-metabolism, the denitrification pathway was predominant in degraded sites, whereas the dissimilatory nitrate reduction pathway was dominant in undisturbed mangroves. The relative ratios of sulphur reducing bacteria (SRB): methanogens were higher in degraded mangrove; however, methanotrophs:methanogens was higher in undisturbed mangrove indicated lower source and greater sink capacity of CH₄ in the system. Microbial manipulation in mangrove-rhizosphere for regulating major energy metabolic pathways of methane could open-up a new window of climate change mitigation in coastal wetlands.

Interplay of Halogen and Hydrogen Bonding through Co-Crystallization in Pharmacologically Active Dihydropyrimidines: Insights from Crystal Structure and Energy Framework

A solvent-assisted grinding method has been used to prepare co-crystals in substituted dihydropyrimidines (DHPM) that constitutes pharmacologically active compounds. These were characterized using FT-IR, PXRD, and single-crystal X-ray diffraction. In order to explore the possibility of formation of halogen (XB) and hydrogen bonding (HB) synthons in the solid state, co-crystallization attempts of differently substituted DHPM molecules, containing nitro, hydoxy, and chloro substituents, with different co-formers, such as 1,4-diiodo tetrafluorobenzene (1,4 DITFB) and 3-nitrobenzoic acid (3 NBA) were performed. The XB co-crystals (C2aXB, C2bXB, and C2cXB) prefer the formation of C-I⋅⋅⋅O/C-I⋅⋅⋅S XB synthon, whereas the HB co-crystal (C2dHB) is stabilized by N-H⋅⋅⋅O H-bond formation. Hirshfeld surface analysis revealed that the percentage contribution of intermolecular interactions for XB co-crystals prefer equal contribution of XB synthon along with HB synthon. Furthermore, the interaction energy was analyzed using energy frameworks, which suggests that their stability, a combination of electrostatics and dispersion, is enhanced through XB/HB in comparison to the parent DHPMs.

A unique bacterial and archaeal diversity make mangrove a green production system compared to rice in wetland ecology: A metagenomic approach

Mangrove provides significant ecosystem services, however, 40% of tropical mangrove was lost in last century due to climate change induced sea-level rise and anthropogenic activities. Sundarban-India, the largest contiguous mangrove of the world lost 10.5% of its green during 1930-2013 which primarily converted to rice-based systems. Presently degraded mangrove and adjacent rice ecology in Sundarban-India placed side by side and create typical ecology which is distinct in nature in respect to soil physicochemical properties, carbon dynamics, and microbial diversities. We investigated the structural and functional diversities of bacteria and archaea through Illumina MiSeq metagenomic analysis using V3-V4 region of 16S rRNA gene approach that drives greenhouse gases emission and carbon-pools. Remote sensing-data base were used to select the sites for collecting the soil and gas samples. The methane and nitrous oxide emissions were lower in mangrove (-0.04 mg m^-2 h^-1 and -52.8 μg m^-2 h^-1) than rice (0.26 mg m^-2 h^-1 and 44.7 μg m^-2 h^-1) due to less availability of carbon-substrates and higher sulphate availability (85.8% more than rice). The soil labile carbon-pools were more in mangrove, but lower microbial activities were noticed due to stress conditions. A unique microbial feature indicated by higher methanotrophs: methanogens (11.2), sulphur reducing bacteria (SRB): methanogens (93.2) ratios and lower functional diversity (7.5%) in mangrove than rice. These could be the key drivers of lower global warming potential (GWP) in mangrove that make it a green production system. Therefore, labile carbon build-up potential (38%) with less GWP (63%) even in degraded-mangrove makes it a clean production system than wetland-rice that has high potential to climate change mitigation. The whole genome metagenomic analysis would be the future research priority to identify the predominant enzymatic pathways which govern the methanogenesis and methanotrophy in this system.

Erratum: Azimuthal Anisotropy at the Relativistic Heavy Ion Collider: The First and Fourth Harmonics [Phys. Rev. Lett. 92, 062301 (2004)]

This corrects the article DOI: 10.1103/PhysRevLett.92.062301.

Anti-tubercular activity and molecular docking studies of indolizine derivatives targeting mycobacterial InhA enzyme

A series of 1,2,3-trisubstituted indolizines (2a-2f, 3a-3d, and 4a-4c) were screened for in vitro whole-cell anti-tubercular activity against the susceptible H37Rv and multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB) strains. Compounds 2b-2d, 3a-3d, and 4a-4c were active against the H37Rv-MTB strain with minimum inhibitory concentration (MIC) ranging from 4 to 32 µg/mL, whereas the indolizines 4a-4c, with ethyl ester group at the 4-position of the benzoyl ring also exhibited anti-MDR-MTB activity (MIC = 16-64 µg/mL). In silico docking study revealed the enoyl-acyl carrier protein reductase (InhA) and anthranilate phosphoribosyltransferase as potential molecular targets for the indolizines. The X-ray diffraction analysis of the compound 4b was also carried out. Further, a safety study (in silico and in vitro) demonstrated no toxicity for these compounds. Thus, the indolizines warrant further development and may represent a novel promising class of InhA inhibitors and multi-targeting agents to combat drug-sensitive and drug-resistant MTB strains.

Crystallography, Molecular Modeling, and COX-2 Inhibition Studies on Indolizine Derivatives

The cyclooxygenase-2 (COX-2) enzyme is an important target for drug discovery and development of novel anti-inflammatory agents. Selective COX-2 inhibitors have the advantage of reduced side-effects, which result from COX-1 inhibition that is usually observed with nonselective COX inhibitors. In this study, the design and synthesis of a new series of 7-methoxy indolizines as bioisostere indomethacin analogues (5a-e) were carried out and evaluated for COX-2 enzyme inhibition. All the compounds showed activity in micromolar ranges, and the compound diethyl 3-(4-cyanobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5a) emerged as a promising COX-2 inhibitor with an IC₅₀ of 5.84 µM, as compared to indomethacin (IC₅₀ = 6.84 µM). The molecular modeling study of indolizines indicated that hydrophobic interactions were the major contribution to COX-2 inhibition. The title compound diethyl 3-(4-bromobenzoyl)-7-methoxyindolizine-1,2-dicarboxylate (5c) was subjected for single-crystal X-ray studies, Hirshfeld surface analysis, and energy framework calculations. The X-ray diffraction analysis showed that the molecule (5c) crystallizes in the monoclinic crystal system with space group P 2₁/n with a = 12.0497(6)Å, b = 17.8324(10)Å, c = 19.6052(11)Å, α = 90.000°, β = 100.372(1)°, γ = 90.000°, and V = 4143.8(4)ų. In addition, with the help of Crystal Explorer software program using the B3LYP/6-31G(d, p) basis set, the theoretical calculation of the interaction and graphical representation of energy value was measured in the form of the energy framework in terms of coulombic, dispersion, and total energy.

Tuning up the photovoltaic performances upon the utility of diketopyrrolopyrrole in PEO-based gel polymer electrolytes

The role of diketopyrrolopyrrole (DPP-H) as an additive on the ionic conductivity of poly(ethylene oxide) (PEO)-based gel polymer electrolytes (GPE) was studied for DSSC applications. The pure PEO/PC/KI/TPAI/I2 GPE was prepared with a mixture of propylene carbonate (PC) as a non-volatile plasticizer and iodide salts, such as potassium iodide (KI), tetrapropylammonium iodide (TPAI) and iodine (I2), together with PEO. The modified GPEs were prepared with different weight percentage (wt%) ratios (0.5%, 0.75%, 1% and 1.25%) of DPP-H using acetonitrile as a solvent. The polymer gel electrolytes were characterized by X-ray diffractometer (XRD) and Fourier transform infrared spectroscopy (FTIR), and the electrochemical properties were analyzed to relate the nature of the polymer and iodine ion conducting properties. The pure PEO/PC/TPAI/KI/I2 electrolyte exhibited an ionic conductivity value of 0.084 mS·cm-1 at room temperature. Upon the optimized addition of DPP-H (0.75 wt%), the ionic conductivity was found to be improved to a maximum value of 0.393 mS·cm-1, and the highest diffusion coefficient of 1.02 × 10-6 cm2 s-1 was observed. The optimized GPEs photovoltaic characterization studies showed higher power conversion efficiency (PCE) of 6.69% for DSSC under light illumination intensity of 100 mW cm-2. The same was compared with pure electrolyte, which delivered PCE of 4.39%. To gain an in-depth understanding of the interfacial resistance of the fabricated devices, the electron lifetime and transient photo response was analyzed. These above studies showed that prepared GPE could be an efficient alternative for traditional DSSCs with liquid electrolyte.

Antidiabetic Activity of Dihydropyrimidine Scaffolds and Structural Insight by Single Crystal X-ray Studies

BACKGROUND

This research project is designed to identify the anti-diabetic effects of the newly synthesized compounds to conclude the perspective of consuming one or more of these new synthetic compounds for diabetes management.

INTRODUCTION

A series of dihydropyrimidine (DHPM) derivative bearing electron releasing and electron-withdrawing substituent's on phenyl ring (a-j) were synthesized and screened for antihyperglycemic( anti-diabetic) activity on streptozotocin (STZ) induced diabetic rat model. The newly synthesized compounds were characterized by using FT-IR, melting point, 1H and 13C NMR analysis. The crystal structure and supramolecular features were analyzed through single-crystal X-ray study. Anti-diabetic activity testing of newly prepared DHPM scaffolds was mainly based on their relative substituent on the phenyl ring along with urea and thiourea. Among the synthesized DHPM scaffold, the test compound c having chlorine group on phenyl ring at the ortho position to the hydropyrimidine ring with urea and methyl acetoacetate derivative shows moderate lowering of glucose level. However, the title compounds methyl 4-(4-hydroxy-3-methoxyphenyl)- 6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate(g) and ethyl 4-(3-ethoxy-4- hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate(h) having methoxy and ethoxy substituents on phenyl ring show significant hypoglycemic activity compared to the remaining compounds from the Scheme 1.

METHODS

The experimental rat models for the study were divided into 13 groups (n = 10); group 1 animals were treated with 0.5% CMC (0.5mL) (vehicle); group 2 were considered the streptozotocin (STZ)/nicotinamide diabetic control group (DC) and untreated, group 3 diabetic animals were administered with gliclazide 50 mg/kg and act as a reference drug group. The remaining groups of the diabetic animals were administered with the newly synthesized dihydropyrimidine compounds in a single dose of 50 mg/kg orally using the oral gavage, daily for 7 days continuously. The blood glucose level was measured before and 72 hrs after nicotinamide-STZ injection, for confirmation of hyperglycemia and type 2 diabetes development.

RESULTS

Blood glucose levels were significantly (p<0.05) reduced after treatment with these derivatives. The mean percentage reduction for gliclazide was 50%, while that of synthesized compounds were approximately 36%.

CONCLUSION

Our result suggests that the synthesized new DHPM derivative containing alkoxy group on the phenyl ring shows a significant lowering of glucose level compared to other derivatives.

Preparation of hydrophobic epoxy-polydimethylsiloxane-graphene oxide nanocomposite coatings for antifouling application

Epoxy-polydimethylsiloxane-graphene oxide (EPG) nanocomposite coatings were successfully developed by loading different wt% of graphene oxide nanosheets (GNs) into an epoxy-hydroxy-terminated-polydimethylsiloxane (EP-hPD) matrix via a facile in situ preparation technique. The inclusion of GNs into EPN led to an increase in modulus of elasticity and tensile strength up to 1570.46 MPa and 31.54 MPa, respectively, in the case of 1 wt% loading of GNs in the EP-hPD matrix. Also, an increase in the water contact angle from 90.1° to 115.2°, 104.5° and 101.7° was discerned at 1, 3 and 5 wt% loadings of GNs respectively. Taber abrasion results demonstrated a decrease in abrasion loss by 33.3% at 1 wt% loading of GNs in comparison to the unreinforced coating. An improvement in the glass transition temperature (T_g) was observed from 63.5 °C for the neat sample to 77.6 °C, 76.3 °C and 71.6 °C for the 1, 3 and 5 wt% EPG nanocomposites, respectively. An inevitable enhancement in the properties of the nanocomposites was affirmed due to the synergistic effect of GNs dispersed within the EP-hPD blend matrix. The prominent findings of this work include a minimum corrosion rate of 0.73 × 10^-2 mm per year and upgradation in the antifouling performance of the nanocomposite coatings in comparison to the neat coating.

Crystal structure of a 1:1 cocrystal of nicotinamide with 2-chloro-5-nitro-benzoic acid

In the 1:1 cocrystal of nicotinamide and 2-chloro-5-nitro­benzoic acid, the mol­ecules form hydrogen bonds through O—H⋯N, N—H⋯O, and C—H⋯O inter­actions along with N—H⋯O dimer hydrogen bonds of nicotinamide. Further additional weak π–π inter­actions stabilize the mol­ecular assembly of this cocrystal.

In the title 1:1 cocrystal, C₇H₄ClNO₄·C₆H₆N₂O, nicotinamide (NIC) and 2-chloro-5-nitro­benzoic acid (CNBA) cocrystallize with one mol­ecule each of NIC and CNBA in the asymmetric unit. In this structure, CNBA and NIC form hydrogen bonds through O—H⋯N, N—H⋯O and C—H⋯O inter­actions along with N—H⋯O dimer hydrogen bonds of NIC. Further additional weak π–π inter­actions stabilize the mol­ecular assembly of this cocrystal.

Novel Series of Methyl 3-(Substituted Benzoyl)-7-Substituted-2-Phenylindolizine-1-Carboxylates as Promising Anti-Inflammatory Agents: Molecular Modeling Studies

The cyclooxygenase-2 (COX-2) enzyme is considered to be an important target for developing novel anti-inflammatory agents. Selective COX-2 inhibitors offer the advantage of lower adverse effects that are commonly associated with non-selective COX inhibitors. In this work, a novel series of methyl 3-(substituted benzoyl)-7-substituted-2-phenylindolizine-1-carboxylates was synthesized and evaluated for COX-2 inhibitory activity. Compound 4e was identified as the most active compound of the series with an IC50 of 6.71 M, which is comparable to the IC50 of indomethacin, a marketed non-steroidal anti-inflammatory drug (NSAID). Molecular modeling and crystallographic studies were conducted to further characterize the compounds and gain better understanding of the binding interactions between the compounds and the residues at the active site of the COX-2 enzyme. The pharmacokinetic properties and potential toxic effects were predicted for all the synthesized compounds, which indicated good drug-like properties. Thus, these synthesized compounds can be considered as potential lead compounds for developing effective anti-inflammatory therapeutic agents.

Design, synthesis, and structural elucidation of novel NmeNANAS inhibitors for the treatment of meningococcal infection

Neisseria meningitidis is the primary cause of bacterial meningitis in many parts of the world, with considerable mortality rates among neonates and adults. In Saudi Arabia, serious outbreaks of N. meningitidis affecting several hundreds of pilgrims attending Hajj in Makkah were recorded in the 2000–2001 season. Evidence shows increased rates of bacterial resistance to penicillin and other antimicrobial agents that are used in the treatment of the meningococcal disease. The host’s immune system becomes unable to recognize the polysialic acid capsule of the resistant N. meningitidis that mimics the mammalian cell surface. The biosynthetic pathways of sialic acid (i.e., N-acetylneuraminic acid [NANA]) in bacteria, however, are somewhat different from those in mammals. The largest obstacle facing previously identified inhibitors of NANA synthase (NANAS) in N. meningitidis is that these inhibitors feature undesired chemical and pharmacological characteristics. To better comprehend the binding mechanism underlying these inhibitors at the catalytic site of NANAS, we performed molecular modeling studies to uncover essential structural aspects for the ultimate recognition at the catalytic site required for optimal inhibitory activity. Applying two virtual screening candidate molecules and one designed molecule showed promising structural scaffolds. Here, we report ethyl 3-benzoyl-2,7-dimethyl indolizine-1-carboxylate (INLZ) as a novel molecule with high energetic fitness scores at the catalytic site of the NmeNANAS enzyme. INLZ represents a promising scaffold for NmeNANAS enzyme inhibitors, with new prospects for further structural development and activity optimization.

Molecular Bases for Anesthetic Agents: Halothane as a Halogen- and Hydrogen-Bond Donor

Although instrumental for optimizing their pharmacological activity, a molecular understanding of the preferential interactions given by volatile anesthetics is quite poor. This paper confirms the ability of halothane to work as a hydrogen-bond (HB) donor and gives the first experimental proof that halothane also works as a halogen-bond (HaB) donor in the solid state and in solution. A halothane/hexamethylphosphortriamide co-crystal is described and its single-crystal X-ray structure shows short HaBs between bromine, or chlorine, and the phosphoryl oxygen. New UV/Vis absorption bands appear upon addition of diazabicyclooctane and tetra(n-butyl)ammonium iodide to halothane solutions, indicating that nitrogen atoms and anions may mediate the HaB-driven binding processes involving halothane as well. The ability of halothane to work as a bidentate/tridentate tecton by acting as a HaB and HB donor gives an atomic rationale for the eudismic ratio shown by this agent.

Influence of non-metallic parts of waste printed circuit boards on the properties of plasticised polyvinyl chloride recycled from the waste wire

Extreme complexity in the range of metallic and non-metallic parts present in waste printed circuit boards leads to incineration for collecting valuable metals. The non-metallic parts of the printed circuit board can be used effectively without affecting the environment. In this study, the non-metallic parts of the printed circuit board, which is made up by cross-linked resin and fibre, was used as a filler in recycled plasticised polyvinyl chloride collected from waste wires and cables. The properties of the plasticised polyvinyl chloride matrix and plasticised polyvinyl chloride-non-metallic parts of printed circuit board composite were compared with each other by means of mechanical properties and thermal properties. Both mechanical and thermal properties results indicated that incorporation of non-metallic parts of printed circuit board significantly improved the hardness, stiffness, abrasion resistance and thermal stability of plasticised polyvinyl chloride-non-metallic parts of printed circuit board composite; however, the tensile strength of the composite material is not improved because of poor adhesion between the plasticised polyvinyl chloride matrix and non-metallic parts of printed circuit board filler. The poor chemical interaction is also observed from Fourier transform infrared spectroscopy results. This plasticised polyvinyl chloride-non-metallic parts of printed circuit board composite can reduce the leaching of a hazardous element from the printed circuit board with effective utilisation of plastics fraction from waste wires and cables.

Complexation of U(VI) with Cucurbit[5]uril: Thermodynamic and Structural investigation in aqueous medium

The assessment of cucurbituril (CBn) for selective removal of actinides from nuclear waste streams requires comprehensive understanding of binding parameters and coordination of these complexes. The present work is the first experimental report on complexation of actinide ion with Cucurbit[5]uril (CB5) in solution. The thermodynamic parameters (ΔG, ΔH and ΔS) for complexation of CB5 with U(VI) in formic acid water medium were determined using microcalorimetry and UV-Vis spectroscopy. The enthalpy and entropy of complexation revealed the partial binding of U(VI) to CB5 portal. The partial binding was confirmed by spectroscopic techniques viz. extended X absorption fine structure spectroscopy (EXAFS), ¹H and ¹³C NMR. The EXAFS χ(r) versus r spectra for U-CB5 complex has been fitted from 1.4 to 3.5 Å with two oxygen shells and a carbon shell. The presence of three carbon atom in secondary shell shows the involvement of only three carbonyl oxygens directly bonding to U(VI) which is in contrast to that calculated from gas phase DFT calculation of unhydrated system. The combined effect of hydration and formic acid encapsulation led to the enhanced stability of partially bound U(VI) to CB5. In the present work the binding of formic acid has also been studied by fluorescence spectroscopy. ESI-MS data shows the unusual stabilization of U(VI) by CB5 in gas phase.

Larvicidal study of tetrahydropyrimidine scaffolds against Anopheles arabiensis and structural insight by single crystal X-ray studies

A series of methyl or ethyl 4-(substitutedphenyl/pyridyl)-6-methyl-2-oxo/thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (HPM) analogues 4a-g were synthesized and evaluated for larvicidal activity against Anopheles arabiensis. These newly synthesized compounds were characterized by spectral studies such as FT-IR, NMR (¹ H and ¹³ C), LC-MS, and elemental analysis. The conformational features and supramolecular assembly of molecules 4a, 4b, and 4e were further analyzed from single crystal X-ray study. The larvicidal activity of these tetrahydropyrimidine pharmacophore series was analyzed based on their relative substituents. Among the synthesized HPM analogous from the series, compounds 4d and 4e both having electron withdrawing chlorine group on phenyl ring at the fourth position of the tetrahydropyrimidine pharmacophore exhibited the most promising larvicidal activity.

Crystal structure and Hirshfeld surface analysis of diethyl 2-[4-(4-fluoro-phen-yl)-2-methyl-4-oxobutan-2-yl]malonate

The title compound, C18H23FO5, was synthesized by reacting diethyl malonate with 1-(4-fluoro-phen-yl)-3-methyl-but-2-en-1-one. The mol-ecule adopts a loose conformation stabilized by weak C-H⋯O and C-H⋯π inter-actions. In the crystal, the mol-ecules are joined by C-H⋯O contacts into infinite chains along the b-axis direction with a C(6) graph-set motif. Hirshfeld surface analysis and fingerprint plots demonstrate the predominance of H⋯H, O⋯H and F⋯H inter-molecular inter-actions in the crystal structure.

Structural analysis of 2-iodo-benzamide and 2-iodo-N-phenyl-benzamide

The title compounds, 2-iodo-benzamide, C7H6INO (I), and 2-iodo-N-phenyl-benzamide, C13H10INO (II), were both synthesized from 2-iodo-benzoic acid. In the crystal structure of (I), N-H⋯O and hydrogen bonds form two sets of closed rings, generating dimers and tetra-mers. These combine with C-I⋯π(ring) halogen bonds to form sheets of mol-ecules in the bc plane. For (II), N-H⋯O hydrogen bonds form chains along the a-axis direction, while inversion-related C-I⋯π(ring) contacts supported by C-H⋯π(ring) interactions generate sheets of mol-ecules along the ab diagonal.

Crystal structure of 1-[3,5-bis-(tri-fluoro-meth-yl)phen-yl]-2-bromo-ethan-1-one

The title compound, C10H5BrF6O, synthesized via continuous stirring of 3,5-bis-(tri-fluoro-meth-yl) aceto-phenone with bromine in an acidic medium and concentrated under reduced pressure, crystallizes with four mol-ecules in the unit cell (Z = 4) and one formula unit in the asymmetric unit. In the crystal, mol-ecules are linked in a head-to-tail fashion into dimers along the b-axis direction through weak C-H⋯Br and C-O⋯Csp2 inter-actions. C-H⋯O, C-F⋯π and F⋯F inter-actions are also observed.

Benzothiazole analogs as potential anti-TB agents: computational input and molecular dynamics

Biotin is very important for the survival of Mycobacterium tuberculosis. 7,8-Diamino pelargonic acid aminotransaminase (DAPA) is a transaminase enzyme involved in the biosynthesis of biotin. The benzothiazole title compounds were investigated for their in vitro anti-tubercular activity against two tubercular strains: H37Rv (ATCC 25,177) and MDR-MTB (multidrug-resistant M. tuberculosis, resistant to isoniazid, rifampicin, and ethambutol) by an agar incorporation method. The possible binding mode and predicted affinity were computed using a molecular docking study. Among the synthesized compounds in the series, the title compound {2-(benzo[d]thiazol-2-yl-methoxy)-5-fluorophenyl}-(4-chlorophenyl)-methanone was found to exhibit significant activity with minimum inhibitory concentrations of 1 μg/mL and 2 μg/mL against H37Rv and MDR-MTB, respectively; this compound showed the highest binding affinity (-24.75 kcal/mol) as well.

Fluorination promotes chalcogen bonding in crystalline solids

Flurorine promotes the electrophilicity of sulfur to the point that chalcogen bond formation affects the crystal packing in the solid.

A storage ring experiment to detect a proton electric dipole moment

A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of 10^-29 e ⋅ cm by using polarized "magic" momentum 0.7 GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the standard model at the scale of 3000 TeV.

Crystal structure of methyl 4-(4-hy-droxy-phen-yl)-6-methyl-2-oxo-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate monohydrate

The title hydrate, C₁₃H₁₄N₂O₄·H₂O, crystallizes with two formula units in the asymmetric unit (Z' = 2). The dihedral angles between the planes of the tetra-hydro-pyrimidine ring and the 4-hy-droxy-phenyl ring and ester group are 86.78 (4) and 6.81 (6)°, respectively, for one mol-ecule and 89.35 (4) and 3.02 (4)° for the other. In the crystal, the organic mol-ecules form a dimer, linked by a pair of N-H⋯O hydrogen bonds. The hydroxy groups of the organic mol-ecules donate O-H⋯O hydrogen bonds to water mol-ecules. Further, the hy-droxy group accepts N-H⋯O hydrogen bonds from amides whereas the water mol-ecules donate O-H⋯O hydrogen bonds to the both the amide and ester carbonyl groups. Other weak inter-actions, including C-H⋯O, C-H⋯π and π-π, further consolidate the packing, generating a three-dimensional network.

Observation and Structure Determination of an Oxide Quasicrystal Approximant

We report on the first observation of an approximant structure to the recently discovered two-dimensional oxide quasicrystal. Using scanning tunneling microscopy, low-energy electron diffraction, and surface x-ray diffraction in combination with ab initio calculations, the atomic structure and the bonding scheme are determined. The oxide approximant follows a 3^{2}.4.3.4 Archimedean tiling. Ti atoms reside at the corners of each tiling element and are threefold coordinated to oxygen atoms. Ba atoms separate the TiO_{3} clusters, leading to a fundamental edge length of the tiling 6.7 Å.

Synthesis, Polymorphism, and Insecticidal Activity of Methyl 4-(4-chlorophenyl)-8-iodo-2-methyl-6-oxo-1,6-dihydro-4H-pyrimido[2,1-b]quinazoline-3-Carboxylate Against Anopheles arabiensis Mosquito

Mosquitoes are the major vectors of pathogens and parasites including those causing malaria, the most deadly vector-borne disease. The negative environmental effects of most synthetic compounds combined with widespread development of insecticide resistance encourage an interest in finding and developing alternative products against mosquitoes. In this study, pyrimido[2,1-b]quinazoline derivative DHPM3 has been synthesized by three-step chemical reaction and screened for larvicide, adulticide, and repellent properties against Anopheles arabiensis, one of the dominant vectors of malaria in Africa. The title compound emerged as potential larvicide agent for further research and development, because it exerted 100% mortality, while adulticide activity was considered moderate.

Study of the negative magneto-resistance of single proton-implanted lithium-doped ZnO microwires

The magneto-transport properties of single proton-implanted ZnO and of Li(7%)-doped ZnO microwires have been studied. The as-grown microwires were highly insulating and not magnetic. After proton implantation the Li(7%) doped ZnO microwires showed a non-monotonous behavior of the negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to the monotonous NMR observed below 50 K for proton-implanted ZnO. The observed difference in the transport properties of the wires is related to the amount of stable Zn vacancies created at the near surface region by the proton implantation and Li doping. The magnetic field dependence of the resistance might be explained by the formation of a magnetic/non-magnetic heterostructure in the wire after proton implantation.

Human bioequivalence evaluation of two losartan potassium tablets under fasting conditions

The bioequivalence of two different tablet formulations containing losartan potassium 100 mg was determined in healthy volunteers after a single oral dose in a randomized crossover study. Test and reference products were administered to 60 volunteers with 240 ml water after overnight fasting. Plasma concentrations of losartan and its active carboxylic acid metabolite were monitored over a period of 36 h after drug administration by validated LC/MS/MS analytical method. The pharmacokinetic parameters C_max, AUC_0-t, AUC_0-∞, AUC_0-t/AUC_0-∞, t_max, K_el and t_½ were determined from plasma concentration time profile of both formulations for losartan and its active metabolite losartan carboxylic acid and were found to be in good agreement. The carboxylic acid metabolite was considered for profiling purpose only. The analysis of variance did not show any significant difference between the two formulations and 90% confidence intervals for the ratio of C_max (84.89-104.09%), AUC_0-t (95.84-102.84%) and AUC_0-∞ (96.43-103.25%) values for losartan between the test and reference products were within the 80-125% interval, satisfying the bioequivalence criteria of the US FDA guidelines. These results indicate that the test and the reference products of losartan potassium are bioequivalent and, thus, may be prescribed interchangeably.

From metallic cluster-based ceramics to nematic hybrid liquid crystals: a double supramolecular approach

Luminescent bulky anionic inorganic species are directly integrated in a liquid crystalline material by a double supramolecular approach combining host–guest and electrostatic interactions.

Orthogonal halogen and hydrogen bonds involving a peptide bond model†Electronic supplementary information (ESI) available: Experimental part, DSC, IR spectroscopic and crystallographic data. CCDC 899779-899785. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4ce01514bClick here for additional data file.Click here for additional data file

The peptide bond model N-methylacetamide self-assembles with a range of dihalotetrafluorobenzenes forming co-crystals that all show the occurrence of orthogonal hydrogen and halogen bonds.

Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture

The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag-TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.

{2-[(1,3-Benzo-thia-zol-2-yl)meth-oxy]-5-chloro-phen-yl}(4-chloro-phen-yl)methan-one

In the title compound, C₂₁H₁₃Cl₂NO₂S, the benzo­thia­zole ring makes dihedral angles of 0.94 (1) and 70.65 (5)° with the 4-chloro­phenyl­methanone unit and the 5-chloro­phenyl ring, respectively. The dihedral angle between the 4-chloro­phenyl­methanone unit and the 5-chloro­phenyl ring is 66.20 (5)°. The crystal structure consists of dimeric units generated by C—H⋯N hydrogen bonds, further linked by C—H⋯O and C—H⋯π inter­actions, leading to a three-dimensional network.

{2-[(1,3-Benzo-thia-zol-2-yl)meth-oxy]-5-fluoro-phen-yl}(4-chloro-phen-yl)methanone

The asymmetric unit of the title compound, C₂₁H₁₃ClFNO₂S, contains two independent mol­ecules with similar conformations. In the mol­ecules, the thia­zole ring is essentially planar [maximum atomic deviations = 0.014 (4) and 0.023 (5) Å] and is oriented with respect to the fluoro­phenyl ring and chloro­phenyl rings at 9.96 (18) and 70.39 (18)° in one mol­ecule and at 7.50 (18) and 68.43 (18)° in the other; the dihedral angles between the fluoro­phenyl and chloro­phenyl rings are 64.9 (2) and 64.6 (2)°, respectively. Inter­molecular C—H⋯O and C—H⋯F hydrogen bonds stabilize the three-dimensional supra­molecular architecture. Weak C—H⋯π and π–π inter­actions [centroid–centroid distance = 3.877 (3) Å] lead to a criss-cross mol­ecular packing along the c axis.

{2-[(1,3-Benzo-thia-zol-2-yl)meth-oxy]-5-bromo-phen-yl}(phen-yl)methanone

In the title compound, C21H14BrNO2S, the dihedral angle between the planes of the benzo-thia-zole and phenyl-methanone groups is 63.4 (2)°. In the crystal, pairs of C-H⋯N hydrogen bonds link the mol-ecules to form inversion dimers, which are further linked by C-H⋯O inter-actions into chains along the c axis. C-H⋯π and π-π inter-actions [centroid-centroid distance = 3.863 (1) Å] further stabilize the mol-ecular assembly.

2-(4-Bromoanilino)-6-(4-chlorophenyl)-5-methoxycarbonyl-4-methyl-3,6-dihydropyrimidin-1-ium chloride

In the title molecular salt, C₁₉H₁₈BrClN₃O₂⁺·Cl⁻, the dihedral angles between the pyrimidine ring and the chlorobenzene and bromobenzene rings are 72.4 (2) and 45.5 (2)°, respectively. The dihedral angle between the chlorobenzene and bromobenzene rings is 27.5 (2)°. The conformation of the mol­ecule is stabilized by an intra­molecular C—H⋯O inter­action. In the crystal, the anion and cation are linked by an N—H⋯Cl hydrogen bond. Pairs of weak C—H⋯O and C—H⋯Cl hydrogen bonds form inversion dimers. Further N—H⋯Cl hydrogen bonds form R₂¹(6) motifs and link the dimers into chains along [101]. Br⋯Cl short contacts [3.482 (2) Å] inter­link the hydrogen-bonded chains along the b-axis direction.

Investigating hydrophobic ligand-receptor interactions in parathyroid hormone receptor using peptide probes

With an increasing number of new chemical entities entering clinical studies, and an increasing share of the market, peptides and peptidomimetics constitute one of the most promising classes of therapeutics. The success of synthetic peptides as therapeutics relies on the lead optimization step in which the lead candidates are modified to improve drug-like properties of peptides related to potency, pharmacokinetics, solubility, and stability, among others. Peptidomimetics based on the N-terminal stretch of the first 11 amino acids of the PTH have been investigated as potential lead compounds for the treatment of osteoporosis. On the basis of a peptide reported in the literature, referred to here as the Parent Peptide (H-Aib-Val-Aib-Glu-Ile-Gln-Leu-Nle-His-Gln-Har-NH2), we conducted systematic SAR analyses to investigate the effects of altering peptide hydrophobicity on PTH receptor functional potency as measured by the cAMP (cyclic adenosine monophosphate) accumulation and β-arrestin recruitment assays. Among hydrophobic residues, we found that the Val2 position shows the least flexibility in terms of the SAR studies, whereas the Leu7 position appeared to be most flexible. Through circular dichroism and nuclear magnetic resonance spectroscopy studies, we were able to establish that changes in hydrophobic residues significantly change the extent of peptide helicity and that the helical character correlates well with receptor agonist activity. Here, we report several novel PTH 1-11 peptidomimetics that show comparable or enhanced potency to stimulate Gs-signaling over β-arrestin recruitment as compared with such properties of PTH 1-34 and the Parent Peptide.

Methyl 4-(4-chloro-phen-yl)-8-iodo-2-methyl-6-oxo-1,6-dihydro-4H-pyrimido[2,1-b]quinazoline-3-carboxyl-ate

In the title compound, C20H15ClIN3O3, the dihedral angle between the quinazolinone ring system [r.m.s. deviation = 0.047 (2) Å] and the pendant benzene ring is 82.63 (11)°. The mol-ecular conformation is stabilized by intra-molecular C-H⋯O inter-actions. In the crystal, the mol-ecules are linked by N-H⋯O hydrogen bonds into chains along the a-axis direction. Another set of chains propagating along [101] is formed due to inter-molecular I⋯Cl short contacts of 3.427 (1) Å, thus giving layers parallel to (010). The layers are connected by C-H⋯π and π-π inter-actions, the shortest distance between the centroids of aromatic rings being 3.8143 (16) Å.

[2-(1,3-Benzothia-zol-2-ylmeth-oxy)-5-bromo-phen-yl](4-chloro-phen-yl)methanone

In the title compound, C21H13BrClNO2S, the dihedral angle between the planes of the benzothia-zole and chloro-phenyl-methanone groups is 71.34 (6)°. In the crystal, weak C-H⋯N hydrogen bonds lead to dimer formation, whereas Br⋯Cl short contacts [3.4966 (11) Å] form infinite chains along the a-axis direction. Further, the C-H⋯O, C-H⋯π and π-π [centroid-centroid distance = 3.865 (2) Å] inter-actions stabilize the three-dimensional network.