Single Crystal X-ray Studies Research Articles

A highly efficient antioxidant based on boron and a Schiff base bridged phenolic diphenylamine: synthesis, crystal structure and thermal and antioxidant properties.

Antioxidants can effectively protect vegetable-oil-based lubricants against oxidative degradation and prolong their service life. A novel compound, (E)-4-({3,5-di-tert-butyl-2-[(diphenylboranyl)oxy]benzylidene}amino)-N-phenylaniline (BSPD) or {2-[(4-anilinophenyl)iminomethyl-κN]-4,6-di-tert-butylphenolato-κO}diphenylboron, C39H41BN2O, was synthesized by a one-pot reaction of the Schiff base bridged phenolic diphenylamine 2,4-di-tert-butyl-6-{N-[4-(phenylamino)phenyl]carboximidoyl}phenol (SPD) with phenylboronic acid. The corresponding single-crystal X-ray study revealed that the B atom in BSPD has a typical tetrahedral geometry, and the N,O-chelated six-membered ring adopts a chair conformation. According to thermogravimetric analysis, the 5% weight-loss temperature of BSPD increases to 328 °C and the 95% weight-loss temperature is up to 414 °C. More importantly, the antioxidant capability of BSPD in vegetable oil is much better than that of commercial antioxidants [diphenylamine (DPA) and 2,6-di-tert-butyl-4-methylphenol (BHT)] and unmodified SPD.

Synthesis, characterizations and single crystal structure of di-nuclear azido-bridged Cd(II) coordination polymer with Schiff base precursor (H2LpentOMe): DFT, fluorescence, solvatochromism and in vitro antimicrobial assay

A di-nuclear azido-bridged Cd(II) 1-D coordination polymer [Cd2(H2LpentOMe)(µ1,1-N3)2]n(1) has been successfully synthesized using less explored bi-compartmental Schiff base ligand (H2LpentOMe) and characterized by elemental analysis, FT-IR, FT-Raman, UV–Visible, SEM-EDAX, powder X-ray diffraction and fluorescence spectroscopy. Solid-state X-ray single crystal study revealed two different geometrical environment of Cd metal centres with distorted square pyramidal (Cd1) and distorted pentagonal bipyramid (Cd2). Overall, small-sized azide ions in asymmetric unit act as µ1,1 bridging mode. Geometry is optimized in gas phase using ORCA 3.0.3 and B3LYP level TZVP basis set to explain frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and global reactivity. The HOMO-LUMO energy gap (3.434 Ev) suggests that chemical reactivity of complex 1 is low but fairly stable. Moreover, molecular electrostatic potential map was drawn to identify reactive regions in terms of electrophilic and nucleophilic. The steady state and time-resolved fluorescence properties have been explored in DCM and solid-state condition at room temperature. Complex 1 exhibit bi and tri-exponential decay in DCM as well as solid-state. The fluorescence behaviours are predominantly intra-ligand in nature (π → π*) with lifetimes in the range (1.16–1.11 ns). Solvatochromism has been reported to show solvent dependent absorption and fluorescence spectral changes. Fascinatingly, red shifted solvatochromism was observed upon increasing solvent polarity. Finally, concentration dependent antimicrobial activity was investigated against two standard bacterial strains (Staphylococcus aureus (ATCC 25923) and Methicillin-resistant Staphylococcus aureus (MRSA) where 250 µg/ml concentration of complex 1 is sufficient to show the antimicrobial effect.

Synthesis, structure and thermogravimetric analysis of novel dithiocarbamate based Zn(II),Cd(II) and Hg(II) complexes

Three new homoleptic complexes having formula [M(L1)2] [L1 = (C13H18N1O3S2−)] with Zn, Cd and Hg have been designed, synthesized and characterized by elemental analysis, IR, 1H and 13C NMR and UV–visible absorption spectra. The single crystal X-ray study of complex 3 indicates that positive charges on the mercury cation (Hg2+) are balanced by dithiocarbamate anion. The X-ray analysis for complex 3 confirms distorted tetrahedral geometry around metal centre. The C–H⋯S intermolecular interaction in this complex is 2.974 Å and H⋯H distance is 2.202 Å contribute towards supramolecular structure in 3. Powder XRD, EDAX and SEM image confirms the formation of metal sulfide as thermal decomposition product in complexes 1–3 and the crystalline size were found to be 48.96 nm, 39.39 nm and 41.81 nm, respectively.

Urea-Appended Amino Acid To Vitalize Yeast Growth, Enhance Fermentation, and Promote Ethanol Production.

The development of sustainable protocols for enhancing the production of ethanol is highly important for its utilization in automotive transportation and energy sector. Up to 15% ethanol can blend with diesel to make e-diesel that can be used in fuel compression ignition engine. Urea-modified amino acids can be used as a very good vitalizer for yeast (Saccharomyces cerevisiae, Baker’s yeast (ATCC 204508)) growth and thus promote ethanol production. A simple, one-step, room-temperature synthetic procedure has been developed for urea-appended α-amino acids from amino acid by treatment with KCNO. Single-crystal X-ray studies confirm the successful synthesis and molecular structures of the urea-appended α-amino acids. Out of 20 urea-appended amino acids, Arg-, Pro-, His-, and Gln-containing compounds promote yeast growth significantly after 12 h at pH 6.8 and 38 °C. These compounds are nontoxic. The urea-appended Arg shows 2-fold increase of yeast growth. However, urea-appended m-aminobenzoic acid and p-aminobenzoic acid inhibit yeast growth. NMR experiments confirmed the enhanced production of ethanol by glucose fermentation in the presence of 2.5 μmol urea-appended Arg. Not only glucose but also commercially available sugars and feedstock of the starch slurry drained out after boiling of rice exhibit significant enhancement of ethanol production under same conditions.

The system thorium-palladium-boron: A DFT study on the stability and properties of Th2Pd15B5

Phase relations in the Th-Pd-B system were determined via electron microprobe and X-ray powder diffraction analyses of ∼20 ternary alloys. Phase equilibria are dominated by the two high-melting thorium borides ThB4, Th1-yB6 and one ternary compound, namely τ1-Th2Pd14+xB5, with a structure deriving from the Sc4Ni29B10-type. Th1-yB6 is the binary starting point of a continuous solid solution up to ThPd0.53B4.28 closely corresponding to the superconducting phase Th1-yPdxB6-2x (x ≤ 0.65; 0 ≤ y ≤ 0.22 at x = 0; TC = 21 K), which was described by Zandbergen et al. in 1995 for x = 0.65 from high resolution electron microscopy. All thorium-rich palladium compounds from 0 to 75 at.% Pd form stable two-phase equilibria with ThB4 without any significant mutual solid solubilities. The solubility of Th in βB has been determined for the first time from a single crystal X-ray study of ThB99: Th atoms occupy sites A1 (occ. = 13%), D (occ. = 11%), and a rather small amount of 2.9% resides in site 18f (Dd-hole).To shed light on the physical properties of the ternary compound, DFT (density functional theory) calculations were performed for two idealized representatives of the τ1-phase, namely for Th2Pd14B5 and Th2Pd15B4. The calculations cover ionic relaxation, electron density of states, band structure and Fermi surfaces, elastic constants (computed via the linear response method) and the phonon density of states. Furthermore the thermodynamic stability (energy of formation) as well as the phonon contribution of the thermodynamic properties, such as the specific heat have been calculated clearly indicating Th2Pd15B4 as the composition thermodynamically more stable than Th2Pd14B5. At the Fermi energy the Pd-d contribution is dominant for both structures, but the number of states is higher for Th2Pd15B4 with DOS(EF) = 13 states/eV/f.u. than for Th2Pd14B5 with DOS(EF) = 8.5 states/eV/f.u. The corresponding Sommerfeld constants, γe = DOS(EF)kBπ2/3 = 30.55 mJ/molK2 for Th2Pd15B4 and 19.98 mJ/molK2 for Th2Pd14B5, clearly indicate metallic behavior of the τ1-phase. In addition, mechanical properties were measured for Th2Pd15B5 and compared with calculated values and data from the literature. Th2Pd15B5 on account of its high content of Pd is only slightly harder than the rather soft and almost ductile binary Pd-borides.

NHC–Au(I) catalyzed enantioselective intramolecular [4+3] cycloaddition of furan propargyl esters

Enantioselectivity up to 75% ee has been achieved for an intramolecular [4 + 3] cycloaddition reaction with a series of chiral gold(I) complexes. Nine new chiral NHC–Au(I) complexes featuring disilylbiphenyl derived chiral N-heterocyclic carbene ligands were synthesized and identified by 1H, 13C NMR spectroscopy and X-ray single crystal structure analysis. The corresponding activated Au(I) catalysts with a phenyl nitrile dynamic ligand were prepared and used in the catalysis of intramolecular [4 + 3] cycloaddition reactions. Moderate to high chemical yields and enantioselectivity were achieved with 5% mol of the chiral NHC–Au(I) catalysts. The stereochemistry of the intramolecular [4 + 3] cycloaddition product was identified by X-ray single crystal structure analysis. The absolute configuration of the cycloaddition products was deduced by a combination of X-ray single crystal structure analysis, NMR and DFT study.

Two bifunctional photoluminescent Zn (II) coordination polymers for detection of Fe3+ ion and nitrobenzene

Two new luminescent metal–organic coordination polymers (MOCPs) of {[Zn6(L)2(H2O)7]·(DMF)2}n (1) and {[Zn(H4L)(bpy)0.5(H2O)2]·H2O}n (2) were solvothermally constructed using zinc salts and ligands (H6L = 5,5′-(propane-2,2-diyl)bis(2-hydroxyisophthalic acid), bpy = 4,4′-bipyridine). The resulted MOCPs were characterized by elemental analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray study results reveal that compounds 1 and 2 belong to P1¯ and P 21/n space group and show a two- and one-dimensional structure, respectively. Their photoluminescence (PL) properties and thermal properties were also studied. Interestingly, the luminescent responses of compounds 1 and 2 show highly sensitive detection of Fe3+ via an obvious fluorescence quenching. The detection limits of compounds 1 and 2 are 0.25 μM and 0.19 μM toward Fe3+. Compound 2 possesses a ring structure, which is big enough to allow small molecules to easily move into the crystal skeleton and interact with each other. Thus, the luminescence responses of compound 2 were investigated for various organic solvents. These results show that compound 2 has great potential to be developed as the favorable sensor for highly selective detection of nitrobenzene.

Ionothermal Synthesis Enables Access to 3D Open Framework Manganese Phosphates Containing Extra-Large 18-Ring Channels

An ionothermal synthesis study of transition metal phosphates using the ionic liquid 1-butyl-4-methylpyridinium hexafluorophosphate [C4mpy][PF6] yielded four new, different open framework manganese compounds, that is, K2Mn3(HPO4)2(PO3F)F2 (1), (NH4)2Mn3(HPO4)2(PO3F)F2 (2), KMn3(H2PO4)(HPO4)2F2 (3), and (NH4)Mn3(H2PO4)(PO3F)2F2 (4). The obtained products not only feature new framework topologies unprecedented in the family of phosphates but also interesting properties as the transition metal gives rise to both luminescent (rendering them potential nonrare earth containing red emitting phosphors) and unconventional magnetic properties governed by geometric frustrations. Aside from the structural analysis (powder and single-crystal X-ray diffraction, infrared spectroscopy), a variety of characterization methods (photoluminescence spectroscopy and magnetic measurements) were applied to study the material’s properties. Single crystal X-ray studies reveal that 1 (P21/c with a = 5.501(1), b = 14.203(3), c = 16.9...

Allan White and Solvento/Aqua Complexes: ScIII Solvation

Addition of various oxygen-donor ligands (L, all dipolar, aprotic solvents), to a solution of hydrated scandium picrate in weakly coordinating solvents (S), has yielded several crystalline adducts of the form Sc(pic)3(L)m(·nS) in which all ligands L are coordinated, subsequently characterised by a series of single crystal X-ray studies. For L=dmso, m=3 and the picrate anions are all bound as phenoxide-O donor units, while for nmp, dma, tmp, and hmpa, m=2 and one of the bound picrates becomes bidentate through phenoxide- and nitro-O donation. For L=ompa, m=2 and two picrate ligands are bound through phenoxide-O while one is displaced from the primary coordination sphere. All complexes contain six-coordinate ScIII, confirming that this coordination number is a consequence of ligand bulk.

Catalytic Application of Tactically Aligned Cd(II)‐Based Luminescent 3D‐Supramolecular Networks

AbstractA new Cd(II) based coordination polymers {[Cd(Azopy)(H2O)4]⋅(NDC)}n (1) has been designed and synthesized by using 4,4′‐Azopyridine (Azopy), and 2, 6‐Naphthalene dicarboxylic acid (NDC) as a linker at ambient condition. The bulk purity of the 1 was analysed by powder X‐ray diffraction (PXRD) analysis, infrared spectroscopy and further confirmed by single crystal X‐ray studies. The crystal structure of 1 revealed a polythreading feature where each 2, 6‐naphthalene dicarboxylate unit are trapped between two one‐dimensional (1D) chain of [Cd(Azopy)(H2O)4]∞ via strong hydrogen bonding interactions. The hydrogen bonding and π⋅⋅⋅π stacking interactions of 1 play a crucial role in the formation of the infinite 3D‐layered supramolecular network. Furthermore, the reduction of nitro‐aromatics to their corresponding amines was performed using green hydrogen source such as D‐glucose in H2O solvent at room temperature. Additionally, the dye adsorption studies revealed that 1 can adsorb Congo Red (CR) dye in a very short span of time. The kinetic study result reveals that the adsorption of CR for 1 is fitted well (R2 =0.996) with a pseudo‐second‐order kinetic model. Moreover, photoluminescence of 1 shows emission in the blue region with λmax at 395 nm and 408 nm at room temperature in the solid state. 1 shows multi‐facet behaviour such as facile synthesis, luminescent nature in solids‐state, emerged as a heterogeneous dye‐adsorbent and catalyst which makes it easy to scaled‐up.

Copper(I) complexes of N-(2/4 methoxy/2-chloro-4-nitro)phenyl-N′ (methoxycarbonyl)thiocarbamides as potential anticancer agents: Synthesis, crystal structure, in vitro cytotoxicity and DNA damage studies

Synthesis and structural assignment of four trigonal planar copper(I) complexes (1a–4a) having the general formula [Cu(CH3OCONHCSNHR)2Cl] where R = 2-methoxyphenyl (1), 4-methoxyphenyl (2), 2-chloro 4-nitrophenyl (3) and 2-methoxy 4-nitrophenyl (4) have been described. The characterization were done by elemental, spectroscopic (FT-IR, 1H, 13C NMR, UV–Vis), TG analysis and single crystal X-ray studies of ligands 1, 3 and complex 2a. In the complex 2a the methoxycarbonyl groups adopt cis conformation with respect to chlorine atom and are nearly coplanar with the central plane in a trigonal planar geometry. Cyclic voltammogram of complexes 1a–4a displayed quasi-irreversible redox behaviour corresponding to Cu(I)/Cu(II) couple. In vitro cytotoxicity of the ligands and their copper(I) complexes screened against five human cancer cell lines revealed that complexes were two to three times more potent than the ligands against all the cell lines. DNA damage study of complexes against 2008, C13* (cervical cancer) and IGROV-1 (ovarian cancer) cell lines indicated that cytotoxicity exerted by them is mainly through perturbation of DNA structure.

Density Functional Theory and Single Crystal X-ray Studies on Some Bis-Chalcone Derivatives

The three bis-chalcone compounds, (2E,6E)-2,6-bis(3-chlorobenzylidene)cyclohexanone (1), (2E,6E)-2,6-bis(2,3-dichlorobenzylidene)cyclohexanone (2) and (2E,5E)-2,5-bis(2,6-dichloro benzylidene) cyclopentanone (3), were studied with theoretical and single-crystal X-ray diffraction (XRD) methods. The molecular geometric parameters, frontier molecular orbitals, MEP, normal mode frequencies and the corresponding vibrational assignments, gauge-including atomic orbital (GIAO) 1H-NMR, 13C-NMR chemical shift values of the bis-chalcone compounds in the ground state have been calculated using the density functional (B3LYP) methods with 6-311G (d,p) basis set. These molecules demonstrate apparently a long and flat shape. Each molecule adopt an (E) configuration about the central olefinic bonds. The most important feature is stacking mode in the molecules. The calculated results reveal that the optimized geometries can well reproduce the crystal structure. The theoretical vibrational frequencies and 1H-NMR and 13C-NMR chemical shift values show good agreement with the experimental data.

Computational, crystallographic studies, cytotoxicity and anti-tubercular activity of substituted 7-methoxy-indolizine analogues.

Indolizines are heteroaromatic compounds, and their synthetic analogues have reportedly showed promising pharmacological properties. In this study, a series of synthetic 7-methoxy-indolizine derivatives were synthesised, characterised and evaluated for in vitro whole-cell anti-tuberculosis (TB) screening against susceptible (H37Rv) and multi-drug-resistant (MDR) strains of Mycobacterium tuberculosis (MTB) using the resazurin microplate assay method. The cytotoxicity was evaluated using the MTT assay. In silico molecular-docking study was conducted for compounds 5a-j against enoyl-[acyl-carrier] protein reductase, a key enzyme of the type II fatty acid synthesis that has attracted much interest for the development of novel anti-TB compounds. Thereafter, molecular dynamic (MD) simulation was undertaken for the most active inhibitors. Compounds 5i and 5j with the methoxy functional group at the meta position of the benzoyl group, which was at the third position of the indolizine nucleus, demonstrated encouraging anti-TB activity against MDR strains of MTB at 16 μg/mL. In silico studies showed binding affinity within the range of 7.07–8.57 kcal/mol, with 5i showing the highest binding affinity. Hydrogen bonding, π-π- interactions, and electrostatic interactions were common with the active site. Most of these interactions occurred with the catalytic amino acids (Pro193, Tyr158, Phe149, and Lys165). MD simulation showed that 5j possessed the highest binding affinity toward the enzyme, according to the two calculation methods (MM/PBSA and MM/GBSA). The single-crystal X-ray studies of compounds 5c and 5d revealed that the molecular arrangements in these two structures were mostly guided by C-H···O hydrogen-bonded dimeric motifs and C-H···N hydrogen bonds, while various secondary interactions (such as π···π and C-H···F) also contributed to crystal formation. Compounds 5a, 5c, 5i, and 5j exhibited no toxicity up to 500 μg/mL. In conclusion, 5i and 5j are promising anti-TB compounds that have shown high affinity based on docking and MD simulation results.

Silver-nitrilotriacetate coordination polymers: Supra-molecular and photoluminescence properties

Three new coordination polymers (CPs), [Ag3(nta)(azpy)3(H2O)]n·5H2O, 1, [Ag3(nta)(bpa)2.5]n·5.5H2O, 2 and [Ag6(nta)2(tmdp)5]n·17H2O, 3 (where nta = nitrilotriacetate, azpy = 4,4′-azobipyridine, bpa = 1,2-di(4-pyridyl)ethane and tmdp = 4,4′-trimethylenedipyridine) have been synthesized and characterized by different techniques viz. elemental analysis, PXRD, IR, UV–vis and X-ray crystallography. Single crystal X-ray studies reveal that CP 1 is one-dimensional structure whereas, 2 and 3 are two-dimensional and three-dimensional structures respectively. By altering the flexibility of bipyridine ligands, different coordination behaviour of nta was observed and also dimensionality of CPs changed from 1D to 3D. A supra-molecular 3D structure of 1 was generated because of π⋯π interactions. The argentophilic interactions involved in the formation of 2D and 3D structures of 2 and 3 respectively. The photoluminescent properties of CPs 1–3 were studied in a solid state at room temperature. CPs 1 and 2 showed emission bands at 432 and 401 nm respectively because of intra-ligand charge transfer transitions. In the case of 1, the emission band is red-shifted with respect to azpy since of π-π stacking in the solid state. CP 3 showed emission in the visible region at 488 nm, is due to the promotion of the lone pair of electrons of the metal to the π* orbital of the ligand.

Coordination behaviour of 2-(Methylthio)Pyrazine with Ag(I) in the presence of different counter anions and emission properties

Three new coordination polymers (CPs), [Ag(MTP)2(PF6)]n1, [Ag(MTP)(NO3)]n2 and [Ag(MTP)(OTf)]n3 (where MTP = 2-(Methylthio)Pyrazine and OTf = CF3SO3−) have been synthesized and characterized by different spectroscopic techniques. The single crystal X-ray study reveals that CPs 1 and 2 are two dimensional, whereas 3 is three dimensional. In the case of CP 1, MTP has two types of bonding behaviour. In one it is coordinated through the nitrogen of pyrazine only, leaving sulfur of –SMe free, whereas, in the other, it bonded through both sulfur and nitrogen of MTP. The sulfur of –SMe is coordinated to the neighbouring [Ag(MTP)]n chain in 2 whereas, in case of 3, sulfur of –SMe remain uncoordinated. Absorption and emission spectra of MTP and CPs have been studied in solution state. The spectral behaviour was supported by time dependent density functional theory. The emission behaviour of CPs in the presence of different metal ions confirms that only CP 1 has some affinity towards Hg(II) and Cu(II) ions.

Structural and chromotropism properties of copper(II) complexes with 3,3′-((pyridin-2-ylmethyl)azanediyl)dipropanamide ligand

A tetra-dentate ligand L [3,3′-((pyridin-2-ylmethyl)azanediyl)dipropanamide] was synthesized and characterized by spectroscopic and structural methods. The reaction of L with two different copper(II) halides [CuX2; X = Br, Cl] in a similar condition yielded two different compounds of [LCuCl]Cl, 1 and [CuLBr]2[CuBr4]·CH3OH·H2O, 2. Both compounds were characterized by several physicochemical techniques. Single-crystal X-ray studies revealed that the Cu(II) centers in the cationic complexes 1 and 2 are in a square pyramidal N2O2X (X = Cl and Br) environment. Compound 1 is chromotropic and its solvatochromism and halochromism properties were investigated. It was found that the observed positive solvatochromism is due to structural change and solvation of the vacant site of the complex. The complex demonstrated distinct reversible spectral change over the pH range 1.3–12.1 and can act as pH-induced off–on–off absorption switch through deprotonation and the Cu–O to Cu–N bond rearrangement of the coordinated amide groups in aqueous solution.

Synthesis and Reactivity of a Hypersilylsilylene.

Stabilization of an amidinatosilylene with a bulky tris(trimethylsilyl)silyl substituent was realized with the preparation of PhC(NtBu)2Si{Si(SiMe3)3} (1) from PhC(NtBu)2SiHCl2 with K{Si(SiMe3)3} in more than 90% yield. The highly deshielded 29Si NMR resonance (δ = 76.91 ppm) can be attributed to the absence of a π-donating substituent. The molecular structure of 1 shows a trigonal-planar geometry around the SiII center with a SiII-SiIV bond length of 2.4339(13) Å. A series of reactions of 1 with Me3NO, S, Se, and Te were performed. While siloxane derivatives (2 and 3) are obtained from reactions with Me3NO, silachalcogenones (4-6) are formed with other chalcogens. The presence of Si═E (E = S, Se, and Te) bonds in 4-6 have been confirmed by single-crystal X-ray studies. Silaoxirane (7) formation was observed when 1 was treated with acetone, demonstrating the importance of the tris(trimethylsilyl)silyl group to kinetically and thermodynamically protect the silaoxirane derivative with less bulky substituents on the C atom.

Drumlike p-methylphenyltin carboxylates: The synthesis, characterization, antitumor activities and fluorescence

The self-assembly of di (p-methylphenyl) oxide (Tol2SnO) with 3-(1,3-Dioxo-1H,3H-benzo [de]isoquinolin-2-yl)-propionic acid (HL1) and 3-(1,3-Dioxo-1,3-dihydro-isoindol-2-yl)-propionic acid (HL2) produced novel organotin carboxylates (TolSnOL1)6 (complex 1) and (TolSnOL2)6 (complex 2) (Scheme 1). Complexes 1 and 2 were characterized by the methods of elemental analysis, IR, 1H, 13C and 119Sn NMR spectroscopy. It has been revealed by single crystal X-ray study that 1 and 2 are mono-organotin carboxylates possessing hexanuclear cage - “Sn6O6” unit, which presented as a drum. The ligands in the complexes chelate with two tin atoms and adopt bidentate coordination. The molecules of 1 and 2 build their complicated 3D structures via intermolecular π···π interactions and H-bonds. The supramolecular structures of the complexes are discussed in detail. The preliminary fluorescence activity of 1 and antitumor activities of 1 and 2 were also studied.

Twinning and incommensurate modulation in baumoite, Ba0.5[(UO2)3O8Mo2(OH)3](H2O)~3, the first natural Ba uranyl molybdate

ABSTRACTBaumoite, Ba0.5[(UO2)3O8Mo2(OH)3](H2O)~3, is a new mineral found near Radium Hill, South Australia, where it occurs in a granite matrix associated with baryte, metatorbernite, phurcalite and kaolinite. Baumoite forms thin crusts of yellow to orange–yellow tabular to prismatic crystals. The mineral is translucent with a vitreous lustre and pale yellow streak. Crystals are brittle, the fracture is uneven and show one excellent cleavage. The Mohs hardness is ~2½. The calculated density is 4.61 g/cm3. Optically, baumoite crystals are biaxial (–), with α = 1.716(4), β = 1.761(4), γ = 1.767(4) (white light); and 2Vcalc= 42.2°. Electron microprobe analyses gave the empirical formula Ba0.87Ca0.03Al0.04U2.97Mo2.02P0.03O22H11.99, based on 22 O atoms per formula unit. The eight strongest lines in the powder X-ray diffraction pattern are [dobsÅ (I) (hkl)]: 9.175(39)(12${\bar 1}$), 7.450(100)(020), 3.554(20)(221), 3.365(31)(004, 202), 3.255(31)(123, 30${\bar 2}$), 3.209(28)(12${\bar 4}$), 3.067(33)(30${\bar 3}$, 222, 32${\bar 2}$) and 2.977(20)(142). Single-crystal X-ray studies (R1= 5.85% for 1892 main reflections) indicate that baumoite is monoclinic, superspace groupX2/m(a0g)0swithX= (0,½,0,½), with unit-cell parameters:a= 9.8337(3),b= 15.0436(5),c= 14.2055(6) Å, β = 108.978(3)°,V= 1987.25(13) Å3andZ= 4. The crystal structure is twinned and incommensurately modulated and is based upon sheets of U6+and Mo6+polyhedra of unique topology. Four independent cationic sites partially occupied by Ba atoms are located between the sheets, together with H2O molecules.

Synthesis and Structural Elucidation of Novel Benzothiazole Derivatives as Anti-tubercular Agents: In-silico Screening for Possible Target Identification.

Benzothiazole derivatives are known for anti-TB properties. Based on the known anti-TB benzothiazole pharmacophore, in the present study, we described the synthesis, structural elucidation, and anti-tubercular screening of a series of novel benzothiazole (BNTZ) derivatives (BNTZ 1-7 and BNTZ 8-13). The study aims to carry out the development of benzothiazole based anti-TB compounds. Title compounds are synthesized by microwave method and purified by column chromatography. Characterization of the compounds is achieved by FT-IR, NMR (1H and 13C), LCMS and elemental analysis. Screening of test compounds for anti-TB activity is achieved by Resazurin Microplate Assay (REMA) Plate method. It was noted that the BNTZ compound with an isoquinoline nucleus (BNTZ 9) exhibited remarkable anti-tubercular activity at 8 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of Mycobacterium tuberculosis. On the other hand, the BNTZ compound with a naphthalene nucleus (BNTZ 2) revealed anti-tubercular activity at 6 µg/mL and 11 µg/mL against both the susceptible strain H37Rv and the multi-drug resistant tuberculosis strains of M. tuberculosis, respectively. One of the selected BNTZ derivatives BNTZ 13 was used for single crystal X-ray studies. To identify the appropriate target for potent BNTZ compounds from the series, molecular modeling studies revealed the multiple strong binding of several BNTZs with mycobacterium lysine-ɛ-aminotransferase and decaprenyl-phosphoryl-β-D-ribose 2'-oxidase. The interaction is derived by forming favorable hydrogen bonds and stacking interactions. This new class of BNTZ compounds gave promising anti-tubercular actions in the low micromolar range, and can be further optimized on a structural basis to develop promising, novel, BNTZ pharmacophore-based anti-tubercular drugs.