Embedding plasmonic nanoparticles in soft crystals: an approach exploiting CTAB-I structures.

Embedding nanoparticles with different functionalities into soft substrates is a convenient tool to realize technologically significant multifunctional materials. This study focuses on incorporating bimetallic plasmonic nanoparticles into soft crystals made of cetyltrimethylammonium bromide-iodide. We observed the emergence of a novel symmetry-lowered cetrimonium crystal polymorph that enables the realization of strong interparticle plasmonic coupling in these composite materials. The observed crystal polymorph exhibits a triclinic structure with significantly reduced unit cell volume compared to standard CTAB. Solid-state nuclear magnetic resonance studies revealed an enhanced cetrimonium chain rigidity and a commensurate decrease in the mobility of the methyl groups. This is attributed to iodide incorporation. To study the influence of these interactions on solution phase dynamical properties, we employed light scattering measurements using gold nanospheres as markers, where we observed aggregation of these particles. We then develop a two step synthetic scheme that successfully enables high levels (533 particles per µm2) of incorporation of bimetallic plasmonic particles into the emergent crystal polymorph.

4-{[Bis(2-hy-droxy-eth-yl)amino]-meth-yl}-6-meth-oxy-2H-chromen-2-one.

In the title compound, C(15)H(19)NO(5), an intra-molecular O-H⋯O hydrogen bond links the hy-droxy-ethyl side chains, forming a seven-membered ring. In the crystal, mol-ecules are linked into chains via O-H⋯O hydrogen bonds along the b axis. Further, mol-ecules are linked by weak inter-molecular C-H⋯O and π-π stacking inter-actions [centroid-centroid distance = 3.707 (4) Å].

Enhanced proton conductivity in amino acid based self-assembled non-porous hydrogen-bonded organic frameworks.

ß-Alaninium oxalate hemihydrate, glycinium oxalate, and L-leucinium oxalate salt-cocrystals as non-porous self-assembled hydrogen-bonded organic frameworks afforded proton conductivity of 2.43 × 10-2 S cm-1 (60 °C, 95% RH), 3.03 × 10-2 S cm-1 (60 °C, 95% RH), and 1.19 × 10-2 S cm-1 (80 °C, 95% RH), respectively. These materials possess an extensive 3-dimensional network of hydrogen bonds in their crystal structures, making them efficient proton conducting membranes. The reduction in conductivity values over 10-1 S cm-1 order upon exposure of the samples to a D2O atmosphere in extreme conditions ratified the role of humidity for the conduction of protons. This work explores the relationship between structural features and proton conductivity for the design of proton conducting membranes that are easy to synthesize, eco-friendly, and cheap with potential for futuristic applications.

Synthesis, structure, negative thermal expansion, and photocatalytic property of Mo doped ZrV2O7.

A new series of compounds identified in the phase diagram of ZrO(2)-V(2)O(5)-MoO(3) have been synthesized via the solution combustion method. Single crystals of one of the compounds in the series, ZrV(1.50)Mo(0.50)O(7.25), were grown by the melt-cool technique from the starting materials with double the MoO(3) quantity. The room temperature average crystal structure of the grown crystals was solved using the single crystal X-ray diffraction technique. The crystals belong to the cubic crystal system, space group Pa3 (No. 205) with a = 8.8969 (4) Å, V = 704.24 (6) Å(3), and Z = 4. The final R(1) value of 0.0213 was achieved for 288 independent reflections during the structure refinement. The Zr(4+) occupies the special position (4a) whereas V(5+) and Mo(6+) occupy two unique (8c) Wyckoff positions. Two fully occupied O atoms, (24d) and (4b), one partially occupied O atom (8c) have been identified for this molybdovanadate, which is a unique feature for these crystals. The structure is related to both ZrV(2)O(7) and cubic ZrMo(2)O(8). The temperature dependent single crystal studies show negative thermal expansion above 370 K. The compounds have been characterized by powder X-ray diffraction, solid-state UV-vis diffuse reflectance spectra, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic activity of these compounds has been investigated for the degradation of various dyes, and these compounds show specificity toward the degradation of non-azoic dyes.

(2E)-1-(5-Chloro-thio-phen-2-yl)-3-(2,4,5-trimeth-oxy-phen-yl)prop-2-en-1-one.

In the title mol-ecule, C(16)H(15)ClO(4)S, the chloro-thio-phene and trimeth-oxy-phenyl rings make a dihedral angle of 31.12 (5)°. The C=C double bond exhibits an E conformation. In the crystal, C-H⋯O inter-actions generate bifurcated bonds, linking the mol-ecules into chains along the b axis.

Ethyl 6-methyl-2-sulfanyl-idene-4-[4-(trifluoro-meth-yl)phen-yl]-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

The title compound, C(15)H(15)F(3)N(2)O(2)S, adopts a conformation with an intra-molecular C-H⋯π inter-action. The dihedral angles between the planes of the 4-(trifluoro-meth-yl)phenyl and ester groups with the plane of the six-membered tetra-hydro-pyrimidine ring are 81.8 (1) and 16.0 (1)°, respectively. In the crystal structure, inter-molecular N-H⋯S hydrogen bonds link pairs of mol-ecules into dimers and N-H⋯O inter-actions generate hydrogen-bonded mol-ecular chains along the crystallographic a axis.

Synthesis, characterization, and crystallographic study of the PbO-Bi2O3-V2O5 system: Pb(3-x)Bi(2x/3)V2O8 (0.20 < or = x < or = 0.50).

A new solid solution Pb(3-x)Bi(2x/3)V(2)O(8) (0.20 < or = x < or = 0.50), stabilizing the high-temperature gamma form of Pb(3)V(2)O(8), has been isolated in the system Pb(3)V(2)O(8)-BiVO(4). The single-crystal structure of the composition x = 0.50 (Pb(2.5)Bi(1/3)V(2)O(8)) was solved using single-crystal X-ray diffraction (XRD) technique. The compound crystallizes in the trigonal crystal system R3m (No. 166) with a palmierite structural type with a = 5.7463(3) A, c = 20.3047(12) A, V = 580.64(5) A(3), and Z = 3. The final R1 value of 0.0406 was achieved for 217 independent reflections during the structure refinement. The variable-temperature powder XRD shows the absence of any phase transition for all of the members of the solid solution in the limit of 398-80 K. The new solid solution has been characterized by neutron powder diffraction, solid-state UV-vis diffuse-reflectance spectra, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS). Alternating-current impedance studies indicate conductivity on the order of 10(-4) Omega(-1) cm(-1) for Pb(2.5)Bi(1/3)V(2)O(8). The change in color of the samples from brown to yellow at high temperature was explained by XPS studies, which indicate the plausible formation of the ppm level of Bi(2)O(3) at such elevated temperature ranges.

In situ surface modification of molybdenum-doped organic-inorganic hybrid TiO2 nanoparticles under hydrothermal conditions and treatment of pharmaceutical effluent.

Molybdenum-doped TiO2 organic-inorganic hybrid nanoparticles were synthesized under mild hydrothermal conditions by in situ surface modification using n-butylamine. This was carried out at 150 degrees C at autogeneous pressure over 18 h. n-Butylamine was selected as a surfactant since it produced nanoparticles of the desired size and shape. The products were characterized using powder X-ray diffraction, Fourier transform infrared spectrometry, dynamic light-scattering spectroscopy, UV-Vis spectroscopy and transmission electron microscopy. Chemical oxygen demand was estimated in order to determine the photodegradation efficiency of the molybdenum-doped TiO2 hybrid nanoparticles in the treatment of pharmaceutical effluents. It was found that molybdenum-doped TiO2 hybrid nanoparticles showed higher photocatalytic efficiency than untreated TiO2 nanoparticles.

Simplifying the complex 1H NMR spectra of fluorine-substituted benzamides by spin system filtering and spin-state selection: multiple-quantum-single-quantum correlation.

The proton NMR spectra of fluorine-substituted benzamides are very complex (Figure 1) due to severe overlap of (1)H resonances from the two aromatic rings, in addition to several short and long-range scalar couplings experienced by each proton. With no detectable scalar couplings between the inter-ring spins, the (1)H NMR spectra can be construed as an overlap of spectra from two independent phenyl rings. In the present study we demonstrate that it is possible to separate the individual spectrum for each aromatic ring by spin system filtering employing the multiple-quantum-single-quantum correlation methodology. Furthermore, the two spin states of fluorine are utilized to simplify the spectrum corresponding to each phenyl ring by the spin-state selection. The demonstrated technique reduces spectral complexity by a factor of 4, in addition to permitting the determination of long-range couplings of less than 0.2 Hz and the relative signs of heteronuclear couplings. The technique also aids the judicious choice of the spin-selective double-quantum-single-quantum J-resolved experiment to determine the long-range homonuclear couplings of smaller magnitudes.

Conjugated polymers for photocatalysis.

The photocatalytic properties of the conjugated polymers have been investigated for the first time. Degradation of various textile dyes such as Alizarin S, Alizarin G, Orange G, and Remazol brilliant blue were studied under UV radiation. The experimental data indicated that the photocatalytic activity of the conjugated polymers was significantly higher than that of Degussa P-25 under similar conditions. The conjugated polymers were characterized by photoluminescent, UV-visible, and IR spectroscopies before and after photocatalytic reactions. The degradation of phenol was also carried out to study the reaction pathway of degradation.

A series of substituted (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-phenylprop-2-en-1-ones.

In the molecular structures of a series of substituted chalcones, namely (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-phenylprop-2-en-1-one, C21H15FO2, (I), (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-fluorophenyl)prop-2-en-1-one, C21H14F2O2, (II), (2E)-1-(4-chlorophenyl)-3-(2-fluoro-4-phenoxyphenyl)prop-2-en-1-one, C21H14ClFO2, (III), (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-methylphenyl)prop-2-en-1-one, C22H17FO2, (IV), and (2E)-3-(2-fluoro-4-phenoxyphenyl)-1-(4-methoxyphenyl)prop-2-en-1-one, C22H17FO3, (V), the configuration of the keto group with respect to the olefinic double bond is s-cis. The molecules pack utilizing weak C-H...O and C-H...pi intermolecular contacts. Identical packing motifs involving C-H...O interactions, forming both chains and dimers, along with C-H...pi dimers and pi-pi aromatic interactions are observed in the fluoro, chloro and methyl derivatives.

Four substituted pyrazolines.

In the title compounds 5-(3-fluoro-4-phenoxyphenyl)-1,3-biphenyl-4,5-dihydro-1H-pyrazole, C27H21FN2O, (I), 3-(4-chlorophenyl)-5-(3-fluoro-4-phenoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C27H20ClFN2O, (II), 5-(3-fluoro-4-phenoxyphenyl)-3-(4-methylphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C28H23FN2O, (III), and 5-(3-fluoro-4-phenoxyphenyl)-3-(4-methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole, C28H23FN2O2, (IV), the five-membered pyrazole ring exists in an envelope conformation. The crystal structure of (I) has three independent C-H...pi intermolecular interactions. In (II), an intermolecular C-Cl...pi contact is present, forming molecular chains. Replacement of this chloro group in (II) by a methyl group yields an isomorphic crystal structure, (III).

1,1'-Binaphthalene-2,2'-diyl hydrogen phosphate.

The title compound, racemic bnppa, C(20)H(13)O(4)P, crystallizes with four mol-ecules in the asymmetric unit. Two independent centrosymmetric O-H⋯O hydrogen-bonded tetra-mers, each involving two of the symmetry-independent mol-ecules in the asymmetric unit generate the packing motif in the crystal structure. The hydro-phobic parts of the tetra-mers connect to their neighbours via C-H⋯π and π-π inter-actions [3.899 (2), 3.895 (2) and 3.803 (2) Šwithin the symmetric unit, 3.851 (2), 4.000 (2), 3.988 (2) and 3.905 (2) Šacross centres of symmetry].

(2R*,3R*,4aS*,6aR*,11aS*,11bS*)-Methyl 2-acet-oxy-11b-hydr-oxy-3,7-dimethyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca-hydro-phenanthro[3,2-b]furan-3-carboxyl-ate.

In the title compound, C(22)H(30)O(6), the conformation of the mol-ecule is dictated by an intra-molecular C-H⋯O contact. The crystal structure is stabilized via inter-molecular C-H⋯O, O-H⋯O and C-H⋯π contacts.

Crystal structure of 2,4,6-tris-(cyclo-hex-yloxy)-1,3,5-triazine.

The title compound, C21H33N3O3, is a tri-substituted cyclo-hex-yloxy triazine. In the crystal, the triazine rings form (C3i-PU) Piedfort units. The inter-centroid distance of the π-π inter-action involving the triazine rings is 3.3914 (10) Å. In the crystal, mol-ecules are linked by C-H⋯O hydrogen bonds, forming ribbons propagating along [1-10]. There are also weak C-H⋯N and C-H⋯O contacts present, linking inversion-related ribbons, forming a three-dimensional structure.

Halogen bonding in fluorine: experimental charge density study on intermolecular F···F and F···S donor-acceptor contacts.

The enigmatic type II C-F···F-C and C-F···S-C interactions in pentafluorophenyl 2,2'-bithiazole are shown to be realistic "σ-hole" interactions based on high resolution X-ray charge density analysis.

Polymorphism and tautomeric preference in fenobam and the utility of NLO response to detect polymorphic impurities.

Crystal structures of polymorphs and solvatomorphs of the potential anxiolytic drug fenobam exhibit an exclusive preference for one of the two possible tautomeric structures. A novel methodology based on nonlinear optical response has been successfully employed to detect the presence of a polymorphic impurity in a mixture of polymorphs.

Thiourea based novel chromogenic sensor for selective detection of fluoride and cyanide anions in organic and aqueous media.

Novel chromogenic thiourea based sensors 4,4'-bis-[3-(4-nitrophenyl) thiourea] diphenyl ether 1 and 4,4'-bis-[3-(4-nitrophenyl) thiourea] diphenyl methane 2 having nitrophenyl group as signaling unit have been synthesized and characterized by spectroscopic techniques and X-ray crystallography. The both sensors show visual detection, UV-vis and NMR spectral changes in presence of fluoride and cyanide anions in organic solvent as well as in aqueous medium. The absorption spectra indicated the formation of complex between host and guest is in 1:2 stoichiometric ratios.

Synthesis, structure and DNA cleavage studies of coumarin analogues of tetrahydroisoquinoline and protoberberine alkaloids.

Novel molecular matrices have been derived from coumarin-4-acetic acids and beta-phenylethylamines using the Bischler-Napieralski protocol which has led to the synthesis of analogues of tetrahydropapaverine in which the dimethoxybenzene moiety has been replaced by substituted coumarins. One carbon homologation has led to cyclization at the C3 position of coumarin generating the protoberberine skeleton. Structures have been confirmed by diffraction studies. The results showed that compounds 6e, 6f, 7e and 7f were found to be very effective against DNA samples of Gram positive bacterium Staphylococcus aureus and fungus Aspergillus niger.

Micellar aggregates and hydrogels from phosphonobile salts.

The aggregation properties of novel bile acid analogs-phosphonobile salts (PBS)-have been studied. The critical micellar concentration of 23 and 24-phosphonobile salts were measured using fluorescence and 31P NMR methods. All the ten synthesized phosphonobile salts formed gels at different pH ranges in water. The pH range at which individual PBSs could gelate water was narrow and influenced by the number and conformation of hydroxyl groups. A reversible thermochromic system has been developed (with 23-phosphonodeoxycholate at pH 3.3), which changes color upon gelation. The investigation of the first hydrogels derived from trihydroxy bile acid analogs 1 and 6 was made using fluorescence, 31P NMR, X-ray crystallography, circular dichroism and SEM. The present studies reveal that the gel network consists of a chiral, fibrous structure possessing hydrophobic interiors.