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We disclose the discovery and X-ray cocrystal data of potent, selective quinazoline inhibitors of PDE1. Inhibitor (S)-3 readily attains free plasma concentrations above PDE1 IC50 values and has restricted brain access. The racemic compound 3 inhibits >75% of PDE hydrolytic activity in soluble samples of human myocardium, consistent with heightened PDE1 activity in this tissue. These compounds represent promising new tools to probe the value of PDE1 inhibition in the treatment of cardiovascular disease. [ABSTRACT FROM AUTHOR]

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2' ligands are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand-backbone interactions in the protease active site. Inhibitors 5c and 5d containing this unprecedented fused 6-5-5 ring system as the P2 ligand, an aminobenzothiazole as the P2' ligand, and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson-Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors. [ABSTRACT FROM AUTHOR]

A Mn2+-based metal-organic framework (coordination porous framework-5, CPF-5) can serve as a crystalline sponge for single crystal X-ray structural characterization of a variety of compounds using a combination of coordinative alignment and second coordination sphere interactions (e.g., hydrogen bonding). This technique requires only a conventional X-ray source to obtain high quality crystallographic data. [ABSTRACT FROM AUTHOR]

Reactions between Mo(N-t-Bu)2(CH2-t-Bu)2 or Mo(NAdamantyl)2(CH2CMe2Ph)2 and 3 equiv of HCl in the presence of 1 equiv of PPh2Me yield Mo(NR)(CHR')(PPh2Me)Cl2 complexes, from which Mo(NR)(CHR')(PPh2Me)(OAr)Cl complexes (OAr = a 2,6-terphenoxide) can be prepared. The Mo(NR)(CHR')(PPh2Me)(OAr)Cl complexes were evaluated as cross-metathesis catalysts between cyclooctene and Z-1,2-dichloroethylene. The efficiencies of the test reaction for complexes in which OAr = OTPP, OHMT, OHIPT, or OHTBT (where OTPP is 2,3,5,6-tetraphenylphenoxide, OHMT is hexamethylterphenoxide, OHIPT is hexaisopropylterphenoxide, and OHTBT is hexa-t-butylterphenoxide) maximize when OAr is OHMT or OHIPT. Mo(N-t-Bu)(CH-t-Bu)(PPh2Me)Cl2 is essentially inactive for the reaction between cyclooctene and Z-1,2-dichloroethylene. X-ray structural studies were carried out on Mo(NAd)(CHCMe2Ph)(PPh2Me)Cl2, Mo(N-t-Bu)(CH-t-Bu)(PPh2Me)(OHMT)Cl, Mo(NAd)(CHCMe2Ph)(Cl)(OHTBT)(PMe3), and [Mo(NAd)(CHCMe2Ph)(PMe3)(Cl)]2(μ-O), the product of the reaction between Mo(NAd)(CHCMe2Ph)(Cl)(OHTBT)(PMe3) and 0.5 equiv of water. [ABSTRACT FROM AUTHOR]

Understanding the penetration of liquids within textile fibers is critical for the development of next-generation smart textiles. Despite substantial research on liquid penetration in the plane of the textile, little is known about how the liquid penetrates in the thickness direction. Here we report a time-resolved high-resolution X-ray measurement of the motion of the liquid-air interface within a single layer textile, as the liquid is transported across the textile thickness following the deposition of a droplet. The measurement of the time-dependent position of the liquid meniscus is made possible by the use of ultrahigh viscosity liquids (dynamic viscosity from 105 to 2.5 × 106 times larger than water). This approach enables imaging due to the slow penetration kinetics. Imaging results suggest a three-stage penetration process with each stage being associated with one of the three types of capillary channels existing in the textile geometry, providing insights into the effect of the textile structure on the path of the three-dimensional liquid meniscus. One dimensional kinetics studies show that our data for the transplanar penetration depth ▵x L vs time do not conform to a power law, and that the measured rate of penetration for long times is smaller than that predicted by Lucas-Washburn kinetics, challenging commonly held assumptions regarding the validity of power laws when applied to relatively thin textiles. [ABSTRACT FROM AUTHOR]

The sugar-phosphate backbone of RNA can exist in diverse rotameric substates, giving RNA molecules enormous conformational variability. The most frequent noncanonical backbone conformation in RNA is α/γ = t/t, which is derived from the canonical backbone by a crankshaft motion and largely preserves the standard geometry of the RNA duplex. A similar conformation also exists in DNA, where it has been extensively studied and shown to be involved in DNA-protein interactions. However, the function of the α/γ = t/t conformation in RNA is poorly understood. Here, we present molecular dynamics simulations of several prototypical RNA structures obtained from X-ray and NMR experiments, including canonical and mismatched RNA duplexes, UUCG and GAGA tetraloops, Loop E, the sarcin-ricin loop, a parallel guanine quadruplex, and a viral pseudoknot. The stability of various noncanonical α/γ backbone conformations was analyzed with two AMBER force fields, ff99bsc0χOL3 and ff99bsc0χOL3 with the recent εζOL1 and βOL1 corrections for DNA. Although some α/γ substates were stable with seemingly well-described equilibria, many were unstable in our simulations. Notably, the most frequent noncanonical conformer α/γ = t/t was unstable in both tested force fields. Possible reasons for this instability are discussed. Our work reveals a potentially important artifact in RNA force fields and highlights a need for further force field refinement. [ABSTRACT FROM AUTHOR]

Despite its importance, the structure and dynamics of liquid water are still poorly understood in many apsects. Here, we report on the observation of optical fluorescence upon soft X-ray irradiation of liquid water. Detection of spectrally resolved fluorescence was achieved by a combination of the liquid microjet technique and fluorescence spectroscopy. We observe a genuine liquid-phase fluorescence manifested by a broad emission band in the 170-340 nm (4-7 eV) photon wavelength range. In addition, another narrower emission near 300 nm can be assigned to the fluorescence of OH (A state) in the gas phase, the emitting species being formed by Auger electrons escaping from liquid water. We argue that the newly observed broad-band emission of liquid water is relevant in search of extraterrestrial life, and we also envision the observed electron-ejection mechanism to find application for exploring solutes at liquid-vapor interfaces. [ABSTRACT FROM AUTHOR]

An ensemble-modeling scheme incorporating coarse-grained simulations with experimental small-angle X-ray scattering (SAXS) data is applied to dengue virus 2 (DENV2) nonstructural protein 5 (NS5). NS5 serves a key role in viral replication through its two domains that are connected by a 10-residue polypeptide segment. A set of representative structures is generated from a simulated structure pool using SAXS data fitting by the non-negativity least squares (NNLS) or standard ensemble optimization method (EOM) based on a genetic algorithm (GA). It is found that a proper low-energy threshold of the structure pool is necessary to produce a conformational ensemble of two representative structures by both NNLS and GA that agrees well with the experimental SAXS profile. The stability of the constructed ensemble is validated also by molecular dynamics simulations with an all-atom force field. The constructed ensemble successfully revealed the domain-domain orientation and domain-contacting interface of DENV2 NS5. Using experimental data fitting and additional investigations with synthesized data, it is found that energy restraint on the conformational pool is necessary to avoid overinterpretation of experimental data by spurious conformational representations. [ABSTRACT FROM AUTHOR]

Experimental mechanistic studies of iridium-catalyzed, enantioselective allylic substitution enabled by (phosphoramidite,olefin) ligands are reported. (η2-Allylic alcohol)iridium(I) and (η3-allyl)iridium(III) complexes were synthesized and characterized by NMR spectroscopy as well as X-ray crystallography. The substrate complexes are catalytically and kinetically competent to be intermediates in allylic substitutions of branched, racemic allylic alcohols with various nucleophiles. In addition, we have identified an off-cycle pathway involving reversible binding of molecular oxygen to iridium, which contributes to the air tolerance of the catalyst system. [ABSTRACT FROM AUTHOR]

Nanocellulose extracted from wood pulps using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidation and sulfuric acid hydrolysis methods was characterized by small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS) techniques. The dimensions of this nanocellulose (TEMPO-oxidized cellulose nanofiber (TOCN) and sulfuric acid hydrolyzed cellulose nanocrystal (SACN)) revealed by the different scattering methods were compared with those characterized by transmission electron microscopy (TEM). The SANS and SAXS data were analyzed using a parallelepiped-based form factor. The width and thickness of the nanocellulose cross section were ∼8 and ∼2 nm for TOCN and ∼20 and ∼3 nm for SACN, respectively, where the fitting results from SANS and SAXS profiles were consistent with each other. DLS was carried out under both the VV mode with the polarizer and analyzer parallel to each other and the HV mode having them perpendicular to each other. Using rotational and translational diffusion coefficients obtained under the HV mode yielded a nanocellulose length qualitatively consistent with that observed by TEM, whereas the length derived by the translational diffusion coefficient under the VV mode appeared to be overestimated. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have been considered as one of the promising power source candidates for the stationary storage industries owing to the much lower cost of sodium than lithium. It is well-known that the electrode materials largely determine the energy density of the battery systems. However, recent discoveries on the electrode materials showed that most of them present distinct lithium and sodium storage performance, which is not yet well understood. In this work, we performed a comparative understanding on the structural changes of porous cobalt oxide during its electrochemical lithiation and sodiation process by in operando synchrotron small angel X-ray scattering, X-ray diffraction, and X-ray absorption spectroscopy. It was found that compared to the lithiation process, the porous cobalt oxide undergoes less pore structure changes, oxidation state, and local structure changes as well as crystal structure evolution during its sodiation process, which is attributed to the intrinsic low sodiation activity of cobalt oxide as evidenced by ab initio molecular dynamics simulations. Moreover, it was indicated that the sodiation activity of metal sulfides is higher than that of metal oxides, indicating a better candidate for SIBs. Such understanding is crucial for future design and improvement of high-performance electrode materials for SIBs. [ABSTRACT FROM AUTHOR]

An investigation of the photoluminescence properties of divalent thulium generated by X-ray irradiation (X-irradiation) of nanocrystalline BaFCl:Tm3+ (250 ± 50 ppm) is reported. The X-irradiated samples show typical Tm2+ f-f luminescence with an excited state lifetime τ = 0.98 ± 0.05 ms in the near-infrared (~1140 nm), but no d-f luminescence is observed for the BaFCl host material within the visible range. The Tm2+ ions are relatively stable under dim room light but are photoionized rapidly by sunlight or by fluorescent tube lighting. To study the X-ray storage mechanism, photoluminescence intensities of both Tm3+ and Tm2+ transitions were measured, and the reverse photoionization of Tm2+ was investigated as a function of the laser power density and the initial radiation dose. The photoionization data was then modeled by employing equations based on dispersive first order kinetics using a standard γ distribution function for the separation between the reduced thulium ions and the hole traps. In accord with previous reports, the hole traps are most likely oxide impurities such as O2-, and the average of the separation is found to be ~6-7 Å, i.e., a few interionic spacings. [ABSTRACT FROM AUTHOR]

The preparation of two crystalline binary transition metal p-toluenesulfonate salts of [MII(OH2)6][OTs]2 stoichiometry, where MII = Co (1) and Ni (2), is described. Their syntheses are accomplished via an oxidation-reduction reaction using metal powders and aqueous p-toluenesulfonic acid hydrate as the reducing and oxidizing reagents, respectively. Over the span of one 4 h session, students learn concepts that include reaction stoichiometry, relative rates, complexation, crystal growth and isolation, and fractional crystallization methods. A second session allows for the origins of color and spectroscopy (UV-vis and infrared) to be investigated by more advanced students. Suitably equipped laboratories may also pursue independent student projects involving additional microscopy, X-ray solution and refinement, and magnetic susceptibility exercises. [ABSTRACT FROM AUTHOR]

A new high-pressure crystal form of ethane has been revealed above 2.46 GPa/295 K. This phase IV is tetragonal, of space group P42/mnm, with the H atom disordered due to the molecular rotations about the C-C bond. The crystal structure has been determined by single-crystal X-ray diffraction up to 5.90 GPa. The structure of phase IV resembles the previously determined low-temperature plastic phase I (stable below 90.32 K), of cubic space group Im3m, metastable phase II observed between 89.78 and 89.68 K, as well as monoclinic phase III (space group P21/n) stable below 89.68 K. In phases III and IV, the molecules are arranged according to the weak electrostatic complementarity between neighbors. Liquid-ethane convection erodes the crystal plate, hence colorful interference pattern. At 2.46 GPa, ethane crystallizes in a new tetragonal phase IV with rotating molecules. Spectacular convection of liquid ethane above the single-crystal surface has been observed. [ABSTRACT FROM AUTHOR]

Triphenylamine (TPA), a propeller-shaped optoelectronic molecule, has been used to generate stimuli-responsive smart fluorescent organic materials and correlate the effect of subtle structural changes on the molecular packing and mechanochromic fluorescence (MCF). The substituent (OCH3) position in the TPA phenyl ring and acceptors (malononitrile, cyanoacetamide, cyanoacetic acid, ethyl cyanoacetate, and diethylmalonate) strongly influenced the solid state and mechanochromic fluorescence as well as the molecular packing. The structure-property studies revealed that (i) TPA derivatives without the OCH3 substituent exhibit strong fluorescence (ϕf = 85% (TCAAD-1, 55% (TDEM)), (ii) higher dihedral angle (τ) between donor (aminophenyl) and acceptor lead to weak/non fluorescent material, (iii) substituent at the ortho position to acceptor increased the dihedral angle (τ = 26.49 (TCAAD-2), τ = 27.14 (TDMM)), and (iv) the increase of alkyl groups produced self-reversible high contrast off-on fluorescence switching materials (TDEM). Powder X-ray diffraction studies indicate that stimuli induced reversible phase transformation from crystalline to amorphous and vice versa was responsible for fluorescence switching. The computational studies also supported that OCH3 substitution at ortho to acceptor increased the dihedral angle and optical band gap. Thus, the present studies provide a structural insight for designing TPA based organic molecules for developing new smart organic materials. Stimuli responsive smart fluorescent triphenylamine derivatives have been synthesized that exhibited reversible and self-reversible mechanochromism, and nonfluorescence solids depend on the position of substitution and acceptor structure. [ABSTRACT FROM AUTHOR]

Pharmaceutical salts have been traditionally used in drug formulation. As a salt former, acesulfame (AH), an aliphatic calorie-free sweetener, is actively being employed. Acesulfamates of active pharmaceutical ingredients (APIs) may provide a pleasant sweet taste along with modified physicochemical properties. In this paper, four quinine (QN) salts were obtained with AH, including two 1:1 anhydrous forms (QNAH11a and QNAH11b), one monohydrate of 1:1 salt (QNAH111), and one 1:2 anhydrous forms (QNAH12). The resulting salts were fully characterized by a range of analytical methods. Crystal structures of QNAH11a, QNAH111, and QNAH12 were determined by single-crystal X-ray diffraction, and the crystal structure of QNAH11b was solved from powder X-ray diffraction data by Rietveld refinement. Ionization states for all samples were confirmed by 13C solid-state NMR spectra. The mutual transformation and thermodynamic relationships of these solid forms were revealed via slurry conversion experiments and differential scanning calorimetry measurements. Additionally, enhanced solubility was observed for each acesulfamate when compared with the pure free base. This study should further highlight the potential of AH as a pharmaceutical salt/cocrystal former. Four quinine (QN) salts were obtained with acesulfame (AH), an aliphatic calorie-free sweetener, including two 1:1 anhydrous forms (QNAH11a and QNAH11b), one monohydrate of 1:1 salt (QNAH111), and one 1:2 anhydrous form (QNAH12). [ABSTRACT FROM AUTHOR]

Two Lewis acid-base bifunctional, isostructural metal-organic frameworks (MOFs), [Zn3(Hbtc)2(atz)2]·CH3CN·2CH3OH (MOF-1) and [Co3(Hbtc)2(atz)2]·H2O·2DMF (MOF-2), containing NH2 groups and four-coordinated metal sites were fabricated successfully, and the structures were thoroughly characterized by X-ray crystallography, powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, and N2 adsorption/desorption techniques. Satisfactorily, the novel MOFs with a three-dimensional framework were highly efficient and stable heterogeneous catalysts for selective fixation of CO2 to cyclic carbonates under mild conditions in the absence of solvent. The influences of various reaction parameters on catalytic performance were systematically investigated. Also the catalysts showed excellent versatility to epoxides with different substituents and could be easily recyclable with high activity. Additionally, the self-catalyzed mechanism as well as synergistic mechanism with tetrabutylammonium bromide (Bu4NBr) for CO2 conversion was proposed. Novel Lewis acid-base bifunctional crystals with three-dimensional frameworks were successfully developed and showed exceptionally efficient activity for selective CO2 cycloaddition to epoxides under mild and solvent-free conditions. [ABSTRACT FROM AUTHOR]

The pure rotational spectrum of diketene has been studied in the millimeter-wave region from ∼240 to 360 GHz. For the ground vibrational state and five vibrationally excited satellites (ν24, 2ν24, 3ν24, 4ν24, and ν16), the observed spectrum allowed for the measurement, assignment, and least-squares fitting a total of more than 10 000 distinct rotational transitions. In each case, the transitions were fit to single-state, complete or near-complete sextic centrifugally distorted rotor models to near experimental error limits using Kisiel's ASFIT. Additionally, we obtained less satisfactory least-squares fits to single-state centrifugally distorted rotor models for three additional vibrational states: ν24 + ν16, ν23, and 5ν24. The structure of diketene was optimized at the CCSD(T)/ANO1 level, and the vibration-rotation interaction (αi) values for each normal mode were determined with a CCSD(T)/ANO1 VPT2 anharmonic frequency calculation. These αi values were helpful in identifying the previously unreported ν16 and ν23 fundamental states. We obtained a single-crystal X-ray structure of diketene at −173 °C. The bond distances are increased in precision by more than an order of magnitude compared to those in the 1958 X-ray crystal structure. The improved accuracy of the crystal structure geometry resolves the discrepancy between previous computational and experimental structures. The rotational transition frequencies provided herein should be useful for a millimeter-wave or terahertz search for diketene in the interstellar medium. [ABSTRACT FROM AUTHOR]

We demonstrate facile and efficient construction of conjugated double helical ladder oligomers from the saddle-shaped cyclooctatetrathiophene (COTh) building blocks. The key step involves deprotonation of tetra[3,4]thienylene (β,β-COTh) with n-BuLi which displays remarkably high ipsilateral selectivity. Three racemic double helical ladder oligomers, rac-DH-1, rac-DH-2, and rac-DH-3, containing two, three, and five COTh annelated moieties are efficiently synthesized by diastereoselective coupling of the racemic precursors. The X-ray crystallographic studies of rac-DH-1, rac-DH-2 and rac-DH-3 unambiguously revealed that each double helical scaffold has two single helices intertwined with each other via the C-C single bonds. Following removal of TMS groups, double helical ladder oligomer rac-DH-1-D had sufficient solubility to be resolved via chiral HPLC, thus enabling determination of its chirooptical properties such as CD spectra and optical rotation. (+)-DH-1-D has a large barrier for racemization, with lower limit of πG > 48 kcal mol-1, which may be compared to DFT-computed barrier of 51 kcal mol-1. The enantiomers of DH-1-D show 1 order of magnitude stronger chirooptical properties than the carbon-sulfur [7]helicene, as determined by the anisotropy factor g = πε/ε = -0.039, based on πεmax = -11 and ε = 2.8 × 10² L mol-1 cm-1 in cyclohexane at 327 nm. [ABSTRACT FROM AUTHOR]

Crystals of Ba7(BO3)4-yF2+3y and Ba4-xSr3+x(BO3)4-yF2+3y solid solutions display a phenomenon that has never been described for borates beforeX-ray irradiation induces strong absorption in the visible range and, as the result, coloring of the crystals up to dark purple. The induced absorption can be removed by illumination with a wavelength of 300-400 nm. Owing to this phenomenon, these crystals are promising sensors applicable to fixing X-ray images. With the use of electron spin resonance and optical spectroscopy, it has been found that the formation of color centers is connected with the [(BO3)F]4- and [F4]4- tetrahedral groups, which are the distinguishing feature of Ba7(BO3)4-yF2+3y and Ba4-xSr3+x(BO3)4-yF2+3y structure. Partial replacement of Ba2+ to Sr2+ in the crystal lattice of Ba4-xSr3+x(BO3)4-yF2+3y leads to the formation of the stable electron-hole pairs under X-ray irradiation. The opportunity to vary the cationic and anionic sublattice composition within the same crystal structure becomes a prospective tool to vary physical and chemical properties of the phosphors. [ABSTRACT FROM AUTHOR]

Elevated levels of human lipoprotein-associated phospholipase A2 (Lp-PLA2) are associated with cardiovascular disease and dementia. A fragment screen was conducted against Lp-PLA2 in order to identify novel inhibitors. Multiple fragment hits were observed in different regions of the active site, including some hits that bound in a pocket created by movement of a protein side chain (approximately 13 Å from the catalytic residue Ser273). Using structure guided design, we optimized a fragment that bound in this pocket to generate a novel low nanomolar chemotype, which did not interact with the catalytic residues. [ABSTRACT FROM AUTHOR]

Cr(VI) removal was investigated in a fixed-bed column using nanozerovalent iron-immobilized calcium alginate beads (nZVI-C-A beads) and a biofilm formed on nZVI-C-A beads. The removal studies were performed at various initial Cr(VI) concentrations, different flow rates, and bed heights. Under optimal conditions, nZVI-C-A beads showed 91.35 ± 1.57% Cr(VI) removal and 320.66 ± 3.87 mg/g removal capacity. For biofilm-coated nZVI-C-A beads, the removal percentage and removal capacity were found to be 97.84 ± 0.56% and 473.9 ± 4.84 mg/g, respectively. Breakthrough data were successfully described by the Thomas and Yoon-Nelson model for removal of Cr(VI) using nZVI-C-A and a biofilm on nZVI-C-A beads. Cr(VI) sorption on nZVI-C-A beads and biofilm-coated nZVI-C-A beads were confirmed by X-ray diffraction, energy-dispersive analysis of X-rays, and Fourier transform infrared. [ABSTRACT FROM AUTHOR]

A systematic X-ray absorption study at actinide N6,7 (4f → 6d transitions) edges was performed for light-actinide oxides including data obtained for the first time for NpO2, PuO2, and UO3. The measurements were supported by ab initio calculations based on local-density-approximation with added 5f-5f Coulomb interaction (LDA+U). Improved energy resolution compared to common experiments at actinide L2,3 (2p → 6d transitions) edges allowed us to resolve the major structures of the unoccupied 6d density of states (DOS) and estimate the crystal-field splittings in the 6d shell directly from the spectra of light-actinide dioxides. The measurements demonstrated an enhanced sensitivity of the N6,7 spectral shape to changes in the compound crystal structure. For nonstoichiometric NpO2-x, the filling of the entire band gap with Np 6d states was observed thus supporting a phase coexistence of Np metal and stoichiometric NpO2 which is in agreement with the tentative Np-O phase diagram. [ABSTRACT FROM AUTHOR]

Although a few architectures have been fabricated by the self-assembly of natural triterpenoids, the precise control of shape and size is rarely studied. Herein, a methyl oleanolate-bearing amphiphile, 1-[2-(methyl oleanolate)-2-oxoethyl]pyridinium bromide (MOP), has been designed and its assembly behavior was investigated. It was found that the morphologies of MOP assemblies ranged from nanoparticles to rigid microrods and flexible nanofibers in chloroform/p-xylene and methanol/water, respectively. During the assembly process, the systematical variational solvophobic/solvophilic effect resulted in the formation of spherical nanoparticles with opposite dipoles and converse bilayer structures. Moreover, such opposite molecular orientations lead to the inversion of supramolecular chirality and distinct mechanical properties. The driving forces and packing patterns of MOP in each solvent system were clearly demonstrated by the combination of NMR, UV-vis, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), theoretical computation, and contact angle experiments, which revealed the roles of triterpenoids and pyridinium cations in the assembly process. This work provides a facile strategy to control the supramolecular structures in triterpenoid-based assemblies by adjusting the solvent polarity and composition. [ABSTRACT FROM AUTHOR]

Newly synthesized octahedral molybdenum cluster compound (n-Bu4N)2[Mo6I8(OOC-1-adamantane)6] revealed uncharted features applicable for the development of X-ray inducible luminescent materials and sensitizers of singlet oxygen, O2(¹Δg). The compound exhibits a red-NIR luminescence in the solid state and in solution (e.g., quantum yield of 0.76 in tetrahydrofuran) upon excitation by UV-vis light. The luminescence originating from the excited triplet states is quenched by molecular oxygen to produce O2(¹Δg) with a high quantum yield. Irradiation of the compound by X-rays generated a radioluminescence with the same emission spectrum as that obtained by UV-vis excitation. It proves the formation of the same excited triplet states regardless of the excitation source. By virtue of the described behavior, the compound is suggested as an efficient sensitizer of O2(¹Δg) upon X-ray excitation. The luminescence and radioluminescence properties were maintained upon embedding the compound in polystyrene films. In addition, polystyrene induced an enhancement of the radioluminescence intensity via energy transfer from the scintillating polymeric matrix. Sulfonated polystyrene nanofibers were used for the preparation of nanoparticles which form stable dispersions in water, while keeping intact the luminescence properties of the embedded compound over a long time period. Due to their small size and high oxygen diffusivity, these nanoparticles are suitable carriers of sensitizers of O2(¹Δg). The presented results define a new class of nanoscintillators with promising properties for X-ray inducible photodynamic therapy. [ABSTRACT FROM AUTHOR]

Effortsto comprehend the structural–spectrochemical correlations ofcrystalline metal–organic framework materials of Pb(II) with(a)cyclic and aromatic chelators linked to photoluminescent applicationsled to the hydrothermal pH-specific synthesis of crystalline materials[Pb{H2BTC}(phen)(H2O)]n·2nH2O(1), [Pb2{CBTC}]n(2), [Pb4(phen)8{CBTC}2(H2O)4]3·70.3H2O(3), and [Pb{HCTA}(H2O)2]n·nH2O(4). X-ray studies showed that 1–4exhibit unique architectures linkedto 2D–3D coordination polymers formulated by Z-type units composedof Pb2O2cores, unusually high number of lattice–watermolecules, and π–π and H-bond interactions. Thecontribution of the nature–structure properties of the aliphatic-(a)cyclicorganic (poly)carboxylic/aromatic chelators-ligands to binary-ternaryPb(II) reactivity weaves into the assembly of supramolecular networks,thereby providing clear structural–spectroscopic inter-relationshipsexemplifying the observed photoluminescent activity in a distinctMOF-linked fashion. [ABSTRACT FROM AUTHOR]

We demonstrate switching of ionic conductivities in wedge-shaped liquid-crystalline (LC) ammonium salts. A thermoreversible phase transition between the rectangular columnar (Colr) and hexagonal columnar (Colh) phases is used for the switch. The ionic conductivities in the Colh phase are about four orders of magnitude higher than those in the Colr phase. The switching behavior of conductivity can be ascribed to the structural change of assembled ionic channels. X-ray experiments reveal a highly ordered packing of the ions in the Colr phase, which prevents the ion transport. [ABSTRACT FROM AUTHOR]

An ability to design peptide-based nanotubes (PNTs) rationally with defined and mutable internal channels would advance understanding of peptide self-assembly, and present new biomaterials for nanotechnology and medicine. PNTs have been made from Fmoc dipeptides, cyclic peptides, and lock-washer helical bundles. Here we show that blunt-ended α-helical barrels, that is, preassembled bundles of α-helices with central channels, can be used as building blocks for PNTs. This approach is general and systematic, and uses a set of de novo helical bundles as standards. One of these bundles, a hexameric α-helical barrel, assembles into highly ordered PNTs, for which we have determined a structure by combining cryo-transmission electron microscopy, X-ray fiber diffraction, and model building. The structure reveals that the overall symmetry of the peptide module plays a critical role in ripening and ordering of the supramolecular assembly. PNTs based on pentameric, hexameric, and heptameric α-helical barrels sequester hydrophobic dye within their lumens. [ABSTRACT FROM AUTHOR]

Homogeneous reaction precursors may be used to form several solid-state compounds inaccessible by traditional synthetic routes, but there has been little development of techniques that allow for a priori prediction of what may crystallize in a given material system. Here, the local structures of FeSbx designed precursors are determined and compared with the structural motifs of their crystalline products. X-ray total scattering and atomic pair distribution function (PDF) analysis are used to show that precursors that first nucleate a metastable FeSb3 compound share similar local structure to the product. Interestingly, precursors that directly crystallize to thermodynamically stable FeSb2 products also contain local structural motifs of the metastable phase, despite their compositional disagreement. While both crystalline phases consist of distorted FeSb6 octahedra with Sb shared between either two or three octahedra as required for stoichiometry, a corner-sharing arrangement indicative of AX3-type structures is the only motif apparent in the PDF of either precursor. Prior speculation was that local composition controlled which compounds nucleate from amorphous intermediates, with different compositions favoring different local arrangements and hence different products. This data suggests that local environments in these amorphous intermediates may not be very sensitive to overall composition. This can provide insight into potential metastable phases which may form in a material system, even with a precursor that does not crystallize to the kinetically stabilized product. Determination of local structure in homogeneous amorphous reaction intermediates from techniques such as PDF can be a valuable asset in the development of systematic methods to prepare targeted solid-state compounds from designed precursors. [ABSTRACT FROM AUTHOR]

A series of metal-organic framework (MOF) materials has been prepared, each containing a mechanically interlocked molecule (MIM) as the linker and a copper(II) paddlewheel as the secondary building unit (SBU). The MIM linkers are [2]rotaxanes with varying sizes of crown ether macrocycles ([22]crown-6, 22C6; [24]crown-6, 24C6; [26]crown-6, 26C6; benzo[24]crown-6, B24C6) and an anilinium-based axle containing four carboxylate donor groups. Herein, the X-ray structures of MOFs UWCM-1 (no crown) and UWDM-1(22) are compared and demonstrate the effect of including a macrocycle around the axle of the linker. The rotaxane linkers are linear and result in nbo-type MOFs with void space that allows for motion of the interlocked macrocycle inside the MOF pores, while the macrocycle-free linker is bent and yields a MOF with a novel 12-connected bcc structure. Variable temperature ²H solid-state nuclear magnetic resonance showed that the macrocycles in UWDM-1(22), UWDM-1(24), and UWDM-1(B24) undergo different degrees and rates of rotation depending on the size and shape of the macrocycle. [ABSTRACT FROM AUTHOR]

We report the crystal structure of a substoichiometric, HMPA-trisolvated lithium pinacolone enolate tetramer (LiOPin)4-HMPA3 abbreviated as T3. In this tetramer one HMPA binds to lithium more strongly than the other two causing a reduction in spatial symmetry with corresponding loss of C3 symmetry. A variety of NMR experiments, including HMPA titration, diffusion coefficient-formula weight (D-FW) analysis, and other multinuclear one- and two-dimensional NMR techniques reveal that T3 is the major species in hydrocarbon solution when more than 0.6 equiv of HMPA is present. Due to a small amount of moisture from HMPA or air leaking into the solution, a minor complex was identified and confirmed by X-ray diffraction analysis as a mixed aggregate containing enolate, lithium hydroxide, and HMPA in a 4:2:4 ratio, [(LiOPin)4-(LiOH)2-HMPA4], that we refer to as pseudo-T4. A tetra-HMPA-solvated lithium cyclopentanone enolate tetramer was also prepared and characterized by X-ray diffraction, leading to the conclusion that steric effects dominate the formation and solvation of the pinacolone aggregates. An unusual mixed aggregate consisting of pinacolone enolate, lithium diisopropyl amide, lithium oxide, and HMPA in the ratio 5:1:1:2 is also described. [ABSTRACT FROM AUTHOR]

Elemental analysis of materials is fundamentally important to science and technology. Many elemental analysis methods have been developed, but three-dimensional nondestructive elemental analysis of bulk materials has remained elusive. Recently, our project team, dreamX (damageless and regioselective elemental analysis with muonic X-rays), developed a nondestructive depth-profiling elemental analysis method after a decade of research. This new method utilizes a new type of probe; a negative muon particle and high-energy muonic X-rays emitted after the muon stops in a material. We performed elemental depth profiling on an old Japanese gold coin (Tempo-Koban) using a low-momentum negative muon beam and successfully determined that the Au concentration in the coin gradually decreased with depth over a micrometer length scale. We believe that this method will be a promising tool for the elemental analysis of valuable samples, such as archeological artifacts. [ABSTRACT FROM AUTHOR]

A new transition-metal-free mode for the catalytic reduction of carbon dioxide via bidentate interaction has been developed. In the presence of Li2[1,2-C6H4(BH3)2], CO2 can be selectively transformed to either methane or methanol, depending on the reducing agent. The bidentate nature of binding is supported by X-ray analysis of an intermediate analogue, which experiences special stabilization due to aromatic character in the bidentate interaction. Kinetic studies revealed a first-order reaction rate. The transformation can be conducted without any solvent. [ABSTRACT FROM AUTHOR]

Protein crystallography is transitioning into a new generation with the introduction of the X-ray free electron laser, which can be used to solve the structures of complex proteins via serial femtosecond crystallography. Sample characteristics play a critical role in successful implementation of this new technology, whereby a small, narrow protein crystal size distribution is desired to provide high quality diffraction data. To provide such a sample, we developed a microfluidic device that facilitates dielectrophoretic sorting of heterogeneous particle mixtures into various size fractions. The first generation device demonstrated great potential and success toward this endeavor; thus, in this work, we present a comprehensive optimization study to improve throughput and control over sorting outcomes. First, device geometry was designed considering a variety of criteria, and applied potentials were modeled to determine the scheme achieving the largest sorting efficiency for isolating nanoparticles from microparticles. Further, to investigate sorting efficiency within the nanoparticle regime, critical geometrical dimensions and input parameters were optimized to achieve high sorting efficiencies. Experiments revealed fractionation of nanobeads from microbeads in the optimized device with high sorting efficiencies, and protein crystals were sorted into submicrometer size fractions as desired for future serial femtosecond crystallography experiments. [ABSTRACT FROM AUTHOR]

We demonstrate a seamless and contactless method from protein crystallization to X-ray analysis using a microfluidic chip with the aim of obtaining a complete crystallographic data set of a protein crystal under cryogenic conditions. Our microfluidics-based approach did not require direct manipulation of the protein crystal. Therefore, the microfluidic chip approach is suitable for novices of X-ray analysis of protein crystals. We also investigated the effect of stepwise cryoprotection on the quality of protein crystals. Protein crystals with cryoprotection via on-chip manipulation did not show deterioration of crystallographic quality of the protein crystal. The complete diffraction data set of a protein crystal, which is required for determining the 3D structure of the target protein, is obtainable by a simple manipulation. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbene-stabilized nitric oxide radicals were prepared by direct addition of nitric oxide to two N-heterocyclic carbenes in solution phase. The compounds were fully characterized by X-ray crystallography and EPR. The nitric oxide moiety in the solid compounds obtained can be thermally transferred to another N-heterocyclic carbene, suggesting potential applications to NO delivery. [ABSTRACT FROM AUTHOR]

Crystal structure determination has revolutionized modern science in biology, chemistry, and physics. However, the difficulty in obtaining periodic crystal lattices which are needed for X-ray crystal analysis has hindered the determination of atomic structure in nanomaterials, known as the "nanostructure problem". Here, by using rigid and bulky ligands, we have overcome this limitation and successfully solved the X-ray crystallographic structure of the largest reported thiolated gold nanomolecule, Au133S52. The total composition, Au133(SPh-tBu)52, was verified using high resolution electrospray ionization mass spectrometry (ESI-MS). The experimental and simulated optical spectra show an emergent surface plasmon resonance that is more pronounced than in the slightly larger Au144 (SCH2CH2Ph)60. Theoretical analysis indicates that the presence of rigid and bulky ligands is the key to the successful crystal formation. [ABSTRACT FROM AUTHOR]

Shortwave infrared (SWIR or NIR-II)light provides significant advantages for imaging biological structuresdue to reduced autofluorescence and photon scattering. Here, we reporton the development of rare-earth nanoprobes that exhibit SWIR luminescencefollowing X-ray irradiation. We demonstrate the ability of X-ray-inducedSWIR luminescence (X-IR) to monitor biodistribution and map lymphaticdrainage. Our results indicate X-IR imaging is a promising new modalityfor preclinical applications and has potential for dual-modality moleculardisease imaging. [ABSTRACT FROM AUTHOR]

We have simulated the oxygen Is Auger-electron spectra of normal and heavy liquid water using ab initio and quantum dynamical methods. The computed spectra are analyzed and compared to recently reported experimental data. The electronic relaxation in liquid water exposed to ionizing X-ray radiation is shown to be far more diverse and complex than anticipated and extremely different than for an isolated water molecule. A core-level ionized water molecule in the liquid phase, in addition to a local Auger process, relaxes through nonlocal energy and charge transfer, such as intermolecular Coulombic decay and electron-transfer mediated decay (ETMD). We evaluate the relative efficiencies for these three classes of relaxation processes. The quantitative estimates for the relative efficiencies of different electronic decay modes help determine yields of various reactive species produced by ionizing X-rays. The ETMD processes which are considered here for the first time in the core-level regime are found to have a surprisingly high efficiency. Importantly, we find that all nonlocal electronic relaxation processes are significantly enhanced by ultrafast proton transfer between the core-ionized water and neighboring molecules. [ABSTRACT FROM AUTHOR]

By using synchrotron X-rays as aprobe and a nanofabricated smart tip of a tunneling microscope asa detector, we have achieved chemical fingerprinting of individualnickel clusters on a Cu(111) surface at 2 nm lateral resolution, andat the ultimate single-atomic height sensitivity. Moreover, by varyingthe photon energy, we have succeeded to locally measure photoionizationcross sections of just a single Ni nanocluster, which opens new excitingopportunities for chemical imaging of nanoscale materials. [ABSTRACT FROM AUTHOR]

The iodinated X-ray contrast medium diatrizoate is known to be very persistent in current waste water treatment as well as in environmental compartments. In this study, the potential of anaerobic processes in soils, sediments, and during waste water treatment to remove and transform diatrizoate was investigated. In anaerobic batch experiments with soil and sediment seven biologically formed transformation products (TPs) as well as the corresponding transformation pathway were identified. The TPs resulted from successive deiodinations and deacetylations. The final TP 3,5-diaminobenzoic acid (DABA) was stable under anaerobic conditions. However, DABA was further transformed under air atmosphere, indicating the potential for the mineralization of diatrizoate by combining anaerobic and aerobic conditions. With the development of a methodology using complementary liquid chromatography--electrospray ionization--tandem mass spectrometry and liquid chromatography--inductively coupled plasma-mass spectrometry techniques, all identified TPs were quantified and the mass balance could be closed without having authentic standards for four of the TPs available. The detection and quantification of diatrizoate TPs in ground water, in technical wetlands with anaerobic zones, and in a pilot wastewater treatment plant established for anaerobic treatment highlights the transferability and up-scaling of the results attained by laboratory experiments to environmental conditions. [ABSTRACT FROM AUTHOR]

Thevoltage sensor domain (VSD) of voltage-gated cation (e.g.,Na+, K+) channels central to neurological signaltransmission can function as a distinct module. When linked to anotherwise voltage-insensitive, ion-selective membrane pore, the VSDimparts voltage sensitivity to the channel. Proteins homologous withthe VSD have recently been found to function themselves as voltage-gatedproton channels or to impart voltage sensitivity to enzymes. Determiningthe conformational changes associated with voltage gating in the VSDitself in the absence of a pore domain thereby gains importance. Wereport the direct measurement of changes in the scattering-lengthdensity (SLD) profile of the VSD protein, vectorially oriented withina reconstituted phospholipid bilayer membrane, as a function of thetransmembrane electric potential by time-resolved X-ray and neutroninterferometry. The changes in the experimental SLD profiles for bothpolarizing and depolarizing potentials with respect to zero potentialwere found to extend over the entire length of the isolated VSD’sprofile structure. The characteristics of the changes observed werein qualitative agreement with molecular dynamics simulations of arelated membrane system, suggesting an initial interpretation of thesechanges in terms of the VSD’s atomic-level 3-D structure. [ABSTRACT FROM AUTHOR]

Selective B-O-Si bond formation was achieved in the reaction of hisboryloxide 0(Bpin)2 (pin = (OCMe2)2)/boroxine (MeBO)3 system with tertiary silane R3SiH in the presence of stoichiometric water and a catalytic amount of [M](CO)5 ([M] = Mo(CO), W(CO), Fe) to give boryl silyl ethers. Moreover, this reaction can be applied to various hydrosUanes (disilyl compounds and secondary silanes) and hydrogermane. Some of the boryl silyl ethers thus formed were confirmed by X-ray analysis. [ABSTRACT FROM AUTHOR]

We have designed two metal-organic frameworks (MOFs) to efficiently convert X-ray to visible-light luminescence. The MOFs are constructed from M6(μ3-O)4(μ3-OH)4(carboxylate)12 (M = Hf or Zr) secondary building units (SBUs) and anthracene-based dicarboxylate bridging ligands. The high atomic number of Zr and Hf in the SBUs serves as effective X-ray antenna by absorbing X-ray photons and converting them to fast electrons through the photoelectric effect. The generated electrons then excite multiple anthracene-based emitters in the MOF through inelastic scattering, leading to efficient generation of detectable photons in the visible spectrum. The MOF materials thus serve as efficient X-ray scintillators via synergistic X-ray absorption by the metal-cluster SBUs and optical emission by the bridging ligands. [ABSTRACT FROM AUTHOR]

We report herein the first general access to fluorinated homoallylic amines by means of an addition of fluorinated organoindium reagent. The corresponding amines were obtained in good to excellent yield with excellent diastereoisomeric ratio. A plausible mechanism is proposed to explain the stereochemical outcome of the reaction based on the X-ray structure of the products. [ABSTRACT FROM AUTHOR]

Theweak interaction patterns in 4,5,6,7-tetrahalogeno-1H-benzimidazoles, protein kinase CK2 inhibitors, in solid state arestudied by the X-ray method and quantum chemistry calculations. Thecrystal structures of 4,5,6,7-tetrachloro- and 4,5,6,7-tetrabromo-1H-benzimidazole are determined by X-ray diffraction andrefined to a final R-factor of 3.07 and 3.03%, respectively,at room temperature. The compound 4,5,6,7-tetrabromo-1H-benzimidazole, which crystallizes in the I41/aspace group, is found to be isostructuralwith previously studied 4,5,6,7-tetraiodo-1H-benzimidazolein contrast to 4,5,6,7-tetrachloro-1H-benzimidazole,which crystallizes as triclinic P1̅ with 4molecules in elementary unit. For 4,5,6,7-tetrachloro-1H-benzimidazole, differential scanning calorimetry (DSC) revealeda second order glassy phase transition at Tg= 95°/106° (heating/cooling), an indication of frozendisorder. The lack of 3D isostructurality found in all 4,5,6,7-tetrahalogeno-1H-benzimidazoles is elucidated on the basis of the intra-and intermolecular interactions (hydrogen bonding, van der Waals contacts,and C–H···π interactions). The topologicalBader’s Quantum Theory of Atoms in Molecules (QTAIM) and Spackman’sHirshfeld surface-based approaches reveal equilibration of electrostaticmatching and dispersion van der Waals interactions between moleculesconsistent with the crystal site-symmetry. The weakening of van derWaals forces accompanied by increasing strength of the hydrogen bond(N–H···N) result in a decrease in the crystalsite-symmetry and a change in molecular packing in the crystallinestate. Crystal packing motifs were investigated with the aid of Hirshfeldsurface fingerprint plots. The ordering 4,5,6,7-tetraiodo > 4,5,6,7-tetrabromo> 4,5,6,7-tetrachloro > 4,5,6,7-tetrafluoro reflects not onlya decrease in crystal symmetry but also increase in chemical reactivity(electronic activation), which could explain some changes in biologicalactivity of compounds from the 4,5,6,7-tetrahalogeno-1H-benzimidazole series. The ability of formation of a given type ofbonds by 4,5,6,7-tetrahalogeno-1H-benzimidazole moleculesis the same in the crystal and in CK2. Analysis of the interactionsin the crystal permits drawing conclusions on the character (the way)of connections between a given 4,5,6,7-tetrahalogeno-1H-benzimidazole as a ligand with CK2 protein to make a protein–ligandcomplex. [ABSTRACT FROM AUTHOR]

Wedescribe the controlled use of a 17 keV X-ray synchrotron nanobeamto progressively change the oxygen doping level in Bi-2212 superconductingwhisker-like single crystals. Our data combine structural and electricalinformation collected on the same crystals, showing a maximum changein the critical temperature Tcof 1.3K and a maximum elongation of ∼1 Å in the c-axis length, compared to the as-grown conditions. Simulations ofour experimental conditions by means of a finite element model excludelocal heating induced by the X-ray nanobeam as a possible cause forthe change in the doping level and suggest an important role of secondaryelectrons. These findings support the possible use of hard X-raysas a novel direct-writing, photoresist-free lithographic process forthe fabrication of superconducting devices, with potential nanometricresolution and 3D capability. [ABSTRACT FROM AUTHOR]

The relatively unexplored luminophore archi-tecture [Ir(N^N^N)(C^N)L]+ (NANAN = tridentate poly-pyridyl ligand, C^N = 2-phenylpyridine derivative, and L = monodentate anionic ligand) offers the stability of tridentate polypyridyl coordination along with the tunability of three independently variable ligands. Here, a new family of these luminophores has been prepared based on the previously reported compound [lr(tpy)(ppy)Cl]+ (tpy = 2,2':6',2"-terpyridine and ppy = 2-phenylpyridine). Complexes are obtained as single stereoisomers, and ligand geometry is unambiguously assigned via X-ray crystallography. Electrochemical analysis of the materials reveals facile HOMO modulation through ppy functionalization and alteration of the monodentate ligand's field strength. Emission reflects similar modulation shifting from orange to greenish-blue upon replacement of chloride with cyanide. Many of the new compounds exhibit impressive room temperature phosphorescence with lifetimes near 3 µs and quantum yields reaching 28.6%. Application of the new luminophores as photosensitizers for photocatalytic hydrogen generation reveals that their photostability in coordinating solvent is enhanced as compared to popular [Ir(ppy)2(bpy)] + (bpy = 2,2'-bipyridine) photosensitizers. Yet, the binding of their monodentate ligand emerges as a source of instability during the redox processes of cyclic voltammetry and mass spectrometry. DFT modeling of electronic structure is provided for all compounds to elucidate experimental properties. [ABSTRACT FROM AUTHOR]

A diiron dithiolate complex with a pendant phosphine coordinated to one of the iron centers, [(µ-SCH2)2N(CH2C6H4-o-PPh2){Fe2(CO)5}] (l), was prepared and structurally characterized. The pendant phosphine is dissociated together with a CO ligand in the presence of excess PMe3, to afford [(µ-SCH2)2N(CH2C6H4-o-PPh2){Fe(CO)2(PMe3)}2] (2). Redox reactions of 2 and related complexes were studied in detail by in situ IR spectroscopy. A series of new FeIIFeI ([3]+ and [6]+); FeIIFeII ([4]2+), and Fe¹Fe¹ (5) complexes relevant to Hox Hoxco, and Hred states of the [FeFe]-hydrogenase active site were detected. Among these complexes, the molecular structures of the diferrous complex [4]2+ with the internal amine and the pendant phosphine co-coordinated to the same iron center and the triphosphine diiron complex 5 were determined by X-ray crystallography. To make a comparison, the redox reactions of an analogous complex, [(µ-SCH2)2N(CH2C6H5){Fe(CO)2(PMe3)}2] (7), were also inves-tigated by in situ IR spectroscopy in the absence or presence of extrinsic PPh3, which has no influence on the oxidation reaction of 7. The pendant phosphine in the second coordination sphere makes the redox reaction of 2 different from that of its analogue 7. [ABSTRACT FROM AUTHOR]

Theinfluence of the monomer diallyldimethylammonium chloride (D) on thelamellar liquid crystal formed by the anionic surfactant aerosol OT(AOT) and water is investigated, determining the lamellar spacingsby SAXS and the quadrupolar splittings by deuterium NMR, as a functionof the D or AOT concentrations. The cationic monomer D induces a destabilizationof the AOT lamellar structure such that, at a critical concentrationhigher than 5 wt %, macroscopic phase separation takes place. Whenthe monomer, which is dissolved in the AOT lamellae, is polymerizedin situ by X-ray initiation, a new collapsed lamellar phase appears,corresponding to the complexation of the surfactant with the resultingpolymer. A theoretical model is employed to analyze the variationof the interactions between the AOT bilayers and the stability ofthe lamellar structure. [ABSTRACT FROM AUTHOR]