OH Donor Research Articles

Hydration structure and dynamics of phosphoric acid and its anions-Ultrafast 2D-IR spectroscopy and abinitio molecular dynamics simulations.

The hydration shells of phosphate ions and phosphate groups of nucleotides and phospholipid membranes display markedly different structures and hydrogen-bond strengths. Understanding phosphate hydration requires insight into the spatial arrangements of water molecules around phosphates and in thermally activated structure fluctuations on ultrafast time scales. Femtosecond two-dimensional infrared spectroscopy of phosphate vibrations, particularly asymmetric stretching vibrations between 1000 and 1200cm-1, and abinitio molecular dynamics (AIMD) simulations are combined to map and characterize dynamic local hydration structures and phosphate-water interactions. Phosphoric acid H3PO4 and its anions H2PO4-, HPO42-, and PO43- are studied in aqueous environments of different pH value. The hydration shells of phosphates providing OH donor groups in hydrogen bonds with the first water layer undergo ultrafast structural fluctuations, which induce a pronounced spectral diffusion of vibrational excitations on a sub-300fs time scale. With a decreasing number of phosphate OH groups, the hydration shell becomes more ordered and rigid. The 2D-IR line shapes observed with hydrated PO43- ions display a pronounced inhomogeneous broadening, reflecting a distribution of hydration geometries without fast equilibration. The AIMD simulations allow for an in-depth characterization of the hydration geometries with different numbers of water molecules in the first hydration layer and different correlation functions of the fluctuating electric field that the water environment exerts on the vibrational phosphate oscillators.

Titanium and Vanadium Complexes of Tridentate Phenoxy-Imine and Phenoxy-Amine Ligands and Their Application in the Ring-Opening Polymerization of Cyclic Esters.

Phenoxy-imine and phenoxy-amine proligands, with the additional OH donor groups 2,4-tBu2-6-(2-CH2(OH)-C6H4N=CH)C6H3OH (L1H2), 6-(2-CH2(OH)-C6H4N=CH)C6H3OH (L2H2), and 2,4-tBu2-6-(2-CH2(OH)-C6H4NH-CH)C6H3OH (L3H2), were synthesized and their titanium (Ti-L1-Ti-L3) and vanadium (V-L1-V-L2) complexes were prepared in reactions with Ti(OiPr)4 and VO(OiPr)3, respectively. All new compounds were characterized with the use of FTIR, 1H, and 13C NMR spectroscopy; X-ray crystallography was also used to study proligands. All the complexes proved to be active catalysts in the ring-opening polymerization (ROP) of ε-caprolactone, rac-lactide, and L-lactide in the melt. The effects of the complex structure (transition metal type, presence of tBu substituents, and type of nitrogen donor group), as well as the polymerization time and temperature, on the monomer conversion and polymer properties were investigated in detail.

Spectroscopic and computational studies of the noncovalent interactions in the structures of the 2-hydroxy-3-iodo-6-methoxybenzenecarbonyl (-C(O)CH3, -CHO) derivatives

The structures of 2‑hydroxy-3-iodo-6-methoxyacetophenone 2a and 2‑hydroxy-3-iodo-6-methoxybenzaldehyde 2b were elucidated using a combination of NMR, IR and UV–Vis spectroscopic techniques complemented with single crystal X-ray diffraction analysis. XRD confirmed the presence of thermodynamically more favourable six-membered intramolecular hydrogen bonding motif designated as S(6) in the graph-set assignments involving interaction between OH (donor) and an oxygen atom (acceptor) of the carbonyl group with hydrogen bond distance, O(2)-H(2)⋯O(1) of 2.463(2) Å and 2.606(2) Å for 2a and 2b, respectively. The halogen bonding affinity of the iodine atom of 2a as a representative model was investigated in the solution phase by 13CNMR spectroscopy in various deuterated solvents (CDCl3, DMSO‑d6, pyridine-d5 & benzene-d6) and also in benzene-d6 in the presence of triethylamine (Et3N) as a Lewis base. XRD analysis determined that the iodine atom of 2b is involved in two main types of halogen bonding, namely C–I⋯O and halogen-halogen (C–I⋯I–C) contacts. The C–I⋯π and intermolecular C–I⋯O–H contacts were observed in the case of 2a. The DFT calculations were also performed in the gas phase to correlate the experimental results with the simulated data.

Bifurcated hydrogen bonding to fluorine in an all cis-difluoro-hydroxy array

In this communication, we present an unusual bifurcated hydrogen bonding array between an OH donor and two C-F bond acceptors. This serendipitously discovered model system was observed in several substrates with various electron demands placed on the OH acceptor, and all show a symmetrical COH—(F-C)2 hydrogen bonding interaction. We employ NMR and IR spectroscopy, X-ray crystallography and DFT theory to characterize this interesting and potentially biochemically relevant hydrogen bonding format.

MgAl Saponite as a Transition-Metal-Free Anode Material for Lithium-Ion Batteries.

Transition-metal compounds (oxides, sulfides, hydroxides, etc.) as lithium-ion battery (LIB) anodes usually show extraordinary capacity larger than the theoretical value due to the transformation of LiOH into Li2O/LiH. However, there has rarely been a report relaying the transformation of LiOH into Li2O/LiH as the main reaction for LIBs, due to the strong alkalinity of LiOH leading to battery deterioration. In this work, layered silicate MgAl saponite (MA-SAP) is applied as a -OH donor to generate LiOH as the anode material of LIBs for the first time. The MA-SAP maintains a layered structure during the (dis)charging process and has zero-strain characteristic on the (001) crystal plane. In the discharging process, Mg, Al, and Si in the saponite sheets become electron-rich, while the active hydroxyl groups escape from the sheets and combine with lithium ions to form LiOH in the "caves" on sheets, and the LiOH continues to decompose into Li2O and LiH. Consequently, the MA-SAP delivers a maximum capacity of 536 mA h·g-1 at 200 mA·g-1 with a good high-current discharging ability of 155 mA h·g-1 after 1000 cycles under 1 A·g-1. Considering its extremely low cost and completely nontoxic characteristics, MA-SAP has great application prospects in energy storage. In addition, this work has an enlightening effect on the development of new anodes based on extraordinary mechanisms.

Water in Deep Eutectic Solvents: New Insights From Inelastic Neutron Scattering Spectroscopy

The effect of water on the physicochemical properties of deep eutectic solvents (DES) is a trending research topic. In this work, inelastic neutron scattering (INS) spectroscopy, was used to probe intermolecular interactions in the water-deep eutectic solvent mixtures for the cases of choline chloride (the hydrogen bond acceptor) and three different hydrogen bond donors, with different degrees of acidity: urea, glycerol and lactic acid. It was found that quenching samples in liquid nitrogen is a procedure that may retain the liquid phase morphology of DES at the low temperatures required by INS spectroscopy. The three studied systems share the preference of water molecules to bind to chloride anion, as predicted by numerous molecular dynamics simulations. Despite this similarity, the three systems present several distinct INS features upon water addition that are related to their unique properties and structure at the molecular level. In the choline chloride:urea system, water molecules promote a strengthening of hydrogen bonds with the NH and OH donors, while for the choline chloride:lactic acid system INS probed the existence of solvated DES clusters instead of specifically interfering water molecules. This study takes advantage from the unique capabilities of INS and paves the way for future studies in these systems.

Ring opening polymerization of \u03b5-caprolactone initiated by titanium and vanadium complexes of ONO-type schiff base ligand

A phenoxy-imine proligand with the additional OH donor group, 4,6-tBu2-2-(2-CH2(OH)-C6H4N = CH)C6H3OH (LH2), was synthesized and used to prepare group 4 and 5 complexes by reacting with Ti(OiPr)4 (LTi) and VO(OiPr)3 (LV). All new compounds were characterized by the FTIR, 1H and 13C NMR spectroscopy and LTi by the single-crystal X-ray diffraction analysis. The complexes were used as catalysts in the ring opening polymerization of ε-caprolactone. The influence of monomer/transition metal molar ratio, reaction time, polymerization temperature as well as complex type was investigated in detail. The complexes showed high (LTi) and moderate (LV) activity in ε-caprolactone polymerization and the resultant polycaprolactones exhibited Mn and Mw/Mn values ranging from 4.0 · 103 to 18.7 · 103 g/mol and from 1.4 to 2.5, respectively.

A TD-DFT molecular screening for fluorescence probe based on excited-state intramolecular proton transfer of 2’-hydroxychalcone derivatives

A systematic screening of fluorescence probe based on excited-state intramolecular proton transfer (ESIPT) of 2’-hydroxychalcone (2HC) derivatives with different electron donating (EDG) and electron withdrawing (EWG) groups at para position of phenol moiety (R1) and para position of the connected benzene ring to carbonyl (R2) of 2HC has been carried out by the best method of choice at ωB97XD/6-311++G(d,p) level. Seven selected 2HC derivatives with OH donor having mono-substitution with –NMe2 at R1 position or di-substitution with –NMe2 at R1 position and EDG (Me, OMe, NMe2) or EWG (Br, Cl, F) at R2 position have passed all required parameters (photophysical parameters, kinetic and thermodynamic parameters). Whereas, seven selected 2HC derivatives with NH donor having the same substituents as the 2HC derivatives with OH donor have passed photophysical parameters but failed kinetic and thermodynamic parameters due to high PT barrier and endothermic reaction. To ensure the effective ESIPT occurrence, a hydrogen atom on the amine group of NH donor derivatives is replaced with a tosyl (Ts) group, providing the Ts-substituted NH donor derivatives. The Ts substituent helps strengthening the intramolecular hydrogen bond, leading to low PT barrier with exothermic reaction thus facilitating ESIPT process. The systematically screening procedure from this theoretical calculation is beneficial for the design of fluorescent molecular probes utilizing the ESIPT process.

Stereochemistry of the methyl-idene-bridged quinazoline-iso-quinoline alkaloid 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-b]quinazolin-9-one methanol monosolvate.

Two potentially bioactive fragments, namely a tricyclic quinazoline derivative with an exocyclic alkene moiety and a substituted iso-quinoline, are coupled to give 3-{[6,7-dimeth-oxy-1-(4-nitro-phen-yl)-1,2,3,4-tetra-hydro-isoquinolin-2-yl]methyl-idene}-1,2,3,9-tetra-hydro-pyrrolo-[2,1-b]quinazolin-9-one. The target product crystallizes as a methanol solvate, C29H26N4O5·CH4O, and is E configured. The alternative Z isomer would necessarily imply either considerable twist about the central double bond or very unfavourable intra-molecular contacts between sterically more demanding substituents. The main residue and the co-crystallized solvent mol-ecule aggregate to discrete pairs via a classical O-H⋯O hydrogen bond with a distance of 2.8581 (7) Å between the methanol OH donor and the quinazolinone O=C acceptor.

Investigating Differences and Similarities between Betaxolol Polymorphs

Betaxolol belongs to the class of β1-adrenergic blocking agent. Several polymorphs of racemic betaxolol have been reported in the literature, but only one of them (BE_I) had the crystal structure determined from single-crystal X-ray diffraction. Here, we present a new crystalline phase of betaxolol (BE_IV). Its solid-state structure has been obtained from single-crystal X-ray diffraction data. The molecular and crystal arrangements of betaxolol in BE_IV have been further investigated by molecular modelling, by Cambridge Structural Database (CSD) surveys and by Hirshfeld surface analysis. A comparison with the solid-state structure of BE_I have been carried out. In the two polymorphs the 2-hydroxy-3-(isopropylamino)-propoxy chain, which is common to other β-blocker drugs, adopts a different conformation. In addition, the rotational isomer found in BE_IV is different with respect to the four already observed in the solid-state structure of analogous compounds. In both the polymorphs, the most significant interaction is due to the H-bonds involving the OH group as donor and the NH as acceptor, while the interaction where OH works as acceptor (NH acts as donor) is definitely less important. The resulting H-bond patterns are however different: Alternate R2,2(10) a > a (OH donors) and R2,2(10) b > b (OH acceptors) in BE_I vs. alternate R4,4 (8) a > b > a > b (OH donors) and R2,2 (10) b > b (OH acceptor) in BE_IV.

Towards the systematic crystallisation of molecular ionic cocrystals: insights from computed crystal form landscapes.

The underlying molecular and crystal properties affecting the crystallisation of ionic cocrystals (ICCs) with the general formula A-B+N (A- = anion, B+ = cation and N = neutral acid molecule; 1 : 1 : 1 stoichiometry) are reported for a limited set of known crystal structures determined following the cocrystallisation of either 4-aminopyridine (which forms salts) or 4-dimethylaminopyridine (which forms salts and ICCs) with the same set of monoprotic acids with a single hydroxy or halogen substitution at the ortho or para position. Periodic density functional theory calculations (PBE + D2) on the energetic driving force for ICC crystallisation for a set of known crystal structures with well characterised acid, salt and ICC structures show that all but 1 of the 7 experimental ICC structures surveyed were more stable than the sum of their component salt and acid structures with 4 displaying relative stabilities (ΔEICC) ranging from 2.47-8.02 kJ mol-1. The majority of molecular ICCs that are more stable with respect to their component salt and acid structures display the formation of discrete intermolecular O-HacidOanion hydrogen bonds with the D11(2) graph set between the carboxylic acid OH donor and the carboxylate oxygen acceptor of the anion. Computed crystal form landscapes for model 1 : 1 salts derived from acid-base pairs (involving 4-dimethylaminopyridine) known to form molecular ICCs show that on average the most stable predicted polymorphs of the 1 : 1 salts have efficient packing of the ions with packing coefficients in the range 65-80% and this is comparable to the packing coefficients of the most stable predicted polymorphs of 1 : 1 salts (involving 4-aminopyridine) that have no ICCs reported. This suggests that the cocrystallisation of equimolar amounts of the 1 : 1 salt and the acid to form a 1 : 1 : 1 molecular ICC is a complicated phenomenon that cannot be explained on the basis of inefficiencies in the crystal packing of the salt ions.

Supramolecular packing and polymorph screening of N-isonicotinoyl arylketone hydrazones with phenol and amino modifications

Thirteen structural variants based on the (E)-N′-(1-arylethylidene)pyridohydrazide template were prepared, investigated and screened for possible polymorphic behaviour. Four variants showed from Differential Scanning Calorimetry Scans thermal events indicative of new solid-state phases. The thirteen variants included substituents R = OH or NH2 placed at ortho, meta and para positions on the phenyl ring; and shifting the pyridyl nitrogen between positions 4-, 3- and 2-. The crystal structures of twelve of the compounds were determined to explore their supramolecular structures. The outcomes of these modifications demonstrated that the pyridyl nitrogen at the 2- position is ‘locked’ by forming a hydrogen bond with the amide hydrogen; while placing the pyridyl nitrogen at positions 3- and 4- offers a greater opportunity for hydrogen bonding with neighbouring molecules. Such interactions include OH⋯N, NH⋯N, OH⋯O, NH⋯O, NH⋯π, π⋯π stacking, as well as other weaker interactions such as CH⋯N, CH⋯O, CH⋯N(pyridyl). When OH or NH2 donors are placed in the ortho position, an intramolecular hydrogen bond is formed between the acceptor hydrazone nitrogen and the respective donor. The meta- and para-positioned donors form an unpredictable array of supramolecular structures by forming hydrogen-bonded chains with the pyridyl nitrogen and carbonyl acceptors respectively. In addition to the intramolecular and chain hydrogen bond formation demonstrated throughout the crystal structures under investigation, larger order hydrogen-bonded rings were also observed in some of the supramolecular aggregations. The extent of the hydrogen-bonded ring formations range from two to six molecular participants depending on the specific crystal structure.

Kinetic Energy Density as a Predictor of Hydrogen-Bonded OH-Stretching Frequencies.

This work considers the nature of the intermolecular hydrogen bond in a series of 15 different complexes with OH donor groups and N, O, P, or S acceptor atoms. To complement the existing literature, room-temperature gas-phase vibrational spectra of the methanol-pyridine, ethanol-pyridine, and 2,2,2-trifluoroethanol-pyridine complexes were recorded. These complexes were chosen, as they exhibit hydrogen bonds of intermediate strength as compared to previous investigations that involved strong or weak hydrogen bonds. Non Covalent Interactions (NCI) theory was used to calculate various properties of the intermolecular hydrogen bonds, which were compared to the experimental OH-stretching vibrational red shifts. We find that the experimental OH-stretching red shifts correlate strongly with the kinetic energy density integrated within the reduced density gradient volume that describes a hydrogen bond [G(s0.5)]. Given that vibrational red shifts are commonly used as a metric of the strength of a hydrogen bond, this suggests that G(s0.5) could be used as a predictor of hydrogen bonding strength.

Glycan OH Exchange Rate Determination in Aqueous Solution: Seeking Evidence for Transient Hydrogen Bonds

Hydrogen bonds (Hbonds) are important stabilizing forces in biomolecules. However, for glycans in aqueous solution, direct NMR detection of Hbonds is elusive because of their transient nature. Here, we present Isotope-based Natural-abundance TOtal correlation eXchange SpectroscopY (INTOXSY), a new 1H-13C heteronuclear single quantum coherence-total correlation spectroscopy based method, to extract OH groups' exchange rate constants (kex) for molecules in natural 13C abundance and show that OH Hbonds can be inferred from "slower" H/D kex. We evaluate kex measured with INTOXSY in light of those extracted with line-shape analysis. Subsequently, we use a set of common glycans to establish a kex reference basis set and to infer the existence of transient Hbonds involving OH donor groups. Then, we report kex values for a series of mono- and disaccharides, as well as for oligosaccharides sialyl Lewis X and β-cyclodextrin, and compare the results with those from the reference set to extract Hbond information. Finally, we utilize NMR experimental data in conjunction with molecular dynamics simulations to establish donor and acceptor Hbond pairs. Our exchange rate measurements indicate that OH/OD exchange rates, kHD, values <10 s-1 are consistent with transient Hbond OH groups and potential acceptor groups can be uncovered through MD simulations.

Intramolecular Hydrogen Bonding in Substituted Aminoalcohols.

The qualifying features of a hydrogen bond can be contentious, particularly where the hydrogen bond is due to a constrained intramolecular interaction. Indeed there is disagreement within the literature whether it is even possible for an intramolecular hydrogen bond to form between functional groups on adjacent carbon atoms. This work considers the nature of the intramolecular interaction between the OH (donor) and NH2 (acceptor) groups of 2-aminoethanol, with varying substitution at the OH carbon. Gas-phase vibrational spectra of 1-amino-2-methyl-2-propanol (BMAE) and 1-amino-2,2-bis(trifluoromethyl)-2-ethanol (BFMAE) were recorded using Fourier transform infrared spectroscopy and compared to literature spectra of 2-aminoethanol (AE). Based on the experimental OH-stretching frequencies, the strength of the intramolecular hydrogen bond appears to increase from AE < BMAE ≪ BFMAE. Non-covalent interaction analysis shows evidence of an intramolecular hydrogen bond in all three molecules, with the order of the strength of interaction matching that of experiment. The experimental OH-stretching vibrational frequencies were found to correlate well with the calculated kinetic energy density, suggesting that this approach can be used to estimate the strength of an intramolecular hydrogen bond.

Chlorometallate-Pyridinium Boronic Acid Salts for Crystal Engineering: Synthesis of One-, Two-, and Three-Dimensional Hydrogen Bond Networks

A series of new crystal structures of salts containing 3- and 4-pyridineboronic acid (3- and 4-pba) with chlorometallate have been prepared: [4-pbaH][MnCl2] (1), [4-pbaH][CdCl2], (2), [4-pbaH]2[CuCl4] (3), [4-pbaH]2[PdCl4] (4), [3-pbaH]2[CdCl4] (5), [3-pbaH][CuCl3(OH2)] (6), and [3-pbaH][PdCl2] (7). In these salts five structural forms for the chlorometallate species are observed: mononuclear square planar [M = Pd (4 and 7)], dimeric square-pyramidal [M = Cu (3)], polymeric square-pyramidal [M = Cu (6)], polymeric trans-edge-sharing octahedral [M = Mn (1), Cd (2)], and polymeric cis-edge-sharing octahedral [M = Cd (5)]. The cyclic R2,2(8) boronic acid dimer is formed in the salt of 1–5. NH···Cl2M synthons A have been exploited in 1–4, 6, and 7. Both NH···Cl2M (sythons A) and B(OH)2···Cl2M (sythons B) interactions give rise to a synthon of form I in 6. The uncommon folded conformation of the NH···Cl2M (synthons A) are formed in 7. The NH or OH donors and consequent branching of the NH···Cl hydrogen-bond network leads to one-, two-, and three-dimensional structures. These structures are further stabilized by CH···O and CH···Cl and π···π stacking interactions.

Cross-linked poly(acrylic acids) microgels and agarose as semi-interpenetrating networks for resveratrol release.

Carbomers, cross-linked poly(acrylic acid) microgels, have been widely used in pharmaceutical formulations as swollen hydrogels. Agarose, whose thermoreversibility may be exploited for drug loading, forms a gel with a mechanism involving coil-helix transition at about 36 °C. In this work carbomer microgels were combined with agarose networks in a semi-interpenetrating polymer network structure, aiming at obtaining suitable delivery systems for the loading and release of molecules with poor bioavailability but high therapeutic interest, like resveratrol. The rheological properties of the formulations and their in vitro cytocompatibility were studied and optimized acting on the neutralizing agent (triethylamine (N,N-diethylethanamine), triethanolamine (tris(2-hydroxyethyl)amine) and sodium hydroxide) and amount of OH donors (1,2-propanediol and glycerol). As a preparation method, autoclaving was introduced to simultaneously obtain heating and sterilising. Among the different neutralizing agents, NaOH was chosen to avoid the use of amines, considering the final application. Without the addition of alcohols as typical OH donors to induce Carbomer gelification, gels with appropriate rheological properties and stability were produced. For this formulation, the release of resveratrol after 7 days was about 80 % of the loaded mass, suggesting it is an interesting approach to be exploited for the development of innovative resveratrol delivery systems.

Search for a Strong, Virtually “No‐Shift” Hydrogen Bond: A Cage Molecule with an Exceptional OH⋅⋅⋅F Interaction

AbstractReported herein is the synthesis of a molecule containing an unusually strong hydrogen bond between an OH donor and a covalent F acceptor, a heretofore somewhat ill‐defined if not controversial interaction. This unique hydrogen bond is to a large extent a product of the tight framework of the rigid caged system. Remarkably, the interaction shows little to no perceptible shift in the OH stretch of the IR spectrum relative to appropriate nonhydrogen‐bound standards in fairly non‐interactive solvents. This fascinating example of what has been termed a virtual “no‐shift” hydrogen bond is investigated through NMR (coupling constants, isotopic chemical shift perturbations, proton exchange rates) and IR studies which all tell a consistent story.

Search for a strong, virtually "no-shift" hydrogen bond: a cage molecule with an exceptional OH⋅⋅⋅F interaction.

Reported herein is the synthesis of a molecule containing an unusually strong hydrogen bond between an OH donor and a covalent F acceptor, a heretofore somewhat ill-defined if not controversial interaction. This unique hydrogen bond is to a large extent a product of the tight framework of the rigid caged system. Remarkably, the interaction shows little to no perceptible shift in the OH stretch of the IR spectrum relative to appropriate nonhydrogen-bound standards in fairly non-interactive solvents. This fascinating example of what has been termed a virtual "no-shift" hydrogen bond is investigated through NMR (coupling constants, isotopic chemical shift perturbations, proton exchange rates) and IR studies which all tell a consistent story.

Preliminary time-of-flight neutron diffraction studies of Escherichia coli ABC transport receptor phosphate-binding protein at the Protein Crystallography Station.

Inorganic phosphate is an essential molecule for all known life. Organisms have developed many mechanisms to ensure an adequate supply, even in low-phosphate conditions. In prokaryotes phosphate transport is instigated by the phosphate-binding protein (PBP), the initial receptor for the ATP-binding cassette (ABC) phosphate transporter. In the crystal structure of the PBP-phosphate complex, the phosphate is completely desolvated and sequestered in a deep cleft and is bound by 13 hydrogen bonds: 12 to protein NH and OH donor groups and one to a carboxylate acceptor group. The carboxylate plays a key recognition role by accepting a phosphate hydrogen. PBP phosphate affinity is relatively consistent across a broad pH range, indicating the capacity to bind monobasic (H2PO4-) and dibasic (HPO4(2-)) phosphate; however, the mechanism by which it might accommodate the second hydrogen of monobasic phosphate is unclear. To answer this question, neutron diffraction studies were initiated. Large single crystals with a volume of 8 mm3 were grown and subjected to hydrogen/deuterium exchange. A 2.5 Å resolution data set was collected on the Protein Crystallography Station at the Los Alamos Neutron Science Center. Initial refinement of the neutron data shows significant nuclear density, and refinement is ongoing. This is the first report of a neutron study from this superfamily.