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Wound healing attempts to maintain homeostasis in the wound while minimizing the risk of infection to the tissue by foreign agents, such as opportunistic bacterial pathogens. Biofilms established by these pathogens are a common cause of chronic infections that slow the healing process. Preparation of skin wound healing devices comprised of electrospun proteins associated with skin have been shown to accelerate the healing process relative to conventional wound dressings. In this work, we have developed electrospinning methods to incorporate the antimicrobial ionic liquid/deep eutectic solvent choline geranate (CAGE) into these devices. Integration of CAGE into the dressing material was verified via 1 H nuclear magnetic resonance spectrometry, and the effect on the material property of the resultant devices were assessed using scanning electron microscopy. CAGE-containing devices demonstrate a concentration-dependent inactivation of exogenously applied solutions of both gram-positive and gram-negative pathogens (Enterococcus sp and Pseudomonas aeruginosa, respectively), but maintain their ability to serve as a compatible platform for proliferation of human dermal neonatal fibroblasts.

Choline geranate (also described as Choline And GEranic acid, or CAGE) has been developed as a novel biocompatible antiseptic material capable of penetrating skin and aiding the transdermal delivery of co-administered antibiotics. The antibacterial properties of CAGE were analyzed against 24 and 72 hour old biofilms of 11 clinically isolated ESKAPE pathogens (defined as Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacter sp, respectively), including multidrug resistant (MDR) isolates. CAGE was observed to eradicate in vitro biofilms at concentrations as low as 3.56 mM (0.156% v:v) in as little as 2 hours, which represents both an improved potency and rate of biofilm eradication relative to that reported for most common standard-of-care topical antiseptics in current use. In vitro time-kill studies on 24 hour old Staphylococcus aureus biofilms indicate that CAGE exerts its antibacterial effect upon contact and a 0.1% v:v solution reduced biofilm viability by over three orders of magnitude (a 3log10 reduction) in 15 minutes. Furthermore, disruption of the protective layer of exopolymeric substances in mature biofilms of Staphylococcus aureus by CAGE (0.1% v:v) was observed in 120 minutes. Insight into the mechanism of action of CAGE was provided with molecular modeling studies alongside in vitro antibiofilm assays. The geranate ion and geranic acid components of CAGE are predicted to act in concert to integrate into bacterial membranes, affect membrane thinning and perturb membrane homeostasis. Taken together, our results show that CAGE demonstrates all properties required of an effective topical antiseptic and the data also provides insight into how its observed antibiofilm properties may manifest.

Ionic liquids containing lanthanide halide anions give the opportunity to investigate magnetic behaviour in non-ordered systems. Reported herein is the synthesis and characterization of ionic liquids containing a series of lanthanide halide anions, with the resulting materials displaying unusual behaviour below 50 K. Specifically, the ionic liquid structural glass formation appears to drive magnetic behaviour due to cluster formation of the anions during rapid cooling. This system presents a possible probe to study the dynamics of glass forming materials.

Antiseptic agents are the primary arsenal to disinfect skin and prevent pathogens spreading within the host as well as into the surroundings; however the Food and Drug Administration published a report in 2015 requiring additional validation of nearly all current antiseptic agents before their continued use can be allowed. This vulnerable position calls for urgent identification of novel antiseptic agents. Recently, the ability of a deep eutectic, Choline And Geranate (CAGE), to treat biofilms of Pseudomonas aeruginosa and Salmonella enterica was demonstrated. Here it is reported that CAGE exhibits broad-spectrum antimicrobial activity against a number of drug-resistant bacteria, fungi, and viruses including clinical isolates of Mycobacterium tuberculosis, Staphylococcus aureus, and Candida albicans as well as laboratory strains of Herpes Simplex Virus. Studies in human keratinocytes and mice show that CAGE affords negligible local or systemic toxicity, and an ≈180-14 000-fold improved efficacy/toxicity ratio over currently used antiseptic agents. Further, CAGE penetrates deep into the dermis and treats pathogens located in deep skin layers as confirmed by the ability of CAGE in vivo to treat Propionibacterium acnes infection. In combination, the results clearly demonstrate CAGE holds promise as a transformative platform antiseptic agent for preventive as well as therapeutic applications.

[Ni(HF(2))(3-Clpy)(4)]BF(4) (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN(4)F(2) octahedra that form chains with bridging HF(2)(-) ligands. In spite of significant distortion of the HF(2)(-) bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J(FHF) = 4.86 K.

[Ni(HF2)(pyz)2]X {pyz = pyrazine; X = PF6- (1), SbF6- (2)} were structurally characterized by synchrotron X-ray powder diffraction and found to possess axially compressed NiN4F2 octahedra. At 298 K, 1 is monoclinic (C2/c) with unit cell parameters, a = 9.9481(3), b = 9.9421(3), c = 12.5953(4) angstrom, and beta = 81.610(3) degrees while 2 is tetragonal (P4/nmm) with a = b = 9.9359(3) and c = 6.4471(2) angstrom and is isomorphic with the Cu-analogue. Infinite one-dimensional (1D) Ni-FHF-Ni chains propagate along the c-axis which are linked via mu-pyz bridges in the ab-plane to afford three-dimensional polymeric frameworks with PF6- and SbF6- counterions occupying the interior sites. A major difference between 1 and 2 is that the Ni-F-H bonds are bent (similar to 157 degrees) in 1 but are linear in 2. Ligand field calculations (LFT) based on an angular overlap model (AOM), with comparison to the electronic absorption spectra, indicate greater pi-donation of the HF2- ligand in 1 owing to the bent Ni-F-H bonds. Magnetic susceptibility data for 1 and 2 exhibit broad maxima at 7.4 and 15 K, respectively, and lambda-like peaks in d chi T/dT at 6.2 and 12.2 K that are ascribed to transitions to long-range antiferromagnetic order (TN). Muon-spin relaxation and specific heat studies confirm these TN's. A comparative analysis of chi vs T to various 1D Heisenberg/Ising models suggests moderate antiferromagnetic interactions, with the primary interaction strength determined to be 3.05/3.42 K (1) and 5.65/6.37 K (2). However, high critical fields of 19 and 37.4 T obtained from low temperature pulsed-field magnetization data indicate that a single exchange constant (J(1D)) alone is insufficient to explain the data and that residual terms in the spin Hamiltonian, which could include interchain magnetic couplings (J(perpendicular)), as mediated by Ni-pyz-Ni, and single-ion anisotropy (D), must be considered. While it is difficult to draw absolute conclusions regarding the magnitude (and sign) of J(perpendicular) and D based solely on powder data, further support offered by related Ni(II)-pyz compounds and our LFT and density-functional theory (DFT) results lead us to a consistent quasi-1D magnetic description for 1 and 2.

A new strategy employs amorphous melts of active pharmaceutical agents, which are formed with metal chlorides, including ZnCl2, through speciation ambiguity. The Lewis acidic, bioinorganic ionic liquid formulations improve shelf life and water solubility and eliminate issues related to crystal polymorphism. This broad-ranging approach produces thermally robust chlorometallate preparations for use as lotions, antibiofilm agents, and in situations without refrigeration.

Multiple ionic liquids (ILs) were assessed for their ability to extract branched, unsaturated hydrocarbons from an aqueous medium. In addition, IL cytotoxicity studies were performed on two phototrophic microbes, Synechocystis sp. PCC6803 and Botryococcus braunii var Showa. The optimum IL for use in an isoprenoid hydrocarbon extraction may vary based on the biological source of the isoprenoids. Our results suggest that ionic liquids have the potential to serve as novel biocompatible milking agents for extracting high-value chem- icals from the microbes, with toxicity to both species minimized by considerations of ionic liquid structure and hydrophobicity.

The structural characterization of a new, asymmetric polyoxoanion, Na12H[(W5O18)Tb(H2W11O39)]·42H2O, is reported herein. This new structure was isolated from a mixture of a number of compounds, including the symmetric Na9[Tb(W5O18)2] sandwich cluster, and the lanthanide-free cluster, Na10(H2W12O42). The major product of the reaction was Na9[Tb(W5O18)2], and the compound reported here is a minor product that is obtained reproducibly. The salts of these three clusters do not differ significantly in their crystal habit, size, and color. The crystal structure of Na12H[(W5O18)Tb(H2W11O39)]·42H2O was determined by single-crystal X-ray diffraction and shows that the cluster is composed of a lacunary Lindqvist (W5O18)6− building block and an unusual lacunary metatungstate (H2W11O39)10− polyanion connected through a central Ln3+ cation. The central Tb3+ cation has a square antiprismatic symmetry, the lacunary metatungstate has a square pyramidal symmetry, and the lacunary Lindqvist polyanion exhibits a cuboctahedral symmetry. This is the first example of a crystallographically characterized sandwich cluster possessing a lacunary metatungstate (H2W11O39)10− ligand.

Room temperature ionic liquids, or RTILs, based on tetraalkylphosphonium (PR(4)(+)) cations were used as the basis of a platform that enables separation of dyes from textiles, extraction of dyes from aqueous solution, and identification of the dyes by MALDI-MS in a single experimental step for forensic purposes. Ionic liquids were formed with PR(4)(+) cations and ferulate (FA), α-cyano-4-hydroxycinnamate (CHCA), and 2,5-dihydroxybenzoate (DHB) anions. The use of tetraalkylphosphonium-based ionic liquids in MALDI-MS allowed detection of small molecule dyes without addition of a traditional solid MALDI matrix.

The low melting point, negligible vapor pressure, good solubility, and thermal and chemical stability make ionic liquids useful materials for a wide variety of applications. Polyoxometalates are early transition metal oxygen clusters that can be synthesized in many different sizes and with a variety of heterometals. The most attractive feature of POMs is that their physical properties, in particular electrical, magnetic, and optical properties, can be easily modified following known procedures. It has been shown that POMs can exhibit cooperative properties, as superconductivity and energy transfer. POM ionic liquids can be obtained by selecting the appropliate cation. Different alkyl ammonium and alkyl phosphonium salts are being used to produce new POM ionic liquids together with organic or inorganic luminescent centers to design light emitting materials. Ammonium and phosphonium cations with activated, polymerizable groups are being used to further polymerize the ionic liquid into transparent, solid materials with high metal density.

A room temperature fulleride-based ionic liquid has been developed and characterized. Utilizing the trihexyl (tetradecyl) phosphonium cation, the ionic liquid [PC6C6C6C14]3 [C60]Cl was synthesized, and distinctly shows spectroscopic characteristics of the [C60]2- anion. The glass transition of the ionic liquid occurs well below room temperature at -56 {degree sign} C, but it still retains an extremely high viscosity at room temperature. Attempts were made to obtain the pure fulleride salt [PR4]3[C60], but nearly always results in the binary fulleride-chloride salt.

A novel class of scintillating materials, which are nanocomposites of known scintillators, is described. These nanocomposite materials are expected to have improved properties with respect to the properties of the bulk scintillators from which they are derived. Improvements include enhanced light output, reduced cost and greater size scalability. Optical properties of the nanocomposite phosphor components are described, with emphasis on the origin of the enhanced light yield. Finally, results from our first nanocomposite scintillator, including photopeak measurements, are described. The photopeak measurements demonstrate the proof-of-principle of the nanocomposite scintillator concept.

The Raman and infrared spectra of a series of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids ([C2-4MIM][BF4]) are reported and analyzed using Density Functional Theory (DFT) and RHF methods at the 6-311+G(2d,p) computational level. The B3LYP (DFT) and RHF calculations reproduce the vibrational spectra of 1-ethyl-3-methyl imidazolium tetrafluoroborate [EMIM][BF4], 1-propyl-3-methyl imidazolium tetrafluoroborate [PMIM][BF4] and 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF4] using correction factors of 0.963–0.967 (DFT) and 0.913–0.916 (RHF) with correlation coefficients R2 of 0.999 using the fully optimized structures. Theoretical (DFT) alkyl side chain conformational changes in the 1-alkyl-3-methyl tetrafluoroborate ionic liquids have only a limited effect on the theoretical gas phase vibrations. The gas phase molecular structures of the [C2–4MIM][BF4] ion pairs suggest hydrogen bonding interactions between the fluorine atoms of the BF4− anion and the C2 hydrogen on the imidazolium ring. Additional interactions are observed between [BF4] and H atoms on the adjacent alkyl side chains in all polymorphic structures.

Ionic liquids are salts that are liquid at or near room temperature. Their wide liquid range, good thermal stability, and very low vapor pressure make them attractive for numerous applications. The general approach to creating ionic liquids is to employ a large, unreactive, low symmetry cation with and an anion that largely controls the physical and chemical properties. The most common cations used in ionic liquids are N-alkylpyridinium and N,N′-dialkylimidazolium. Another very effective cation for the creation of ionic liquids is tetraalkylphosphonium, [PR1R2R3R4]+. The alkyl groups, Rn, generally are large and not all the same. The halide salts of several phosphonium cations are available as starting materials for metathesis reactions used to prepare ionic liquids. The large phosphonium cations can combine with relatively large anions to make viscous but free flowing liquids with formula mass greater than 1000 g mol−1. Some other more massive salts are waxes and glasses. The synthesis and the physical, chemical, and optical properties of phosphonium-ionic liquids having anions with a wide range of masses were measured and are reported here.

The crystal structures and magnetic properties of the nitronyl nitroxide radicals 4,5-dihydro-4,4,5,5-tetramethyl-3-oxido(1H-imidazol-1-yloxyl) (1), 4,5-dihydro-2,4,4,5,5-pentamethyl-3-oxido(1H-imidazol-1-yloxyl) (2), 2-(4-chlorophenyl)-4,5-dihydro-4,4,5,5-tetramethyl-3-oxido(1H-imidazol-1-yloxyl) (3), and 4,5-dihydro-2-(2-hydroxy-5-nitrophenyl)-4,4,5,5-tetramethyl-3-oxido(1H-imidazol-1-yloxyl) (4) are reported. Compound 1 has two polymorphic forms: the α phase is monoclinic (P21/n space group), with a single molecule in the asymmetric unit, and the β phase is monoclinic (P21/c space group), with four molecules in the asymmetric unit. In the two polymorphs, the molecules are arranged in dimers formed by hydrogen bonds of the type CH⋅⋅⋅ON. The crystal structure of 3 contains layers of antiparallel ribbons of molecules. Compound 4 crystallizes with solvent molecules, and an intramolecular hydrogen bond is formed between the 2-OH group of the phenyl ring and the nitroxide O-atom. Compound 4 also loses the two O-atoms of the nitroxide moiety upon heating to 90°. Magnetic measurements showed that both α and β polymorphs of 1 exhibit antiferromagnetic coupling. The best fit to the experimental data was obtained using BleanyBower's singlet-triplet model (H=−2JSaSb): J=−11.2 K for the α phase and J=−15.0 K for the β phase. Compounds 3 and 4 show no evidence for spin coupling.

Three groups of singlet ground state [TCNE](2) (2-) (TCNE=tetracyanoethylene) dimers with characteristic intradimer CC separations (r) and dihedral angles (d) [i.e., group S(t) (r approximately 1.6 A; d=180 degrees ), L(t) (r approximately 3.5 A; d=180 degrees ), and L(c) (r approximately 2.9 A; d= approximately 0 degrees ); notation: S/L: short/long bond length; subscript t/c: trans/cis, respectively] are experimentally characterized. The S(t) group is comprised of sigma-dimers of [TCNE](.-) and octacyanobutanediide, [C(4)(CN)(8)](2-), which have a typical, albeit long, sp(3)-sp(3) sigma bond (r approximately 1.6 A) between each [TCNE](.-) moiety and characteristic nu(CN), nu(CC), and delta(CCN) IR absorptions. The L groups are structurally characterized as pi-dimers of [TCNE](.-) that are either eclipsed with r approximately 2.9 A (L(c)) and the nitriles bend away from the nominal TCNE plane away from the center of the dimer by 5.0 degrees (approximately sp(2.17)) or are noneclipsed with r approximately 3.5 A (L(t)) and the nitriles bend toward the center of the dimer by 1.9 degrees ( approximately sp(2.06)). Ab initio computations on isolated dimers were used to study the formation and stability of these exceptionally long CC (> or =2.9 A) bonding interactions as well as the process of pi-[TCNE](2) (2-) dimer formation for the L(c) and L(t) groups. The results of these computational studies show that the ground-state potential curve is that of a closed-shell/open-shell singlet, depending on the distance. The short S(t) group (r approximately 1.6 A) of dimers in this surface are true minimum-energy structures; however, the L(t) and L(c) groups are unstable, although two different nonphysical minima are found when imposing a double occupancy of the orbitals. These minima are metastable relative to dissociation into the isolated [TCNE](.-) units. Consequently, the existence of dimer dianions in crystals is due to cation.[TCNE](-) interactions, which provide the electrostatic stabilization necessary to overcome the intradimer electrostatic repulsion. This cation-mediated pi*-pi* [TCNE](-).[TCNE](-) interaction complies with Pauling's definition of a chemical bond. This bonding interaction involves the pi* orbitals of each fragment, and arise from the overlap of the b(2g) SOMO on each of the two [TCNE](.-)s to form a filled b(2u) [TCNE](2) (2-) orbital. Although a pi dimer typically forms, if the fragments are close enough a sigma dimer can form. Due to the presence of cation-mediated intradimer CC bonding interactions the L(c) group of pi-[TCNE](2) (2-) dimers exhibits experimentally observable nu(CN) IR absorptions at 2191+/-2 (m), 2173+/-3 (s), and 2162+/-3 cm(-1) (s) and nu(CC) at 1364+/-3 cm(-1) (s) as well as a new UV-Vis feature in the range of 15 000 to 18 200 cm(-1) (549 to 667 nm) and averaging 16 825+/-1180 cm(-1) (594 nm) assigned to the predicted new intradimer (1)A(1g) --> (1)B(1u) transition and is purple on reflected light. Upon cooling to 77 K in 2-methyl tetrahydrofuran, this new band occurs at 18 940 cm(-1) (528 nm) for [[Et(4)N](+)](2)[TCNE](2) (2-), and the yellow solution turns deep red. Group L(t) is characterized by nu(CN) absorptions at 2215+/-2, 2197+/-3, and 2180+/-4 cm(-1) and nu(CC) at 1209+/-9 cm(-1) (w), while group S(T) has nu(CN) bands at 2215+/-4, 2157+/-3, and 2107+/-4 cm(-1) and nu(CC) at 1385+/-1 cm(-1) (vs).

By using the tripodal tetradentate ligand tris(2-benzimidazolylmethyl)amine (H(3)ntb), which can have several charge states depending on the number of secondary amine protons, mononuclear octahedral and dinuclear trigonal bipyramidal Fe(III) complexes were prepared. The reaction of mononuclear octahedral [Fe(III)(H(3)ntb)Cl(2)]ClO(4), 1, with 3 equiv of sec-butylamine in methanol led to the formation of mononuclear cis-dimethoxo octahedral Fe(III)(H(2)ntb)(OMe)(2), 2. One equivalent of the sec-butylamine was used to generate the monoanionic H(2)ntb(-) ligand where one of the three amines in the benzimidazolyl groups was deprotonated. The remaining 2 equiv were used to generate two methoxides that were coordinated to the octahedral Fe(III) ion in a cis fashion as demonstrated by the chlorides in 1. Reaction of 1 with excess (7 equiv) sec-butylamine generated the doubly deprotonated dianionic Hntb(2-) that stabilized the dinuclear mu-oxo Fe(III)(2)O(Hntb)(2), 3, adopting a five-coordinate trigonal bipyramidal geometry. The magnetic data for 3 are consistent with the antiferromagnetically coupled Fe(III) (S = 5/2) sites with the coupling constant J = -127 cm(-1).

Reaction of 2,4,6-tricyano-s-triazine (TCT) with tetrathiafulvalene (TTF) and N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) leads to 1∶1 charge transfer complexes. The crystal structures of the TTF[TCT], as well as the decomposition product due to hydrolysis of the [TMPD][TCT], i.e. [HTMPD]+[2,4-dicyano-6-oxy-s-triazine]−, are reported and spectroscopically characterized.

Many of the Cm[TCNE]n (C = cation) salts have intradimer C–C interactions in the range of 2.9 to 3.5 A and show the electronic fingerprints associated with C–C bond formation (IR and UV spectra, magnetic properties, structural changes), despite the fact that two [TCNE]˙− anions should repel each other due to purely Coulombic considerations. Herein, we analyze these pairwise interactions in detail for a particular crystal in which such a C–C bond is found, to understand when and why these bonds are formed in a general case.

Biofilm-protected microbial infections in skin are a serious health risk that remains to be adequately addressed. The lack of progress in developing effective treatment strategies is largely due to the transport barriers posed by the stratum corneum of the skin and the biofilm. In this work, we report on the use of Ionic Liquids (ILs) for biofilm disruption and enhanced antibiotic delivery across skin layers. We outline the syntheses of ILs, analysis of relevant physicochemical properties, and subsequent neutralization effects on two biofilm-forming pathogens: Pseudomonas aeruginosa and Salmonella enterica. Further, the ILs were also examined for cytotoxicity, skin irritation, delivery of antibiotics through the skin, and treatment of biofilms in a wound model. Of the materials examined, choline-geranate emerged as a multipurpose IL with excellent antimicrobial activity, minimal toxicity to epithelial cells as well as skin, and effective permeation enhancement for drug delivery. Specifically, choline-geranate was comparable with, or more effective than, bleach treatment against established biofilms of S. enterica and P. aeruginosa, respectively. In addition, choline-geranate increased delivery of cefadroxil, an antibiotic, by >16-fold into the deep tissue layers of the skin without inducing skin irritation. The in vivo efficacy of choline-geranate was validated using a biofilm-infected wound model (>95% bacterial death after 2-h treatment). This work establishes the use of ILs for simultaneous enhancement of topical drug delivery and antibiotic activity.

Copper(II) carboxylates have been synthesized to develop a magnetostructure function relationship. The pseudopolymorphs Cu 2a (OH 2 ) 2 ·H 2 O and Cu 2a (OH 2 ) 2 ( 2a =1 ,4-benzenedicarboxylate (terephthalate)) form 1-D ( θ =−7.2 K; J / k B =−9.15 K ( H=−2J S 1 · S 2 )) and 2-D layers with ferromagnetic coupling ( θ =+0.8 K), respectively. In contrast, formation of isolated dimers of (Cu 2 (O 2 CMe)( 3 ) 3 (EtOH) 2 ) ( 3 =2 -(4′-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl) enables the coupling of S= 1 2 spins on the nitroxides to the S =1 excited state of the copper(II) dimer. This coupling of −157 K is two orders of magnitude greater than the S= 1 2 nitroxide–nitroxide coupling of −1.5 K.

Attractive interaction with the cation overcomes the electrostatic repulsion between two tetracyanoethylene radical anions, [TCNE].- , and leads to the formation of a diamagnetic dimer [TCNE]22- , for example, in [K(glyme)]2 [TCNE]2 . The bonding is described as two-electron, four-center bonding arising from π*-π* overlap. Crystallographic as well as spectroscopic (IR and UV/Vis) features of this bonding are observed.

Ionic liquids, with their vast applications, have been touted as being thermally stable to very high temperatures. However, decomposition not detected by standard TGA and NMR techniques are observed with spectroscopic techniques sensitive enough to see small amounts of impurities. Decomposition temperatures of common ionic liquids appear to occur at hundreds of degrees below those temperatures previously reported.

A series of ionic liquids containing different paramagnetic anions have been prepared and all show paramagnetic behavior with potential applications for magnetic and electrochromic switching as well as novel magnetic transport; also, the tetraalkylphosphonium-based ionic liquids reveal anomalous magnetic behavior.

A tetragonal polymorph of [Ni(HF(2))(pyz)(2)]PF(6) (designated β) is isomorphic to its SbF(6)-congener at 295 K and features linear Ni-FHF-Ni pillars. Enhancements in the spin exchange (J(FHF) = 7.7 K), Néel temperature (T(N) = 7 K), and critical field (B(c) = 24 T) were found relative to monoclinic α-PF(6). DFT reveals that the HF(2)(-) bridges are significantly better mediators of magnetic exchange than pyz (J(pyz)), where J(FHF) ≈ 3J(pyz), thus leading to quasi-1D behavior. Spin density resides on all atoms of the HF(2)(-) bridge whereas N-donor atoms of the pyz ring bear most of the density.

The promotion for hydrogen release from ammonia–borane (AB) was observed in the presence of ZIF-8. Even at concentrations of ZIF-8 as low as 0.25 mol %, a reduction of the onset temperature for dehydrogenation accompanies an increase in both the rate and amount of hydrogen released from AB.

Reduction of tetracyanoethylene, TCNE, with tetrakis(n-propyl)ammonium iodide, [Pr4N]I, results in a new example of long π*-CC bonded π-[TCNE]22− dimers with a 2.870(4) A intradimer CC bond, which is structurally and spectroscopically characterized. This reaction also results in isolation of [Pr4N]2[TCNE][I3] possessing isolated [TCNE]˙− radical anions.

Neutron flux from linear accelerators is conventionally monitored using ionization chambers containing one or more foils thinly coated with a fissionable or fissile material. Due to the long pulse rise times resulting from the ionization mechanism, fission chambers are prone to pulse pile-up in high-neutron-flux environments. In addition, their relatively low efficiencies result in extremely long counting times in low-flux environments. To ameliorate these effects, a novel type of neutron flux monitor, consisting of fissionable material loaded in a liquid scintillator, has been developed, characterized, and tested in the beam line at the Los Alamos Neutron Science Center. This is a rugged, cost-efficient detector with high efficiency, a short signal rise time, and the ability to be used in low neutron-flux environments. Compared with a conventional fission chamber, the fissionable scintillator displays a significantly higher event rate. Related research on nanocomposite scintillators for gamma-ray detection suggests the possibility of extending this approach by synthesizing fissionable material nanoparticles and loading them into an organic scintillator. We will present results of the design and characterization process and an analysis of the results of the beam line experiments.

The reaction of [Et4N]I and tetracyanoethylene (TCNE) forms [Et4N]2[TCNE]2, which possesses [TCNE]22− with a 2.827(3) A intradimer CC bond distance and exhibits νCN at 2191, 2170 and 2163 cm−1, νCC at 1365 cm−1, and UV-Vis bands at 26 150 and 16 850 cm−1.

Herein we describe the unique luminescent behavior observed in [CeIV(W5O18)2]8− clusters and examine the photophysical properties using density functional theory.

Nanocomposite scintillators consist of nanoparticles of an inorganic scintillator dispersed in a matrix material. This technique is particularly well suited for applications requiring large or unusually shaped detectors, since these can be fabricated without requiring the growth of large crystals and using an inexpensive matrix. Nanocomposite scintillators may additionally make it possible to use scintillating materials not currently available in large sizes and quantities. Los Alamos National Laboratory is currently conducting a large nanocomposite scintillator development program. Several potential scintillator materials have been identified. We have successfully fabricated nanoparticles, for example CeF 3 , with sizes ≪ 10 nm and dispersed them in an optimized liquid scintillator solution and in several polymers. We have measured their size, structure, and radiation detection characteristics and have found good agreement between their scattering behavior and a Rayleigh scattering model. Current research results will be presented.

Molecular orbital calculations indicate that molecules with a high electron density diffused over a large volume will have third order nonlinear optical activity. Anions often have higher second hyperpolarizability values(gamma) than similar neutral molecules. Also, molecules or ions containing higher row elements have higher gammas. Salts with cations that have their positive charge only weakly interacting with the anion also enhance the third order nonlinear optical activity. That looks like the recipe for ionic liquids. A number of sulfur-containing mono- and dianion salts were synthesized and characterized through Z-scan measurements. Most were ionic liquids, and some showed significant third order nonlinear optical behavior. The general features of ionic liquids such as wide liquidus range, good thermal stability, and low vapor pressure are particularly advantageous for applications of nonlinear optical materials. Potential applications are in optical limiting and other all-optical devices.

An intriguing and novel charge-transfer complex between dimethyldihydrophenazine and diethylviologen has been crystallized from an ionic liquid at room temperature, resulting in an interesting stacking motif of interrupted D***A***D type triads: efficient formation of the complex is seen within an ionic liquid and acetone, with the complex absorbing strongly across nearly the entire visible-NIR spectral region.

The ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) and 1-methyl-3-propylimidazolium tetrafluoroborate ([PMIM][BF4]) were studied by H,H-NOESY NMR using a cross-relaxation matrix analysis. Cross-peak intensities are seen to increase with increasing mixing time. Experimental and theoretical hydrogen–hydrogen distances are in agreement at short mixing times (50 ms). Mixing times longer than 50 ms result in an increasing contribution of spin diffusion that produces unrealistically short hydrogen–hydrogen distances. Gas-phase ab initio molecular structures are obtained using Hartree–Fock (HF) and density functional theory (B3LYP) methods at the 6311 + G(2d,p) basis set level. The hydrogen–hydrogen distances obtained from the theoretical structures are in reasonable agreement with those calculated from the cross-relaxation matrices. Published in 2003 by John Wiley & Sons, Ltd.

A number of dithioacetate and dithiolate mono- and dianions have been synthesized and characterized through Z-scan measurements, with some showing significant third order nonlinear optical (NLO) behavior. Tetralkylphosphonium cations were utilized in tandem with the nonlinear anions so as to minimize electrostatic interactions within the salt, consequently resulting in the materials being room temperature ionic liquids (RTILs), which have numerous advantages over typical organic-based materials. Anions composed of metal-ligand systems were also tested for NLO behavior as components of novel ionic liquid materials. These RTILs introduce a new class of materials with potential applications in optical limiting and other all-optical devices.

Chemical reduction of 2,4,6-tricyano-1,3,5-triazine, TCT, results in the formation of an unstable radical anion that undergoes immediate dimerization at a ring carbon to form [C(12)N(12)](2-), [TCT](2)(2-), characterized by a long 1.570 (4) A central C[bond]C. [TCT](2)(2-) can decompose into the radical anion of 4,4',6,6'-tetracyano-2,2'-bitriazine, [TCBT]*-, the one-electron reduced form of planar (D(2h)) TCBT, which is also structurally characterized as the [TMPD][TCBT] charge-transfer complex (TMPD = N,N,N',N'-tetramethyl-p-phenylenediamine) with a 1.492 (2) A central sp(2)[bond]sp(2) C[bond]C. Although crystals could not be obtained for the radical anion [TCBT]*-, the electrochemistry (E degrees = +0.03 V), EPR (g = 2.003, (2)A((14)N) = 3.347 G, and (4)A((14)N) = 0.765 G and a line width of 0.24 G), and theoretical calculations support the formation of [TCBT]*-. In addition, thermolysis of [TCT](2)(2-) yields [TCBT]*-. Chemical reduction of 2,4,6-tricyanobenzene, TCB, forms an unstable radical anion that immediately undergoes dimerization at a ring carbon to form [C(12)H(6)N(6)](2-), [TCB](2)(2-), which has a long 1.560 (5) A central C[bond]C. Reaction of TCT with tetrathiafulvalene (TTF) forms structurally characterized [TTF][TCT], and in the presence of water, TCT hydrolyzes to 2,4-dicyano-6-hydroxy-s-triazine, DCTOH. In contrast, the reaction of TCT with TMPD forms [TMPD][TCT], which in the presence of water forms structurally characterized [HTMPD](+)[DCTO](-).

Three groups of singlet ground state [TCNE](2) (2-) (TCNE=tetracyanoethylene) dimers with characteristic intradimer CC separations (r) and dihedral angles (d) [i.e., group S(t) (r approximately 1.6 A; d=180 degrees ), L(t) (r approximately 3.5 A; d=180 degrees ), and L(c) (r approximately 2.9 A; d= approximately 0 degrees ); notation: S/L: short/long bond length; subscript t/c: trans/cis, respectively] are experimentally characterized. The S(t) group is comprised of sigma-dimers of [TCNE](.-) and octacyanobutanediide, [C(4)(CN)(8)](2-), which have a typical, albeit long, sp(3)-sp(3) sigma bond (r approximately 1.6 A) between each [TCNE](.-) moiety and characteristic nu(CN), nu(CC), and delta(CCN) IR absorptions. The L groups are structurally characterized as pi-dimers of [TCNE](.-) that are either eclipsed with r approximately 2.9 A (L(c)) and the nitriles bend away from the nominal TCNE plane away from the center of the dimer by 5.0 degrees (approximately sp(2.17)) or are noneclipsed with r approximately 3.5 A (L(t)) and the nitriles bend toward the center of the dimer by 1.9 degrees ( approximately sp(2.06)). Ab initio computations on isolated dimers were used to study the formation and stability of these exceptionally long CC (or =2.9 A) bonding interactions as well as the process of pi-[TCNE](2) (2-) dimer formation for the L(c) and L(t) groups. The results of these computational studies show that the ground-state potential curve is that of a closed-shell/open-shell singlet, depending on the distance. The short S(t) group (r approximately 1.6 A) of dimers in this surface are true minimum-energy structures; however, the L(t) and L(c) groups are unstable, although two different nonphysical minima are found when imposing a double occupancy of the orbitals. These minima are metastable relative to dissociation into the isolated [TCNE](.-) units. Consequently, the existence of dimer dianions in crystals is due to cation.[TCNE](-) interactions, which provide the electrostatic stabilization necessary to overcome the intradimer electrostatic repulsion. This cation-mediated pi*-pi* [TCNE](-).[TCNE](-) interaction complies with Pauling's definition of a chemical bond. This bonding interaction involves the pi* orbitals of each fragment, and arise from the overlap of the b(2g) SOMO on each of the two [TCNE](.-)s to form a filled b(2u) [TCNE](2) (2-) orbital. Although a pi dimer typically forms, if the fragments are close enough a sigma dimer can form. Due to the presence of cation-mediated intradimer CC bonding interactions the L(c) group of pi-[TCNE](2) (2-) dimers exhibits experimentally observable nu(CN) IR absorptions at 2191+/-2 (m), 2173+/-3 (s), and 2162+/-3 cm(-1) (s) and nu(CC) at 1364+/-3 cm(-1) (s) as well as a new UV-Vis feature in the range of 15 000 to 18 200 cm(-1) (549 to 667 nm) and averaging 16 825+/-1180 cm(-1) (594 nm) assigned to the predicted new intradimer (1)A(1g) --(1)B(1u) transition and is purple on reflected light. Upon cooling to 77 K in 2-methyl tetrahydrofuran, this new band occurs at 18 940 cm(-1) (528 nm) for [[Et(4)N](+)](2)[TCNE](2) (2-), and the yellow solution turns deep red. Group L(t) is characterized by nu(CN) absorptions at 2215+/-2, 2197+/-3, and 2180+/-4 cm(-1) and nu(CC) at 1209+/-9 cm(-1) (w), while group S(T) has nu(CN) bands at 2215+/-4, 2157+/-3, and 2107+/-4 cm(-1) and nu(CC) at 1385+/-1 cm(-1) (vs).

We report the supramolecular chemistry of several metal complexes of N-(4-pyridyl)benzamide (NPBA) with the general formula [Ma(NPBA)2AbSc], where M = Co2+, Ni2+, Zn2+, Mn2+, Cu2+, Ag+; A = NO3-, OAc-; S = MeOH, H2O; a = 0, 1, 2; b = 0, 1, 2, 4; and c = 0, 2. NPBA contains structural features that can engage in three modes of intermolecular interactions: (1) metal-ligand coordination, (2) hydrogen bonding, and (3) pi-pi stacking. NPBA forms one-dimensional (1-D) chains governed by hydrogen bonding, but when reacted with metal ions, it generates a wide variety of supramolecular scaffolds that control the arrangement of periodic nanostructures and form 1- (2-4), 2- (5), or 3-D (6-10) solid-state networks of hydrogen bonding and pi-pi stacking interactions in the crystal. Isostructural 7-9 exhibit a 2-D hydrogen bonding network that promotes topotaxial growth of single crystals of their isostructural family and generates crystal composites with two (11) and three (12) different components. Furthermore, 7-9 can also form crystalline solid solutions (M,M')(NPBA)2(NO3)2(MeOH)2 (M, M' = Co2+, Ni2+, or Zn2+, 13-16), where mixtures of Co2+, Ni2+, and Zn2+ share the same crystal lattice in different proportions to allow the formation of materials with modulated magnetic moments. Finally, we report the effects that multidimensional noncovalent networks exert on the magnetic moments between 2 and 300 K of 1-D (4), 2-D (5), and 3-D (7, 8, 10, and 13-16) paramagnetic networks.

Attractive interaction with the cation overcomes the electrostatic repulsion between two tetracyanoethylene radical anions, [TCNE]

Transparent nanocomposites have been developed which consist of nanocrystals embedded in an organic matrix. The materials are comprised of up to 60% by volume of 7–13 nm crystals of the phosphor CexLa1−xF3, and are greater than 70% transparent in the visible region at a thickness of 1 cm. Consistencies of the nanocomposites range from a solid polymer to a wax to a liquid, depending on the workup conditions of the nanoparticle synthesis. These transparent nanophosphor composite materials have potential applications in radiation detection as scintillators, as well as in other areas such as imaging and lighting, and can be produced on large scales up to near-kilogram quantities at near ambient conditions, much lower in temperature than typical nanoparticle syntheses.

Reduction of 2,4,6-tricyano-1,3,5-triazine (1) and 1,3,5-tricyanobenzene (2) leads to dianionic dimers with long, ∼1.57 A, central C–C bonds. In contrast to 1, which dimerizes at the nitrile substituted carbon, 2 has a different motif as it dimerizes at the hydrogen substituted carbon.

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Ionic liquids are being employed in almost all areas of chemistry and materials, yet there are inherent issues which arise if the utmost care is not taken in the preparation and purification of these materials. They are not easily synthesized and purified using the existing methods. We describe a reliable method for producing large quantities of high quality ionic liquids. Additionally, we show that imidazoliums are not ‘special’ due to their ‘inherently fluorescent’ nature, that spectroscopically clean imidazoliums are attainable, and most classes of ionic liquids do exhibit fluorescent backgrounds when extreme care is not taken during their synthesis and purification.