Dicyanamide Anion Research Articles

Cationic effect on properties related to thermal stability and ignition delay for hypergolic ionic liquids

Hypergolic ionic liquids (HILs) are considered as a promising alternative of toxic hydrazine derivatives in the field of liquid bipropellants. The anionic structure plays an important role in determining the hypergolic performance of HILs. Nevertheless, the structure–activity relationship between the cationic structure and ignition properties is still unclear. In this study, the aromaticity, electrostatic potentials (ESPs), natural bond orbital (NBO) analysis, and molecular orbital gap of 25 ionic liquids based on dicyanamide anion were studied to gain more insight into the correlation between cationic structure and hypergolic properties. For the HILs based on the same type of cation with different substituents, better aromaticity leads to better thermal stability of HILs. For the HILs with different types of cations, when the ESPs distribution is relatively concentrated around a certain value, the thermal stability of HILs is relatively higher. The second-order perturbation energy (E(2)) would be responsible for ignition delay (ID) time. The larger the E(2), the more stable the system, and the longer the ID time of HILs. It is also proved for the first time that the energy gap between the HOMO of cations and LUMO of HNO3 could not be used as a method to determine whether this cation-based IL is hypergolic. All these results can be fully justified with experimental data and have important theoretical instructive significance in the design of new high-performance HILs.

New Energetic Complexes as Catalysts for Ammonium Perchlorate Thermal Decomposition

Main observation and conclusionIn this study, four new energetic complexes (1) [Cu(vimi)4]DCA2, (2) [Co(vimi)4]DCA2, (3) [Ni(vimi)4]DCA2, and (4) [Cu(vimi)4]CBH2 (vimi: 1‐vinylimidazole, DCA: dicyanamide anion, CBH: cyanoborohydride anion) were prepared, and their structures were characterized via single‐crystal X‐ray diffraction, elemental analysis, and Fourier‐transform infrared spectroscopy. The catalytic effects of the complexes on ammonium perchlorate thermal decomposition were studied via thermal analysis methods, including differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Among the complexes, complex 2 showed the best catalytic performance. The two decomposition peaks in the DSC curve of the pure ammonium perchlorate—low‐temperature decomposition (LTD) peak: 295 °C and high‐temperature decomposition (HTD) peak: 418 °C—were merged into a lower decomposition peak (325 °C) in the curve of AP with complex 2. Moreover, the heat released by ammonium perchlorate with complex 2 (1661.7 J g−1) was significantly higher than that released by the pure ammonium perchlorate (814.5 J g−1). The kinetic parameters calculated using Kissinger's method revealed that the complexes had a significant effect on the activation energy of ammonium perchlorate decomposition (223.5 kJ mol−1), and complex 2 lowered the activation energy to 115.6 kJ mol−1. The results indicate that complex 2 is a potential energetic additive for ammonium perchlorate‐based solid propellants.

Ultrasonic-Assisted Technique as a Novel Method for Removal of Naphthenic Acid from Model Oil Using Piperidinium-Based Ionic Liquids.

In this study, piperidinium-based ionic liquids (IL) containing trifluoromethanesulfonate, phenolate, and dicyanamide anions were synthesized. Using the ILs, extraction of naphthenic acid from highly acidic oil with a total acid number (TAN) of 1.44 was studied. Two agitation techniques have been implemented for the extraction process, which were mechanical stirring and ultrasonic-assisted irradiation. 1-Butyl-1-methylpiperidinium phenolate [BMPi][Phe] showed the best potential in extracting naphthenic acid from oil, with complete removal of naphthenic acid with IL-to-oil ratios of 0.010 and 0.0025 for the mechanical stirring method and the ultrasonic-assisted method, respectively. Ultrasonic-assisted extraction process shows very good potential in enhancing the extraction efficiency of naphthenic acid. Optimization and study on the effects of ultrasonic parameters, namely, IL-to-oil ratio, ultrasonic amplitude, and time, were studied through response surface methodology (RSM). Using [BMPi][Phe], the optimum conditions obtained are IL-to-oil ratio of 0.03, 53.91% of amplitude, and 4.29 min of extraction time. Under these optimum conditions, 100% removal of naphthenic acid was achieved.

Hypergolic ionic mixtures with task-specific ions: A new strategy to improve performances of ionic liquids as propellant fuels

Task-specific dicyanamide anion ([DCA]−), cyanoborohydride anion ([CBH]−) and 1-ethyl or 1-allyl-3-methylimidazolium cations ([EMIM]+ or [AMIM]+) were mixed in different ratios to form hypergolic ionic mixtures. Their viscosities, densities, decomposition temperatures, specific impulses were determined and calculated. Ignition delay time was obtained by a drop test recorded by a high-speed camera. Theoretical calculations and molecular dynamics simulations were applied for exploring their energy and microstructure. The results indicated that ionic nature and ionic ratio in mixtures were two decisive factors for properties of ionic mixtures. Specially, mixture [EMIM][CBH]0.7[DCA]0.3 possessed the shortest ignition delay time of 3 ms with white fuming nitric acid (WFNA) as oxidizer, which was shorter than that of pure ionic liquid [EMIM][DCA] (32 ms) or [EMIM][CBH] (8 ms). However, with a reverse ratio of anions, mixture [EMIM][CBH]0.3[DCA]0.7 possessed a very long ignition delay time of 373 ms and showed a different phenomenon in ignition process. Thermogravimetric analysis indicated that mixture [EMIM][CBH]0.7[DCA]0.3 decomposed faster than mixture [EMIM][CBH]0.3[DCA]0.7. The radial distribution functions (RDFs) suggested that the H-bond interactions in mixtures obviously were influenced by ionic ratios. As a new design strategy, hypergolic ionic mixtures can not only combine properties of different ions, but also show more prominent performances in a specific ionic ratio than each parent ionic liquid.

Enhancing Artemisinin Solubility in Aqueous Solutions: Searching for Hydrotropes based on Ionic Liquids

Artemisinin is a sesquiterpenoid lactone peroxide, known for its potent antimalarial activity that can be extracted from Artemisia annua L. This compound is only sparingly soluble in water, making its extraction using environmental-friendly and non-toxic aqueous solvents difficult. In the attempt to overcome this limitation, hydrotropes, which are a class of compounds that can assist in increasing the solubility of hydrophobic solutes in water, were investigated in this work. In particular, the hydrotropic capability of ionic liquids (ILs) on the aqueous solubility of artemisinin was studied. The effects of IL concentration and anion nature of 1-butyl-3-methylimidazolium-based ILs on the solubility of artemisinin at 303.2 K in water were evaluated. It is here shown the excellent capacity of ILs containing thiocyanate or dicyanamide anions to enhance the solubility of artemisinin in aqueous media, with a magnitude comparable to that obtained with the best organic solvents. Furthermore, solvatochromic parameters of the ILs aqueous solutions were also measured and combined with COSMO-RS and the cooperative hydrotropy model to establish relations between the artemisinin solubility enhancement and the solvent characteristics. The solubility enhancement of artemisinin is favored by the apolarity of the medium and the lower hydrogen-bond acceptor character of the hydrotrope.

Syntheses, structures and magnetic properties of two isostructural dicyanamide-bridged 2D polymers

Complexes [Co(biq)(μ1,5-dca)2]n (1) and [Ni(biq)(μ1,5-dca)2]n (2) (biq is 2,2′-biquinoline, dca is dicyanamide anion, N(CN)2−) have been characterized by crystal structure analysis, and spectral and magnetic measurements.

Molecular Dynamics Simulations, Reaction Pathway and Mechanism Dissection, and Kinetics Modeling of the Nitric Acid Oxidation of Dicyanamide and Dicyanoborohydride Anions.

Direct dynamics simulations of HNO3 with dicyanamide anion DCA- (i.e., N(CN)2-) and dicyanoborohydride anion DCBH- (i.e., BH2(CN)2-) were performed at the B3LYP/6-31+G(d) level of theory in an attempt to elucidate the primary and secondary reactions in the two reaction systems. Guided by trajectory results, reaction coordinates and potential energy diagrams were mapped out for the oxidation of DCA- and DCBH- by one and two HNO3 molecules, respectively, in the gas-phase and in the condensed-phase ionic liquids using the B3LYP/6-311++G(d,p) method. The oxidation of DCA- by HNO3 is initiated by proton transfer. The most important pathway leads to the formation of O2N-NHC(O)NCN-, and the latter reacts with a second HNO3 to produce O2N-NHC(O)NC(O)NH-NO2-(DNB-). The oxidation of DCBH- by HNO3 may follow a similar mechanism as that of DCA-, producing two analogue products: O2N-NHC(O)BH2CN- and O2N-NHC(O)BH2C(O)NH-NO2-. Moreover, two new, unique reaction pathways were discovered for DCBH- because of its boron-hydride group: (1) isomerization of DCBH- to CNBH2CN- and CNBH2NC- and (2) H2 elimination in which the proton in HNO3 combines with a hydride-H in DCBH-. The Rice-Ramsperger-Kassel-Marcus (RRKM) theory was utilized to calculate reaction kinetics and product branching ratios. The RRKM results indicate that the formation of DNB- is exclusively important in the oxidation of DCA-, whereas the same type of reaction is a minor channel in the oxidation of DCBH-. In the latter case, H2 elimination becomes dominating. The RRKM modeling also indicates that the oxidation rate constant of DCBH- is higher than that of DCA- by an order of magnitude. This rationalizes the enhanced preignition performance of DCBH- over DCA- with HNO3.

Imidazolium-Based Ionic Liquids as Clay Swelling Inhibitors: Mechanism, Performance Evaluation, and Effect of Different Anions.

Clay swelling is one of the challenges faced by the oil industry. Water-based drilling fluids (WBDF) are commonly used in drilling operations. The selection of WBDF depends on its performance to improve rheology, hydration properties, and fluid loss control. However, WBDF may result in clay swelling in shale formations during drilling. In this work, the impact of imidazolium-based ionic liquids on the clay swelling was investigated. The studied ionic liquids have a common cation group, 1-allyl-3-methyllimidozium, but differ in anions (bromide, iodide, chloride, and dicyanamide). The inhibition behavior of ionic liquids was assessed by linear swell test, inhibition test, capillary suction test, rheology, filtration, contact angle measurement, scanning electron microscopy, and X-ray diffraction (XRD). It was observed that the ionic liquids with different anions reduced the clay swelling. Ionic liquids having a dicyanamide anion showed slightly better swelling inhibition performance compared to other inhibitors. Scanning electron microscopy images showed the water tendency to damage the clay structure, displaying asymmetrical cavities and sharp edges. Nevertheless, the addition of an ionic liquid to sodium bentonite (clay) exhibited fewer cavities and a smooth and dense surface. XRD results showed the increase in d-spacing, demonstrating the intercalation of ionic liquids in interlayers of clay. The results showed that the clay swelling does not strongly depend on the type of anion in imidazolium-based ILs. However, the type of anion in imidazolium-based ILs influences the rheological properties. The performance of ionic liquids was compared with that of the commonly used clay inhibitor (sodium silicate) in the oil and gas industry. ILs showed improved performance compared to sodium silicate. The studied ionic liquids can be an attractive alternative for commercial clay inhibitors as their impact on the other properties of the drilling fluids was less compared to commercial inhibitors.

Correlated counterion effects on the solvation of proteins by ionic liquids

Ionic liquids are versatile compounds for biotechnological applications. However, even the chemical systems composed only of the IL, water, and of the biomolecules display complex interactions that are not reducible in terms of the possible pairs of components. Here, we illustrate this complexity and provide a molecular understanding of cooperative solvation effects by studying Ubiquitin in solutions of the four ionic liquids formed by the combinations of the cations 1-Ethyl-3-methylimidazolium (EMIM), and 1-Butyl-3-methylimidazolium (BMIM), and of the anions Tetrafluoroborate (BF4), and Dicyanamide (DCA), using computer simulations. The structure and thermodynamics of the protein-IL interactions were evaluated by means of minimum-distance distribution functions (MDDFs) and the Kirkwood-Buff (KB) theory of solvation using the ComplexMixtures (http://m3g.iqm.unicamp.br/ComplexMixtures) software. The cooperativity of the interactions of the ions with the protein stems from the necessary electrical neutrality of the bulk solution. Specifically, the counterions' KB integrals are identical despite their contrasting interactions with the protein surface. Therefore, varying the hydrophobicity of the cation or the chemical nature of the anion implies different distributions of the corresponding counterions in the solution. The DCA anion, by forming hydrogen bonds to the protein surface, can drive the cations to the proximity of the protein surface. This effect is localized in the first two or three solvation shells of the protein. Direct correlations of the positions of the ions by alternating density augmentations can be observed at specific protein surface sites. At the same time, the protein can become preferentially hydrated by increasing the hydrophobicity of the cation and its concentration, independently of the strength of the interactions of the anion with the protein surface. In summary, cooperative ion effects determine the strength of the interactions of each component of the solution with the protein and the final solubility, and stability, of the biomolecules. Tuning the properties of ILs for specific applications rely on the understanding of these many-component effects.

Effect of ionic liquid electrolytes on the electrochemical stability and optical tunability of polyaniline-based infrared variable emittance devices

In this study, ionic liquids (ILs) are used instead of conventional volatile aqueous or organic electrolytes to fabricate durable polyaniline (PANI)-based infrared variable emittance devices (IR-VEDs). It is of significance to find that different IL electrolyte systems have a great effect on the electrochemical stability and IR tunability of the PANI films. The present PANI films exhibit much better electrochemical stability when cycling in ILs having tetrafluoroborate and bis(trifluoromethylsulfonyl)imide anions than cycling in ILs with dicyanamide and tricyanomethanide anions. Furthermore, compared with pure IL electrolytes, the addition of high-mobility cations (Li+) into ILs can significantly enhance the IR tunability of PANI films. The IR-VED based on a preferable ionogel electrolyte membrane exhibits a high emittance variation (Δԑ) of 0.42 in 2.5–25 µm region, and fast switching times of 14.6 s/17.0 s. More importantly, the device still maintains a high Δԑ value of 0.35 after 500 electrochemical cycles, demonstrating promising applications in the dynamic IR regulation field.

Effect of Ionic Liquid Structure on the Electrochemical Response of Dopamine at Room Temperature Ionic Liquid‐modified Carbon Paste Electrodes (IL–CPE)

AbstractIn this work 12 different ionic liquids (ILs) have been used added as co‐binders in the preparation of modified carbon paste electrodes (IL–CPEs) used for the voltammetric analysis of dopamine in Britton‐Robinson buffer. The ionic liquids studied were selected based on three main criteria: (1) increasing chain length of alkyl substituents (studying 1‐ethylimidazolium and ethyl, propyl, butyl, hexyl and decylmethylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids); (2) nature of the counter ion (dicyanamide, bis(trifluoromethylsulfonyl)imide and hexafluorophosphate) in 1‐butyl‐3‐methylimidazolium ionic liquids; and (3) cation ring structures (1‐butyl‐3‐methylimidazolium, 1‐butyl‐1‐methylpiperidinium, 1‐butyl‐1‐methylpyrrolidinium and 1‐butyl‐3‐methylpyridinium) in bis(trifluoromethylsulfonyl)imide or hexafluorophosphate (1‐butyl‐3‐methylimidazolium or 1‐butyl‐3‐methylpyridinium as cations) ionic liquids. The use of IL as co‐binders in IL–CPE results in a general enhancement of both the sensitivity and the reversibility of dopamine oxidation. In square wave voltammetry experiments, the peak current increased up to a 400 % when 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was used as co‐binder, as compared to the response found with the unmodified CPE. Experimental data provide evidence that electrostatic and steric effects are the most important ones vis‐à‐vis these electrocatalytic effects on the anodic oxidation of dopamine on IL–CPE. The relative hydrophilicity of dicyanamide anions reduced the electrocatalytic effects of the corresponding ionic liquids, while the use of 1‐ethyl‐3‐methylimidazolium hexafluorophosphate or 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (two relatively small and highly hydrophobic ionic liquids) as co‐binders in IL–CPE resulted in the highest electrocatalytic activity among all of the IL–CPE studied.

Exploring enthalpies of formation of imidazolium-, pyridinium-, and pyrrolidinium-based ionic liquids with dicyanamide anion using quantum chemical methods

Abstract In this work, quantum chemical calculations have been performed on the ionic liquids based on imidazolium, pyridinium, and pyrrolidinium cations with the dicyanamide anion. The dispersion-corrected B3LYP exchange-correlation functional was used to optimize geometries. Enthalpies of formation were calculated at the high-level G3(MP2) theory by employing both the atomization energy and reaction enthalpy approaches. There exists a very good agreement between the predicted enthalpies of formation and available experimental values. For the first time, the enthalpies of formation have been predicted for 21 ion pairs with no available experimental data. The calculated enthalpies of formation are decreased with increasing alkyl chain length. Linear correlations were observed between enthalpy of formation and number of carbon atoms in the alkyl side-chain for all of the studied series of cations. Regardless of the cation type, the contribution of each CH2 group in the alkyl chain to the enthalpy of formation was also determined.

Inorganic-organic hybrid materials with methylviologen dication confined in magnetic hosts: Synthesis, crystal structures and magnetic properties

Two novel coordination polymers {(MV)[M3(dca)8]}n (MV2+ = methylviologen dication, dca = dicyanamide anion, M = Co (1) and Ni (2)) have been synthesized by the reactions of methylviologen dichloride andsodium dicyanamidewith cobalt(II) or nickel(II) ions. Their structures have been determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis, infrared spectra, and thermogravimetric analytical techniques. Compounds 1 and 2 are isomers, and crystallize in a centrosymmetric P21/n space group. In the structures of 1 and 2, the metal ions are attached through the µ1,3,5- dicyanamide groups generating a 2D sheet in bc plane. Furthermore, the neighbouring sheets are supported by the strut µ1,5-dca ligands into a 3D framework with open channels occupied by MV2+ cations. Magnetic studies indicate that, compound 1 exhibits antiferrimagnetic coupling between cobalt(II) ions, whereas ferromagnetic interaction was occurred between nickel(II) ions in compound 2.

Synthesis, characterization and thermal properties of 1,10-phenanthroline mixed-ligand complexes of cobalt(II) and copper(II): metal-mediated transformations of the dicyanamide ion

The reaction of 1,10-phenanthroline and dicyanamide ligands with Cu(II) and Co(II) nitrates afforded the complexes [Cu(phen)(BMCA)](NO3)] (1) and [Co(phen)2(NO3)](dcg-)·(H2O) (2). The dicyanamide anion was transformed in 1 and 2 to bis(methoxycarbimido)aminato (BMCA) and dicyanoguanidinate (dcg) anions, respectively. The complexes were characterized by elemental analysis, infrared spectroscopy and ultraviolet–visible spectroscopy, magnetic susceptibility measurement and X-ray crystallography. Both complexes crystallize in the monoclinic crystal system, and the structures are stabilized by extended hydrogen bonding networks as well as aromatic π–π stacking interactions. The thermal and antimicrobial properties of the complexes have also been evaluated. Density functional theory calculations were also performed in order to gain insights into the molecular interactions in the synthesized compounds and to predict some of their electronic properties.

Synthesis, characterization and structures of binuclear copper(II) and polynuclear cobalt(II), nickel(II) and cadmium(II) complexes involving N4-donor pyrazolyl based ligand and dicyanamide as bridging ligand

Binuclear copper(II) complex [Cu(bdpab)(μ-1,5dca)]2(ClO4)2 and polynuclear complexes [M(bdpab)(μ-1,5dca)]n(ClO4)n [M = Ni(II), Co(II) and Cd(II) and dca = dicyanamide anion, {N(CN)2-}] were synthesized using pyrazolyl containing tetradentate N4- coordinate ligand bdpab and bridging ligand dca and characterized by spectral data and single crystal X-ray diffraction studies. Structural characterization by single crystal X-ray diffraction studies show copper complex is binuclear and two copper centres are bridged by two μ-1,5dca ligands whereas Co(II) and Cd(II) complexes are polynuclear and two metal centres are bridged by one μ-1,5dca ligand in zig-zag pattern and all metal centres have octahedral geometry.

Electrodeposition of chromium on single-crystal electrodes from solutions of Cr(II) and Cr(III) salts in ionic liquids

Herein, we present a study on the initial stages of chromium electrodeposition on platinum and gold single-crystal surfaces from an ionic liquid containing dicyanamide anions. We employed conventional electrochemical techniques in combination with in situ and ex situ scanning probe microscopy (in situ scanning tunneling microscopy (STM), ex situ atomic force microscopy (AFM)) and ex situ X-ray photoemission spectroscopy (XPS). Cr electrodeposition was carried out from Cr(II) and Cr(III) solutions of low (10 mM) and high (250 mM) Cr concentrations. The microscopic and spectroscopic approaches clearly demonstrate the formation of a Cr deposit, although the voltammetric responses are difficult to interpret. The absence of a pronounced Cr dissolution peak in the backward scan of the cyclic voltammograms and a relatively low amount of Cr deposit (as confirmed by AFM) suggest the passivation of Cr and the substrate during deposition, thus hindering both further deposition of Cr and its anodic dissolution.

Expanding the Electrochemical Window: New Tunable Aryl Alkyl Ionic Liquids (TAAILs) with Dicyanamide Anions.

A set of new tunable aryl alkyl ionic liquids (TAAILs) based on the 1-aryl-3-alkyl imidazolium motif has been synthesized, in which the following variables were systematically changed: alkyl chain length, aryl substitution (group and position), and counter ion. TAAILs with dicyanamide (DCA) and bis(trifluoromethylsulfonyl)imide (N(SO2 CF3 )2 , NTf2 ) anions showed remarkable differences of their physical properties: NTf2 ionic liquids were found to have high decomposition temperatures and viscosities well below those of the DCA TAAILs. In contrast, the dicyanamide anion increased the electrochemical stability leading to TAAILs with an extremely wide electrochemical window of up to 7.17 V. Additionally, both classes of TAAILs extract transition metals from aqueous solutions: TAAILs with the DCA anion extract both platinum and copper while TAAILs with the NTf2 anion are selective towards platinum. This demonstrates that minor changes of the molecular structure lead to TAAILs with drastically changed physicochemical properties.

Tribological Performance of Non-halogenated Phosphonium Ionic Liquids as Additives to Polypropylene and Lithium-Complex Greases

Four non-halogenated ionic liquids (ILs) with trihexyl(tetradecyl)phosphonium cation are tested as lubricant additives to polypropylene (PP) and lithium-complex (LiX) greases. In pin-on-disk tests at elevated temperatures, the addition of an IL with bis(oxalato)borate ([BOB]) anion reduces wear by up to 50% when compared to the neat LiX base grease; an IL with bis(mandelato)borate ([BMB]) anion reduces friction by up to 60% for both PP and LiX. Elemental analysis reveals that oxygen-rich tribofilms help to reduce wear in case of [BOB], while the friction reduction observed for [BMB] is likely caused by adsorption processes. We find that temperature has a pronounced effect on additive expression, yet additive concentration is of minor importance under continuous sliding conditions. In contrast, rolling-sliding experiments at 90 °C show that the traction performance of LiX grease is dependent on additive concentration, revealing a reduction in traction by up to 30 and 40% for [BMB]- and [BOB]-containing ILs at concentrations of 10 wt%. Finally, an IL with dicyanamide anion reduces friction and increases wear in pin-on-disk tests at room temperature, while an IL with bis-2,4,4-(trimethylpentyl)phosphinate anion increases wear, showing only limited potential as grease additives. Overall, this work demonstrates the ability of non-halogenated ILs to significantly extend grease performance limits.

Tuning Sodium Interfacial Chemistry with Mixed-Anion Ionic Liquid Electrolytes.

The interphase layer that forms on either the anode or the cathode is considered to be one of the critical components of a high performing battery. This solid-electrolyte interphase (SEI) layer determines the stability of the electrode in the presence of a given electrolyte as well as the internal resistance of a battery, and hence the overpotential of a cell. In the case of lithium ion batteries where carbonate based electrolytes are used, additives including hexafluorophosphate (PF6), bis-trifluoromethylsulfonimide (TFSI), (fluorosulfonyl)(trifluoromethanesulfonyl)imide (FTFSI), and fluorosulfonimde (FSI) are used to obtain favorable SEI layers. Ionic liquids and salts based on anions containing nitrile groups, including dicyanamide (DCA), offer a less expensive alternative to a fluorinated anion and have also been shown to support stable electrochemistry in lithium and sodium systems. However, longer term cycling leads to the eventual passivation of the electrode, presumed to be due to the instability of the DCA anion. We herein consider the use of a fluorinated anion to control the interfacial electrochemistry and provide a more stable SEI in DCA ILs. We investigate the addition of NaDCA, NaFSI, NaTFSI, and NaFTFSI to the methylpropylpyrrolidinium dicyanamide ([C3mpyr]DCA) ionic liquid. NaFSI was found to generate a more stable SEI layer, as evidenced by extended symmetric cell cycling, while the TFSI and FTFSI salts both lead to thicker, highly passivating surfaces. We use molecular dynamics, infrared spectroscopy and X-ray photoelectron spectroscopy to interrogate and discuss the influence of the anion on the bulk electrolyte, the interfacial electrolyte structure, and the formation of the SEI layer, in order to rationalize the contrasting electrochemical observations.

Structural and photoluminescent studies of non-centrosymmetric manganese(II) N-(2-pyridylmethyl)-(L)-alanine) dicyanamide

The dinuclear compound, [Mn2(Pyala)2(Dca)2(H2O)]n·2H2O (1) (Pyala = N-(2-pyridylmethyl)-L-alanine and Dca = dicyanamide anion) has been synthesized and characterized by elemental analysis, IR and single crystal X-ray diffraction techniques. The crystal data for C22H26Mn2N10O6: orthorhombic, space group P212121 (no. 19), a = 10.3728(8) Å, b = 15.9780(12) Å, c = 16.3585(13) Å, V = 2711.2(4) Å3, Z = 4, T = 198(2) K, μ(MoKα) = 0.989 mm-1, Dcalc = 1.559 g/cm3, 129607 reflections measured (3.564° ≤ 2Θ ≤ 60.046°), 7923 unique (Rint = 0.0324, Rsigma = 0.0155) which were used in all calculations. The final R1 was 0.0169 (I > 2σ(I)) and wR2 was 0.0458 (all data). The obtained non-centrosymmetric dinuclear Mn(II) complex contains two unique Mn(II) cations with similar octahedral coordination environment. Photoluminescent measurements on the complex in the solid state show that it displays strong photoluminescence at 442 nm.