The ionicity and transport properties of a series of diethylmethylamine (DEMA) based protic ionic liquids (PILs) were characterized, principally utilizing nuclear magnetic resonance (NMR) spectroscopy. PILs were formed via the protonation of DEMA by an array of acids spanning a large range of acidities. A correlation between the (1)H chemical shift of the exchangeable proton and the acidity of the acid used for the synthesis of the PIL was observed. The gas phase proton affinity of the acid was found to be a better predictor of the extent of proton transfer than the commonly used aqueous ΔpKa. Pulsed field gradient (PFG) NMR was used to determine the diffusivity of the exchangeable proton in a subset of the PILs. The exchangeable proton diffuses with the acid if the PIL is synthesized with a weak acid, and with the base if a strong acid is used. The ionicity of the PILs was characterized using the Walden analysis and by comparing to the ideal Nernst-Einstein conductivity predicted from the (1)H PFG-NMR results.
Effects of foliar sprays of zinc and manganese sulfates on the fruit yield and quality as well as leaf nutrients concentration of pomegranate were studied during 2010 growing season in an orchard with a soil pH of 7.5 and EC of 5.2 (dS m -1 ). Zinc and manganese sulfates were applied two times at the rate of 0, 0.3 and 0.6 percent under a factorial design on the base of completely randomized blocks. Mn sprays had positive significant effects on the fruit yield, the aril/peel ratio, TSS, weight of 100 arils, juice content of arils, anthocyanin index, fruit diameter and leaf area. Zn effects were also significant for TSS, TSS/TA ratio, juice content of arils and leaf area. Foliar spray of Mn significantly increased Mn and N but decreased Zn and Cu concentrations in leaves. Foliar sprays of Zn significantly increased Zn but decreased Mn and P concentrations in the leaves. According to the results, the suitable combination of these two micronutrients for studied characters of pomegranate under prevailing conditions was foliar spray of 0.6% MnSO 4 and 0.3% ZnSO 4 .
Protic ionic liquids are known to form extended hydrogen-bonded networks that can lead to properties different from those encountered in the aprotic analogous liquids, in particular with respect to the structure and transport behavior. In this context, the present paper focuses on a wide series of 1-alkyl-imidazolium bis(trifluoromethylsulfonyl)imide ionic liquids, [HC n Im][TFSI], with the alkyl chain length (n) on the imidazolium cation varying from ethyl (n = 2) to dodecyl (n = 12). A combination of several methods, such as vibrational spectroscopy, wide-angle X-ray scattering (WAXS), broadband dielectric spectroscopy, and 1H NMR spectroscopy, is used to understand the correlation between local cation–anion coordination, nature of nanosegregation, and transport properties. The results indicate the propensity of the −NH site on the cation to form stronger H-bonds with the anion as the alkyl chain length increases. In addition, the position and width of the scattering peak q1 (or the pre-peak), resolved by WAXS and due to the nanosegregation of the polar from the nonpolar domains, are clearly dependent on the alkyl chain length. However, we find no evidence from pulsed-field gradient NMR of a proton motion decoupled from molecular diffusion, hypothesized to be facilitated by the longer N–H bonds localized in the segregated ionic domains. Finally, for all protic ionic liquids investigated, the ionic conductivity displays a Vogel–Fulcher–Tammann dependence on inverse temperature, with an activation energy E a that also depends on the alkyl chain length, although not strictly linearly.
The need for reliable means of ordering and quantifying the Lewis basicity of anions is discussed and the currently available methods are reviewed. Concluding that there is need for a simple impurity-insensitive tool, we have sought, and here describe, a new method using NMR spectroscopy of a weak base, a substituted urea, 1,3-dimethyl-2-imidazolidinone (DMI), as it is protonated by Brønsted acids of different strengths and characters. In all cases studied the product of protonation is a liquid (hence a protic ionic liquid). NMR spectroscopy detects changes in the electronic structure of the base upon interaction with the proton donors. As the proton-donating ability, that is, acidity, increases, there is a smooth but distinct transition from a hydrogen-bonded system (with no net proton transfer) to full ionicity. The liquid state of the samples and high concentration of nitrogen atoms, despite the very low natural abundance of its preferred NMR-active isotope ((15) N), make possible the acquisition of (15) N spectra in a relatively short time. These (15) N, along with (13) C, chemical shifts of the carbonyl atom, and their relative responses to protonation of the carbonyl oxygen, can be used as a means, sensitive to anion basicity and relatively insensitive to impurities, to sort anions in order of increasing hydrogen bond basicity. The order is found to be as follows: SbF6 (-)
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