A new DABCO-based ionic liquid, namely 1-octyl-1,4-diazabicyclo [2.2.2] octan-1-ium Bromide ([C 8 DABCO + ][Br -]) has been synthesized through N-alkylation of 1,4-diazabicyclo [2.2.2] octane with 1-bromooctane using a simple procedure in one step. This [C 8 DABCO + ] [Br -] IL was characterized by FT-IR, FT-Raman and by 1 H and 13 C-NMR spectroscopies. The structure of [C 8 DABCO + ][Br -] IL was confirmed combining 1 H and 13 C-NMR spectroscopies with B3LYP/6-31G* calculations. Three ionic C-H•••Br bonds were predicted by natural bond orbital (NBO), atoms in molecules (AIM) calculations and bond orders but a monodentate coordination between cation and anion is suggested because only one of them has higher energy and lower distance. The effect of Br on properties of IL is clearly observed by the change in orientation and direction of dipole moment vector in the IL, as compared with the cation. NBO studies reveal that the Br anion strongly stabilizes to cation to form the IL. The complete vibrational assignments of 129 and 132 vibration modes expected for the cation and its IL were performed by using two harmonic force fields with the SQMFF methodology and transferable scaling factors. The scaled harmonic force constants were also reported for both species. The Br confers a higher reactivity to [C 8 DABCO + ][Br -], as suggested by analyses of frontier orbitals. The effect of Br is also observed in the different assignments observed for the IL and its cation. Reasonable correlations were found between the experimental IR, Raman and NMR spectra and the corresponding theoretical ones.

Four ionic liquids (ILs) based on the bis(trifluoromethanesulfonyl)imide (NTf2) anion were synthesized and characterized concerning their thermal stability, the occurrence of low temperature phase transitions and their volatility. All these physical quantities are highly important for possible applications. Both monocationic and dicationic ILs were considered. All ILs exhibit thermal stability exceeding 350 °C, an extremely high value, due to the presence of the NTf2 anion. Monocationic ILs can undergo crystallization, and they melt at 1 and 38 °C. On the contrary, dicationic ILs containing large positively charged ions display only a glass transition around −40 °C, without any crystallization or melting process; this fact is particularly important in view of the possibly low temperature applications of the dication ILs. The vapor pressure, pv, of the four ILs was measured by isothermal thermogravimetry in the temperature range between 250 and 325 °C; the lowest values of pv were obtained for the two dicationic liquids, suggesting that they are particularly well suited for high temperature applications. The vaporization enthalpy was calculated through the Clausius–Clapeyron equation and was found in the range between ~140 and ~180 kJ/mol depending on the specific IL.

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A junction of emeraldine salt (ES [BF4 −]) doped by [BMIM] [BF4] may be preferred over the other junctions due to its low ideality factor and maximum rectification ratio. Schottky barrier diode based on composite of polyaniline (ES [BF4 −]) with polystyrene has been created and characterized using aluminium as Schottky contact and argent as an ohmic contact. The observed current–voltage characteristics can be satisfactorily fitted using the modified Schottky equation. Capacitance–voltage (C–V) in reverse bias and current–voltage (I–V) plots indicates a rectification. Various junction parameters were calculated from the temperature dependent I–V and C–V data and discussed. These results indicate that the composite materials have better mechanical strength and diode quality compared to the pure semiconducting polymer.

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