Tuning the nonlinear optical properties of the [alkyl-Py]+[NO3]− and [alkyl-MIM]+[NO3]− ionic liquids

Synthesis, NMR, Raman, thermal and nonlinear optical properties of dicationic ionic liquids from experimental and theoretical studies

“…Further, studying DILs is another highly active area of research that aims at understanding the structure-property relationships. Despite the wealth of papers on DILs and their applications [13,14], there are a few experimental and computational studies on DILs to understand their structure-property relationships and NLO properties [15][16][17].…”

“…Studies of NLO properties of DILs are very important due to their potential applications in photonics and telecommunication, because each combination of anion and cation gives different value of NLO properties depending on the weak interaction of coupled cations with anions [16].…”

Charge delocalization and hyperpolarizability in ionic liquids

“…For the pyridinium cation, at the same k interval, we obtained first hyperpolarizability values of 4.1 -15.0 Á 10 À30 esu and, in Ref. [50], it was approximately obtained 2.3 -4.9 Á 10 À30 esu. Moreover, for the [C 4 mim] + cation, our first hyperpolarizability value is slightly higher than that given by Bardak et al [53] using the M06-2X functional, while, our second hyperpolarizability value, is almost one order of magnitude smaller, showing the strong functional dependence of these magnitudes.…”

“…For instance, for the imidazolium cation with k = 4 -8, our first hyperpolarizability (see Supplementary Material) is in the range of 1.6 -4.2 Á 10 À30 esu while in Ref. [50] it is approximately in the range of 1.2 -3.2 Á 10 À30 esu. For the pyridinium cation, at the same k interval, we obtained first hyperpolarizability values of 4.1 -15.0 Á 10 À30 esu and, in Ref.…”

“…In contrast, several characterization techniques based on NL optics were successfully applied to ILs for studying their ultra-fast dynamics [36][37][38][39], bulk [23,40], or interface [41][42][43][44][45][46][47][48] structure. Recently, some computational works have shed more light in the magnitude of the NL optical response of ILs by calculating the first and second hyperpolarizabilities of some ILs as well as of their forming ions [23,[49][50][51]35,52,53]. However, despite these pioneering works, further investigation on the origins of this NL response is required to determine reliable rules to design ILs with tailored NL optical properties.…”