R. D. Rogers and K. R. Seddon, Ionic liquids--solvents of the future?, Science, vol.302, issue.5646, pp.792-793, 2003.

E. Sundstrom, J. Yaegashi, J. Yan, F. Masson, G. Papa et al.,

J. Gladde, Demonstrating a separation-free process coupling ionic liquid pretreatment, saccharification, and fermentation with Rhodosporidiumtoruloides to produce advanced biofuels, Green Chem, vol.20, pp.2870-2879, 2018.

D. G. Seo and H. C. Moon, Mechanically robust, highly ionic conductive gels based on random copolymers for bending durable electrochemical devices, vol.28, p.1706948, 2018.

A. A. Elgharbawy, F. A. Riyadi, M. Z. Alam, and M. Moniruzzaman, Ionic liquids as a potential solvent for lipase-catalysed reactions: a review, J. Mol. Liq, vol.251, pp.150-166, 2018.

T. Welton, Ionic liquids: a brief history, Biophysical reviews, vol.10, pp.691-706, 2018.

K. Oster, J. Jacquemin, C. Hardacre, A. P. Ribeiro, and A. Elsinawi, Further development of the predictive models for physical properties of pure ionic liquids: Thermal conductivity and heat capacity, J. Chem. Thermodyn, vol.118, pp.1-15, 2018.
URL : https://hal.archives-ouvertes.fr/hal-02055697

M. F. Ali, J. Gan, X. Chen, G. Yu, Y. Zhang et al., Hydrodynamic modeling of ionic liquids and conventional amine solvents in bubble column, Chem. Eng. Res. Des, vol.129, pp.356-375, 2018.

J. L. Shamshina, O. Zavgorodnya, P. Berton, P. K. Chhotaray, H. Choudhary et al., Ionic Liquid Platform for Spinning Composite Chitin-Poly (lactic acid) Fibers, ACS Sustain. Chem. Eng, vol.6, pp.10241-10251, 2018.

M. B. Vazquez-santos, P. Tartaj, E. Morales, and J. M. Amarilla, TiO 2 Nanostructures as Anode Materials for Li/Na-Ion Batteries, Chem. Rec, vol.18, pp.1178-1191, 2018.

B. Haddad, D. Villemin, E. H. Belarbi, N. Bar, and M. Rahmouni, New dicationicpiperidiniumhexafluorophosphate ILs, synthesis, characterization and dielectric measurements, Arab. J. Chem, vol.7, pp.781-787, 2014.

B. Haddad, T. Moumene, D. Villemin, J. F. Lohier, and E. Belarbi, Bis-methyl imidazoliummethylidenebis (trifluoromethanesulfonyl) imide, crystal structure, thermal and dielectric studies, Bull. Mater. Sci, vol.39, pp.797-801, 2016.

D. K. Kaczmarek, K. Czerniak, and T. Klejdysz, Dicationic ionic liquids as new feeding deterrents, Chem. Pap, vol.72, pp.2457-2466, 2018.

R. A. Patil, M. Talebi, A. Berthod, and D. W. Armstrong, Dicationic ionic liquid thermal decomposition pathways, Anal. Bioanal. Chem, vol.410, pp.4645-4655, 2018.
URL : https://hal.archives-ouvertes.fr/hal-01858978

E. Gurung, D. Meng, L. Xue, G. Tamas, R. M. Lynden-bell et al., Optical Kerr effect spectroscopy of CS2 in monocationic and dicationic ionic liquids: insights into the intermolecular interactions in ionic liquids, Phys. Chem. Chem. Phys, vol.20, pp.26558-26569, 2018.

J. C. Águila and M. Trejo-durán, Theoretical study of the second-order nonlinear optical properties of ionic liquids, J. Mol. Liq, vol.269, pp.833-838, 2018.

J. E. Castellanos-Águila, M. A. Olea-amezcua, H. Hernández-cocoletzi, and M. Trejo-durán, J. Mol. Liq, vol.285, pp.803-810, 2019.

I. Severiano-carrillo, E. Alvarado-méndez, K. A. Barrera-rivera, M. A. Vázquez, M. Ortiz-gutierrez et al., Studies of optical nonlinear properties of asymmetric ionic liquids, vol.84, pp.166-171, 2018.

M. Trejo-durán, E. Alvarado-méndez, K. A. Barrera-rivera, and V. M. Castaño, Nonlinear optical phenomena in Bi-ionic Liquids, pp.895-899, 2017.

S. Anandhi, K. M. Rahulan, and T. S. Shyju, Hyperpolarizability and two photon observation of imidazoliumpicrate, Optik, vol.125, pp.7132-7135, 2014.

D. J. Williams, Nonlinear optical properties of organic and polymeric materials, ACS symposium series 233, 1983.

R. F. Souza, M. A. Alencar, M. R. Meneghetti, J. Dupont, and J. M. Hickmann, Nonlocal optical nonlinearity of ionic liquids, J. Phys. Condens. Matter, vol.20, p.155102, 2008.

M. S. Kodikara, R. Stranger, and M. G. Humphrey, Computational studies of the nonlinear optical properties of organometallic complexes, Coord. Chem. Rev, vol.375, pp.389-409, 2018.

G. Marino, P. Segovia, A. V. Krasavin, P. Ginzburg, N. Olivier et al., Second-harmonic generation from hyperbolic plasmonicnanorodmetamaterialslab, Laser Photonics Rev, vol.12, p.1700189, 2018.

O. Ostroverkhova and W. E. Moerner, Organic photorefractives: mechanisms, materials, and applications, Chem. Rev, vol.104, pp.3267-3314, 2004.

C. E. Song, Enantioselective chemo-and bio-catalysis in ionic liquids, Chem. Comm, pp.1033-1043, 2004.

S. Bugaychuk, G. Klimusheva, Y. Garbovskiy, T. Mirnaya, and A. Ischenko, Nonlinear optical properties of composites based on conductive metal-alkanoate liquid crystals, Opto-Electron Rev, vol.14, pp.275-279, 2006.

B. Haddad, A. Paolone, M. Drai, M. Boumediene, D. Villemin et al.,

O. Abbas, Para-xylyl linked bis-imidazolium ionic liquids: A study of the conformers of the cation and of the anion-cation hydrogen bonding, J. Mol. Struct, vol.1175, pp.175-184, 2019.
URL : https://hal.archives-ouvertes.fr/hal-02371861

R. Bader, AIMPAC: a suite of programs for the theory of atoms in molecules, Atoms in Molecules: A Quantum Theory, p.198558651, 1990.

F. B. König, J. Schönbohm, and D. Bayles, AIM2000-a program to analyze and visualize atoms in molecules, J. Comput. Chem, vol.22, pp.545-559, 2001.

P. Pulay, G. Fogarasi, G. Pongor, J. E. Boggs, and A. Vargha, Combination of theoretical ab initio and experimental information to obtain reliable harmonic force constants. Scaled quantum mechanical (QM) force fields for glyoxal, acrolein, butadiene, formaldehyde, and ethylene, J. Am. Chem. Soc, vol.105, pp.7037-7047, 1983.

G. Rauhut and P. Pulay, Transferable scaling factors for density functional derived vibrational force fields, J. Phys. Chem, vol.99, pp.3093-3100, 1995.

A. T. Sundius, Scaling of ab initio force fields by MOLVIB, Vib. Spectrosc, vol.29, pp.89-95, 2002.

M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb et al.,

H. Nakatsuji, Gaussian09, revisions D. 01 and B. 01, 2010.

R. Dennington, T. Keith, and J. Millam, GaussView, 2009.

A. D. Becke, Density-functional exchange-energy approximation with correct asymptotic behaviour, Phy. Rev. A, vol.38, p.3098, 1988.

P. Ugliengo, DipartimentoChimica IFM, 1998.

H. Boumediene, S. A. Brandán, A. M. Amin, A. Paolone, D. Villemin et al., Bidentatecation-anion coordination in the ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate supported by vibrational spectra and NBO, AIM and SQMFF calculations, J. Mol. Struct, vol.1212, p.128104, 2020.

K. Noack, P. S. Schulz, N. Paape, J. Kiefer, P. Wasserscheid et al., The role of the C2 position in interionic interactions of imidazolium based ionic liquids: a vibrational and NMR spectroscopic study, Phys. Chem. Chem. Phys, vol.12, pp.14153-14161, 2010.

A. D. Headley and N. M. Jackson, The effect of the anion on the chemical shifts of the aromatic hydrogen atoms of liquid 1-butyl-3-methylimidazolium salts, J. Phys. Org, vol.15, pp.52-55, 2002.

J. Rigby and E. I. Izgorodina, Assessment of atomic partial charge schemes for polarisation and charge transfer effects in ionic liquids, Phys. Chem. Chem. Phys, vol.15, pp.1632-1646, 2013.

R. K. Blundell and P. Licence, Tuning cation-anion interactions in ionic liquids by changing the conformational flexibility of the cation, Chem. Commun, vol.50, pp.12080-12083, 2014.

P. A. Hunt, I. R. Gould, and B. Kirchner, The structure of imidazolium-based ionic liquids: Insights from ion-pair interactions, Aust. J. Chem, vol.60, pp.9-14, 2007.

S. Tsuzuki, H. Tokuda, and M. Mikami, Theoretical analysis of the hydrogen bond of imidazolium C 2-H with anions, Phys. Chem, vol.9, pp.4780-4784, 2007.

T. Cremer, C. Kolbeck, K. R. Lovelock, N. Paape, R. Wölfel et al., Towards a Molecular Understanding of Cation-Anion Interactions-Probing the Electronic Structure of Imidazolium Ionic Liquids by NMR Spectroscopy, X-ray Photoelectron Spectroscopy and Theoretical Calculations, Chem. Eur. J, vol.16, pp.9018-9033, 2010.

H. Ibrahim, N. A. Koorbanally, D. Ramjugernath, M. D. Bala, and V. O. Nyamori, Synthesis and characterization of imidazolium salts bearing fluorinated anions, Z. Anorg. Allg. Chem, vol.638, pp.2304-2309, 2012.

B. Haddad, D. Mokhtar, M. Goussem, E. H. Belarbi, D. Villemin et al.,

J. Kiefer, Influence of methyl and propyl groups on the vibrational spectra of two imidazolium ionic liquids and their non-ionic precursors, J. Mol. Struct, vol.1134, pp.582-590, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01829518

B. Haddad, A. Paolone, D. Villemin, J. F. Lohier, M. Drai et al.,

E. H. Belarbi, para-Xylyl bis-1-methylimidazolium bis (trifluoromethanesulfonyl) imide: Synthesis, crystal structure, thermal stability, vibrational studies, J. Mol. Liq, vol.260, pp.391-402, 2018.
URL : https://hal.archives-ouvertes.fr/hal-01829548

B. Haddad, A. Paolone, D. Villemin, M. Taqiyeddine, E. H. Belarbi et al., Synthesis, conductivity, and vibrational spectroscopy of tetraphenylphosphonium bis (trifluoromethanesulfonyl) imide, J. Mol. Struct, vol.1146, pp.203-212, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01829534

M. Boumediene, B. Haddad, A. Paolone, M. Drai, D. Villemin et al., Synthesis, thermal stability, vibrational spectra and conformational studies of novel dicationic meta-xylyl linked bis-1-methylimidazolium ionic liquids, J. Mol. Struct, vol.1186, pp.68-79, 2019.
URL : https://hal.archives-ouvertes.fr/hal-02371882

A. M. Moschovi, S. Ntais, V. Dracopoulos, and V. Nikolakis, Vibrational spectroscopic study of the protic ionic liquid 1-H-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, Vib. Spectrosc, vol.63, pp.350-359, 2012.

V. H. Paschoal, L. F. Faria, and M. C. Ribeiro, Vibrational Spectroscopy of Ionic Liquids, vol.117, pp.7053-7112, 2017.

T. Endo, H. Murata, M. Imanari, N. Mizushima, H. Seki et al., NMR Study of Cation Dynamics in Three Crystalline States of 1-Butyl-3-methylimidazolium Hexafluorophosphate Exhibiting Crystal Polymorphism, J. Phys. Chem. B, vol.116, pp.3780-3788, 2012.

E. R. Talaty, S. Raja, V. J. Storhaug, A. Dölle, and W. R. Carper, Raman and infrared spectra and ab initio calculations of C2-4MIM imidazolium hexafluorophosphate ionic liquids, J. Phys. Chem. B, vol.108, pp.13177-13184, 2004.

B. Haddad, J. Kiefer, H. Brahim, E. Belarbi, D. Villemin et al., Effects of C(2) Methylation on Thermal Behavior and Interionic Interactions in Imidazolium-Based Ionic Liquids with Highly Symmetric Anions, Appl. Sci, vol.8, issue.7, p.1043, 2018.
URL : https://hal.archives-ouvertes.fr/hal-01829556

T. Moumene, E. H. Belarbi, B. Haddad, D. Villemin, O. Abbas et al., Vibrational Spectroscopic Study of Imidazolium Dicationic Ionic Liquids: Effect of Cation Alkyl Chain Length, J. Appl. Spectrosc, vol.83, issue.2, pp.165-171, 2016.
URL : https://hal.archives-ouvertes.fr/hal-01829921

F. Castet, E. Bogdan, A. Plaquet, L. Ducasse, B. Champagne et al., Reference molecules for nonlinear optics: A joint experimental and theoretical investigation, J. Chem. Phys, vol.136, p.24506, 2012.

R. Bersohn, Y. H. Pao, and H. L. Frisch, Double-quantum light scattering by molecules, J. Chem. Phys, vol.45, pp.3184-3198, 1966.

V. Rodriguez, J. Grondin, F. Adamietz, and Y. Danten, Local structure in ionic liquids investigated by hyper-Rayleigh scattering, J Phys. Chem. B, vol.114, pp.15057-15065, 2010.

D. Hadji and A. Rahmouni, Theoretical study of nonlinear optical properties of some azoic dyes, Mediterr. J. Chem, vol.4, pp.185-192, 2015.

D. Hadji and A. Rahmouni, Molecular structure, linear and nonlinear optical properties of some cyclic phosphazenes: A theoretical investigation, J. Mol. Struct, vol.1106, pp.343-351, 2016.

D. Hadji and H. Brahim, Structural, optical and nonlinear optical properties and TD-DFT analysis of heteroleptic bis-cyclometalated iridium (III) complex containing 2-phenylpyridine and picolinate ligands, Theor. Chem. Acc, vol.137, p.180, 2018.

M. Shkir, S. Alfaify, H. Abbas, and S. Muhammad, First principal studies of spectroscopic (IR and Raman, UV-visible), molecular structure, linear and nonlinear optical properties of l-arginine p-nitrobenzoate monohydrate (LANB): a new non-centrosymmetric material, Spectrochimica Acta Part A, vol.147, pp.84-92, 2015.

G. Raabe and J. Köhler, Thermodynamical and structural properties of imidazolium based ionic liquids from molecular simulation, J. Chem. Phys, vol.128, p.154509, 2008.

D. M. Bishop and J. Pipin, Dipole, quadrupole, octupole, and dipole-octupole polarizabilities at real and imaginary frequencies for H, HE, and H 2 and the dispersion-energy coefficients for interactions between them, Int. J. Quantum Chem, vol.45, pp.349-361, 1993.

I. Khan, M. Taha, P. Ribeiro-claro, S. P. Pinho, and J. A. Coutinho, Effect of the cation on the interactions between alkyl methyl imidazolium chloride ionic liquids and water, J. Chem. Phys. B, vol.118, pp.10503-10514, 2014.

Z. H. Zhang, J. S. Li, J. Tang, L. L. Yang, K. X. Guo et al., Binding energy and the third-order nonlinear optical susceptibility of an exciton in GaAs/AlGaAs core/shell spherical quantum dot, J. Opt, vol.47, pp.445-455, 2018.

D. Sakthi, M. Prakasam, A. Prakasam, S. Sivakumar, and P. M. Anbarasan, A Complete DFT, TD-DFT and Non-Linear Optical Property Study on 6-Amino-2-Methylpyridine-3-Carbonitrile, Computational Chemistry, vol.5, p.129, 2017.

I. Ledoux and J. Zyss, Influence of the molecular environment in solution measurements of the second-order optical susceptibility for urea and derivatives, Chem. Phys, vol.73, pp.203-213, 1982.

A. Yousefi, S. Javadian, N. Dalir, J. Kakemam, and J. Akbari, Imidazolium-based ionic liquids as modulators of corrosion inhibition of SDS on mild steel in hydrochloric acid solutions: experimental and theoretical studies, RSC Advances, vol.5, pp.11697-11713, 2015.

D. Hadji, A. Rahmouni, D. Hammoutène, and O. Zekri, First theoretical study of linear and nonlinear optical properties of diphenyl ferrocenyl butene derivatives, J.Mol. Liq, vol.286, p.110939, 2019.