A general design platform for ionic liquid ions based on bridged multi-heterocycles with flexible symmetry and charge

Abstract

A conceptual design platform for new ionic liquids with variable heterocycles, bridges, symmetry, and charge was developed using simple alkylation, click, and ionic liquid chemistries and demonstrated with 1-(2-(5-tetrazolidyl)ethyl)-3-(5-1H-tetrazolyl)methylimidazolium and its conversion into room-temperature ionic liquids as cation or as anion.

Azolate Anions in Ionic Liquids: Promising and Under‐Utilized Components of the Ionic Liquid Toolbox

“…The selection of the appropriate synthetic approach to an azolate‐containing IL is of course dependent on the desired ion pair; however, three key methods underlie the preparation for the 122 unique azolate‐containing ILs we have found reported in the literature: a) metathesis between an imidazolium salt and a neutral azole or an inorganic azolate, b) neutralization reactions with [HCO 3 ] − , and c) direct neutralization with an IL‐forming base to give protic ILs, all methods of which are summarized in Scheme . Another interesting and promising route to achieve tailored azolate‐containing ILs was demonstrated by Rogers group in 2010 involving click reactions …”

“…Aside from an initial report highlighting the novelty of an all‐azole IL, the first motivations for exploring azolate anions as an IL component was in the field of energetic and hypergolic materials for rocket fuels . The advantage of energetic salts, and thus ILs, in hypergolic materials is their lower vapor pressure and higher densities relative to volatile neutral molecules.…”

Current Developments in the Syntheses of 1,2,4-Triazole Compounds

“…Great interest is directed towards triazole ionic liquids in combination with tetrazoles due to their excellent energetic properties. The reaction of triazole with acrylonitrile in the presence of triethylamine effectively produced 1-(2-cyanoethyl)-1,2,4-triazole 175, and further transformation with sodium azide afforded triazole containing tetrazole salt 176 which could be served as excellent ionic liquid (Scheme 73) [251]. This synthetic strategy has opened a new direction to develop novel diheterocyclic energetic ionic liquids.…”

A general halide-to-anion switch for imidazolium-based ionic liquids and oligocationic systems using anion exchange resins (A− form)

“…[2][3][4] The role of ionic liquids (ILs), besides their increasing importance as green solvents, has been broadened to ionic liquid salt forms of active pharmaceutical ingredients (APIs), 5 energetic ionic liquids (EILs) 6 and tuneable aryl alkyl ionic liquids (TAAILs). 17 There are only a few reports on the application of anion exchange resins to imidazolium-based ILs using either an AER (OH À form) or AER (A À form) for the counteranion exchange (Scheme S1, ESIz). 8 Chemical aspects of imidazolium-based ILs concern their preparation, counteranion exchange and purity.…”

“…13 From 1986 onwards, this procedure was then conveniently applied to a variety of N-azolylimidazolium salts with several interannular linkers, including aza-analogues of sesquifulvalene with a betaine character. 17 There are only a few reports on the application of anion exchange resins to imidazolium-based ILs using either an AER (OH À form) or AER (A À form) for the counteranion exchange (Scheme S1, ESIz). 15,16 Recently, Rogers and co-workers have reported an imidazolium-based platform for ILs built up from a methyleneimidazolium tetrazolate subunit, and using an AER (OH À form) to prepare the betaine structural motif.…”