Supramolecularly assisted synthesis of chiral tripodal imidazolium compounds

Abstract

Supramolecular interactions based on amide groups direct the preferential formation of tritopic instead of monotopic or ditopic imidazolium compounds.

Highly Selective Anion Template Effect in the Synthesis of Constrained Pseudopeptidic Macrocyclic Cyclophanes

“…As much as four bromide anions are generated for each macrocycle formed, an anion effect can be expected for this process according to previous results in this field. − When the macrocyclization using 1a was carried out in the presence of 10 equiv of NEt 4 Br, a clear increase in the reaction rate was observed (100% conversion and 96% yield after 1.5 h against ca. 65% yield in the absence of added salt).…”

“…9 The selection of the suitable anion can be crucial, as anions can act either as kinetic or as thermodynamic templates, stabilizing the corresponding transition state or final macrocycle through specific supramolecular interactions. 10 In the framework of previous studies on minimalistic pseudopeptidic compounds, 11,12 the efficient preparation of macrocyclic structures was achieved through the reaction of C2 symmetric pseudopeptides with bis(halomethyl)arenes. This was based, in some cases, on the proper conformational and configurational preorganization of the open-chain precursors, 13 while, in other instances, the use of anionic templates allowed high yielding macrocyclization processes, even for systems for which conformational or configurational factors were unfavourable.…”

Proton Exchange Membrane Fuel Cells (PEMFCs): Advances and Challenges

“…Ionic liquids are used as fillers with the intention to increase proton conductivity of polymeric membranes and also to improve thermal, chemical, and mechanical stability of the membranes. Ionic liquids have found tremendous applications in a wide variety of fields of chemistry, such as organic chemistry [ 133 ], which includes their use as green solvents in organic synthesis [ 134 , 135 ]; catalysis [ 136 , 137 ]; supramolecular chemistry [ 138 , 139 ]; pharmaceutical chemistry [ 140 ]; and as transport agents [ 141 ]. They have also been used in analytical chemistry in engineering applications, sensing, separation, extraction, and drug sensing [ 142 , 143 , 144 , 145 , 146 , 147 , 148 , 149 ], and also in materials science and electrochemistry [ 150 ], among other fields.…”

Recent Progress in the Development of Composite Membranes Based on Polybenzimidazole for High Temperature Proton Exchange Membrane (PEM) Fuel Cell Applications

“…ILs are purely ionic materials with generally low, below 100 °C, melting temperatures [ 214 ]. ILs have found applications in a wide variety of fields including their use as green solvents in organic synthesis [ 215 ], catalysis [ 216 , 217 ], extraction, separation [ 218 ], supramolecular chemistry [ 219 , 220 ], transport agents [ 221 ], pharmaceutical chemistry [ 222 ], materials science, and drug sensing [ 223 ], among others. ILs have several favorable properties including their temperature stability, non-volatility and non-flammability, rather high ionic conductivity, and reduced environmental impact.…”