Normally, fluorescence is inversely proportional to concentration, this effect is due to aggregation-caused quenching (ACQ). Quenching is the reduction of luminesce due to molecular π-stacking, any emission emitted by one molecule is absorbed by another. Molecules that have no emission in dilute solutions but fluoresce when concentrated are deemed Aggregate Induced Emission (AIE) materials. The work presented herein aims at quickly synthesize new AIE materials using a reaction methodology that involves hypervalent iodonium alkynyl triflate (HIAT). The long term goal of the project is to use non-toxic fluorophores to light-up upon aggregation and effectively “turn-on” when encountering specific stimuli inside biological systems.<br/><br/>From previous work on HIATs it is known that the mechanism starts with a nucleophilic attack on the β-carbon. Electrons from the two π bonds rearrange to form an iodo-ylide and after subsequent loss of iodobenzene, a vinylidene carbene is produced. Thus far, two HIATs have been used in the reaction, a propyl-HIAT and a phenyl-HIAT. The exact mechanism for the product formation of these reactions is currently being investigated. In the reaction using the propyl-HIAT, the alkyl chain undergoes a 1,5 C-H insertion. In the case of the phenyl-HIAT, there is evidence of a 1,2-shift rearrangement. In both products only fragments of the original Tos-MIC is present; this suggests that the sulfinate is the nucleophile.

Reactions of hypervalent iodonium alkynyl triflates with toluenesulfonylmethyl isocyanide (Tos-MIC)

255th National Meeting (2018)

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