Discussions

SPAAC can be carried out efficiently. On the one hand, the chemical potential energy of azide and alkyne substrates as reactants is very high. When cycloaddition reaction generates stable triazole, it can release more than 188 kJ/mol of heat, which satisfies the condition that reactants need high energy. On the other hand, azides and alkynes are difficult to react with biomolecules under reaction conditions, and they are inert to most other reaction reagents and solvents. In addition, alkynyl and azide groups have small molecular weights and weak polarities, which have little influence on the chemical properties of the connected structures, and meet the selectivity required in many applications such as biology and materials. Therefore, SPAAC takes advantage of the high ring tension of the cyclic alkyne itself, and the click reaction with chemical regioselectivity can occur without the participation of copper catalyst. It is a new and efficient azide alkyne cycloaddition reaction.