Monitoring dynamic pre-crystallization aggregation processes in solution by VT-DOSY-NMR spectroscopy

Equimolar mixtures of pyridine (Py) with para-halotetrafluoropyridine (BrTFP and ITFP) were investigated by VT-diffusion NMR experiments. The formation of a halogen-bond-stabilized ITFP center dot Py complex was detected upon cooling a solution in methylcyclohexane-d(14) to 260 K; this allows monitoring a halogen-bond-driven aggregation process preceding crystallization in solution.

Automated summary

Equimolar mixtures of pyridine with para-halotetrafluoropyridine were studied using VT-diffusion NMR experiments. A halogen-bond-stabilized ITFP·Py complex was detected at 260 K in methylcyclohexane-d14 solution, indicating a halogen-bond-driven aggregation process before crystallization occurs.