Solid-state structure by X-ray and 13C CP/MAS NMR of new 6-acetyl-8-bromo-5-O-alkylamino-4,7-dimethylcoumarins

6-Acetyl-8-bromo-5-[2-(N,N-dimethylamino)ethoxy)-4,7-dimethylcoumarin (1) and 6-acetyl-8-bromo-5-[2-(N,N-diethylamino)ethoxy)-4,7-dimethylcoumarin (2) were synthesized using microwave conditions. Crystal of 1 was investigated using single-crystal X-ray diffraction at 296 K and 100 K. The crystal undergoes reversible order-disorder, temperature-driven phase transition. The high-temperature form contains two molecules in the asymmetric unit of which one moiety is disordered over two sites. The low-temperature phase is fully ordered and contains four molecules in the asymmetric unit. A complexity of the solid form of 1 is with an agreement with recorded C13 CP/MAS NMR spectrum indicating split of signals. The solid-state structures of 1 and 2 derived from 13C CP/MAS NMR spectra were also proposed.