Acceptor number of halogenated solvents and its potential as a criterion for the ability of halogen bonding as a specific solvent effect using the 31P NMR chemical shift of triethylphosphine oxide as a probe

► Acceptor number relates positively to the halogen bonding energy. ► Acceptor number can acts as a criterion for the ability of halogen bonding. ► Acceptor number of CCl4 implies it can act as a halogen bonding donor in solution. ► The research is significant for more deeply understanding the solvent effects.