You cannot collect rent on any mortgaged property, even if you just purchased it.
If a player goes bankrupt to you and turns over mortgaged properties, the same "immediate 10%" rule applies. You must pay the 10% fee right away, then decide whether to pay off the principal or wait (incurring the extra 10% later). buying a mortgaged property in monopoly
When you acquire a mortgaged property through a trade or sale, you have two immediate options regarding the mortgage: You cannot collect rent on any mortgaged property,
You cannot build houses or hotels on any property in a color group if even one property in that group remains mortgaged. buying a mortgaged property in monopoly