What instrument should I use to secure loan through property

[Jin Kilomana]

Hi. I am lending friends $30k to buy property and I want my loan to be secured by a promissory note (with a due date I can choose later with 1 month notice) which is secured by a deed on that property. There will be no monthly payments to me. Pretty basic stuff. However, I also want first right to buy the property at any time I choose for 30k (the money they own me) even if the value of the property has gone up a lot. Is there an elegant way to do this? Can I work this into the proimissory note perhaps? Thank you much