Answer

The recipients of interest money are the poor and destitute. Some scholars have said that one may use the interest money to make toilets for the poor or to repay an interest based loan. (Raddul Muhtar p.553 v.9 & Jadeed Fiqhi Masaail p.406 v.1)

With regards to your question it will not be permissible to use interest money to print leaflets for charity events like the one mentioned in question.

Only Allah Knows Best