3 Responses to use at work instead of "I don't know"

A) I'm not sure I'm the best person to answer that but, I can connect you to the right person.

OR

A.1) I'm not sure but, I can find out. and let you know.

B) Here's what I know _______ however, I am not sure of _________

C) I don't have the right information now, let me look into it and get back to you by end-of-day.

Keep it honest, short, and brief. I use these lines when I am uncertain about concepts or information. It shows your manager that you are willing to take an initiative to learn and revert to them.