はっきりに means clearly but I'm not sure about はっきりとは and what's the difference between both.
Thanks in advance.
Check the word class of はっきり. From jisho.org:
はっきり is an adverb that optionally takes と. はっきりに is always ungrammatical because it's not a na-adjective in the first place.
は in はっきりとは知らない is a contrast marker. In this case, this は implies that the speaker does not know much about the matter, but he at least vaguely knows about it.
はっきり(と)知らない can mean "I absolutely know nothing", but usually まったく知らない or 全然知らない is used for this meaning.