Forget "no" and "not" for a second - they seem related, but it is a false comparison.
Instead, think about
"There is" vs. "There is not". These are related expressions but one is positive and one is negative.
Things are simple when the (reflexive) subject of the sentence is expressed positively.
For example, suppose the subject is "life".
There is (life on Mars).
There is not (life on Mars).
The complication is that sometimes the subject is expressed negatively.
Suppose the subject was "no life".
The verb-positive sentence remains the same.
There is (no life on Mars).
The verb-negative sentence has to change, though, because English (unlike Spanish) has rules against double negatives.
It is incorrect to say:
There is not (no life on Mars).
Instead, we say
There is not (any life on Mars).
Other examples of a negative subject becoming positive because the verb is negative:
There is no reason to agree with him. There is not any reason to agree with him.
There is no way out of this situation. There is not a way out of this situation.
There is no one alive who remembers him. There is not anyone alive who remembers him.
In each case, the "not" in "There is not" is part of the verb, making the verb negative, whereas the "no" is part of the subject, making the subject negative. So you can't really compare "there is no" with "there is not" - just remember that in English, you are not allowed to have both the verb and subject expressed negatively.
In 3, "any thing" should be replaced with the word "anything".
4 and 5 are grammatically correct but sound awkward.
In 6, "are" should be replaced with "is". After that replacement, it would be the most natural way for native speakers to say it.
Best Answer
They are both correct. It is a difference of register. Sentences with contractions such as don't are used in less formal contexts.
Though some have suggested a difference in emphasis, "Do they not know it?" is simply the usual word order in cases where the contraction don't has been avoided. By contrast, "Do not they know it?" sounds very awkward, although where a noun is used instead of a pronoun, both word orders are used:
Similarly, "Aren't I ..." usually expands to "Am I not ..." (I have never heard "Am not I ..." and it may be ungrammatical); "Isn't he ..." becomes "Is he not ...", and so on.