How do I search based on a contact date field please?

My date field is called "Contact Created"

I have tried:

Using php, I have tried:

$datetime = date('m/d/Y H:i:s', strtotime("-1 day"));

$search_criteria = '(Contact Created:' . $datetime . ')';

But it does not work!

Also, is there anyway to get the results of a custom view, as that would be another great way to get today's contacts.