Hi @topgummy,

I’m not sure if this is the best way to do it, but here’s an idea. You would have to create a profile property for subscribers who have not placed an order, then use that profile property to show the content. For exmaple:

Create a text profile property of: Placed Order

Export a list of subscribers who have not paced an order, then re-import them with the profile property set to: No

Then, in the block you want to show, use this logic:

person|lookup:'Placed Order' == 'No'

If you don’t want to create profile properties, here is another idea:

Create a segment of customers who haven’t placed an order.
Duplicate your campaign email, and add the block with the coupon in the duplicate email only. 
Send the original campaign to your subscribers, but exclude the segment that hasn’t purchased.
Send the duplicate campaing to the segment that hasn’t purchased.

Hope all this makes sense, let me know if I can explain further.

Good luck!