I'm confused on how to get a snippet of elisp to work. I'm trying to do

(setq org-refile-targets `(((concat dropbox-dir "/Org/archive.org") :maxlevel . 1))) 

I want emacs to execute the concat before the setq essentially, so the value of org-refile-targets becomes

(("~/[USER]/Dropbox/Org/archive.org" :maxlevel . 1)) 

What is actually happening is that emacs is storing org-refile-targets as

(((concat dropbox-dir "/Org/archive.org") :maxlevel . 1)) 

Which causes a type error whenever I run org-refile

I'm quite new to elisp, so it's definitely me not understanding how this works. What am I doing wrong?