tmux new-window command plus argument including spaces - bash var

I'm trying to execute a command on a new tmux window. A simple console/terminal pdf reader. The script needs argument, a PDF file, the file name may include spaces. I've tried this:

#!/bin/bash

tmux new-window "pdftotext -layout -nopgbrk "${1}" - | less"

It works on files without spaces, eg 1.pdf. I've tried sh instead of bash, $1, "$1" instead of "${1}", no effect.