The problem turned out to be that the path to pdflatex was being defined in my $HOME/.profile. I thus changed the cronjob to:
* * * * * . $HOME/.profile; bash .../cron.sh 2>&1 > .../cron.log in accordance with http://unix.stackexchange.com/a/27291/37050https://unix.stackexchange.com/a/27291/37050.