Quoting from Journal of Chemical Research, Synopses (2003), (5), 260-261,
"Thermochromic ethylenes were obtained by the reaction of anthrone with tricyclic ketones or terephthalaldehyde in DMF in the presence of tert-BuOK under reflux (8 h) or under microwave irradn. (10 min). "
The tricyclic ketone they use is 9,10 Anthraquinone.
So basically:
You get anthrone, 9,10 anthraquinone and t-BuOK in DMF and reflux it for 8 hours and you should get bianthrone