USE OF LINKER FOR PREPARATION OF MISSING SOLID-STATE PHOTOPRODUCTS - HEAD-TO-HEAD PHOTODIMERIZATION OF ANTHRACENE-9-PROPIONIC ACID IN ITS CRYSTALLINE DOUBLE SALT WITH CYCLOHEXANE-L,2-DIAMINE

In order to realize the uncommon head-to-head photodimerization of 9-s ubstituted anthracenes rather than the common head-to-tail photodimeri zation, a regiochemical control of the reaction through use of supramo lecular linkers has been attempted in the solid state. Thus, crystalli ne double salts are prepared from anthracene-9-propionic acid (9-AP) a nd 1,2-diamines such as ethylenediamine (en), racemic or optically act ive (R,R)- or (S,S)-trans-cyclohexane-1,2-diamine (t-chxn), and cis-cy clohexane-1,2-diamine (c-chxn), and these salts are irradiated in the solid state. The 1,2-diamine is used as a linker molecule to connect t wo molecules of 9-AP by formation; of a double salt. Like the previous ly published head-to-head photodimerization of (E)-cinnamic acids, the head-to-head photodimer of 9-AP is successfully produced from solid-s tate photolysis of the double salts of gauche 1,2-diamines, i.e. (R,R) - and (S,S)-t-chxn and c-chxn. The crystal structure for the low-photo reactivity double salt with (+/-)-t-chxn has been successfully solved.