Viedma ripening is ad eracemizationp rocess that has been used to deracemize ar ange of chiral molecules. The method hast wo major requirements:t he compound needs to crystallize as ac onglomerate and it needs to be racemizable under the crystallization conditions. Although conglomerate formation can be induced in different ways, the number of racemization methods is still ratherl imited. To extend the scope of Viedma ripening, in the present research we applied UV-light-induced racemization in a Viedmar ipening process, and report the successful deracemizationo faB INOL derivative crystallizing as ac onglomerate. Irradiation by UV light activatest he target compound in combination with an organic base, required to promote the excited-state proton transfer (ESPT), leadingt hereaftert o racemization. This offers an ew tool towards the development of Viedma ripening processes, by using ac heap and "green"c atalytic source like UV light to racemize suitable chiral compounds.

The picture displays a population of racemic conglomerate crystals of a BINOL derivative undergoing deracemization through Viedma ripening, leading to the formation of enantiopure crystals. The combined use of UV light and an organic base is an essential prerequisite to allow the compound to continuously racemize in solution via an ESPT (excited state proton transfer) mechanism. This research represents the first successful Viedma ripening deracemization of a chiral compound with the use of a cheap and green source, such as UV light, as a racemization tool. More information can be found in the Full Paper by S. B. Tsogoeva, E. Vlieg et al. on page 839.