The Twelfth Solved Structure of ROY: Single Crystals of Y04 Grown from Melt Microdroplets

How many more polymorphs of ROY remain undiscovered

“…thiophenecabonitrile in Figure 1, which is often called ROY due to its vividly-colored red, orange, and yellow crystals, is currently the most prolific organic polymorph former known. Twelve fully characterized ROY crystal structures have been discovered in the past twenty-five years: Y, 19,20 ON, 19,20 R, 19,20 OP, 20 YN, 20 ORP, 20 YT04, 21 Y04, 21,22 R05, 23,24 PO13, 25,26 R18, 27 and Y19. 26 The structure for a thirteenth RPL polymorph 28 has been proposed, 29 but it has not yet been definitively characterized.…”

The unexpected discovery of the ninth polymorph of tolfenamic acid

“…Although polymorphism is common, there is only a limited number of compounds with over four characterised forms. 18 Compounds with more than eight known polymorphs include ROY, [19][20][21][22] aripiprazole, [23][24][25][26] flufenamic acid 18 and galunisertib. 27 Matzger et al proposed the concept of "polymorphophore" 28 which is a chemical substructure likely to induce rich polymorphic behaviour in a compound.…”

Direct evidence for distinct colour origins in ROY polymorphs

“…The 'ROY' family of crystal structures, crystallising from the 5methyl-2-[(2-nitrophenylamino)]-3-thiophenecarbonitrile compound, is numerous, [1][2][3] with the most recent literature citing the discovery of the thirteenth form, 4 making it the most polymorphic material in the Cambridge Structural Database (CSD) at the time of writing, ahead of other rivals including galunisertib (eight forms), the structurally-similar ufenamic acid (ten), and aripiprazole (twelve). The ROY molecule exhibits signicant exibility about the s SCNC dihedral angle between the crystal structures and, to a lesser extent, the s CNCC angle (shown in Fig.…”