3-[2,6-Bis(diethylcarbamoyl)pyridin-4-yl]-N-(tert-butoxycarbonyl)alanine methyl ester: a chiral tridentate ligand that causes a diastereomeric excess of its lanthanide complexes in solution.

L(4), or 3-[2,6-bis(diethylcarbamoyl)pyridin-4-yl]-N-(tert-butoxycarbonyl)alanine methyl ester, C(24)H(38)N(4)O(6), crystallizes in neat [010] laths stabilized by abundant intra- and intermolecular hydrogen bonds. The strongest of these form [010] chains of molecules, thus rationalizing the fastest growth direction, while the slowest direction coincides with the normal to the (110) layers, which are linked by very weak hydrogen bonds. There exist two independent molecules, the distances and bond angles of which differ in a random manner only. The torsion and dihedral angles, however, differ so as to achieve optimal packing. The influence of the chiral group in the 4-position of the pyridine ring on the helical wrapping and on the ensuing diastereomeric induction is briefly discussed.