ORIGINAL PAPER Synthesis and Characterizations of Keplerate Nanocapsules Incorporating L- and D-Tartrate Ligands Mouhamad Awada 1 • Se ´bastien Floquet 1 • Je ´ro ˆme Marrot 1 • Mohamed Haouas 1 • Sara P. Morcillo 2 • Christophe Bour 2 • Vincent Gandon 2 • Vincent Coeffard 1 • Christine Greck 1 • Emmanuel Cadot 1 Received: 30 September 2016 Ó Springer Science+Business Media New York 2017 Abstract Five new tartrate-containing Keplerate compounds have been synthesized and characterized in the solid state and in solution. These characterizations evi- denced the total replacement of inner sulfate ligands by L- or D-tartrate ligands in aqueous medium under heating during several days. To our knowledge these compounds correspond to the first Keplerate molecules incorporating chiral ligands. The 1 H NMR studies supported by X-ray crystallographic analysis are consistent with the coordination of 24–30 tartrates within the Mo 132 capsule which are located in close vicinity. The NMR signals of the encapsulated ligands appear particularly broad which precludes the use of advanced NMR methodologies but the solid state NMR provided further characterization of ligand substitution within the capsule by carboxylates. To our knowledge it is the first time that a solid state NMR study of a Keplerate is reported in the literature. Keywords Keplerate Á Hollow molecules Á Tartaric acid Á Tartrate Á Solid state NMR Introduction Polyoxometalates (POMs) are often described as metal-oxide clusters with structural, electronic and functional versatility. POMs provide striking molecular arrangements resulting from self-assembly processes and can include almost all the elements of the periodic table. Consequently, much current activity in POMs & Se ´bastien Floquet sebastien.floquet@uvsq.fr 1 Institut Lavoisier de Versailles, CNRS UMR 8180, Univ. Versailles Saint Quentin, Universite ´ Paris-Saclay, 45 av. des Etats-Unis, 78035 Versailles Cedex, France 2 Institut de Chimie Mole ´culaire et des Mate ´riaux d’Orsay, CNRS UMR 8182, Univ. Paris-Sud, Universite ´ Paris-Saclay, ba ˆtiment 420, 91405 Orsay Cedex, France 123 J Clust Sci DOI 10.1007/s10876-017-1171-7