A Supramolecular Derivative of a Nanoporous Molybdenum Oxide Based Inorganic Keplerate with Self‐Defocusing Nonlinear Optical Properties

Abstract

Abstract A new derivative of the highly charged inorganic Keplerate of the type {pentagon} 12 {linker} 30 ≡ {(Mo)Mo 5 O 21 (H 2 O) 6 } 12 {Mo 2 O 4 (SO 4 )} 30 with the formula (NH 4 ) 28 (NH 2 CHNH 2 ) 6 Gd 3 [{(NH 2 CHNH 2 ) 20 + Gd 3 + (H 2 O) 50 } ⊂ {(Mo VI )Mo VI 5 O 21 (H 2 O) 6 } 12 {Mo V 2 O 4 (SO 4 )} 30 ] · ca.250H 2 O was isolated and characterized by elemental analysis, IR and UV/Vis spectroscopy, single‐crystal X‐ray analysis, and magnetic susceptibility measurements. Three Gd 3+ ions are found inside the internal cavity of the capsule. The coordination sphere of each Gd 3+ ion is completed by the oxygen atoms of SO 4 groups that act as bidentate ligands to a {Mo 2 } linker and by the oxygen atoms of the encapsulated new two‐shell underoccupied [{H 2 O} 60+20 + {H 2 O} 20 ] water cluster that acts as polydentate ligand. Twenty HC(NH 2 ) 2 + cations interact with the twenty {Mo 9 O 9 } pores through hydrogen bonds between the O and H atoms of the two NH 2 groups, which demonstrates a surface supramolecular chemistry. Of importance, a third‐order nonlinear optical investigation, using the Z‐scan technique, shows for the first time that the derivative demonstrates a strong self‐defocusing third‐order nonlinear optical effect with large third‐order nonlinear optical susceptibility. This observation implies that these unique inorganic Keplerates and their derivatives might find applications in nonlinear optical materials science.