Functional metal-organic molecules and materials derived from rigid and flexible P-N scaffolds

Employing phosphoramide ligands of formula, (RNH)(3)PO in reaction with Pd(OAc)(2), a facile route to access the highly basic trianions, [(RN)(3)PO](3-) ((X)(3-)) analogous to PO43- ion were developed. The (X)(3-) ligand, containing a central binding group, acts as a rigid cis-blocking ligand and stabilizes trimeric or prismatic Pd(II) clusters of formula {Pd3X(OAc)(3)}(1 or 2). Further, the trinuclear (Pd3X)(3+) motifs were utilized as supramolecular synthons for obtaining neutral cluster cages for Pd(II) ions in tetrahedral and cubic topologies via a bridging ligand substitution strategy. In contrast, phosphoramides containing peripheral metal binding groups provide a flexible ligand platform and yield multi-metallic assemblies in various dynamic architectures. By using pyridyl functionalized flexible dipodal phosphoramide ligand (L) we were able to generate interesting examples of centrosymmetric and noncentrosymmetric {(CuL2)-L-II}(n) frameworks. Investigation of the electric field-dependent polarization (P-E loop) of the noncentrosymmetric {(CuL2)-L-II}(n) frameworks leads to the observation of a potentially ferroelectric behavior in them that are governed by the counter anions and topology of the framework.