Highly phosphorescent organometallic nanomaterials of the polymeric double salts [Au(NHC)(2)][M(CN)(2)] (NHC = N-heterocyclic carbene, M = Au or Ag) with emission quantum yields of up to 90% were prepared from simple precursors, namely, [Au(NHC)(2)]Cl and K[M(CN)(2)], by a facile, modular protocol with water as the benign solvent. These functional nanostructures were fully characterized and investigated by various spectroscopic and microscopic techniques, and diffraction analysis. The role played by the extended metallophilic d(10)...d(10) interactions in the anisotropic growth and phosphorescence of these quasi-2D polymeric nanostructures has been evaluated. One of the polymeric organometallic complexes has been demonstrated to be a blue light-emitter in a solution-processable OLED.