New Structural Motifs, Unusual Quenching of the Emission, and Second Harmonic Generation of Copper(I) Iodide Polymeric or Oligomeric Adducts with Para-Substituted Pyridines or trans-Stilbazoles

The structural, emissive, and nonlinear optical properties of new CuI adducts with para-substituted trans-stilbazolic and pyridinic ligands are reported. Single-crystal X-ray diffraction results indicate that the para-substituent on the organic ligand greatly influences the structural motif by its steric (tert-butyl), electronic/steric (dimethylamino), or bridging-donor (cyano) properties so that two absolutely new structural motifs, polymeric and oligomeric, are found when trans-stilbazole and pyridine carry a dimethylamino group in the para-position. In addition, a surprising photoemission behavior is observed, being the solid-state emission of [CuI(trans-4-stilbazole)]n, [CuI(trans-4'-(dimethylamino)-4-stilbazole)]n, and [CuI(4'-tert-butyl-4-stilbazole)]n totally quenched. In the case of the noncentrosymmetric CuI adduct of trans-4'-(dimethylamino)stilbazole a discrete second harmonic generation (SHG) occurs.