Facile synthesis of two new hexa-/octa-nuclear silver clusters and investigation of their optical features

Two new silver clusters, [Ag6(PhC C)2(bpy)4(NO3)4] (1), bpy = 2,2′-bipyridine, Ag8(Phen)4(NEA)8(CH3CN)2 (2), NEA = naphthalene acetic acid, were synthesized with assistance of ultrasonic irradiation and their unique structure investigated by single-crystal X-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction analysis (PXRD) and Ultraviolet–visible spectrum (UV–Vis). Thermal stability of the clusters were studied through thermogravimetric analysis (TGA). The photoluminescence analysis of 2 was also carried out. Clusters 1 and 2 show the absorption bands at λmax in the range 200–380 nm and 310 nm, respectively. The band gap widths for clusters are 3.05 eV and 3.20 eV. The Ag…Ag contact range in the cluster 1 is 2.7211(4) A–3.1102(3) A and for the cluster 2 is 2.867–3.047 A.