Synthesis of Two Neutral Silver Alkynyl Nanoclusters by a Single Divalent Tetrahedral Anion Template and a Study of Their Optical Features.

ABSTRACT

The synthesis of nanoclusters from simple structural units is usually a challenging process because of the complexity and unpredictability of the self-assembly process of these types of compounds. Herein, two new neutral 19-nuclearity silver nanoclusters based on alkynyl ligands with the formulas [(CrO4)@Ag19(C≡CtBu)8(Ph2PO2)6(tfa)3(CH3OH)2] (1) and [(SO4)@Ag19(C≡CtBu)8(Ph2PO2)6(tfa)3(CH3OH)2] (2), in which tfa = trifluoroacetate, were synthesized, and their structures were investigated by single-crystal and powder X-ray diffraction, electrospray ionization mass spectrometry, elemental analyses, and Fourier transform infrared spectroscopy. The surface ligands of Ph2PO2H and trifluoroacetate were assembled through hydrogen bonding, metal-aromatic interactions, and coordination bonding around 19 silver atoms as the metal skeletons of the nanoclusters. Sulfate and chromate anions, as a template within the metal skeleton of clusters through bonding with silver atoms, stabilized the structure. In addition, the UV-vis absorption spectroscopy, luminescence properties, and thermal stability of the nanoclusters were investigated.