Multidisciplinary study on the hydrogelation of the digold(i) complex [{Au(9N-adeninate)}2(μ-dmpe)]: optical, rheological, and quasi-elastic neutron scattering perspectives

Abstract

Herein, the syntheses of [{Au(⁹N-adeninate)}₂(μ-dmpe)] (2, dmpe = 1,2-bis(dimethylphosphino)ethane) and its chloride precursor [(AuCl)₂(μ-dmpe)] (1) are described. X-ray diffraction of 2 reveals a short intramolecular aurophilic interaction (2.9921(7) Å), which is present even when 2 crystallizes from its own hydrometallogel (3.0512(3) Å). This interaction is demonstrated by TD-DFT calculations to be participating in the intense blue phosphorescence that 2 displays in the solid state and, presumably, also in the hydrogel one. Finally, as complex 2 could be understood as a formal dimer of LMWG [Au(⁹N-adeninate)(PMe₃)] (3), the hydrogelation of the former is examined, with special regard to its optical, rheological and quasi-elastic neutron scattering properties, which are compared to those of 3.