Heterobimetallic Ln(III)-Containing Materials Based on One-Dimensional Aurophilic Chains of Gold(I) Dithiolate Dimers and Their Vapochromic Response to DMF

The synthesis, characterization, X-ray structures and luminescence of a series of lanthanide coordination polymers containing anionic gold(I) iso-maleonitriledithiolate units ([Au-2(i-mnt)(2)](2-); {Au-2[S2C=C(CN)(2)](2)}(2-)) are described. Crystals of ((Bu4N)-Bu-n)Ln(DMF)(8)[Au-2(i-mnt)(2)](2) (Ln=Gd, Tb, Eu) contain 1-D aurophilic chains of [Au-2(i-mnt)(2)](2-) units and DMF-saturated Ln(III) cations. The Ln=Gd and Tb systems are emissive, with lambda(max)=596 and 625 nm respectively, attributable to the aurophilic chains. The luminescence intensities and emission energies qualitatively correlate to the local concentration of DMF vapour, where emission-quenched ((Bu4N)-Bu-n)Ln(DMF)(5)[Au-2(i-mnt)(2)](2) is formed upon sample removal from a DMF atmosphere for 24 hours; the emissive species was regenerated by exposure to fresh DMF vapour. A similar turn-on luminescence effect was also observed when a quenched sample of ((Bu4N)-Bu-n)Tb(DMF)(5)[Au-2(i-mnt)(2)](2) powder was exposed to pyridine, resulting in emission with lambda(max)=625 nm. Structure-property correlations show that the emission maximum is influenced not only by the intermolecular Au-Au distances but also by a combination of the Au-Au-Au angles and other geometric factors in the [Au-2(i-mnt)(2)] units.

Automated summary

The synthesis, characterization, X-ray structures, and luminescence of a series of lanthanide coordination polymers containing anionic gold(I) iso-maleonitriledithiolate units were described. The crystals of ((Bu4N)-Bu-n)Ln(DMF)(8)[Au-2(i-mnt)(2)](2) (Ln=Gd, Tb, Eu) contain 1-D aurophilic chains of [Au-2(i-mnt)(2)](2-) units and DMF-saturated Ln(III) cations. The Ln=Gd and Tb systems exhibit emission, with lambda(max) of 596 nm and 625 nm, respectively.