New compounds and coordination polymers with highly polarizable metals (M = Hg, Pb) and 2,2′;6′2′-terpyridine (terpy) and 2,6-bis(benzimidazol-2-yl)pyridine (bbp) ligands have been synthesized and characterized for their photo-physical and optical properties. Hg(L)(CN)2 (L = terpy, bbp) exhibit π-stacking interactions, which form a supramolecular alignment of the planar terpy and bbp units. Pb(terpy)X2[Hg(CN)2]0.5 (X = Cl, Br) generate one-dimensional coordination polymers through bridging Hg(CN)2 linkers and hydrogen-bonding interactions. All of the metal centres have very distorted coordination geometries. Hg(L)(CN)2 (L = terpy, bbp) and Pb(terpy)Br2[Hg(CN)2]0.5 show terpy or bbp based emission. The materials are very birefringent, with Δn ranging from 0.37(2) to 0.45(2). The magnitude of the observed birefringence depends on the orientation of the highly polarizable terpy and bbp units in relation to the viewing axis of the crystals. These materials represent rare examples of multifunctional emissive and birefringent systems.
The synthesis, characterization, X-ray structures and luminescence of a series of lanthanide coordination polymers containing anionic gold(I) iso-maleonitriledithiolate units ([Au 2 (imnt) 2 ] 2À ; {Au 2 [S 2 C=C(CN) 2 ] 2 } 2À ) are described. Crystals of ( n Bu 4 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 ] 2À units and DMF-saturated Ln(III) cations. The Ln=Gd and Tb systems are emissive, with λ 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 ( n Bu 4 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 ( n Bu 4 N)Tb(DMF) 5 [Au 2 (i-mnt) 2 ] 2 powder was exposed to pyridine, resulting in emission with λ max = 625 nm. Structure-property correlations show that the emission maximum is influenced not only by the intermolecular AuÀ Au distances but also by a combination of the AuÀ AuÀ Au angles and other geometric factors in the [Au 2 (i-mnt) 2 ] units.
The Front Cover shows the luminescence turn‐on response of a gold(I)‐containing dithiolate complex after exposure to dimethylformamide (DMF) vapor. The switch represents the toggleable nature of this response, as the complex is non‐luminescent in the absence of DMF. The intensity of the luminescence depends on the concentration of DMF present. The structure of the luminescent gold(I) dithiolate is depicted, with chains affixed to the gold(I) atoms, symbolic of the aurophilic interactions binding each monomeric unit into polymeric one‐dimensional chains. Notably, in these materials, the observed emission energy may be dependent on more than just the length of the aurophilic interactions. More information can be found in the Research Article by D. B. Leznoff and co‐workers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.