Structural and Photophysical Properties of (Phosphane)gold(I)‐Decorated 4,4′‐Diethynyl‐2,2′‐bipyridine Ligands

Abstract

Treatment of 4,4′‐diethynyl‐2,2′‐bipyridine with R3PAuCl (R = Ph, 4‐Tol, Et, iPr) leads to the formation of a family of (phosphane)gold(I)‐decorated 4,4′‐diethynyl‐2,2′‐bipyridine ligands. The solid‐state structures of the compounds are significantly affected by the change from aryl‐ to alkyl‐substituted phosphanes, whereas the progression from ethyl to isopropyl substituents leads to a subtle change in the packing that results in the propagation of two different polymeric chain motifs, both supported by close Au···Au contacts [3.1239(1) Å for R = Et, and 3.395(1) Å for R = iPr]. In CH2Cl2 solution, each of the compounds 1–4 is a dual emitter at room temperature. When the excitation wavelength is approximately 238 nm, the emission spectra of 1 and 2 exhibit new bands at 288 and 570 nm at the expense of the original emissions. The photodegradation is not inconsistent with the formation of gold nanoclusters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Photoactive building blocks for coordination complexes: Gilding 2,2′:6′,2″-terpyridine

“…For 1, the HMBC spectrum exhibited a cross-peak between the signal for H B3 and a poorly resolved signal at δ 102.3 ppm, and the latter was assigned to alkyne carbon C≡CAu. The resonance for the second alkyne 13 C nucleus was not observed in either 1 or 2, a feature that we have also reported for gold(I) phosphane 4,4'-diethynyl-2,2'-bipyridine derivatives [20].…”

“…When λ ex was at wavelengths higher than 230 nm, photodecay was much slower. We have not been able to determine the identities of the photodegradation products, but note that comparable decay and growth of bands in the emission spectra of gold(I) phosphane derivatives of 4,4'-diethynyl-2,2'-bipyridine are observed over time [20]. In particular, as 1 decays, the emission centred around 570 nm (Fig.…”

“…We have previously shown that coupling of 4,4'-diethynyl-2,2'-bipyridine and R 3 PAuCl in the presence of diisopropylamine and CuI yields gold(I) phosphanederivatized bpy ligands [20]. When this methodology was extended to the synthesis of gold(I) phosphane derivatives of 4'-ethynyl-2,2':6',2"-terpyridine, we found that it was more convenient to replace the organic base by NaOAc.…”

“…The luminescent properties of gold(I) species [13,14] and the ease of synthesis of gold(I) alkynyls make them attractive candidates for derivatization of other metal-binding domains such as pyridine [15][16][17][18][19], 2,2'-bipyridine (bpy) [16,20,21] and 2,2':6',2"-terpyridine (tpy) [21,22]. The combination of a luminescent gold(I) unit and a chelating ligand provides an approach to the design of metal ion sensors.…”

“…short Au...Au contact of around 3.00-3.20 Å) [23] are considered important in influencing their emissive behaviour [24,25]. Recently, we reported the solid-state structures of four bis(gold(I) phosphane)-decorated 4,4'-diethynyl-2,2'-bipyridines (Scheme 1) [20]. Changing the phosphane from PEt 3 to P i Pr 3 alters the packing, producing different polymeric chain motifs.…”