Polypyridyl-functionalizated alkynyl gold(i) metallaligands supported by tri- and tetradentate phosphanes

Abstract

A series of alkynyl gold(I) tri and tetratopic metallaligands of the type [Au 3 (CuC-R) 3 (μ 3 -triphosphane)] (R = 2,2'-bipyridin-5-yl or C 10 H 7 N 2 , 2,2':6',2''-terpyridin-4-yl or C 15 H 10 N 3 ; triphosphane = 1,1,1-tris(diphenylphosphanyl)ethane or triphos, 1,3,5-tris(diphenylphosphanyl)benzene or triphosph) and [Au 4 (CuC-R) 4 (μ 4 -tetraphosphane)] (R = C 10 H 7 N 2 , C 15 H 10 N 3 ; tetraphosphane = tetrakis(diphenylphosphanylmethyl)methane or tetraphos, 1,2,3,5-tetrakis(diphenylphosphanyl)benzene or tpbz, tetrakis(diphenylphosphaneylmethyl)-1,2-ethylenediamine or dppeda) were obtained in moderate to good yields. All complexes could be prepared by a reaction between the alkynyl gold(I) polymeric species [Au(CuC-R)] n and the appropriate polyphosphane. An alternative strategy that required the previous synthesis of the appropriate acetylacetonate precursors [Au n (acac) n (μ n -polyphosphane)] ("acac method") was assayed, nevertheless only the polyacac derivatives The photophysical properties of the synthesized compounds were carefully studied and used as a probe of their possible use as multidentate ligands for Cu(I) and Zn(II). The UV-Vis speciation studies of the complexation reactions were conducted via metal titration and, in most cases the dangling units of the ligand were found to behave in a fairy independent manner. While in the case of Cu(I) multiple equilibria exist in solution a single complex is detected for Zn(II) under the conditions studied.

Influence of the Attachment of a Gold(I) Phosphine Moiety at the Upper Rim of a Calix[4]pyrrole on the Binding of Tetraalkylammonium Chloride Salts

“…In particular,t he introduction of gold(I) alkynyls ubstituents in the meso-aryl groupsw ould provide intrinsic luminescence properties to the receptors and their complexes. [17] In this sense, calix [4]arene receptors modified with alkynyl gold derivatives showedc hanges in their opticalp roperties upon cation binding. [18][19][20] In addition, this typeo fs ubstituents endow the supramolecularr eceptorsw itht he possibility to be involved in weak aurophilic interactions (Au···Au).…”

“…In particular, the introduction of gold(I) alkynyl substituents in the meso ‐aryl groups would provide intrinsic luminescence properties to the receptors and their complexes . In this sense, calix[4]arene receptors modified with alkynyl gold derivatives showed changes in their optical properties upon cation binding .…”

A Versatile Approach to Access Trimetallic Complexes Based on Trisphosphinite Ligands

“…We have focused on a family of trisphosphinites derived from the condensation of commercially available and affordable 1,1,1-tris(4-hydroxyphenyl)ethane, with several chlorophosphines under basic conditions in good yields (63-84%; Scheme 1). This method contrasts with traditional approaches for the preparation of trisphosphines, which require several synthetic steps and the use of aggressive reagents [9,[38][39][40][41][42]. The synthetic procedure is highly versatile and permits the incorporation of phosphines bearing both aliphatic and aromatic substituents, including sterically congested functionalities, such as the two xylyl (2,6-Me 2 -C 6 H 3 ) groups per phosphorus center in trisphosphinite 1b.…”

“…An additional advantage of phosphinites, compared to more traditional phosphines, is the easiness of the experimental procedures by which these ligands can be prepared. Polydentate phosphines are laborious to synthesize, often lack selectivity, and require the use of highly reactive reagents [9,[38][39][40][41][42]. In stark contrast, we report herein a simple and versatile method to prepare several tridentate phosphinites by common procedures [43], in one-step, and from commercially available reagents.…”

Dinuclear Diphosphine Complexes of Gold(I) Alkynyls, the Effects of Alkynyl Substituents onto Photophysical Behavior

“…Alkynyl‐phosphine gold(I) complexes based on mono‐ and polyphosphine ligands attract considerable attention due to their rich structural chemistry and unique photophysical properties, which are determined by the nature of the alkynyl ligands, formation of inter‐ and intramolecular aurophilic bonds and by spin‐orbit coupling (SOC), the latter being of particular importance for such heavy coordination center as gold atom. It is well documented that coordinated {C≡C–R} moieties containing various aromatic substituents play a key role in emission of these compounds because of the ligand π* orbitals involvement into emissive excited states of various nature: 1 IL(π–π*), 3 IL(π–π*), 3 MLCT, and 3 MMLCT. Depending on the nature of alkynyl ligand substituents the complexes of this type may display either phosphorescence or dual phosphorescence from the triplet excited states: 3 IL(π–π*), 3 MLCT, and 3 MMLCT.…”