Alkynylgold(I) C₃‐Chiral Concave Complexes: Aggregation and Luminescence

Abstract

Chiral gold(I) acetylide trinuclear complexes 1–3 based on the cyclotribenzylene platform and terminal PR3 ligands (R=Ph, Et, and Cy, respectively), were characterized and their light emission studied. They exhibited long‐lived blue phosphorescence in CHCl3 and a weak fluorescence in the UV. In MeOH/CHCl3 mixtures of >1:1 volume ratio, 1 and 2 exhibited a new emission band at ca. 540 nm that developed at the expense of the UV emission. DLS studies demonstrated the presence of molecular aggregates of Ø 30–80 nm. The green emission observed in MeOH‐rich solvent mixtures was therefore induced by aggregation, and could originate from Au⋅⋅⋅Au interactions. The AIE spectrum of 3 was observed only in solutions containing 99 % of MeOH, and correlated with its solid state emission. The AIE profiles of the enantiomers of 1 differed from that of rac‐1, suggesting that the latter is a true racemate.

Cyclotribenzylene alkynylgold(i) phosphine complexes: synthesis, chirality, and exchange of phosphine

“…CTB(OMe,C 2 H) was resolved into its enantiomerically pure forms by HPLC on a chiral stationary phase, which provided (−)-CTB(OMe,C 2 H) followed by (+)-CTB(OMe,C 2 H). The resolution of CTB(H,C 2 H) by the same means was reported earlier, 36 and afforded also (−)-CTB(H,C 2 H) first, followed by (+)-CTB(H,C 2 H). Polarimetric data are collected in Tables S6 ( C1–C3 ) and S7 ( C4–C6 ) †.…”

“…1. The complexes derive from the ethynyl γ′-substituted cyclotribenzylenes CTB(H,C 2 H) 36 and CTB(OMe,C 2 H), 37 both displaying the C 3 symmetry, and the latter differing from the former by the methoxy substituents in γ position. Two groups of complexes were therefore synthesized and investigated, depending on the precursor CTB: C1 , C2 , and C3 derive from CTB(H,C 2 H), and C4 , C5 , and C6 derive from CTB(OMe,C 2 H).…”

“…We also included the data that we had obtained for CTB(H,C 2 H). 36 The DOSY spectra were acquired at two concentrations for each of the three complexes. We considered two models for the shape of the C n dimers, either the oblate ellipsoid or the cylinder.…”

“…Unit: 10 10 m 2 s −1 .cHydrodynamic radius (Å), see footnote of Table S5† for the details of calculation.dHydrodynamic volume .e Ref. 36.…”

“…The resolution of the CTB complexes by chiral HPLC was not as straightforward, because in most cases the compounds were prone to partial decomposition upon elution through the column. Separation of the enantiomers by chiral HPLC was restricted to C1 , affording (+)- C1 and (−)- C1 , as reported earlier; 36 C5 , which afforded (−)- C5 then (+)- C5 ; and C6 , which afforded (+)- C6 then (−)- C6 . However, the enantiopurity of (+)- C6 was not satisfactory.…”