Gold(I), Phosphanes, and Alkynyls: The Perfect Allies in the Search for Luminescent Compounds

Abstract

A family of mixed phosphane/alkynyl gold(I) complexes was prepared by addition of PPh3 or PPh2py to suspensions of the polymeric species [Au(C≡CR)n] [R = Ph, 2‐pyridyl (py)] and [Au2{C≡C(CH2)3C≡C}]n. The resulting complexes are luminescent both at room and low temperature, in solution and in the solid state. The emissions are assigned to intraligand transitions associated with the C≡C moieties or related to 3[σ(Au–P)→π*(C≡Cpy)] transitions. The crystal structure of dinuclear complex [Au2{C≡C(CH2)3C≡C}(PPh2py)2] shows the presence of dimers stabilized by intermolecular aurophilic interactions.

Effect of Gold(I) on the Room‐Temperature Phosphorescence of Ethynylphenanthrene

“…The Au−C and C≡C distances and P‐Au‐C and Au‐C≡C angles (Table 1) are in the usual ranges for Au I alkynyl complexes [28, 31–41] . Linear coordination of the phenanthrene ligands at the Au I centers is observed, with P‐Au‐C angles of 172.6–179.0°.…”

Luminescent phosphine gold(I) alkynyl complexes. Highlights from 2010 to 2018

“…The lower-energy absorptions around 300 nm correspond to σ→π transitions from the Au-P bond to the antibonding orbitals of the aromatic rings. [15]…”

“…PPh 3 (31a), PPh 2 py (31b) [15] PEt 3 (32a), PCy 3 (32b), P t Bu 3 (32c), PPh 3 (32d), PTA (32e) [37] P(p-tol) 3 ( 33) [38] PPh 3 (34) [39] PPh 3 (35) [39]…”

“…H 2 N dppa (50a), dppet (50b), dppe (50c), dppp (50d) [16] N dppe (51) [15] N dppm (52a), dppb (52b); dcypm (52c), dcypb (52d) [49] dppe (53a), dppp (53b) [50] dppb (54a), dpppent (54b), dpph (54c) [58] dppe (55a), dppp (55b) [50] N N dppe (56a), dppp (56b) [50] Ph dppz (57a), dpbp (57b), dpib (57c)…”

“…The corresponding fluorescence or phosphorescence assignment is based on the Stokes' shift, lifetime measurements and/or effect of oxygen in the recorded emission intensity and supported by DFT calculations. In some cases,[15,[23][24][25][26] the vibronically structured emission band with progressional spacings of 1400-2000 cm -1 are also indicative of an intraligand origin.Delayed Fluorescence (DF)[27] was also recorded by C.-M. Che group for 21, 22 and 24 with luminescent lifetimes in the order of microseconds [28]. A carefully photophysical study determines that two different mechanisms for DF can be involved being triplettriplet annihilation (TTA) or germinate electron-hole pair (GP) recombination [29].…”