Gold(I)-Coordination Triggered Multistep and Multiple Photochromic Reactions in Multi-Dithienylethene (DTE) Systems

Abstract

The preparation, characterization, and photochromic properties of a mononuclear gold(I) complex (1oo) with two identical DTE-acetylides and a dinuclear gold(I) complex (2ooo) with both DTE-acetylide and DTE-diphosphine are described. Both gold(I) complexes exhibit multistep and multiple photocyclization/cycloreversion reactions. Particularly, four-state and four-color photochromic switch is successfully achieved for the dinuclear gold(I) complex upon irradiation with appropriate wavelengths of light. In contrast, fully ring-closed form is unattained through multiple photocyclization for the two corresponding model organic compounds coupling with the same DTE units as gold(I) complexes but without gold(I)-participation. It is demonstrated that coordination of gold(I) ion to DTE-acetylides exerts indeed a crucial role in achieving stepwise and selective photocyclization and cycloreversion reactions for both gold(I) complexes, in which the coordinated gold(I) atom acts as an effective "barrier" to prohibit intramolecular energy transfer between multi-DTE moieties.

Light-Driven Chiral Switching of Supramolecular Metallacycles with Photoreversibility

“…We also investigated the absorption spectra to rule out the possibility of a step-by-step phototransformation, which would result in an obvious absorption red-shift of newly appeared peaks in the visible region. [59][60][61] In the absorption spectra of metallacycles, the absorption in the visible region only exhibited the intensity enhancement along with a clear isosbestic point during the UV-light-triggered process. Indeed, we did not observe any obvious peak change or shift of absorption bands in the region from 480-630 nm ( Figures 2B and S23).…”

Regulation of Charge Delocalization in a Heteronuclear Fe2Ru System by a Stepwise Photochromic Process

“…The distinct redshift of the ring-closure absorption maximum from l = 666 to 691 nm suggests that a stepwise photocyclization is substantially exhibited following the conversion of 2 oo!2 co!2 cc. [62][63][64][65][66] The photocyclization for 2 co!2 cc is much slower than that for 2 oo!2 co; this implies that ring closure of the second step is highly impeded by that of the first step due to substantial energy transfer in 2 co from ring-opened L1 o to ring-closed L1 c across the {Ru(dppe) 2 } moiety. The redshift of the ring-closing absorption maximum (ca.…”

“…14-18 nm) described previously. [62][63][64][65][66] On the other hand, complex 2 cc reverts to the original state, 2 oo, upon irradiation at l = 672 nm through stepwise cycloreversion following the conversion of 2 cc!2 co! 2 oo ( Figure S5 in the Supporting Information).…”

“…[53][54][55][56][57][58] Nevertheless, when the oo species is irradiated by UV light, stepwise photocyclization to attain all possible isomers is mostly unattainable because of facile energy transfer from a higher level of the ring-open moiety to a lower level of the ring-closed one in co or oc; [11,[59][60][61] thus prohibiting further formation of fully ring-closed form cc. In an effort to access all three photochromic isomers (oo, co, and cc) in a molecule containing two identical DTE moieties, it is revealed that the coordination of two DTE-acetylide moieties to a metal (Ru, [62,63] Pt, [64,65] or Au [66] ) center through metal-acetylide bonding is a feasible approach to achieve stepwise photochromic processes of ooÐcoÐcc. For further research, we wish to take advantage of such stepwise photochromic processes to regulate electronic or magnetic interactions to achieve photoswitchable optoelectronic performance in a stepwise mode.…”

Dithienylethene metallodendrimers with high photochromic efficiency

“…or organometallic spacers (Pt-acetylide, Ru-acetylide, or Au-acetylide, etc.) in these compounds [10][11][12][13][14][15][16][17][18] . It should be noted that, rapid energy transfer from the ring-open DTE to an adjacent ring-closed one would be favored instead of full photocyclization in the most cases 19 .…”