Modulation of the conductance in platinum(ii) bis(acetylide) molecules through “gating” metal ions?

Journal of Materials Chemistry C Pub Date: 2019-05-09 DOI: 10.1039/C9TC02100K

Abstract

Mononuclear platinum(II) complex trans-Pt(PPh3)2(C[triple bond, length as m-dash]CC6H4SMe-4)2 (1-Pt) and its derivatives [PtM(dppm)2(C[triple bond, length as m-dash]CC6H4SMe-4)2]+ (dppm = bis(diphenylphosphino)methane; M = Au, 2-PtAu; Ag, 2-PtAg; Cu, 2-PtCu) with “mono-gating” metal ions and [PtM2(dpmp)2(C[triple bond, length as m-dash]CC6H4SMe-4)2]2+ (dppm = bis(diphenylphosphinomethyl)phenylphosphine; M = Au, 3-PtAu2; Ag, 3-PtAg2) with “dual-gating” metal ions were elaborately designed to modulate the conductance in platinum(II) bis(σ-acetylide) complexes through “gating” d10 metal ions. The single-molecule conductance measurements by the STM-BJ technique demonstrate that the conductance follows 10?4.5 (1-Pt) > 10?4.8 (2-PtAu) > 10?4.9 (2-PtAg) > 10?5.0 (2-PtCu) > 10?5.1 (3-PtAu2) > 10?5.3 (3-PtAg2) G0. Undoubtedly, charge transport along the platinum(II) bis(σ-acetylide) backbone is progressively restricted by introducing one to two “gating” M ions to the mononuclear platinum(II) molecule. As revealed by X-ray crystallography, the “gating” d10 metal ion is substantially bound to the acetylide and in fact the M–acetylide bonding is progressively enhanced in the order Au–Cacetylide → Ag–Cacetylide → Cu–Cacetylide, which coincides with a progressive decrease in the conductance as 10?4.8 (2-PtAu) > 10?4.9 (2-PtAg) > 10?5.0 (2-PtCu) G0. The M–acetylide coordination blocks the charge transport along the platinum(II) bis(σ-acetylide) backbone so that the d10 metal ion behaves as a resistor to suppress the conductance. Theoretical studies confirm that the “gating” metal ions control the HOMO energy, which is lowered by the increased d orbital contribution of “gating” metal ions through Pt–M interactions.

Graphical abstract: Modulation of the conductance in platinum(ii) bis(acetylide) molecules through “gating” metal ions
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