Synthesis and characterization of platinum (II) di-ynes and poly-ynes incorporating ethylenedioxythiophene (EDOT) spacers in the backbone


Muhammad S. Khan, Mohammed K. Al-Suti, Hakkikulla H. Shah, Said Al-Humaimi,
Fathiya R. Al-Battashi, Jens K. Bjernemose, Louise Male, Paul R. Raithby, Ning Zhang, Anna Köhler
and John E. Warrend

Dalton Tans., 40 (2011) 10174

A series of trimethylsilyl-protected di-alkynes incorporating 3,4-ethylenedioxythiophene (EDOT) linker
groups Me3Si–C C–R–C C–SiMe3 (R = ethylenedioxythiophene-3,4-diyl 1a, 2,2¢-bis-3,4-
ethylenedioxythiophene-5,5¢-diyl 2a, 2,2¢,5¢,2¢¢-ter-3,4-ethylenedioxythiophene-5,5¢¢-diyl 3a) and the
corresponding terminal di-alkynes, H–C C–R–C C–H 1b–2b has been synthesized and characterized
and the single crystal X-ray structure of 1a has been determined. CuI-catalyzed dehydrohalogenation
reaction between trans-[(Ph)(Et3P)2PtCl] and the terminal di-alkynes 1b–2b in iPr2NH/CH2Cl2 (2 : 1
mole ratio) gives the Pt(II) di-ynes trans-[(Et3P)2(Ph)Pt–C C–R–C C–Pt(Ph)(Et3P)2] 1M–2M while
the dehydrohalogenation polycondensation reaction between trans-[(nBu3P)2PtCl2] and 1b–2b (1 : 1 mole
ratio) under similar reaction conditions affords the Pt(II) poly-ynes trans-[Pt(PnBu3)2–C C–R–C C-]n
1P–2P. The di-ynes and poly-ynes have been characterized spectroscopically and, for 1M and 2M, by
single-crystal X-ray which confirms the “rigid rod” di-yne backbone. The materials possess excellent
thermal stability, are soluble in common organic solvents and readily cast into thin films. Optical
absorption spectroscopic measurements reveal that the EDOT spacers create stronger donor-acceptor
interactions between the platinum(II) centres and conjugated ligands along the rigid backbone of the
organometallic polymers compared to the related non-fused and fused oligothiophene spacers.