Impact of the Alkyne Substitution Pattern and Metalation on the Photoisomerization of Azobenzene-Based Platinum(II) Diynes and Polyynes

Rayya A. Al-Balushi, Ashanul Haque, Maharaja Jayapal, Mohammed K. Al-Suti, John Husband, Muhammad S. Khan, Jonathan M. Skelton, Kieran C. Molloy, Paul R. Raithby

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Trimethylsilyl-protected dialkynes incorporating azobenzene linker groups, Me3SiC ≡ CRC ≡ CSiMe3 (R = azobenzene-3,3′-diyl, azobenzene-4,4′-diyl, 2,5-dioctylazobenzene-4,4′-diyl), and the corresponding terminal dialkynes, HC ≡ CRC ≡ CH, have been synthesized and characterized. The CuI-catalyzed dehydrohalogenation reaction between trans-[Ph(Et3P)2PtCl] and the deprotected dialkynes in a 2:1 ratio in iPr2NH/CH2Cl2 gives the platinum(II) diynes trans-[Ph(Et3P)2PtC ≡ CRC ≡ CPt(PEt3)2Ph], while the dehydrohalogenation polycondensation reaction between trans-[(nBu3P)2PtCl2] and the dialkynes in a 1:1 molar ratio under similar reaction conditions affords the platinum(II) polyynes, [-Pt(PnBu3)2-C ≡ CRC ≡ C-]n. The materials have been characterized spectroscopically, with the diynes also studied using single-crystal X-ray diffraction. The platinum(II) diynes and polyynes are all soluble in common organic solvents. Optical-absorption measurements show that the compounds incorporating the para-alkynylazobenzene spacers have a higher degree of electronic delocalisation than their meta-alkynylazobenzene counterparts. Reversible photoisomerization in solution was observed spectroscopically for the alkynyl-functionalized azobenzene ligands and, to a lesser extent, for the platinum(II) complexes. Complementary quantum-chemical modeling was also used to analyze the optical properties and isomerization energetics.

Original languageEnglish
Pages (from-to)10955-10967
Number of pages13
JournalInorganic Chemistry
Issue number21
Publication statusPublished - Nov 7 2016


ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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