title: Impact of the Alkyne Substitution Pattern and Metalation on the Photoisomerization of Azobenzene-Based Platinum(II) Diynes and Polyynes.
abstract: 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 iniPr2NH/CH2Cl2gives 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.
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: Rayya A
authors.initials: RA
authors.lastname: Al-Balushi
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: Ashanul
authors.initials: A
authors.lastname: Haque
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: Maharaja
authors.initials: M
authors.lastname: Jayapal
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: Mohammed K
authors.initials: MK
authors.lastname: Al-Suti
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: John
authors.initials: J
authors.lastname: Husband
authors.affiliation: Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Sultanate of Oman.
authors.forename: Muhammad S
authors.initials: MS
authors.lastname: Khan
authors.affiliation: Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Skelton
authors.affiliation: Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K.
authors.forename: Kieran C
authors.initials: KC
authors.lastname: Molloy
authors.affiliation: Department of Chemistry, University of Bath , Claverton Down, Bath BA2 7AY, U.K.
authors.forename: Paul R
authors.initials: PR
authors.lastname: Raithby