Experimental and Theoretical Investigation for the Level of Conjugation in Carbazole-Based Precursors and Their Mono-, Di-, and Polynuclear Pt(II) Complexes.
A series of trimethylsilyl-protected monoalkynes (Me3SiC≡C-R) and bis-alkynes (Me3 SiC≡C-R-C≡CSiMe3) incorporating carbazole spacer groups (R = carbazole-2-yl, carbazole-3-yl, carbazole-2,7-diyl, N-(2-ethylhexyl)carbazole-2,7-diyl, carbazole-3,6-diyl, N-(2-ethylhexyl)carbazole-3,6-diyl), together with the corresponding terminal monoalkynes (H-C≡C-R) and bis-alkynes (H-C≡C-R-C≡C-H), have been synthesized and characterized. The CuI-catalyzed dehydrohalogenation reaction between trans-[(Ph)(Et3P)2PtCl], trans-[(Et3P)2PtCl2], and trans-[(P(n)Bu3)2PtCl2] and the terminal alkynes in (i)Pr2NH/CH2Cl2 affords a series of Pt(II) mono- and diynes, while the dehydrohalogenation polycondensation reactions with trans-[(P(n)Bu3)2PtCl2] under similar reaction conditions yields four Pt(II) poly-ynes of the form trans-[(P(n)Bu3)2Pt-C≡C-R-C≡C-]n. The acetylide-functionalized carbazole ligands and the mono-, di-, and polynuclear Pt(II) σ-acetylide complexes have been characterized spectroscopically, with a subset analyzed using single-crystal X-ray diffraction. The Pt(II) mono-, di-, and poly-ynes incorporating the carbazole spacers are soluble in common organic solvents, and solution absorption spectra show a consistent red-shift between the 2- and 2,7- as well as 3- and 3,6-carbazole complexes. Computational modeling is used to explain the observed spectral shifts, which are related to the enhanced electronic delocalization in the latter systems. These results also indicate that the inclusion of carbazole-2,7-diyl units into rigid-rod organometallic polymers should enhance electronic transport along the chains.
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
Rayya A
RA
Al-Balushi
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
Ashanul
A
Haque
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
Maharaja
M
Jayapal
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
Mohammed K
MK
Al-Suti
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
John
J
Husband
Department of Chemistry, Sultan Qaboos University , P.O. Box 36, Al Khod 123, Muscat, Sultanate of Oman.
Muhammad S
MS
Khan
Department of Chemistry, University of Bath , Claverton Down, Bath, Avon BA2 7AY, United Kingdom.
Olivia F
OF
Koentjoro
Department of Chemistry, University of Bath , Claverton Down, Bath, Avon BA2 7AY, United Kingdom.
Kieran C
KC
Molloy
Department of Chemistry, University of Bath , Claverton Down, Bath, Avon BA2 7AY, United Kingdom.
Jonathan M
JM
Skelton
Department of Chemistry, University of Bath , Claverton Down, Bath, Avon BA2 7AY, United Kingdom.
Paul R
PR
Raithby