Pt-tetraethynylethene molecular scaffolding: Synthesis and characterization of a novel class of organometallic molecular rods

Citation
P. Siemsen et al., Pt-tetraethynylethene molecular scaffolding: Synthesis and characterization of a novel class of organometallic molecular rods, CHEM-EUR J, 7(6), 2001, pp. 1333-1341
Citations number
73
Categorie Soggetti
Chemistry
Journal title
CHEMISTRY-A EUROPEAN JOURNAL
ISSN journal
09476539 → ACNP
Volume
7
Issue
6
Year of publication
2001
Pages
1333 - 1341
Database
ISI
SICI code
0947-6539(20010316)7:6<1333:PMSSAC>2.0.ZU;2-#
Abstract
The series of monodisperse Pt-bridged TEE oligomers 3a-f was prepared by ox idative Glaser-Hay oligomerization of monomer 7 under endcapping conditions . These novel molecular rods extend in length from 3.3 nm (monomeric 3a) to 12.1 nm (hexameric 3f), Their isolation was achieved by high performance g el permeation chromatography (GPC), and their purification was best monitor ed by analytical GPC in combination with matrix-assisted laser-desorption-i onization mass spectrometry (MALDI-TOF MS). The mass spectra of each oligom er revealed the molecular ion or its sodium complex as parent ion together with a clean, highly characteristic fragmentation pattern. Delayed addition of the end-capping reagent PhC drop CH to the oligomerization mixture affo rded polymer 10 with an average of approximate to 32 repeat units and a rem arkably narrow molecular weight distribution (M-w/M-n=1.06), which is indic ative of a living polymerization process. UV/Vis spectral data as well as m easurements of the second hyperpolarizability gamma by third harmonic gener ation (THG) revealed a nearly complete lack of pi -electron delocalization along the oligomeric backbone. The Pt atoms act as true insulating centers, and the Pt-C(sp) bonds hardly possess any pi character. The synthesis of t he molecular rods 3a-f provides another demonstration of the power of oxida tive acetylenic homocouplings for the preparation of unusual nanoarchitectu re.