Tetraethynylethenes

Extended tetrathiafulvalenes with acetylenic cores are interesting compounds because of their redox and chromophoric properties. Such molecules are both interesting from materials and supramolecular chemistry perspectives. A tetraethynylethene-extended tetrathiafulvalene, for instance, was prepared using a microwave-promoted Sonogashira reaction [72]. Coup-... 

Keywords Acetylene chemistry. Cross-coupling reactions, Cyclo[n]carbons, Expanded radialenes. Molecular scaffolding. Nanostructures, Perethynylated chromophores, Poly(triacetylene), Tetraethynylethene. 

Scheme 8. Oligomers and polymers with a poly(triacetylene) (PTA) backbone that are derived from tetraethynylethenes (TEEs)...

Structure-Property Relationships In Nonlinear Optical Tetraethynylethenes... 

The state of research on the two classes of acetylenic compounds described in this article, the cyclo[ ]carbons and tetraethynylethene derivatives, differs drastically. The synthesis of bulk quantities of a cyclocarbon remains a fascinating challenge in view of the expected instability of these compounds. These compounds would represent a fourth allotropic form of carbon, in addition to diamond, graphite, and the fullerenes. The full spectral characterization of macroscopic quantities of cyclo-C should provide a unique experimental calibration for the power of theoretical predictions dealing with the electronic and structural properties of conjugated n-chromophores of substantial size and number of heavy atoms. We believe that access to bulk cyclocarbon quantities will eventually be accomplished by controlled thermal or photochemical cycloreversion reactions of structurally defined, stable precursor molecules similar to those described in this review. 

In contrast, the synthesis of tetraethynylethene (TEE, C10H4) was described in 1991 and, since then, a rich variety of cyclic and acyclic molecular scaffolds incorporating this carbon-rich molecule as a construction module have been prepared. The majority of these compounds, such as the expanded radialenes or the oligomers and polymers of the poly(triacetylene) type, are highly stable and... 

The link between cyclo[ ]carbons and tetraethynylethene is the occurrence of both structural motifs as repeat units in fascinating two-dimensional all-carbon networks [3,4]. The development of viable preparative approaches toward these elusive acetylenic networks represents one of the true challenges for synthesis at the turn of the millennium. 

Diederich F (1997) Tetraethynylethenes Versatile Carbon-rich Building Blocks for Two-dimensional Acetylenic Scaffolding. In Michl J (ed) Modular Chemistry. Kluver,... 

To generate the pentagonal structure 188, two equivalents of 182 were first coupled with the tetraethynylethene 186. After deprotection of the appropriate ethynyl groups the resulting intermediate 187 could be roofed with 183 to yield the desired product 188 (yield of last step 15%) (equation 28)107 108. 

Several two-dimensional all-carbon networks comprise the core of tetraethynylethene (TEE 17) as a monomeric repeat unit11,121 In 1991, we synthesized the hitherto dusive perethynylated ethene 17 on the way to these novel materials.1361 In the... 

Molecular scaffoldings with tetraethynylethenes (TEEs, 3,4-diethynylhex-3-ene-l,5-diynes) and trans-1,2-diethynylethenes [DEEs, (E)-hex-3-en-l,5-diynes] are at a particularly advanced stage.114,37 38 441 A collection of dose to one hundred partially protected and functionalized derivatives have been prepared in the meantime, providing starting materials for the perethynylated dehydroannulenes and expanded radialenes shown in Figure 6.136 441 TEEs and DEEs, as well as dimeric derivatives substituted at the terminal alkynes with donor (D, p-(dimethyl-... 

Figure 9. Tetraethynylethene (TEE) and diethynylethene (DEE) molecular scaffoldings, a) Donor-acceptor substituted chromophores for nonlinear optical studies, b) A three-way...

R. R. Tykwinski, F. Diederich, Tetraethynylethene Molecular Scaffolding , Liebigs Ann/Recueil 1997, 649-661. 

R. Spreiter, C. Bosshard, G. Knopfle, P. Gunter, R. R. Tykwinski, M. Schreiber, F. Diederich, One- and Two-Dimensionally Conjugated Tetraethynylethenes Structure versus Second-Order Optical Polarizabilities , J. Phys. Chem B. 1998,102,29-32... 

In addition, [TEE][Au(PCy3)]4 (TEE-H4 = tetraethynylethene) was found to interestingly show l[jt tt (TEE)] fluorescence emission at 428 nm, while [TEB][Au(PCy3)]3 (TEB-H3 = 1,3,5-triethynylbenzene) displayed 3[tt -> tt (TEB)] phosphorescence emission at 479 nm in dichloromethane at 298 K [93]. The polymorphic nature of [(Cy3P)Au(4-C=CC6H4N02)] was studied by Che [94]. Two forms, namely E- and N-forms, were structurally characterized, and were polymorphs with molecular dipoles in different... 

A special case are the two-dimensionally conjugated tetraethynylethenes (TEE). In this case the conjugation is expanded in one direction and functional groups are added along the other conjugation direction, laterally to the backbone (Fig. 16). 

Fig. 16. Two-dimensional framework of tetraethynylethenes. One dimension can be used for the polymerization and the other for substitution with functional groups (Rj)...

Fig. 22. Conjugation paths for tetraethynylethene molecules. Whereas paths (a) are in the (x,y)-plane paths (b) are only along the x-direction, providing a total of four conjugation paths along the x-direction but only two along the y-direction. The conjugation along the so-called cross-conjugation paths (c) is weak relative to paths (a) and (b)...

Functional Conjugated Materials for Optonics and Electronics by Tetraethynylethene Molecular Scaffolding... 

---