2,2 :5 ,2":5",2" -Quaterthiophene

Fig. 5 (Left) The 5,5" -Z7/5(aminoethyl)-2,2 5, 2" 5",2 "-quaterthiophene molecule. (Center) perovskite structure of the (AEQT) PbBr4. (Right) (a) Cross section of the OILED device structure (not to scale) (b) view of the circular substrate containing four devices. For clarity, the OXD7 layer (on the top of the patterned hybrid perovskite layer) is not shown. (Adapted from Ref. [32].) (View this art in color at WWW,dekker.com.)...

Here we show the crystallographic features of DMQtT [22], choosing this compound as a representative of the family of oligothiophenes. The results are briefly compared with those for another tetramer compound of 4,4, 3",4" -tetramethyl-2,2 5, 2" 5 , 2" -quaterthiophene [104]. 

More recently, partially substituted quarterthiophenes have been investigated by Collard and co-workers who polymerized 3,3 -dioctyl-2,2 5, 2 5 ,2" -quaterthiophene.(42) Polymerization of the quaterthiophene by FeCU was inefficient even at elevated temperatures (50 C), the majority of the material recovered (73%) was the dimerized monomer (the octathiophene). However, approximately 10% of the oxidized material was polymeric and exhibited absorption maxima of 463 nm in CHCI3 and 514 nm as thin films. Although the FeCh polymerization of the dimethyl analog has also been reported without the difficulties described above, the polymerized product was completely insoluble.(75)... 

Figure 7. Crystal structure of a,o -diinethyl-2,2 5, 2 5",2 "-quaterthiophene viewed along the fl-axis. From ref. [33].

Figure 9. ORTEP (Top) andciystal (Bottom) structures of tetrakis(methylsulfanyl)- 2,2 5, 2" 5",2" -quaterthiophene (a) in its triclinic orange form (from ref. [88]) and (b) in its monoclinic yellow form. From ref [89].

Quaterthiophene, a representative of the oligomers of thiophene [97JPC(A)4437] reacts with the labile 16-electron species [(triphos)RhH] to yield 252 (970M1517). The sulfur atom bonded to rhodium has expressed nucleophilic properties and attack by methyl iodide followed by NaBPlu gives the thioether 253. The latter reacts with [(triphos)RhH] to give the binuclear complex 254 that can be further methylated to give 255. 

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