No abstract

A method for the synthesis of the 3 substituted polythiophene derivatives including two crown containing styryl fragments was proposed. The optical properties of the obtained com pounds are characterized by the presence of intense absorption and fluorescence bands. The oxidation to the thiophene derivatives involves the crown containing styryl fragment and should be sensitive to the presence of the metal cation in the crown ether cavity.The intensive development of chemistry of poly thiophenes is associated with their electronic and optical properties, which makes it possible to use these compounds for the creation of efficient field transistors, 1,2 organic la ser diodes, 3 cells of solar batteries, 4 and electrolumines cence devices. 5 Specific functionalization of conducting thiophene polymers is important for the development of chemical sensors with high sensitivity and stability. 6-8 In particu lar, crown ethers with ionophoric properties and covalent ly linked with polythiophenes undergo complex formation reactions with metal ions to change considerably the opti cal and electrochemical characteristics of the whole sys tem, thus providing these compounds with the properties of efficient sensors.Crown containing polythiophenes were first obtained 9 in 1993, when the starting monomers represented bis thiophenes linked at positions 3,3´ by the polyether chain. Crown annelated polythiophenes were studied, 10-13 and aza and oxathiacrown ethers containing three thiophene fragments were obtained. 14,15 Oligothiophenes linked with the crown ether fragment through the spacer were synthe sized. 16-19 The influence of complex formation of the thiophene containing crown ethers on their optical and electrochemical characteristics was described only in sev eral works 9,10,12,13,15 for several cations (Na, K, Ba, Sr, Pb) and, therefore, studies in this direction are significant for the development of new efficient receptors.We have earlier 20,21 reported the synthesis and proper ties of new crown containing bis(2 styryl)polythiophenes. The compounds demonstrated the properties of optical and electrochemical sensors for alkaline earth metal cat ions. A distinctive feature of the compounds is their ability to intermolecular sandwich organization in the presence of cations with larger sizes and in monolayers. The forma tion of intermolecular aggregates considerably decreased the intensity of the absorption and fluorescence spectra of the molecules and increased their electrochemical activi ty. In the present work, we developed methods for the synthesis of earlier unknown crown containing 3 styryl n = 0, R = H; n = 1,2, R =

No abstract

ChemInform Abstract Under the conditions of the Ritter reaction, norbornene (I) affords the expected exo-configurated 2-acetyl derivative (III), whereas norbornadiene (IV) undergoes rearrangement of the cation intermediate to yield the tricyclene (V). The mechanism of its formation is not quite clear. Brex-4-ene (VI) affords a mixture of products, whose main components are the exo and endo isomers (VII), which are formed via protonation at C-4 of the starting (VI). Brexa-3,8-diene (VIII) is protonated exclusively at C-5 to yield the product (IX) after rearrangement of the cation intermediate. The methods described here establish a convenient access to the derivatives (III), (V) and (IX). Finally, the reactivities of the four starting compounds are compared. The reactivity follows this sequence: (IV)< (I) < (VI) ≈ (VIII).