Optical properties oligothiophenes

Radical cations and dications of oligothiophenes have been investigated by many research groups to understand the nature of polarons and bipolarons in polythiophenes which are responsible for the electrical and optical properties of these re-conjugated polymers. 

A series of luminescent mercury(II) bis(alkynyl) complexes containing oligothiophenes have been synthesized by Wong via direct merciuation of the corresponding alkynes (see equation S). Most importantly, the optical properties of these species have been found to be easily tuned by modifying the... 

Well-defined oligothiophenes surrounded by bicyclo[2.2.2]octane fiameworks 173-176 have been synthesized and their crystal structures, electrochemical, optical properties have been studied. The solid state properties of the oligomers as a function of increasing number of thiophene units have been reported <03JOC8305>. 

Garcia, P., Pemaut, J.M., Witgens, V., Valat, P., Gaunier, F., and Delabouglise, D. 1992. Effect of end substitution on electrochemical and optical properties of oligothiophenes. Journal of Physical Chemistry 91, 513-516. 

The absorption maxima of the oligothiophene dimers in solution range from 361 nm (BT3) and 426 nm (BT5) to 451 run (BT7). These values are similar to the optical properties of the corresponding unsubstituted linear oligothiophenes T3-T6 [28]. There is only a minor redshift of max of ca. 9 nm in BT3 compared to T3 and BT5 compared to T5, which is probably due to a weak intramolecular electronic interaction of the arms in BT3 and BT5. Comparison of the solution and solid state spectra (Figure 6.2a, b) shows a distinct red shift of the films spectra, which is more pronounced for the more extended dimers... 

Due to their variable absorption and emission wavelengths, oligothiophenes can also be used as unique photostable fluorescent markers for biomolecules. Thus, Barbarella el al. reported the introduction of isothiocyanate functionalities into oligothiophene backbones. These can react with amino groups of lysine residues to form urea bonds without affecting the optical properties of the oligothiophene. Consequently,... 

A. Jaafari, V. Ouzeau, M. Ely, F. Rodriguez, K. Chane-Ching, A. Yassar and J. J. Aaron, Synthesis and optical properties of novel 1,3-propanedione bearing oligothiophene substituents, Synth. Met., 147, 183-189 (2004). 

The geometric, electronic and optical properties of oligothiophenes of two, four, six and eight units of head-to-head-tail-to-tail (HH-TT) regioselectivity and substituted by methyl, thiol and thiomethyl groups (Chart 8.15) were characterized in their neutral and p-doped states with quantum chemical calculations derived from semiempirical HF approaches and with the nonempirical valence effective Hamiltonian (VEH) method. Such calculations provide a good insight into the electronic properties measured for electropoly-merized chains [91]. 

F. Costanzo, D. ToneUi, G. Scahnani, J. Cornil, Theoretical investigation of the electronic and optical properties of oligothiophenes upon methyl, thiol and thiomethyl substitutions. Polymer, 47, 6692-6697 (2006). 

Table I. Optical Properties of Oligothiophene-based Chromophores...

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