Regioregular structures

This method was also used for the polymerization of disubstituted 1,4-dibromobenzene (equation 70) (272). This produced a polymer with a regioregular structure connected in a 1,4-manner. The maximum DP obtained was 13. Two types of end groups were identified (a) unreacted Br and (b) reduced Br. The proton for reduction may be from adventious water sources or from Ni-catalyzed... 

Kobashi, M. Takeuchi, H. 1998. Inhomogeneity of spin-coated and cast non-regioregular poly(3-hexylthiophene) films. Structures and electrical and photophysical properties. Macromolecules 31 7273-7278. 

P. Barta, P. Dannetun, S. Stafstrom, M. Zagorska, and A. Pron, Temperature evolution of the electronic band structure of the undoped and doped regioregular analog of poly(3-alkylthio-phenes) a spectroscopic and theoretical study, J. Chem. Phys., 100 1731-1741, 1994. 

MM7525 99SM(101)11), although the emission of substituted PTs is not very predictable due to the interplay of several factors (steric effects, regioregularity, electronic effects, side-chain crystallization, etc.), the full visible range of PL and EL emission, from red to blue, can be covered by variations of the PT structure via substituents in 3,4-positions. 

In the highly regioregular polymer 522, in its pristine amorphous form, the absorption maximum of spin-cast films is 493 nm (2.86 eV) (94MM6503 01JPC(B)7624). On treating the films with chloroform vapor, the maximum was shifted to 602 nm (2.06 eV), and the spectrum showed a fine vibronic structure with AE = 0.19 eV, typical of a more-planar ordered conformation. 

Molecular self-organization in solution depends critically on molecular structural features and on concentration. Molecular self-organization or aggregation in solution occurs at the critical saturation concentration when the solvency of the medium is reduced. This can be achieved by solvent evaporation, reduced temperature, addition of a nonsolvent, or a combination of all these factors. Solvato-chromism and thermochromism of conjugated polymers such as regioregular polythiophenes are two illustrative examples, respectively, of solubility and temperature effects [43-45]. It should therefore be possible to use these solution phenomena to pre-establish desirable molecular organization in the semiconductor materials before deposition. Our studies of the molecular self-assembly behavior of PQT-12, which leads to the preparation of structurally ordered semiconductor nanopartides [46], will be described. These PQT-12 nanopartides have consistently provided excellent FETcharacteristics for solution-processed OTFTs, irrespective of deposition methods. 

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