引言的写作
1、Conjugated polymers are emerging as the basis of major new technologies in organic optoelectronics and organic electronics 。Consequently, there is tremendous interest in the preparation and the purification of these material s.Among the most i nteresting materials under investi gati on are the polyfluorenes and the poly(3-alkylthiophenes) and their copolymers。
2、The preparation of poly-3-alkylthiophenes has been extensively investigated in the past decade。
3、Optimization of this procedure and extensive purification gives material with iron impurities as low as 80 ppm, compatible with their application in low performance electronic devices.
4、Recently, efficient synthetic pathways using nickel-catalyzed cross couplings of heterofunctional monomers that give access to extremely pure materials with a high degree of control over the polymer regiochemistry have been developed。
5、These materials have established new standards of performance for polymeric semiconductors in devices such as organic thin film transistors
6、Given the interesting properties of polyfluorenes and poly(3-alkylthiophenes), recent work has focused on polycyclopentadithiophenes, as structural analogues of polyfluorenes based on thiophene.
7、To date, very few preparative methods for the synthesis of soluble polycyclopentadithiophenes have been reported.
8、Analogous polymers of moderate molecular weight (M n 5000-9000) have been prepared by a Ni- (0)-catalyzed reductive coupling of 2,6-dibromo-functionalized dialkylcyclopentadithiophenes.
9、In this contribution, we report three novel approaches to the synthesis of solution-processable poly(4,4- dialkylcyclopentadithiophenes).The structural features and optical properties of the materials prepared by each approach are discussed, including an analysis of the polymer end groups and their subsequent reaction to remove undesirable halogen termini. Part of this work has been previously communicated。
10、Monomers 3a -c were prepared from cyclopenta[2,1-b;3,4-b ]dithiophen-4-one (1) 24-26 by a new synthetic route, outlined in Scheme 1
11、In the examples reported, the molecular weight of the polymer decreases with increasing alkyl chain length (see Table 1)。
12、These results can be contrasted with the high molecular weights and low polydispersities achieved in an analogous preparation of poly(3-hexylthiophene) (M n 30 000, pd 1.4) using the same source of magnesium (3 M solution of MeMgBr in diethyl ether) on a similar scale.
13、Purification by precipitation and repeated Soxhlet extraction gave polymers with moderate
molecular weights (see Table 1) that are generally lower than those achieved in an analogous preparation of poly-3-hexylthiophene (M n 12 000, pd 1.3).
14、NMR spectroscopy is extremely useful for the elucidation of backbone regiochemistry and for the identification of structural defects in conjugated polymers
15、MALDITOF
mass spectrometry gives valuable information on the repeat unit and the end groups of the polymer, potentially giving useful information about the polymerization mechanism.
16、The UV-vis spectra of thin films of 5-7 spin-coated from chloroform solution and annealed at 100 °C for 2h were recorded.
17、The thin film spectra show an increase in the vibronic structure, but the position of the absorption maxima was unchanged
18、It appears that these polymers do not self-assemble in the solid state in a fashion similar to that reported for regioregular poly-3-alkylthiophenes
19、This observation is consistent with the absence of any mesophase behavior for polymers 5-7 observable by DSC or optical microscopy for temperatures up to their decomposition.
核磁表述
NMR studies conducted in chloroform on poly(9-alkyl-9H -carbazole)-2,7-diyls polymers confirmed their assi gned structure and linkage of the carbazole repeat units at the 2,7-positions. 1H NMR studies reveal in the aromatic region a broad doublet, a broad singlet, and another broad doublet with equal integral intensities, centered around 8.25, 7.76, and 7.66 ppm, corresponding to the three chemical environments of hydrogens at, respectively, the 4- and 5-positions, 1- and 8-positions, and 3- and 6-positions of carbazole rings. In addition broad peaks centered around 4.36 ppm, corresponding to hydrogens of the methylene groups directly attached to the 9-position of carbazole rings, were observed for polymers with branched alkylsubstituents (P1a and P1b ). Additional shoulder peaks next to these peaks at 4.27 ppm were also observed for polymers with low average molecular weights. These were attributed to hydrogens with similar chemical environments from carbazole repeat units at the end of polymer chains. Hydrogens belonging to the methylene directly attached to the 9-position of carbazole rings in polymers with linear chains (P1c and P1d ) revealed broad peaks centered around 4.45 ppm. Additional shoulder peaks next to these peaks at 4.36 ppm were also observed for polymers with low average molecular weights. 13C NMR studies on polymers in the
poly(9-alkyl-9H -carbazole)-2,7-diyl series reveal six chemical environments at around 142, 140, 122, 121, 119, and 108 ppm, corresponding, respectively, to carbons at the 8a- and 9a-positions, 2- and 7-positions, 4- and 5-positions, 3- and 6-positions, 4a- and 4b-positions, and 1- and 8-positions of carbazole rings. It is worth noting that no peaks could be observed around 133 ppm (signals attributed to carbons at the 3,6-positions in poly(9-alkyl- 9H -carbazole)-3,6-diyls) in the 13C NMR spectra for all polymers in this series, indicating the absence of any 3,6-linkage defects, and demonstrating exclusive 2,7- linkage of carbazole repeat units on polymer chains。
引言的写作
1、Conjugated polymers are emerging as the basis of major new technologies in organic optoelectronics and organic electronics 。Consequently, there is tremendous interest in the preparation and the purification of these material s.Among the most i nteresting materials under investi gati on are the polyfluorenes and the poly(3-alkylthiophenes) and their copolymers。
2、The preparation of poly-3-alkylthiophenes has been extensively investigated in the past decade。
3、Optimization of this procedure and extensive purification gives material with iron impurities as low as 80 ppm, compatible with their application in low performance electronic devices.
4、Recently, efficient synthetic pathways using nickel-catalyzed cross couplings of heterofunctional monomers that give access to extremely pure materials with a high degree of control over the polymer regiochemistry have been developed。
5、These materials have established new standards of performance for polymeric semiconductors in devices such as organic thin film transistors
6、Given the interesting properties of polyfluorenes and poly(3-alkylthiophenes), recent work has focused on polycyclopentadithiophenes, as structural analogues of polyfluorenes based on thiophene.
7、To date, very few preparative methods for the synthesis of soluble polycyclopentadithiophenes have been reported.
8、Analogous polymers of moderate molecular weight (M n 5000-9000) have been prepared by a Ni- (0)-catalyzed reductive coupling of 2,6-dibromo-functionalized dialkylcyclopentadithiophenes.
9、In this contribution, we report three novel approaches to the synthesis of solution-processable poly(4,4- dialkylcyclopentadithiophenes).The structural features and optical properties of the materials prepared by each approach are discussed, including an analysis of the polymer end groups and their subsequent reaction to remove undesirable halogen termini. Part of this work has been previously communicated。
10、Monomers 3a -c were prepared from cyclopenta[2,1-b;3,4-b ]dithiophen-4-one (1) 24-26 by a new synthetic route, outlined in Scheme 1
11、In the examples reported, the molecular weight of the polymer decreases with increasing alkyl chain length (see Table 1)。
12、These results can be contrasted with the high molecular weights and low polydispersities achieved in an analogous preparation of poly(3-hexylthiophene) (M n 30 000, pd 1.4) using the same source of magnesium (3 M solution of MeMgBr in diethyl ether) on a similar scale.
13、Purification by precipitation and repeated Soxhlet extraction gave polymers with moderate
molecular weights (see Table 1) that are generally lower than those achieved in an analogous preparation of poly-3-hexylthiophene (M n 12 000, pd 1.3).
14、NMR spectroscopy is extremely useful for the elucidation of backbone regiochemistry and for the identification of structural defects in conjugated polymers
15、MALDITOF
mass spectrometry gives valuable information on the repeat unit and the end groups of the polymer, potentially giving useful information about the polymerization mechanism.
16、The UV-vis spectra of thin films of 5-7 spin-coated from chloroform solution and annealed at 100 °C for 2h were recorded.
17、The thin film spectra show an increase in the vibronic structure, but the position of the absorption maxima was unchanged
18、It appears that these polymers do not self-assemble in the solid state in a fashion similar to that reported for regioregular poly-3-alkylthiophenes
19、This observation is consistent with the absence of any mesophase behavior for polymers 5-7 observable by DSC or optical microscopy for temperatures up to their decomposition.
核磁表述
NMR studies conducted in chloroform on poly(9-alkyl-9H -carbazole)-2,7-diyls polymers confirmed their assi gned structure and linkage of the carbazole repeat units at the 2,7-positions. 1H NMR studies reveal in the aromatic region a broad doublet, a broad singlet, and another broad doublet with equal integral intensities, centered around 8.25, 7.76, and 7.66 ppm, corresponding to the three chemical environments of hydrogens at, respectively, the 4- and 5-positions, 1- and 8-positions, and 3- and 6-positions of carbazole rings. In addition broad peaks centered around 4.36 ppm, corresponding to hydrogens of the methylene groups directly attached to the 9-position of carbazole rings, were observed for polymers with branched alkylsubstituents (P1a and P1b ). Additional shoulder peaks next to these peaks at 4.27 ppm were also observed for polymers with low average molecular weights. These were attributed to hydrogens with similar chemical environments from carbazole repeat units at the end of polymer chains. Hydrogens belonging to the methylene directly attached to the 9-position of carbazole rings in polymers with linear chains (P1c and P1d ) revealed broad peaks centered around 4.45 ppm. Additional shoulder peaks next to these peaks at 4.36 ppm were also observed for polymers with low average molecular weights. 13C NMR studies on polymers in the
poly(9-alkyl-9H -carbazole)-2,7-diyl series reveal six chemical environments at around 142, 140, 122, 121, 119, and 108 ppm, corresponding, respectively, to carbons at the 8a- and 9a-positions, 2- and 7-positions, 4- and 5-positions, 3- and 6-positions, 4a- and 4b-positions, and 1- and 8-positions of carbazole rings. It is worth noting that no peaks could be observed around 133 ppm (signals attributed to carbons at the 3,6-positions in poly(9-alkyl- 9H -carbazole)-3,6-diyls) in the 13C NMR spectra for all polymers in this series, indicating the absence of any 3,6-linkage defects, and demonstrating exclusive 2,7- linkage of carbazole repeat units on polymer chains。