Grignard Metathesis Polymerization and Properties of 1,1-Disubstituted-2,5-dibromo-3,4-diphenylsiloles

2015

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Copolymerization of 2,5‐dibromo‐1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silole with dichlorodisubstitutedsilanes using n‐butyllithium was performed to synthesize conjugated polycarbosilanes of poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(disubstitutedsilylene)]s such as poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(dimethylsilylene)], poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(diethylsilylene)], poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(methylphenylsilylene)], poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(diphenylsilylene)], and poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(tetramethyldisilylene)]. The characteristic diene stretching frequencies appeared at 1593–1601 cm−1 in the Fourier–transform infrared spectra of all the polymers. The obtained materials were highly soluble in organic solvents such as tetrahydrofuran (THF) and chloroform. The molecular weights of the polymers were determined by gel permeation chromatography. The prepared materials in THF solvent showed strong absorption maximum peaks at 249–336 nm with molar absorptivities of 9.84 × 102 to 3.67 × 104 L/(cm·mol) in the UV–Vis absorption spectra, indicating red‐shifts of 6–19 nm as compared with those of 2,5‐dibromo‐1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silole, strong excitation maximum peaks at 320–336 nm, and strong emission maximum peaks at 393–398 nm in the fluorescence emission spectra. All of the absorption and emission spectra strongly indicate that the obtained polycarbosilanes were conjugated along the polymer main chain. Cyclic voltammogram profiles showed that the oxidation and reduction potentials of the prepared polymers were very similar to each other, 0.91 to 1.06 and −0.97 to −1.18 V vs. Ag/Ag+, respectively. Thermogravimetric analyses showed that most of the polymers were thermally stable up to 200 °C in general, with a weight loss of 3–6% in nitrogen.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis, Photoelectronic, and Electrochemical Properties of Poly[(1,1‐dihexyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(disubstitutedsilylene)]s

2015

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“…As outlined in Scheme 1, we synthesized the monomer 3,4-diphenyl-2,5-dibromo-1,1diisopropylsilole (3) for oligomerization according to a previously published two-step reaction. 3,4,29 In the first step, we reacted dichlorodiisopropylsilane (1) with phenylethynyllithium, which was synthesized in situ through the treatment of phenylacetylene with n-BuLi in THF at −78 C, to afford diisopropylbis(phenylethynyl)silane (2) quantitatively. In the second step, we carried out reductive cyclization of compound 2 by treatment with lithium naphthalenide (4 mol) and the sequential reaction of 2 with anhydrous ZnCl 2 and N-bromosuccinimide (NBS), yielding monomer 3 in reasonable yield.…”

Section: Resultsmentioning

confidence: 99%

“…We have reported the preparation of poly(1,1-disubstituted-3,4diphenyl-2,5-silole)s utilizing the so-called Grignard metathesis polymerization of 2,5-dibromo-1,1-disubstituted-3,4-diphenylsiloles with a turbo-GRIM reagent. 29 Previously, we have also prepared polymeric carbosilanes containing conjugated diacetylene with aromatic functional groups, e.g., phenylene or thiophene combined in the polymer main chain. 30 In addition, we have reported the energy dynamics of these conjugated molecules utilizing time-resolved fluorescence emission spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Preparation and Photoelectronic and Electrochemical Properties of Oligo[(1,1‐diisopropyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(alkylphenylsilylene)]s

Jung

Baek

2017

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We oligomerized 2,5‐dibromo‐1,1‐diisopropyl‐3,4‐diphenyl‐2,5‐silole with dichloroalkylphenylsilanes utilizing n‐BuLi to yield conjugated oligo[(1,1‐diisopropyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(alkylphenylsilylene)]s. Gel permeation chromatography measurements confirm that the synthesized materials are oligomeric. In addition, the prepared oligomers show characteristic diene stretching bands at 1579–1599 cm−1 in their FT‐IR spectra. Furthermore, the oligomers are highly soluble in common organic solvents such as tetrahydrofuran and chloroform. In tetrahydrofuran, the oligomers show strong maximum electronic absorption bands at 253–292 nm with molar absorptivities of 1.61 × 102 to 2.57 × 104 /cm M in their UV–vis electronic absorption spectra, indicating that the maxima are red‐shifted by 5–8 nm compared to the 2,5‐dibromo‐1,1‐diisopropyl‐3,4‐diphenyl‐2,5‐silole monomer, strong maximum electronic excitation bands at 292–312 nm, and strong maxima electronic emission bands at 385–396 nm in the emission fluorescence spectra. The emission and absorption spectra strongly suggest that the prepared silole‐containing oligomers may be conjugated through the oligomer backbone. In particular, cyclic voltammetry measurements of oligo[(1,1‐diisopropyl‐3,4‐diphenyl‐2,5‐silolene)‐co‐(diphenylsilylene)] deposited on a glassy carbon electrode in 1.0 M aqueous hydrogen chloride show two oxidation potentials at 0.98 and 1.61 V vs. Ag/Ag+, and two reduction potentials at 0.00 and −1.93 V vs. Ag/Ag+. The oligomers were stable on heating to 200 °C under nitrogen, as determined by thermogravimetric analysis, losing between 4% and 23% of their starting weights.

“…We have previously reported the preparation of poly(1,1‐disubstituted‐3,4‐diphenyl‐2,5‐silole)s by the Grignard methathesis polymerization of 1,1‐disubstituted‐2,5‐dibromo‐3,4‐diphenylsiloles . We also prepared poly(carbosilane) oligomers containing silacyclopenta‐2,5‐dienylene and silylene groups, i.e ., poly[(1,1‐dihexyl‐3,4‐diphenyl‐1‐silacyclopenta‐2,5‐dienylene)‐ co ‐(disubstituted‐silylene)]s …”

Section: Methodsmentioning

confidence: 99%

Cooligomers of 1,1‐Diethyl‐ or Diisopropyl‐2,5‐Dibromo‐3,4‐Diphenyl‐Siloles with Dichlorodisubstituted‐Germanes and Their Characteristics

Jung

Jang

2018

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Silole or silacyclopentadiene is a silacyclic 5-membered diene compound 1 that has a low-lying π-electronic lowest unoccupied molecular orbital energy value in comparison with its analogue cyclopentadiene. 2 This is ascribed to the orbital interactions between the silylene σ* and butadiene π* orbitals. 3 Silole-containing materials with π-conjugated electronic systems have been intensively studied as electronic materials for OLEDs, 4 photoluminescence, 5-7 and electroluminescence applications. 8-10 For example, endcapped 2,5-silole dendrimeric compounds such as phenylethenyl-carbosilanes are examples of green or greenish-blue fluorescence emitting materials for electroluminescent devices. 11 We have previously reported the preparation of poly(1,-1-disubstituted-3,4-diphenyl-2,5-silole)s by the Grignard methathesis polymerization 12 of 1,1-disubstituted-2,5-dibromo-3,4-diphenylsiloles. 13 We also prepared poly(carbosilane) oligomers containing silacyclopenta-2,-5-dienylene and silylene groups, i.e., poly[(1,1-dihexyl-3,4-diphenyl-1-silacyclopenta-2,5-dienylene)-co-(disubstitutedsilylene)]s. [14][15][16] Herein, we report the synthesis of new cooligomers containing both 2,5-silolene and germylene groups, namely, poly[(1,1-diethyl-or diisopropyl-3,4-diphenyl-2,5-silolene)co-(disubstituted-germylene)]s (6a-6d), and their characteristic photoelectronic and thermal properties.Scheme 1 depicts the synthesis of 1,1-diethyl-and 1,1-diisopropyl-2,5-dibromo-3,4-diphenyl-siloles (3a and 3b) via the previously reported two-step reactions. 3,[15][16][17] First, dichlorodiethyl-and -diisopropyl-silanes (1a and 1b) were reacted with lithium phenylacetylide, which was prepared in situ in tetrahydrofuran (THF) by treating phenylacetylene with n-BuLi, to afford diethyl-and diisopropyl bis(phenylethynyl)silanes (2a and 2b). Subsequently, intramolecular reductive cyclizations of 2a and 2b were performed utilizing lithium naphthalenide and anhydrous zinc chloride with N-bromosuccinimide to yield compounds 3a and 3b, respectively. We confirmed the formation of 3a and 3b through 1 H, 13 C, and 29 Si NMR spectral data.The 1 H NMR spectral data of 3a and 3b exhibit multiplets at 1.03-1.15 and 1.24-1.54 ppm corresponding to the ethyl and isopropyl groups, respectively. The 13 C NMR spectral data of 3a and 3b exhibit carbon resonances at 1.74 and 6.75 ppm corresponding to the ethyl group and at 10.05 and 17.41 ppm for the isopropyl group, respectively. The 29 Si NMR spectral data of 3a and 3b exhibit silicon resonances at 8.54 and 7.46 ppm, respectively. These data indicate that the compounds 3a and 3b were successfully prepared through these intramolecular reductive cyclizations of 2a and 2b, respectively.We studied the absorption properties of compounds 3a and 3b in THF solution. The absorption maxima of 3a and 3b were found at 260 and 253 nm and had molar absorptivities of 1.19 × 10 4 and 1.21 × 10 4 /cm/M, respectively. These strong absorptions in the UV-Vis spectra of 3a and 3b might be due to the characteristic phenyl and diene chromo...