Study of the correlation between the backbone conformation and the electronic structure of polydiacetylenes by solid state 13C n.m.r.

Tanaka, Hajime; Thakur, M.; Gómez, M. A.; Tonelli, Alan E.

doi:10.1016/0032-3861(91)90372-p

Cited by 28 publications

(32 citation statements)

References 27 publications

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“…This, in return, suggested that a decrease or even complete loss of the p-electron conjugation along the PTA backbone could occur in the higher generation compounds, which should be observable by means of spectroscopic measurements. 8 In the electronic absorption spectra of all three oligomeric series (CHCl 3 , Fig. 1), the longest-wavelength absorption maximum (l max ) is bathochromically shifted with increasing rod length and evidently no saturation in either case was observed, confirming recent findings.…”

supporting

confidence: 88%

Dendritic rods with a poly(triacetylene) backbone: insulated molecular wires

Ito¹,

Diederich²,

Schenning³

et al. 1998

Chem. Commun.

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supporting

confidence: 88%

Dendritic rods with a poly(triacetylene) backbone: insulated molecular wires

Ito¹,

Diederich²,

Schenning³

et al. 1998

Chem. Commun.

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“…21,22 In saturation conditions, only about 20 diacetylene monomers are calculated to be bound on a single 1.6 nm diameter NP, a number insufficient to produce the polymer blue form that, on the basis of the Kuhn's model, 23 requires a delocalization length involving 25-50 monomer units. 24 On the contrary, for the 4.1 nm diameter particles the maximum amount of potentially chemisorbed DS9 is B160 molecules per core, enough to make the blue phase formation possible.…”

Section: Polymerization Of Ds9 Chemisorbed On Gold Nanoparticlesmentioning

confidence: 99%

Photopolymerization of diacetylene-capped gold nanoparticles

Alloisio

Demartini

Cuniberti

et al. 2008

Phys. Chem. Chem. Phys.

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Gold nanoparticles (AuNPs) coated with the diacetylene henicosa-10,12-diyn-1-yl (DS9) disulfide were successfully prepared by direct synthesis in toluene solutions. The average size of the nanohybrid metal core was finely adjusted by manipulation of the preparative conditions in the diameter range from 1.6 to 7.5 nm, as determined by TEM characterization. The topochemical polymerization of DS9 chemisorbed onto the gold nanoclusters of different size was carried out in colloidal suspensions by exposure to UV radiation and the process was monitored by UV-Vis and Raman spectroscopies. The results showed that in these assemblies the monomer undergoes an intra-particle polymerization and that the dominant polydiacetylene phase present is ruled by the core size. The deposition of the photoirradiated colloids onto different substrates was found to leave the polydiacetylene conjugation unaltered.

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“…Dendron synthesis was pursued via two routes, either repetitive hydrosilylation/allylation or repetitive hydrosilylation/vinylation. The former approach started from 4-allylanisole (25) or from the corresponding tert-butyl ether 26, which was prepared by demethylation of 25 with Br 3 B [31] to give 27, followed by acid-catalyzed etherification with isobutene [32] (Scheme 3). The two aromatic ethers 25 and 26 were subsequently reacted with HSiCl 3 in the presence of Karstedt catalyst (a (divinyltetramethylsiloxane)platinum complex in xylene) [33] to yield the hydro- silylated products 28 and 29, respectively, with complete regioselectivity ( 1 H-NMR).…”

Section: 2mentioning

confidence: 99%

“…[(E)-1,10-Diphenyldec-5-ene-1,3,7,9-tetrayne-5,6-diyl]dimethylene Bis (3,5- [(5E,11E,17E,23E,29E)-1, 11,17,23,3,7,9,13,15,19,21,25,27,31,6,11,12,17,18,23,24,29, Oxidative Oligomerization of 23. According to the procedure for 1a ± e, 23 (200 mg, 0.097 mmol), PhCCH (20 mg, 0.196 mmol), CuCl (1 mg, 0,01 mmol), and TMEDA (4 mg, 0.005 ml, 0.035 mmol) were reacted in dry CH 2 Cl 2 over molecular sieves (4 ) in the air to give, after GPC (CH 2 Cl 2 ), FC (SiO 2 ; CH 2 Cl 2 / hexane 1 : 1), and precipitation from MeOH, the pure oligomers 2a ± c.…”

Section: Methyl 35-bis{[4-(tert-butyl)benzyl]oxy}benzoatementioning

confidence: 99%

“…In the 13 C-NMR spectra, the number of C(sp) resonances, which appear as clearly discernable signals between 73 and 90 ppm, increases by 2 2n, where n is the number of monomeric units in the oligomers. The spectra did not display a significant difference in chemical shift between these resonances in oligomers of same length but different dendritic generation (Table 1) [25]. Force-field calculations [26] showed clearly that the conformation of the PTA backbone, including the two end-capping Ph groups, is not planar in the higher-generation dendritic rods ± in particular in the third-generation dimer 3b ± due to the steric hindrance of the bulky dendritic wedges.…”

mentioning

confidence: 99%

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Insulated Molecular Wires: Dendritic Encapsulation of Poly(triacetylene) Oligomers, Attempted Dendritic Stabilization of Novel Poly(pentaacetylene) Oligomers, and an Organometallic Approach to Dendritic Rods

Schenning

Arndt

Ito

et al. 2001

HCA

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Dendrons 8, 13, and 17 were subsequently attached to (E)-2,3-bis[(triisopropylsilyl)ethynyl]but-2-ene-1,4-diol (18) [4] [21] using the Mitsunobu reaction [22] to give the dendritic silyl-protected monomers 19 ± 21, respectively (Scheme 2). The yield of the third-generation compound 21 was very low (4%), possibly due to steric hindrance of the reacting COOH group by the bulky dendritic wedges in dendron 17. After deprotection with Bu 4 NF in wet THF, the free (E)-enediynes 22 ± 24 were obtained. The dendritic wedges substantially stabilize the usually rather unstable free (E)enediynes [23], and compounds 22 ± 24 can be stored in the air at ambient temperature for months without decomposition. Oxidative Hay coupling [24] of 22 ± 24 in the presence of PhCCH as an end-capping reagent [21] provided the oligomeric PTAs as solids. The first-generation compound 22 afforded separable oligomers up to the pentamer (1a ± e), which extend in length from 19.4 (1a) to 49.4 (1e) [11] [21]. For steric reasons, the second-generation derivative 23 yielded isolable oligomers only up to the trimer (2a ± c). Finally, due to severe steric overcrowding, conversion of the third generation enediyne 24 gave only end-capped monomer and dimer (3a, b) in pure form and sufficient yields.Analytical gel-permeation chromatography (GPC) proved to be extremely useful for monitoring the purification of our compounds. The separation of the oligomers was achieved by preparative GPC (Bio-Beads S-X1; CH 2 Cl 2 ), and the purity of the fractions was determined by analytical GPC because, specifically for the higher oligomers, thin-layer chromatography (TLC) was useless. With other techniques such as 1 H-and 13 C-NMR spectroscopy, we could not detect impurities (lower and higher oligomers) with less than 10% abundance, while analytical GPC was sensitive for impurities with an abundance of less than 1%. The analytical GPC traces of the firstgeneration dendritic oligomers 1a ± e are shown in Fig. 4. Optical detection occurred at 300 nm in the absorption region of the aromatic wedges. GPC Separations of the higher-generation compounds were equally efficient.The molecular constitution of the dendritic rods was confirmed by matrix-assisted laser-desorption-ionization mass spectra (MALDI-TOF-MS; matrix: 9-nitroanthracene), which depicted either the [M Na] or [M K] ions as base peaks, and NMR spectra. In the 1 H-NMR spectra of the centrosymmetrical oligomers, the number of the t-Bu resonances increases with the number of monomeric units ( Table 1). Similar behavior was observed for the aromatic protons positioned between the two alkoxy substituents of the central benzene rings that serve as linkers between PTA backbone and dendritic wedges.

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Study of the correlation between the backbone conformation and the electronic structure of polydiacetylenes by solid state 13C n.m.r.

Cited by 28 publications

References 27 publications

Dendritic rods with a poly(triacetylene) backbone: insulated molecular wires

Dendritic rods with a poly(triacetylene) backbone: insulated molecular wires

Photopolymerization of diacetylene-capped gold nanoparticles

Insulated Molecular Wires: Dendritic Encapsulation of Poly(triacetylene) Oligomers, Attempted Dendritic Stabilization of Novel Poly(pentaacetylene) Oligomers, and an Organometallic Approach to Dendritic Rods

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