Synthesis, structure, and photoluminescence of organosilicon based compounds containing stilbene, butadiene or styrene subunits

Yan, Duanchao; Bolte, Michael; Auner, Norbert

doi:10.1016/j.jorganchem.2007.11.041

Cited by 13 publications

(12 citation statements)

References 43 publications

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“…Both main emissions reach far into the visible range. The Stokes shifts for the main maxima are 113 and 102 nm, which compares well to values obtained for silacyclobutenes 1a,b. The spectra of the mixed alkenylalkynylgermane 5 are also shown in Figure 4.…”

Section: Resultssupporting

confidence: 82%

Germacyclobutenes: Generation by 1,1‐Carbalumination or 1,1‐Carbagallation and Their Photophysical Properties

Uhl

Pelties

Tannert

et al. 2014

Chemistry A European J

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Aluminium- and gallium-functionalised alkenylalkynylgermanes, R(1) 2 Ge(C≡C-R(2) )[C{E(CMe3 )2 }=C(H)-R(2) ] (E=Al, Ga), exhibit a close contact between the coordinatively unsaturated Al or Ga atoms and the α-C atoms of the intact ethynyl groups. These interactions activate the Ge-C(alkynyl) bonds and favour the thermally induced insertion of these C atoms into the E-C(vinyl) bonds by means of 1,1-carbalumination or 1,1-carbagallation reactions. For the first time the latter method was shown to be a powerful alternative to known metallation processes. Germacyclobutenes with an unsaturated GeC3 heterocycle and endo- and exocyclic C=C bonds resulted from concomitant Ge-C bond formation to the β-C atoms of the alkynyl groups. These heterocyclic compounds show an interesting photoluminescence behaviour with Stokes shifts of >110 nm. The fascinating properties are based on extended π-delocalisation including σ*-orbitals localised at Ge and Al. High-level quantum chemical DFT and TD-DFT calculations for an Al compound were applied to elucidate their absorption and emission properties. They revealed a biradical excited state with the transfer of a π-electron into the empty p-orbital at Al and a pyramidalisation of the metal atom.

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Section: Resultssupporting

confidence: 82%

Germacyclobutenes: Generation by 1,1‐Carbalumination or 1,1‐Carbagallation and Their Photophysical Properties

Uhl

Pelties

Tannert

et al. 2014

Chemistry A European J

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“…The proton-NMR spectra of the other ringopened photoproducts (2-Me, 3-Me, 3-Ph) indicates that they also possess a similar E structure. These results are also confirmed from the crystal structure 2-C C-Ph, [14] and pro-Scheme 2. a) Photochemical ring-opening reaction of 1,1-Me 2 -silacyclobtuene (DMSCB) and subsequent trapping of silene intermediate with -OR group. [17] b) Photochemical ring-closure of cis-stilbene to form metastable 9,10-dihydrophenanthrene (DHP), followed by irreversible hydrogen abstraction by oxygen to form phenanthrene.…”

Section: Photochemistry In Solution and Doped-polymer Thin Filmssupporting

confidence: 75%

“…Solid-state photoluminescence: Previous reports on derivatives of 1-R as solid-state powders [14,35] indicated an appreciable photoluminescence (PL) intensity, as well as a significant influence of the Si substituents R on the wavelength and emission strength. Here we employ measurements on both pure powder samples and dilutely doped KBr powder samples to allow i) determination of the absorbance spectra (and hence transition origin) in the solid state and ii) quantitative estimates of the fluorescence quantum yields.…”

Section: Effect Of Aggregation In Solutionmentioning

confidence: 99%

“…After two months reaction time, the solvent was removed by vacuum and the resulting mixture was subjected to column chromatography on a silica gel (R f = 0.62, acetone/hexane 1:10) to give a colorless oil of 3-Ph (0.45 g, 41.6 %). 1 [14].…”

Section: -Phmentioning

confidence: 99%

“…Here we present the synthesis, crystal structures, and photophysical/photochemical behavior of a set of organosilicon compounds, 1,1-R 2 -2,3-diphenyl-4-neopentyl-1-silacyclobut-2-enes (1-R, see Figure 1 for structures). [12][13][14] The relatively small number of previous reports on 1-silacyclobut-2-enes (SCBs) [15][16][17][18][19][20][21][22][23] have been chiefly devoted to the 1,1-dimethyl and 1,1-dimethyl-2-phenyl derivatives (DMSCB, Ph-DMSCB) and the ring-opening photoreaction that occurs upon excitation of the lowest-energy (p-p*) absorption band. This band lies at relatively short wavelengths (i.e., below 230 nm), [22] and the photophysical and photochemical properties are similar to those of (alkyl-substituted) cyclobutene derivatives (such as the 3,4-dimethyl derivative, DMCB).…”

mentioning

confidence: 99%

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Synthesis, Structure, Photoluminescence and Photoreactivity of 2,3‐Diphenyl‐4‐neopentyl‐1‐silacyclobut‐2‐enes

Yan

Thomson

Bäcker

et al. 2009

Chemistry A European J

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A series of six 2,3-diphenyl-4-neopentyl-1-silacyclobut-2-enes with different 1,1-substituents has been prepared and characterized by single-crystal X-ray crystallography. These compounds possess a cis-stilbene-like chromophore involving also the four-membered ring, and exhibit a photophysical behavior similar to that of previously reported 1,2-diphenyl-cycloalkenes. This chromophore system is confirmed by a theoretical investigation of the electronic structure and excitation spectra. The absorption and photoluminescence of selected derivatives were studied in solution, as solid powder samples, and in doped-polymer thin films. In well-dissolved solution, the silacyclobutenes show only very weak fluorescence emission (quantum yield approximately 0.1%), due to competition with photochemical and non-radiative photophysical relaxation. When the solubility is degraded in a poor (aqueous) solvent, the formation of nanoscale aggregates leads to a significant enhancement factor in the emission intensity, due to the suppression of the photoreactivity in the more rigid molecular environment, although the quantum yield still remains below a few percent. In the solid-state, however, photoreactivity is completely suppressed leading to fluorescence quantum efficiencies of 8-23% depending on the 1,1-substituents, which demonstrates these compounds' potential as chromophores for condensed-phase luminescence applications. Two dominant competing photochemical reactions have been identified in solution (for excitation in the lowest-energy absorption band, >260 nm), which are analogous to related (sila-)cyclobutenes and stilbenoids. The first involves ring-opening due to cleavage of the 1,4-Si-C bond to form metastable silabutadienes, which was confirmed by isolating the stereospecifically formed allylsilane which results from a secondary reaction with trapping agents such as methanol or water. The second photochemical reaction involves ring closure of the 2,3-diphenyl substructure to form a dihydrophenanthrene analogue, which was confirmed by isolating the phenanthrene derivative that results following subsequent hydrogen abstraction in the presence of oxygen. Measurements of the silacyclobutenes in doped-polymer thin films reveal a spectroscopic behavior ranging from that in solution to the nano-aggregate case as the silacyclobutene dopant concentration is increased.

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Quaternary Ammonium Salts: Catalysts for Hydrosilylation of Alkynes with Hydrosilanes

et al. 2023

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Mixing i‐PrI and DABCO in solvent EtCN gave two quaternary ammonium salts (QASs) quantitatively, one of which is monocationic (QAS‐1) and the other is dicationic (QAS‐2). These QASs were found to catalyze hydrosilylation of alkynes with hydrosilanes (HAH) without the aid of metal and metalloid catalysts. This organocatalysis can be applied to a variety of alkynes: terminal/internal aryl and alkyl alkynes with/without a functional group. With dihydrosilanes (H2Si), the HAH occurred with high E‐selectivity through syn addition, which was exclusively observed when using terminal alkyl alkynes, irrespective of a hydrosilane used. A scalable HAH is also feasible. The H−Si unit remaining in alkenylsilanes derived from H2Si is available for dehydrogenative alkynylation and N‐heteroarylation under zinc–pyridine catalysis. This synthetic application delivers unique silicon compounds that have, for instance, alkyl, aryl, alkenyl, and alkynyl groups in a single molecule. Mechanistic studies suggested that alkynes activated by QASs irreversibly react with hydrosilanes that become more nucleophilic by the coordination of EtCN. A radical pathway is unlikely. The QAS catalysts can be recovered and reused at least 5 times.

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Synthesis, structure, and photoluminescence of organosilicon based compounds containing stilbene, butadiene or styrene subunits

Cited by 13 publications

References 43 publications

Germacyclobutenes: Generation by 1,1‐Carbalumination or 1,1‐Carbagallation and Their Photophysical Properties

Germacyclobutenes: Generation by 1,1‐Carbalumination or 1,1‐Carbagallation and Their Photophysical Properties

Synthesis, Structure, Photoluminescence and Photoreactivity of 2,3‐Diphenyl‐4‐neopentyl‐1‐silacyclobut‐2‐enes

Quaternary Ammonium Salts: Catalysts for Hydrosilylation of Alkynes with Hydrosilanes

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