Photoluminescence from silsesquioxanes R8(SiO1.5)8

Azinović, Davorka; Cai, Jianjun; Eggs, C.; König, Holger; Marsmann, H.C.; Vepřek, S.

doi:10.1016/s0022-2313(01)00422-7

Cited by 23 publications

(24 citation statements)

References 14 publications

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“…Recently, high-frequency magnetization has been induced by intense laser light in a wide variety of materials including simple chemical compounds. − Nonlinear scattering experiments can characterize 3-D silsesquioxane structures in a novel way that exploits their susceptibility to the joint forces of magnetic and electric optical fields. Magnetoelectric scattering at the molecular level is sensitive to the potential energy surface V within each molecule.…”

Section: Resultsmentioning

confidence: 99%

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

et al. 2019

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Macromonomers [RPhSiO 1.5 ] 8,10,12 and [RCH CHSiO 1.5 ] 8,10,12 , where R is a conjugated group, have previously been shown to offer photophysical properties wherein excitation promotes an electron from the HOMO to an excited-state LUMO that sits in the center of the cage and allows communication between all conjugated groups, suggesting 3-D delocalization. In the current work, we explore replacing one conjugated group in [RPhSiO 1.5 ] 8 with either Me or nPr or s i m p l y r e m o v i n g o n e c o r n e r f r o m t h e c a g e , [RPhSiO 1.5 ] 7 (O 0.5 SiMe 3 ) 3 , and examine its effect on any potential LUMO that might form. We report here that such changes seem to have no effect on the existence of a 3-D LUMO-derived delocalization as witnessed by emission redshifts from the R = 4-Me-/4-CN-stilbene moieties essentially identical to those for the original [RPhSiO 1.5 ] 8 macromonomers. Of particular importance is the fact that removing one corner from the cage also has little effect on the photophysics, indeed significantly improving fluorescence emission quantum efficiencies. However, removing most of the conjugated groups on the corner missing cage (from 7 to 2), e.g., [MeStilSiO 1.5 ] 2 [PhSiO 1.5 ] 5 (O 0.5 SiMe 3 ) 3 , eliminates the red-shift, implying the absence of a LUMO inside the cage. This suggests a minimum number of groups are needed to form such a LUMO. Also, for the first time, the radiation patterns for nonlinear, optically induced magnetic scattering at elevated light intensities are reported for these compounds and shown to support the same conclusiona spherical LUMO exists inside the cage.

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Section: Resultsmentioning

confidence: 99%

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

et al. 2019

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“…A potential explanation was identified based on theoretical studies. Silsesquioxanes in general have been the subject of a large number of theoretical studies. − Most of the studies find that the highest occupied molecular orbital (HOMO) involves 2p lone pair states of A 2g symmetry on the oxygen atoms which is not surprising. However, these same studies find that the lowest unoccupied molecular orbital (LUMO) has 4A 1 symmetry and involves contributions from all Si and oxygen atoms and the organic substituents, is spherical, and resides in the core center.…”

Section: Properties Of Stilbenesqsmentioning

confidence: 99%

“…It is not uncommon for DFT-calculated band gaps to overestimate experimental results. Thus, Marsmann et al demonstrated that band gap calculations on the [RSiO 1.5 ] 8 cages are high, reporting that [XSiO 1.5 ] 8 where X = CH 3 −, CH 3 CH 2 , ..., decyl) absorb 3.8 eV (325 nm) light and emit at ≈2.8−3.5 eV (330−370 nm). Their calculations suggest a 6.0 eV band gap for [HSiO 1.5 ] 8 , but the experimental value was 4.4 eV, which is 1.6 eV lower.…”

Section: Properties Of Stilbenesqsmentioning

confidence: 99%

Polyhedral Phenylsilsesquioxanes

Laine¹,

Roll²

2011

Macromolecules

239

184

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Our objectives are to provide a comprehensive review solely concerning the synthesis and chemistries of polyhedral phenylsilsesquioxanes. The review covers the basic efforts to synthesize and characterize the compounds [PhSiO 1.5 ] 8 , [PhSiO 1.5 ] 10 , and [PhSiO 1.5 ] 12 . Thereafter, we discuss general methods of functionalizing these compounds with emphasis on electrophilic substitution to produce, for example, [NO 2 PhSiO 1.

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“…We suspect that the addition of the first substituent may increase the overall reactivity of all vinyl groups in OVS, thus leading to the observed higher substituted products. As unique electronic and luminescent properties have been described for SSQ materials, a pseudo‐electron delocalization possibility exists 34,35. This issue is a topic of continued study in our group.…”

Section: Resultsmentioning

confidence: 81%

Auto‐thermal combustion of lean gaseous fuels utilizing a recuperative annular double‐layer catalytic converter

Budzianowski

Miller

2008

Can J Chem Eng

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The results of the investigations on the auto-thermal combustion of lean gaseous fuels in a recuperative annular double-layer catalytic converter were reported in the current contribution. Several modifications were proposed to improve the stationary and transient behaviour of the converters. The miniaturized recuperative converter exhibited reduced resistances to the mass and heat transfer and attractive bifurcation changes of a very low combustible content, that is, the histeresis for T in and C in and isola for mf in and h g . It was revealed that the utilization of an adiabatic recuperative converter led to an autothermal operation for T in = 300 K and C in = 177 ppmv of propane. The inlet fuel mass flow rate range to apply was wider than earlier reported in the literature, that is, 0.63-2.94 × 10 −6 kg s −1 for C in = 200 ppmv. Transient experiments showed that recuperative converter was able to transfer short-time inlet disturbances of parameters due to the energy accumulation and temporal reversed recuperation counteracting to extinction or to destructive overheating of the catalysts. Stability analysis was performed showing location of folds, stable and unstable branches of solutions for the different parameters of the recuperative converter. A two-dimensional process model was developed.Le résultats d'investigation d'auto-thermique combustion du pauvre gazeux combustible dans un convertisseur catalytique récupéré deux-couché aété reporté au présent travail. Plusieurs modifications aété proposé pour améliorer stationnaire et non-stationnaire conduite du convertisseur. Le convertisseur miniaturisé recuperé affiche réduit résistancesá masse et chaud transfert et attractive bifurcation pour trés bas contenu du combustible, that is, histeresis pour T in et C in et isola pour mf in and h g . On a découvré que l'utilization du convertisseur adiabatique recuperé conduitá l'operation autothermique pour T in = 300 K et C in = 177 ppmv du propane. Les limites des mf in pour appliquer aété supérieurá ceux-ci rapporté dans la littérature, that is, 0.63-2.94 × 10 −6 kg s −1 pour C in = 200 ppmv. Le non-stationnaire expérience a indiqué que convertisseur recuperé aété capableá transfert court-temps perturbations des parametres de l'entrée graceá l'accumulation de l'énergie et intermittente recuperation renversé interféreáéteindre ouá destructif surchauffe du cataliseur. L'analyse de stabilité présente arcs, stable et non-stableétat pour les parametres du convertisseur recuperé. Un modèle bidimensionnel du procédé aété développé.

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Photoluminescence from silsesquioxanes R8(SiO1.5)8

Cited by 23 publications

References 14 publications

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

Polyhedral Phenylsilsesquioxanes

Auto‐thermal combustion of lean gaseous fuels utilizing a recuperative annular double‐layer catalytic converter

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Photoluminescence from silsesquioxanes R8(SiO1.5)8

Cited by 23 publications

References 14 publications

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO1.5]7[Me/nPrSiO1.5] and [RSiO1.5]7[O0.5SiMe3]3 (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO1.5]7[Me/nPrSiO1.5] and [RSiO1.5]7[O0.5SiMe3]3 (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

Polyhedral Phenylsilsesquioxanes

Auto‐thermal combustion of lean gaseous fuels utilizing a recuperative annular double‐layer catalytic converter

Contact Info

Product

Resources

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Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light

Photophysical Properties of Partially Functionalized Phenylsilsesquioxane: [RSiO_1.5]₇[Me/nPrSiO_1.5] and [RSiO_1.5]₇[O_0.5SiMe₃]₃ (R = 4-Me/4-CN-Stilbene). Cage-Centered Magnetic Fields Form under Intense Laser Light