2039-80-7Relevant academic research and scientific papers
Synthesis and photophysical properties of stilbeneoctasilsesquioxanes. emission behavior coupled with theoretical modeling studies suggest a 3-D excited state involving the silica core
Laine,Sulaiman,Brick,Roll,Tamaki,Asuncion,Neurock,Filhol,Lee,Zhang,Goodson III,Ronchi,Pizzotti,Rand,Li
, p. 3708 - 3722 (2010)
A set of stilbene-substituted octasilicates [p-RStilxPh a-xSiO1.5]8 (R = H, Me, MeO, Cl, NMe 2 and x= 5.3-8) and [o-MeStilSiO1.5]8 were prepared. Model compounds were also prepared including the corner and half cages; [p-MeStilSi(OEt)3]. [p-Me2NStilSi(OSiMe 3)3], and [p-Me2NStilSi(O)(OSiMe)]4. These compounds were characterized by MALDI-TOF, TGA, FTIR, and 1H NMR techniques. Their photophysical properties were characterized by UV-vis, two-photon absorption, and cathodoluminescence spectroscopy (on solid powders), Including studies on the effects of solvent polarity and changes In concentration, These molecules are typically soluble, easily purified, and robust, showing Td(5%) > 400°C in air. The full and partial cages all show UV-vis absorption spectra (in THF) identical to the spectrum of frans-stilbene, except for [o-MeStilSiO1.5]8, which exhibits an absorption spectrum blue-shifted from trans-stilbene, However, the partial cages show emissions that are red-shifted by ～20 nm, as found for stilbene-siloxane macrocycles, suggesting some interaction of the silicon center(s) with the stilbene π* orbital in both the corner and half cages. In contrast, the emission spectra of the full cages show red-shifts of 60-100 nm. These large red-shifts are supported by density functional theoretical calculations and proposed to result from interactions of the stilbene π* orbitals with a LUMO centered within the cage that has 4A1 symmetry and involves contributions from all Si and oxygen atoms and the organic substituents, Given that this LUMO has 3-D symmetry, it appears that all of the stilbene units interact in the excited state, consistent with theoretical results, which show an increased red-shift with an increase in the functionalization of a single corner to functionalization of all eight corners with stilbene. In the case of the Me2N- derivatives, this interaction is primarily a charge-transfer interaction, as witnessed by the influence of solvent polarity on the emission behavior. More importantly, the two-photon absorption behavior is 2-3 times greater on a per p-Me2Nstilbene basis for the full cage than for the corner or half cages. Similar observations were made for p-NH2stilbenevinyl8OS cages, where the greater conjugation lengths led to even greater red-shifts (120 nm) and two-photon absorption cross sections, Cathodoluminescence studies done on [p-MeStilSiO1.5]8 or [p-MeStilOS]8 powders exhibit essentially the same emissions as seen in solution at high dilution. Given that only the emissions are greatly red-shifted in these molecules, whereas the ground-state UV-vis absorptions are not changed from trans-stilbene, except for the ortho derivative, which is blue-shifted 10 nm. It appears that the interactions are only in the excited state. Theoretical results show that the HOMO and LUMO states are always the π and π* states on the stilbene, which show very weak shifts with increasing degrees of functionalization, consistent with the small changes in the UV-vis spectra. The band gap between the lowest unoccupied 4a1 symmetry core state localized inside the silsesquioxane cage and the highest occupied state (π state on stilbene), however, is markedly decreased as the number of stilbene functional groups is increased. This is consistent with the significant red-shifts in the emission spectra. The results suggest that the emission occurs from the 4a1 state localized on the cage. Moreover, for the compounds [p-RStil6-7Ph 2-1OS]8, the emissions are blue-shifted compared to those of the fully substituted compounds, suggesting the molecular symmetry is reduced (from cubic), thereby reducing the potential for 3-D delocalization and raising the energy of the LUMO, The implications are that these octafunctional molecules exhibit some form of 3-D interaction in the excited state that might permit their use as molecular transistors as well as for energy collection and dispersion as molecular antennas, for example, and for nonlinear optical applications.
Novel 1,8-naphthalimide derivatives for standard-red organic light-emitting device applications
Luo, Shuai,Lin, Jie,Zhou, Jie,Wang, Yi,Liu, Xingyuan,Huang, Yan,Lu, Zhiyun,Hu, Changwei
, p. 5259 - 5267 (2015)
Three red-emissive D-π-A-structured fluorophores with an aromatic amine as the donor, ethene-1,2-diyl as the π-bridge, and 1,8-naphthalimide as the acceptor subunit, namely, (E)-6-(4-(dimethylamino)styryl)-2-hexyl-1H-benzo[de]isoquinoline-1,3(2H)-dione (Nap1), (E)-2-(2,6-di(isopropyl)phenyl)-6-(4-(dimethylamino)styryl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (Nap2) and (E)-2-(2,6-di(isopropyl)phenyl)-6-(2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)vinyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (Nap3), were designed and synthesized. In-depth investigations on the correlations between their molecular structures and photophysical characteristics revealed that the presence of an electron-rich 4-dimethylaminophenyl donor moiety in compound Nap1 could endow it with a red emission (e.g., λPLmax = 641 nm in the host-guest blend film with a 14 wt% guest composition); moreover, the replacement of the n-hexyl group of Nap1 bonding to the imide nitrogen atom for a more bulky 2,6-di(isopropyl)phenyl one would result in compound Nap2 with more alleviated concentration quenching. Alteration of the 4-(dimethylamino)phenyl donor subunit of Nap2 into a more electron-donating 1,1,7,7-tetramethyljulolidin-9-yl substituent would render compound Nap3 with more improved chromaticity (e.g., λPLmax = 663 nm in a 14 wt% guest-doped film). Consequently, Nap3 could not only emit standard-red fluorescence with satisfactory chromaticity, but it also showed suppressed intermolecular interactions. Using Nap3 as the dopant, a heavily doped standard-red organic light-emitting diode (OLED) with the device configuration of ITO/MoO3 (1 nm)/TcTa (40 nm)/CzPhONI:Nap3 (14 wt%) (20 nm)/TPBI (45 nm)/LiF (1 nm)/Al (80 nm) was fabricated, and the Commission Internationale de L'Eclairage coordinates, maximum external quantum efficiency and maximum current efficiency of this OLED were (0.67,0.32), 1.8% and 0.7 cd A-1, respectively. All these preliminary results indicated that 1,8-naphthalimide derivatives could act as quite promising standard-red light-emitting materials for OLED applications. This journal is
Styryl conjugated coumarin caged alcohol: Efficient photorelease by either one-photon long wavelength or two-photon NIR excitation
Bao, Chunyan,Fan, Guanshui,Lin, Qiuning,Li, Bo,Cheng, Shuiyu,Huang, Qi,Zhu, Linyong
, p. 572 - 575 (2012)
The synthesis and photorelease properties of a new phototrigger for alcohols are described. Compared to ester 4 caged by the reported [7-(diethylamino)coumarin-4-yl]methoxycarbonyl (DEACM) phototrigger, the caged ester 3 shows an efficient single-photon photolysis efficiency upon irradiation of long wavelength light (λ = 475 nm) and a stronger two-photon photolysis sensitivity with 800 nm laser light. Its promising properties and the efficient photorelease of adenosine make it very useful as a caging group for biological applications.
Catalyst-Free Visible-Light-Mediated Iodoamination of Olefins and Synthetic Applications
Engl, Sebastian,Reiser, Oliver
supporting information, p. 5581 - 5586 (2021/07/26)
Herein we report a catalyst- and metal-free visible-light-mediated protocol enabling the iodoamination of miscellaneous olefins. This protocol is characterized by high yields under environmentally benign reaction conditions utilizing commercially available substrates and a green and biodegradable solvent. Furthermore, the protocol allows for late-stage functionalization of bioactive molecules and can be scaled to gram quantities of product, which offers manifold possibilities for further transformations, including morpholine, piperidine, pyrrolidine, and aziridine synthesis.
Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy
Alansari, Isabella Y.,Clark, Joseph R.,Holdren, Martin S.,Neill, Justin L.,Pate, Brooks H.,Reyes, Albert,Sloane, Samantha E.,Sonstrom, Reilly E.,Vang, Zoua Pa
supporting information, p. 7707 - 7718 (2021/06/21)
A copper-catalyzed alkene transfer hydrodeuteration reaction that selectively incorporates one hydrogen and one deuterium atom across an aryl alkene is described. The transfer hydrodeuteration protocol is selective across a variety of internal and terminal alkenes and is also demonstrated on an alkene-containing complex natural product analog. Beyond using 1H, 2H, and 13C NMR analysis to measure reaction selectivity, six transfer hydrodeuteration products were analyzed by molecular rotational resonance (MRR) spectroscopy. The application of MRR spectroscopy to the analysis of isotopic impurities in deuteration chemistry is further explored through a measurement methodology that is compatible with high-throughput sample analysis. In the first step, the MRR spectroscopy signatures of all isotopic variants accessible in the reaction chemistry are analyzed using a broadband chirped-pulse Fourier transform microwave spectrometer. With the signatures in hand, measurement scripts are created to quantitatively analyze the sample composition using a commercial cavity enhanced MRR spectrometer. The sample consumption is below 10 mg with analysis times on the order of 10 min using this instrument - both representing order-of-magnitude reduction compared to broadband MRR spectroscopy. To date, these measurements represent the most precise spectroscopic determination of selectivity in a transfer hydrodeuteration reaction and confirm that product regioselectivity ratios of >140:1 are achievable under this mild protocol.
In-situ facile synthesis novel N-doped thin graphene layer encapsulated Pd@N/C catalyst for semi-hydrogenation of alkynes
Lin, Shanshan,Liu, Jianguo,Ma, Longlong,Sun, Jiangming
, (2021/12/03)
Transition metal-catalyzed semi-hydrogenation of alkynes has become one of the most popular methods for alkene synthesis. Specifically, the noble metal Pd, Rh, and Ru-based heterogeneous catalysts have been widely studied and utilized in both academia and industry. But the supported noble metal catalysts are generally suffering from leaching or aggregation during harsh reaction conditions, which resulting low catalytic reactivity and stability. Herein, we reported the facile synthesis of nitrogen doped graphene encapsulated Pd catalyst and its application in the chemo-selective semi-hydrogenation of alkynes. The graphene layer served as “bulletproof” over the active Pd Nano metal species, which was confirmed by X-ray and TEM analysis, enhanced the catalytic stability during the reaction conditions. The optimized prepared Pd@N/C catalyst showed excellent efficiency in semi-hydrogenation of phenylacetylene and other types of alkynes with un-functionalized or functionalized substituents, including the hydrogenation sensitive functional groups (NO2, ester, and halogen).
Overcoming Selectivity Issues in Reversible Catalysis: A Transfer Hydrocyanation Exhibiting High Kinetic Control
Bhawal, Benjamin N.,Ehinger, Christian,Morandi, Bill,Reisenbauer, Julia C.
supporting information, p. 10914 - 10920 (2020/07/13)
Reversible catalytic reactions operate under thermodynamic control, and thus, establishing a selective catalytic system poses a considerable challenge. Herein, we report a reversible transfer hydrocyanation protocol that exhibits high selectivity for the thermodynamically less favorable branched isomer. Selectivity is achieved by exploiting the lower barrier for C-CN oxidative addition and reductive elimination at benzylic positions in the absence of a cocatalytic Lewis acid. Through the design of a novel type of HCN donor, a practical, branched-selective, HCN-free transfer hydrocyanation was realized. The synthetically useful resolution of a mixture of branched and linear nitrile isomers was also demonstrated to underline the value of reversible and selective transfer reactions. In a broader context, this work demonstrates that high kinetic selectivity can be achieved in reversible transfer reactions, thus opening new horizons for their synthetic applications.
Palladium-Catalyzed Mizoroki-Heck Reaction of Nitroarenes and Styrene Derivatives
Okita, Toshimasa,Asahara, Kitty K.,Muto, Kei,Yamaguchi, Junichiro
supporting information, p. 3205 - 3208 (2020/04/10)
We have developed a Mizoroki-Heck reaction of nitroarenes with alkenes under palladium catalysis. The use of a Pd/BrettPhos catalyst promoted the alkenylation, whereas other catalysts led to a decrease in the product yield. In addition to nitroarenes, nitroheteroarenes were also applicable to the present reaction. The combination of a nucleophilic aromatic substitution (SNAr) with the denitrative alkenylation produced a multifunctionalized arene in a one-pot operation.
Synthesis of All-Carbon Quaternary Centers by Palladium-Catalyzed Olefin Dicarbofunctionalization
Koy, Maximilian,Bellotti, Peter,Katzenburg, Felix,Daniliuc, Constantin G.,Glorius, Frank
supporting information, p. 2375 - 2379 (2020/01/24)
The redox-neutral dicarbofunctionalization of tri- and tetrasubstituted olefins to form a variety of (hetero)cyclic compounds under photoinduced palladium catalysis is described. This cascade reaction process was used to couple styrenes or acryl amides with a broad range of highly decorated olefins tethered to aryl or alkyl bromides (>50 examples). This procedure enables one or two contiguous all-carbon quaternary centers to be formed in a single step. The products could be readily diversified and applied in the synthesis of a bioactive oxindole analogue.
6MNEP: A molecular cation with large hyperpolarizability and promise for nonlinear optical applications
Bloxham, Joseph C.,Brock, Daniel J.,Jackson, Erika W.,Johnson, Jeremy A.,Kenney, Karissa C.,Michaelis, David J.,Smith, Stacey J.,Valdivia-Berroeta, Gabriel A.,Wayment, Adam X.
supporting information, p. 11079 - 11087 (2020/09/09)
Molecular organic crystals are strategically designed for nonlinear optical applications using push-pull chromophores as the core feature. In this approach, electron-donating and accepting groups are connected through a π-conjugated bridge to obtain planar molecules with high hyperpolarizability. However, the non-centrosymmetric packing that is required for nonlinear optical (NLO) applications is a critical challenge that must be addressed to design useful materials. In this article, we present the new organic cation 6MNEP that shows a large hyperpolarizability and can be crystallized in ideal non-centrosymmetric structures for NLO applications, when paired with T and 4NBS anions. The 6MNEP cation was obtained by extending the conjugation length of already existing chromophores. We compare the 6MNEP crystals with other crystals that also have cations with extended conjugation lengths, but result in centrosymmetric crystal structures. Using the effective hyperpolarizability, we found 6MNEP-T and 6MNEP-4NBS to have 1.6 to 2.5 times larger macroscopic nonlinearities than benchmark NLO organic crystals. Additionally, the significantly lower absorption wavelength compared with other state-of-the-art crystals make 6MNEP-T and 6MNEP-4NBS promising materials for NLO applications like intense terahertz generation.
