One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives

• Feng-Ming Xie,
• Qingdong Ou,
• Qiang Zhang,
• Jiang-Kun Zhang,
• Guo-Liang Dai,
• Xin Zhao and
• Huai-Xin Wei

Beilstein J. Org. Chem. 2018, 14, 869–874, doi:10.3762/bjoc.14.73

• lifetime. Carbazole groups are widely used in host materials because of their high triplet energy levels and high hole mobility [15]. The Lee group [16] linked carbazolyl groups to diphenyl phosphoramines to design asymmetric (9-phenyl-9H-carbazole-2,5-diyl)bis(diphenylphosphine oxide) (PCPOs) with a

• intermolecular forces of molecules. The high thermal values ensure high thermostability and that the amorphous structure can form homogeneous and stable films by vacuum deposition to improve the lifetime of the PhOLEDs. The photophysics, electrochemical and thermal properties of CEPDO and CBPDO are summarized in

Phosphodiester models for cleavage of nucleic acids

• Satu Mikkola,
• Tuomas Lönnberg and
• Harri Lönnberg

Beilstein J. Org. Chem. 2018, 14, 803–837, doi:10.3762/bjoc.14.68

• intermediate [31]. The lifetime for the dianionic pentacoordinated species obtained by the attack of the hydroxide ion on the phosphorus has been argued to represent an energy minimum between the transition states for the attack of HO− and the departure of EtO− and to have a lifetime of 1 picosecond. With

• leaving groups that are less basic than EtO−, such as 5´-O− of nucleoside, the lifetime expectedly is shorter. If the leaving group is very good, such as an aryl group, a synchronous concerted mechanism (ANDN) may take over the stepwise mechanism (AN + DN). Model compounds and experimental tools Studies

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• lifetime of the prompt and delayed components of the time-resolved transient PL decay curves at room temperature, the PLQY of their respective components and rate constant of different kinetic processes were calculated, as shown in Table 4. The rate constants were calculated following Equations 1–4 below

Heterogeneous Pd catalysts as emulsifiers in Pickering emulsions for integrated multistep synthesis in flow chemistry

• Katharina Hiebler,
• Georg J. Lichtenegger,
• Manuel C. Maier,
• Eun Sung Park,
• Renie Gonzales-Groom,
• Bernard P. Binks and
• Heidrun Gruber-Woelfler

Beilstein J. Org. Chem. 2018, 14, 648–658, doi:10.3762/bjoc.14.52

• and lifetime. Apart from that, ligand-free Pd catalysts are also known in the literature [11][12]. However, homogeneous Pd catalysis often requires catalyst loadings in the order of mol % to achieve effective coupling and suffers from catalyst re-use and recycling problems [11][13]. Furthermore

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• dramatic efficiency roll-off at high current density was observed, as the result of a long TADF lifetime (270 μs). This issue was addressed with D4 [41]. By replacing the tert-butyl groups of D3 by methoxy groups in D4, a significant decrease of ΔEST was obtained (0.21 eV instead of 0.32 eV for D3

• ), reducing the TADF lifetime and efficiency roll-off. More precisely, the higher electron-donating ability and the longer conjugation length of the 3,6-dimethoxycarbazole compared to the 3,6-di-tert-butylcarbazole lowered the S1 state and to a greater extend the T1 state of D4, furnishing in turn a molecule

• with a smaller ΔEST than D3. Jointly, due to the reduction of ΔEST, a TADF lifetime of 93 μs was determined for D4, far from the value measured for D3 (270 μs). When tested in a similar device structure than that previously used for D3, a maximum EQE of 14.5% and a smaller efficiency roll-off was

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• monomer–excimer switching beacons are also fluorescent in the unbound state, and therefore it is possible to monitor the success of cellular delivery. In the case of pyrene monomer–excimer switching, the long fluorescence lifetime of the pyrene excimers allows facile elimination of background signals from

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• decays of tC are all monoexponential in single- as well as in double-stranded DNA resulting in a single lifetime of 5–7 ns depending on the sequence surroundings [30]. For tCO single-stranded surroundings generally result in biexponential decays, whereas duplex surroundings, as in the case for tC, result

Continuous-flow processes for the catalytic partial hydrogenation reaction of alkynes

• Carmen Moreno-Marrodan,
• Francesca Liguori and
• Pierluigi Barbaro

Beilstein J. Org. Chem. 2017, 13, 734–754, doi:10.3762/bjoc.13.73

• terms of productivity per unit active metal, volume or time, absence of additives or catalyst lifetime [26][27]. In the present paper we shortly review the heterogeneous catalytic systems engineered for the partial hydrogenation reaction of substituted and unsubstituted alkynes under continuous flow and

Membrane properties of hydroxycholesterols related to the brain cholesterol metabolism

• Malte Hilsch,
• Ivan Haralampiev,
• Peter Müller,
• Daniel Huster and
• Holger A. Scheidt

Beilstein J. Org. Chem. 2017, 13, 720–727, doi:10.3762/bjoc.13.71

• astrocytes and neurons [5]. The tight control of the cholesterol concentration and homeostasis is of paramount importance for the functions of all cells of the body but particularly for the brain. More so as the rate of cholesterol accumulation and synthesis is subject to subtle alterations over the lifetime

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• biexponential kinetic with a longer, dominant lifetime (τ) of 1.44 ns (83%) and a minor shorter component of 0.48 ns (17%). The decay of the 2–β-CD conjugate was more complex and was fitted by a triexponential fit with lifetimes of 4.26 ns (3%), 1.77 ns (45%) and below 0.2 ns (52%). This behavior may

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

• Yi Lai,
• Zhijian Zong,
• Yujie Tang,
• Weimin Mo,
• Nan Sun,
• Baoxiang Hu,
• Zhenlu Shen,
• Liqun Jin,
• Wen-hua Sun and
• Xinquan Hu

Beilstein J. Org. Chem. 2017, 13, 213–221, doi:10.3762/bjoc.13.24

• ]. Alternatively, the palladacycles reported by Herrmann and Beller in the 1990s [30] effectively elongated the lifetime of the active Pd species through employing bidentate or multidentate ligands [31][32][33][34][35][36]. Meanwhile nitrogen ligands are also widely used for palladium catalysts in coupling

A self-assembled cyclodextrin nanocarrier for photoreactive squaraine

• Ulrike Kauscher and
• Bart Jan Ravoo

Beilstein J. Org. Chem. 2016, 12, 2535–2542, doi:10.3762/bjoc.12.248

• atmospheric conditions. At these conditions the concentration of oxygen in water is 1.25 mM while the concentration of oxygen in acetonitrile is between 8.1–12.1 mM, depending on the type of measurement. [39]. The lower oxygen concentration in water can enhance the lifetime of AdSq on CDV. Conclusion We

Ionic liquids as transesterification catalysts: applications for the synthesis of linear and cyclic organic carbonates

• Maurizio Selva,
• Alvise Perosa,
• Sandro Guidi and
• Lisa Cattelan

Beilstein J. Org. Chem. 2016, 12, 1911–1924, doi:10.3762/bjoc.12.181

• allows reactions to be performed under very mild conditions and with a variety of raw materials. However, the high cost and relatively short lifetime of enzymes partly offset their advantages and an implementation of biocatalytic processes makes sense almost exclusively for the preparation of high added

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• organic substrate and the dye, and the solubility as well as the lifetime of oxygen in its singlet state (1O2) [76]. All reactions were performed under irradiation with an energy-saving light bulb (Osram Dulux Superstar) against a back-pressure of 2.4 bar while one parameter was varied in each experiment

On the cause of low thermal stability of ethyl halodiazoacetates

• Magnus Mortén,
• Martin Hennum and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2016, 12, 1590–1597, doi:10.3762/bjoc.12.155

• acid was employed in all experiments. The temperature dependence in toluene-d8 as solvent was found to be similar in CD2Cl2 (Table 1, entries 11–13). Next, the effect of additives on the stability of the compounds was investigated. We first tested NEt3 (not shown), inspired by the prolonged lifetime of

• bromodiazoacetate lifetime (Table 1, entries 14–18). Thus the half-life of 2b increased ~6 times in the presence of 1 equiv TMEDA in CDCl3 solution. EDA has been reported to be stable in glacial acetic acid [4]. Halodiazoesters 2a and 2b on the other hand decomposed with half-lives of approx. 33 min (2a) and 63 min

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells

• Wei Li,
• Munechika Otsuka,
• Takehito Kato,
• Yang Wang,
• Takehiko Mori and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134

• carrier lifetime or time constant (τ) is related to the recombination of an electron and a hole at the interfaces between the perovskite and TiO2 or hole-transporting layers. This parameter can be calculated according to Equation 2 [47]: where f is the maximum frequency derived from the semicircle of the

• impedance spectra, also known as the character frequency. The calculated τ values are listed in Table 2. The device based on 3,6-Cbz-EDOT displayed the longest lifetime of 3.98 μs, which is almost twice as high as that of the device based on P3HT. This result can be explained by the LUMO levels of the HTMs

• prolonged carrier lifetime. It is worth noting that there is still a room for improvement of the carrier mobility and lifetime by the increase in the molecular weights of these polymers. Overall, the Cbz-EDOT polymers, especially 2,7-Cbz-EDOT, are solution-processable promising HTMs of the PSCs

Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems

• Fabrizio Palumbo,
• Francisco Bosca,
• Isabel M. Morera,
• Inmaculada Andreu and
• Miguel A. Miranda

Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115

• luminescence at 1270 nm, using a germanium diode as detector. The singlet oxygen lifetime (Figure 7A) was found to be ca. 70 μs in all cases (in agreement with the1O2 lifetime reported in the literature [20] for the same solvent). The photosensitized singlet oxygen production was established with a quantum

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• emission lifetime. Notably, a considerable number of solvatochromic molecules is based on charge-transfer (CT) processes in the excited state resulting from a pronounced donor–acceptor interplay within the fluorophore [8]. Thus, upon excitation of such compounds, a CT – or in charged species a charge shift

Dynamic behavior of rearranging carbocations – implications for terpene biosynthesis

• Stephanie R. Hare and
• Dean J. Tantillo

Beilstein J. Org. Chem. 2016, 12, 377–390, doi:10.3762/bjoc.12.41

• level, this scenario can result in bypassed intermediates, i.e., an IRC having a minimum calculated along the pathway to the product, but with a lifetime that is not long enough to allow for equilibration; some pathways/trajectories will also skirt past the deepest parts of the energy well. Additionally

• ), with no secondary carbocation found as a stationary point on the PES. However, molecular dynamics simulations initiated from the reactant revealed trajectories that predominantly followed a stepwise mechanism (Figure 5, green), with a lifetime of the secondary carbocation of up to 4000 fs. This is the

• presence of a “hidden intermediate” [47][48][49][50][51], i.e., a structure along the IRC that is not a minimum but is associated with an energy plateau and may have a substantial lifetime. Such IRCs have subsequently been observed for many reactions for which secondary carbocations are putative

My maize and blue brick road to physical organic chemistry in materials

• Anne J. McNeil

Beilstein J. Org. Chem. 2016, 12, 229–238, doi:10.3762/bjoc.12.24

• , exploring our world together (Figure 8). Professionally, I have taken on new leadership roles at the University of Michigan and elsewhere. My lifetime love of learning has led me down a path to better understand how other people learn. This path involved starting a funded research program in chemistry

Pyridylidene ligand facilitates gold-catalyzed oxidative C–H arylation of heterocycles

• Kazuhiro Hata,
• Hideto Ito,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2015, 11, 2737–2746, doi:10.3762/bjoc.11.295

• elimination steps, we believe that the strongly electron-donating PyC not only facilitates gold(I)-to-gold(III) oxidation in catalysis but also prolongs the catalyst lifetime by preventing the ligand dissociation and formation of inactive gold nanoparticles. Conclusion In summary, we have developed the

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• lifetime τ = 0.7 ns and 0.8 ns, whereas the 3·TM-γCD polyrotaxane shows a bi-exponential decay consisting of a main component (with a weight of 98% of the total luminescence) with a relatively short decay constant of τ1 = 0.7 ns and a minor component with a longer lifetime of τ2 = 5.4 ns (2%). The

• weights of 98 and 2%, respectively. The longer τ for the 3·TM-γCD polyrotaxane is consistent with “interchain states”. While these do not dominate the luminescence of the materials (the longer lifetime only accounts for 2% of the total PL weight), they are plausible, considered the significantly bigger

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• species. Table 2 shows that 3a displays a slightly shorter excited state lifetime (10.6 ns) than its alkyl analogue 5 (12.3 ns). The higher emission quantum yield of 3a results from a ≈2.3 times higher value of kr and a concomitant ca. 1.8 times lower value of knr. Notably, compound 4 displays a kr value

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• -links that have finite lifetime. On the other hand, the infinite network exhibited an abnormally low Young’s modulus, ~1 kPa, which is not explainable by traditional rubber theory. In addition, the composite gels were tough enough to completely maintain the network structure under 80% compression strain

• independent of the strain. These results clearly indicate that the silica nanocomposite polyrotaxane gels form an infinite network structure with negligible physical cross-links that have finite lifetime to exhibit stress relaxation, similar to ideal chemical gels. At the same time, the negligible relaxation