Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• and ΦDF values were estimated according to [50]. Time-integrated fluorescence, phosphorescence spectra as well as fluorescence decay kinetics were recorded with a time-gated intensified iCCD camera iStar DH340T (Andor) with a spectrograph SR-303i (Shamrock) coupled with nanosecond YAG:Nd3+ laser NT

Iridium-catalyzed hydroacylation reactions of C1-substituted oxabenzonorbornadienes with salicylaldehyde: an experimental and computational study

• Angel Ho,
• Austin Pounder,
• Krish Valluru,
• Leanne D. Chen and
• William Tam

Beilstein J. Org. Chem. 2022, 18, 251–261, doi:10.3762/bjoc.18.30

• under the experimental reaction conditions. As such, we theorize the origin of regioselectivity for the title reaction is the reductive elimination step. Based on the relative kinetics, we predict the point of selectivity must occur before the irreversible C–C forming step. Comparing the two competing

Mechanistic studies of the solvolysis of alkanesulfonyl and arenesulfonyl halides

• Malcolm J. D’Souza and
• Dennis N. Kevill

Beilstein J. Org. Chem. 2022, 18, 120–132, doi:10.3762/bjoc.18.13

• molecule, makes what was already a rather controversial area of reaction kinetics even more complicated and controversial. The reader wanting more detail is referred to the above mentioned comprehensive review entitled “Solvolysis Revisited” [31]. 2. Application of simple and extended forms of the Grunwald

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

• Hendrik Gruß,
• Rebecca C. Feiner,
• Ridhiwan Mseya,
• David C. Schröder,
• Michał Jewgiński,
• Kristian M. Müller,
• Rafał Latajka,
• Antoine Marion and
• Norbert Sewald

Beilstein J. Org. Chem. 2022, 18, 1–12, doi:10.3762/bjoc.18.1

• accurate values would be obtained with methods better adapted for kinetics, such as Markov models (for a general overview see reference [94]). Yet, such low barriers are not sufficient to trap the SMC peptide in conformations that can be separated experimentally at ambient conditions [95] and the analysis

DABCO-promoted photocatalytic C–H functionalization of aldehydes

• Bruno Maia da Silva Santos,
• Mariana dos Santos Dupim,
• Cauê Paula de Souza,
• Thiago Messias Cardozo and
• Fernanda Gadini Finelli

Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205

• not be appropriate for this reaction. However, our results clearly show that DABCO is a perfectly fit for the job. This apparent contradiction can be more easily understood by recalling that a BDE analysis is essentially thermodynamic, but is connected to the kinetics of the reaction step by means of

A photochemical C=C cleavage process: toward access to backbone N-formyl peptides

• Haopei Wang and
• Zachary T. Ball

Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202

• irradiation, the product 11 was isolated in 28% yield, the modest yield reflecting the instability in water and on silica of this compound. The purified N-formyl 11 was then dissolved in buffer (pH 8), and its hydrolysis to amide 12 was assessed (Figure 4, inset). We observed clean first-order kinetics to

• 1 in acetone. Preparation and hydrolysis kinetics (inset) of N-formyl product 11. Dashed line: first-order decay fit used in calculating the rate constant. Proposed mechanism for the formation of aldehyde 3 and N-formyl product 8. Supporting Information Supporting Information File 280: Experimental

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• measurement (Supporting Information File 1, Figure S5b,c) showed multiexponential decay kinetics and lifetimes with an average τp of 8.6 ns [τ1 = 3.5 ns (37.5%), τ2 = 11.6 ns (62.5%)] and an average τd of 156.1 µs [τ1 = 27.98 µs (39.5%), τ2 = 239.7 µs (60.5%)], respectively. The average prompt fluorescence

Halides as versatile anions in asymmetric anion-binding organocatalysis

• Lukas Schifferer,
• Martin Stinglhamer,
• Kirandeep Kaur and
• Olga García Macheño

Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145

• species. However, the cationic counterpart can have important effects on the kinetics of the systems. This hypothesis has evidently been identified in enzymatic reactions [68]. Mechanistic studies have shown that in such processes, cationic species are stabilized through various attractive interactions

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• , which via a gold catalysis can be triggered to release the drug on specific sites of the target cell in a controlled manner (Scheme 15A) [123]. A proposed catalytic cycle based on kinetic isotopic effect and kinetics data is illustrated in Scheme 15D. At the beginning of the reaction, intermediate III

Chemical approaches to discover the full potential of peptide nucleic acids in biomedical applications

• Nikita Brodyagin,
• Martins Katkevics,
• Venubabu Kotikam,
• Christopher A. Ryan and
• Eriks Rozners

Beilstein J. Org. Chem. 2021, 17, 1641–1688, doi:10.3762/bjoc.17.116

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

• close to optimal as possible. Certain drawbacks to using a flow-approach must also however be acknowledged. Problems may arise due to quenching requirements, the necessity for solvent switching, concentration limitations, compensating for different encountered reaction kinetics over multiple steps when

• reactor is, in certain instances, indicated to give rise to superior reaction kinetics [79]. It is also easy to create staged temperature gradients to compensate for changes in reaction kinetics based upon concentration or complicating effects such as product derived auto-catalysis. The use of immobilised

• intensification. The implicit high pressure self-contained environment created by a pumped flow system allows for superior reaction kinetics often achieved by elevating the working temperature of the system. This capability also opens up the opportunity for the integration of volatile and gaseous reagents into

Beyond ribose and phosphate: Selected nucleic acid modifications for structure–function investigations and therapeutic applications

• Christopher Liczner,
• Kieran Duke,
• Gabrielle Juneau,
• Martin Egli and
• Christopher J. Wilds

Beilstein J. Org. Chem. 2021, 17, 908–931, doi:10.3762/bjoc.17.76

• kinetics and higher solubility in organic solvents, useful for automated synthesis, such as the Beaucage reagent [86]. Conveniently, during deprotection of the support-bound oligonucleotide, aminolysis removes the β-thiobenzoylethyl group from the backbone to generate the free PS2-modified oligonucleotide

Kinetics of enzyme-catalysed desymmetrisation of prochiral substrates: product enantiomeric excess is not always constant

• Peter J. Halling

Beilstein J. Org. Chem. 2021, 17, 873–884, doi:10.3762/bjoc.17.73

• Peter J. Halling WestCHEM, Dept Pure & Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland, UK 10.3762/bjoc.17.73 Abstract The kinetics of enzymatic desymmetrisation were analysed for the most common kinetic mechanisms: ternary complex ordered (prochiral ketone reduction); ping

• enantioselective enzymes in the resolution of a racemate. As such resolution reactions proceed, there are progressive changes in the enantiomeric excesses (ee), that of the product falling while that of the residual starting material increases. In a classic study of the kinetics of resolution, Chen and Sih [1

• kinetics of such reactions are straightforward, they have received little study. Smith et al. [32] and more recently, Yamane [33] have studied the kinetics of example reactions, but without progress data for the ee. Kroutil et al. [34] derived a model for consecutive reactions, but the desymmetrisation

Simulating the enzymes of ganglioside biosynthesis with Glycologue

• Andrew G. McDonald and
• Gavin P. Davey

Beilstein J. Org. Chem. 2021, 17, 739–748, doi:10.3762/bjoc.17.64

• includes cellular transport and recycling. A limitation of the model is that it considers only absolute changes to enzyme activity, in which an activity is either off or on, which a kinetic model based on differential-equation-based rate laws [44][45][46][47][48] or stochastic kinetics [49][50] would

• will also influence the kinetics [48][51]. Future extensions to this work will consider the effects of acetylation of sialic acid residues, since this modification reduces the negative charge of the carbohydrate, thus altering binding affinity, while an increased incidence of 9-O-acetylated GD3 is

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• ones is plausible. In fact, it has been proved convincingly [79] that a series of [5,6]-open fulleroids with stabilizing substituents in the methane bridge are rearranged into [6,6]-closed fullerenes, both by a photochemical process of zero-order kinetics and by a high-energy monomolecular route. The

Valorisation of plastic waste via metal-catalysed depolymerisation

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

Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53

• ]. This justifies for the easier depolymerisation of polyesters and polycarbonates compared to polyolefins [79][80]. By contrast, poor selectivity and slow kinetics of depolymerisation can be circumvented using a catalyst. 2.1 Chemolysis Several catalytic depolymerisation processes of plastics have been

• kinetics, cost of metals, toxicity, difficulty in catalyst reusing and need of downstream processing. Significant efforts have thus been made to develop greener and sustainable catalytic systems featuring high efficiency under mild conditions. The use of sodium carbonate or bicarbonate as ecofriendly

• the conventional PET-insoluble EG system, greatly enhanced the depolymerisation kinetics, resulting in improved conversions (the solubility of PET at T > 130 °C was aniline > NMP > nitrobenzene > DMSO) [202]. For instance, the use of a DMSO/EG 2:1, w/w solvent mixture resulted in an increase of PET

Synthesis and physicochemical evaluation of fluorinated lipopeptide precursors of ligands for microbubble targeting

• Masayori Hagimori,
• Estefanía E. Mendoza-Ortega and
• Marie Pierre Krafft

Beilstein J. Org. Chem. 2021, 17, 511–518, doi:10.3762/bjoc.17.45

• , reflecting a progressive adsorption at the interface, then reached a plateau, and stabilized at the equilibrium surface pressure (πeq). The adsorption kinetics demonstrate that the F-lipopeptides formed stable monolayers at the interface. The πeq values increased with the degree of fluorination of the F

• ; purity (retention time): >99% (13.9 min). Adsorption kinetics of lipopeptides at the air/water interface. The experiments were conducted in a home-made Teflon adsorption trough (11.9 × 5.0 × 0.3 cm3) filled with HEPES buffer (pH 7.4). The surface pressure π was measured using the Wilhelmy plate method

• preparation and upon time were determined on 5–10 slides using Fiji (an open-source image processing package [45]) and the standard deviations were calculated using Origin9 (OriginLab Corp. Northampton, MA, USA). Adsorption kinetics of perfluoroalkylated lipopeptides 1–3 and the hydrocarbon analog 4 at the

Biochemistry of fluoroprolines: the prospect of making fluorine a bioelement

• Vladimir Kubyshkin,
• Rebecca Davis and
• Nediljko Budisa

Beilstein J. Org. Chem. 2021, 17, 439–460, doi:10.3762/bjoc.17.40

• incorporates them into proteins [16]. The effects of fluoroprolines have been examined in a number of protein structures. These studies demonstrated an altered stability and altered folding kinetics that occurred upon the proline-to-fluoroproline replacement, as reviewed in [17]. Nonetheless, no whole-cell

• preferences should be considered when judging the stability of the folded structures containing fluoroprolines. 2.6 Kinetics of the amide rotation The kinetic stability of the amide conformers generates another important aspect of protein folding. Generally, the amide rotation is considered very slow in

• ten proline positions [117]. The incorporation of R-Flp resulted in an insoluble protein, indicating associated folding issues. In contrast, the protein containing S-Flp produced a well-structured fluorescent protein, exhibiting faster folding kinetics and producing crystals suitable for diffraction

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

• solvolysis rate for derivatives 13f or 13g and the solvent polarity parameter YOTs [45]. The solvent participation in the solvolysis of these tertiary benzylic tosylates was thus defined as “unimportant” by the authors. Gassman and Harrington successfully measured the solvolysis kinetics of CF3-substituted

¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• ). Each independent intermediate was characterized on the basis of its 19F NMR chemical shift and the kinetics by which each species formed or decayed were evaluated in real-time. By combining the 19F NMR data with that provided by complementary analytical techniques, mass spectrometry (electrospray

• investigated in detail [59][76], as well as the kinetics of α-Syn oligomerization and fibril formation both in vitro [60][75] and in vivo [77][78]. In these more recent studies, incorporation of 4-tfmF residues using amber-suppressing codons at various positions was shown to be more advantageous as a 19F

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

• -difluorocyclopropanes (Scheme 40) [86]. Vinylcyclopropane rearrangements: O’Neal and Benson examined the influence of fluorine substituents on the kinetics of the vinylcyclopropane-to-cyclopentene rearrangement [87]. They noted the effect of an additional strain (approximately 5 kcal/mol per fluorine atom) in raising

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• dependence was observed. The decay kinetics of the 5% THF and 5%→0% THF systems demonstrated power dependence (Figure 5A and Figure S9A, Supporting Information File 1, respectively). In contrast, 10% THF nanocrystals exhibit essentially power-independent kinetics (Figure 5B). Power dependence is indicative

• distance between the carboxylic groups of two PDIs. E) Schematic representation of the assembly structuring. Cryo-TEM images of 1 × 10−4 M compound 1 in THF/water solutions after one minute of aging. A) 5% THF: monomolecular 1D π-stack fibers and B) 10% THF: crystalline platelets. Transient kinetics at

Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• additive that decides on preferential 2’-O-silylation. The salt has been suggested to influence reaction kinetics in the way that the silylation reagent TBDMS chloride is changed to the nitrate, which subsequently is consumed faster by nucleophilic attack of the 2’-OH group onto the silica atom as compared

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• as a function of the temperature, which enabled an extrapolation of the population differences at an elevated temperature (via the van ‘t Hoff equation). The latter experiments provided information directly on the kinetics of the interconversion between the sites. A series of spectra were then

• acquired at elevated temperature; here, the kinetics of the interconversion between the sites could be derived directly from the linewidth. Figure 3 illustrates the spectra acquired over a range of temperatures using compound 3a as an example. With the rate constants of the interconversion between the

Particle size effect in the mechanically assisted synthesis of β-cyclodextrin mesitylene sulfonate

• Stéphane Menuel,
• Sébastien Saitzek,
• Eric Monflier and
• Frédéric Hapiot

Beilstein J. Org. Chem. 2020, 16, 2598–2606, doi:10.3762/bjoc.16.211

• of a reaction in the solid state. As such, we recently investigated the influence of the particle size of β-CD in the synthesis of β-CD mesitylene sulfonate (β-CDMts) in the solid state using a vibrating ball-mill. We were particularly interested in the role of the particle size on the kinetics of

• out in the presence of KOH as a base. The data series were confronted with kinetics models to get insight in the way the reactions proceeded. The diversity of possible models suggests that multiple mechanochemical processes can account for the formation of β-CDMts in the solid state. Throughout the

• effects to only focus on the influence of grinding the CDs prior to the mechanically assisted reaction on the kinetics. In this context, we considered the synthesis of mono- and poly-β-CD mesitylene sulfonate (β-CDMts) from β-CD and mesitylenesulfonyl chloride (MtsCl) as a model reaction. MtsCl was found