Effects of the aldehyde-derived ring substituent on the properties of two new bioinspired trimethoxybenzoylhydrazones: methyl vs nitro groups

• Dayanne Martins,
• Roberta Lamosa,
• Talis Uelisson da Silva,
• Carolina B. P. Ligiero,
• Sérgio de Paula Machado,
• Daphne S. Cukierman and
• Nicolás A. Rey

Beilstein J. Org. Chem. 2023, 19, 1713–1727, doi:10.3762/bjoc.19.125

• stability in aqueous medium. Thus, the electronic absorption spectra of hdz-CH3 and hdz-NO2 were recorded in a 10% DMSO/buffer solution (pH 7.4) immediately after preparation and at regular time intervals. The UV–vis spectrum of hdz-CH3 between 250 and 450 nm (Figure 6A) shows two multicomponent absorptions

• of the resulting hydrazone: a considerable amount of hdz-NO2 deprotonates immediately upon dilution in the aqueous-rich medium at pH 7.4, affording a deep yellow solution due to phenolate-based absorptions centered at around 440 nm. For this reason, we decided to investigate this deprotonation by

• registering the UV–vis spectra of a series of hdz-NO2 10% DMSO/buffer (acetate, phosphate or Tris-HCl) solutions with different pH values, ranging from 3.8 to 8.2 (Figure 7A). By plotting the absorbance at λmax as a function of pH and then fitting the curve with a sigmoidal function (Figure 7A, inset), an

Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds

• Xiaofeng Zhang,
• Xiaoming Ma and
• Wei Zhang

Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123

• , serine, and norvaline to give products 11a–f in 53–88% yields with greater than 8.5 dr (Scheme 7). The reactions with leucine and phenylglycine (R2 = iPr and Ph) as amino acids gave mainly mono-cycloaddition products and very little double cycloaddition products 11g and 11h due to the steric hindrance of

• -aminoisobutyric acid, phenylglycine and valine with Ph or iPr groups could also be used for the synthesis of the monocycloaddition products for the post-condensation reactions. It is worth noting that in the one-pot synthesis involving an intramolecular click reaction, no Cu catalyst was used. A similar reaction

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

• Swagat K. Mohapatra,
• Khaled Al Kurdi,
• Samik Jhulki,
• Georgii Bogdanov,
• John Bacsa,
• Maxwell Conte,
• Tatiana V. Timofeeva,
• Seth R. Marder and
• Stephen Barlow

Beilstein J. Org. Chem. 2023, 19, 1651–1663, doi:10.3762/bjoc.19.121

• the aromatic ring of the 1g+I− is 41.5°, close to the range of values previously reported for 1b+ salts (42.5–52.5°) [19][34] and for salts of Y = Ph, R = R' = H cations with different counterions (42.0–54.9°) [51][52][53]. As expected, owing to reduced steric interactions associated with the five

Radical chemistry in polymer science: an overview and recent advances

• Zixiao Wang,
• Feichen Cui,
• Yang Sui and
• Jiajun Yan

Beilstein J. Org. Chem. 2023, 19, 1580–1603, doi:10.3762/bjoc.19.116

• –substrate interface. The mfp's contain up to 27 mol % of DOPA (ʟ-3,4-dihydroxyphenylalanine), which plays a crucial role on mussel adhesion [11]. Although the crucial role of DOPA in mussel adhesion is not fully understood, a prevailing view suggests that DOPA can be oxidized to o-quinones at an acidic pH

• and the quinones react with unoxidized catechols to form o-semiquinone radicals afterwards [12]. The semiquinone radicals can help DOPA adhere onto organic surfaces. At a basic pH, the system is cured and mechanically stabilized through the formation of DOPA-metal coordination bonds. The cohesion of

Cyclodextrins permeabilize DPPC liposome membranes: a focus on cholesterol content, cyclodextrin type, and concentration

• Ghenwa Nasr,
• Hélène Greige-Gerges,
• Sophie Fourmentin,
• Abdelhamid Elaissari and
• Nathalie Khreich

Beilstein J. Org. Chem. 2023, 19, 1570–1579, doi:10.3762/bjoc.19.115

• ether/methanol 6:6:1 (v/v/v). After a short sonication, the aqueous phase made of SRB (150 mM) dissolved in Tris HCl buffer (0.1 M, pH 7.4) was added to the lipid solution and the mixture was sonicated at 60 °C under a nitrogen stream. The removal of organic solvents was achieved by evaporation at 45 °C

• , 4 °C) and a molecular sieves chromatography (using a Sephadex G25 gel filtration column). A Tris HCl buffer (0.1 M, pH 7.4) containing 150 mM NaCl was used for elution and liposome storage. Exposure of SRB-loaded liposomes to CDs The concentration of DPPC was determined for each formulation

• liposomes of each formulation treated or not with CDs were incubated in a water bath at 37 °C. Aliquots were taken from each sample at 0, 4, and 24 h and the fluorescence signal was measured after a dilution of 100 times in the Tris HCl (0.1 M, pH 7.4) buffer containing 150 mM NaCl. The measurements were

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent

• Stéphanie Hesse

Beilstein J. Org. Chem. 2023, 19, 1537–1544, doi:10.3762/bjoc.19.110

• characterized; a pH value of 10.07 was measured at 30 °C by Shah et al. [16] and a viscosity of 750 cP at 25 °C was reported by Mjalli et al. [17] (Table 1). It remains today one of the most used DES and studies on it are still conducted [14]. ChCl/glycerol (ChCl/Gly; 1:2) is another classical DES with a

• synthesis of NaDES plays a major role in the resulting viscosity [20]. For example, ʟ-proline/glycerol (Pro/Gly; 1:2) was found to have a pH value of 7.25 and a viscosity of 5064 cP [20]. In 2018, Molnar et al. reported the antioxidant activity of a series of rhodanine derivatives synthesized by a

Complexes of resorcin[4]arene with secondary amines: synthesis, solvent influence on “in-out” structure, and theoretical calculations of non-covalent interactions

• Waldemar Iwanek

Beilstein J. Org. Chem. 2023, 19, 1525–1536, doi:10.3762/bjoc.19.109

• the amine nitrogen of the guest molecule. In addition to hydrogen bonding, other interactions such as π–π stacking and electrostatic interactions also play a role in the complexation process. These interactions can be modulated by changing the pH, solvent, and temperature of the solution. The binding

Functions of enzyme domains in 2-methylisoborneol biosynthesis and enzymatic synthesis of non-natural analogs

• Binbin Gu,
• Lin-Fu Liang and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 1452–1459, doi:10.3762/bjoc.19.104

• added dropwise. The mixture was stirred overnight and the solvent was removed under reduced pressure. The resulting residue was dissolved in aqueous NH4HCO3 solution (0.25 M) and loaded onto a DOWEX 50WX8 ion-exchange column (NH4+ form, pH 7.0). The column was flushed slowly with 1.5 column volumes of

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• -butylthiolate clusters [41]. Following a similar strategy, a series of silyl and stannyl-substituted NHC–Cu(I) complexes were prepared through the reaction of [(NHC)Cu–Ot-Bu] with the respective silyl and stannylboranes. In addition, it was possible to obtain phenyl and alkynyl complexes [(NHC)Cu–R] (R = Ph, CC

• -Ph) in this manner (Scheme 29) [42]. The X-ray studies revealed two major structure types of the compounds [(NHC)Cu-ER3] in the solid state. In the case of bulky NHC ligands, such as IDipp, IMes, and It-Bu, the CuI complexes with ER3 = SiMe2Ph, SiPh3, SnMe3 as well as for Ph and CC-Ph, have monomeric

• , Me, C≡C-n-hep, Ph, CO2Me) and trialkylaluminum (alkyl = Me, Et, iBu) were used for the reactions. This approach is particularly attractive for asymmetric conjugate additions to pentenones, which are otherwise difficult to accomplish. 2.2.3 Reaction with organoboron reagents: In 2010, Hoveyda and co

Synthesis of ether lipids: natural compounds and analogues

• Marco Antônio G. B. Gomes,
• Alicia Bauduin,
• Chloé Le Roux,
• Romain Fouinneteau,
• Wilfried Berthe,
• Mathieu Berchel,
• Hélène Couthon and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96

Metal catalyst-free N-allylation/alkylation of imidazole and benzimidazole with Morita–Baylis–Hillman (MBH) alcohols and acetates

• Olfa Mhasni,
• Jalloul Bouajila and
• Farhat Rezgui

Beilstein J. Org. Chem. 2023, 19, 1251–1258, doi:10.3762/bjoc.19.93

• solvent of choice for the reaction using DABCO as additive. Next, the treatment of acrylate-derived alcohols 1b,c (1b, EWG = CO2Et, R = Ph; 1c, EWG = CO2Me, R = Me) [41], under the previously optimized conditions afforded the corresponding 1,4-adducts 8b,c in 70–75% yield (Table 3, entries 2 and 3), as 55

Enabling artificial photosynthesis systems with molecular recycling: A review of photo- and electrochemical methods for regenerating organic sacrificial electron donors

• Grace A. Lowe

Beilstein J. Org. Chem. 2023, 19, 1198–1215, doi:10.3762/bjoc.19.88

• ]. It is important to note that unless special electrodes (ultra microelectrodes) or cells are used, voltammetric measurements of redox potentials require an ionically conductive salt to be added to the solution [19]. Oxidation and reduction potentials can vary with factors such as pH [14][15] and

• NADH-analogues are the subject of most studies for recycling sacrificial donors. NADH has been electrochemically recycled but a careful control of pH is required to prevent dimerization reactions [44][45]. For example, Glusac and co-workers recycled BIH and acridine analogues using platinum electrodes

• photosensitizers is important for designing photocatalytic systems. Potential electron donors can be screened by comparing their oxidation potential to the redox potentials of the photosensitizer. Because redox potentials are solvent and pH-dependent, it is important to compare potentials recorded in conditions as

Two new lanostanoid glycosides isolated from a Kenyan polypore Fomitopsis carnea

• Winnie Chemutai Sum,
• Sherif S. Ebada,
• Didsanutda Gonkhom,
• Cony Decock,
• Rémy Bertrand Teponno,
• Josphat Clement Matasyoh and
• Marc Stadler

Beilstein J. Org. Chem. 2023, 19, 1161–1169, doi:10.3762/bjoc.19.84

• , cotton seed flour 5 g/L in distilled water), were mixed, pH adjusted to 7.2, and autoclaved. The media flasks were inoculated with 10 mycelial plugs (5 mm) each and incubated for 28 days, under shaking and static conditions for liquid and solid cultures, respectively. The cultures were extracted after

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• substituents on the NI unit (NI-PTZ-F, NI-PTZ-Ph, NI-PTZ-CH3, NI-PTZ-OCH3), and the electron-donating ability of the PTZ unit was modified by oxidation of the sulfur atom to the sulfoxide (NI-PTZ-F-O, NI-PTZ-Ph-O, NI-PTZ-C5-O). The advantage of the oxidation approach is that almost only the energy of the 1CS

• unit (Figure 2e and 2f) [57]. Moreover, it is noted that the CS emission wavelength of NI-PTZ-F-O and NI-PTZ-Ph-O is different from a 4-diphenylamino-substituted NI [58]. These results indicate that the 1CS state of these two dyads involves the oxidized PTZ unit as a whole electron donor, not only the

• N atom of the PTZ unit [59][60]. Further, the NI-PTZ-F-O and NI-PTZ-Ph-O compounds adopt an orthogonal geometry, and the N atom in the PTZ unit is not in π-conjugation with NI moiety due to a conformational restriction [55]. Thus, it is not the ordinary intramolecular charge transfer (ICT) state

CO₂ complexation with cyclodextrins

• Cecilie Høgfeldt Jessen,
• Jesper Bendix,
• Theis Brock Nannestad,
• Heloisa Bordallo,
• Martin Jæger Pedersen,
• Christian Marcus Pedersen and
• Mikael Bols

Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78

• change in spectrum of 7 provided 7 and CO2 compete for the binding site. To avoid problems with formation of hydrogencarbonate the experiments were conducted in a buffer at pH 3 where only a minor fraction of the carbonic acid (pKa1 = 3.6) is dissociated and since the hydration constant of CO2 is small

• (1.7 × 10–3) more than 99% of CO2 in solution is the dissolved gas at this pH. First the dissociation constants of 7–CD complexes at pH 3, were determined (Table 2). When a solution of 7 and excess cyclodextrin was subjected to a CO2 atmosphere at 2–8 bar in the pressure cell this gave, after

• coverage of the bottom. The analysis shown in Figure 3 was started at 28 °C, and was finished at a temperature of 150 °C with a heating rate of 5 °C/min. Determination of dissociation constants between 7 and CD’s. Samples were prepared that consisted of citrate-phosphate buffer (pH 3, 50 mM), 7 (40 μM) and

Intermediates and shunt products of massiliachelin biosynthesis in Massilia sp. NR 4-1

• Till Steinmetz,
• Blaise Kimbadi Lombe and
• Markus Nett

Beilstein J. Org. Chem. 2023, 19, 909–917, doi:10.3762/bjoc.19.69

• acids, 0.5 g/L glucose, 0.5 g/L soluble starch, 0.3 g/L KH2PO4, 0.05 g/L MgSO4 × 7 H2O. The pH of the medium was adjusted to pH 7.2. The cultivation was conducted on a rotary shaker at 130 rpm and 30 °C for one week. Afterwards adsorber resin (XAD-7, 20 g/L) was added to the culture broth to bind the

First synthesis of acylated nitrocyclopropanes

• Kento Iwai,
• Rikiya Kamidate,
• Khimiya Wada,
• Haruyasu Asahara and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

• the literature [26]. To a solution of ammonium acetate (2.63 g, 36 mmol) in acetic acid (10 mL), were added 4-methylbenzaldehyde (2 mL, 15 mmol) and nitromethane (5.3 mL, 98 mmol), and the resultant mixture was heated at 100 °C for 6 h. After adjusting the pH value to 7 by 2 M sodium hydroxide (40 mL

A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

• Xiaoqian Chen,
• Naqin Yang,
• Yue Ma,
• Xinan Yang and
• Peihua Ma

Beilstein J. Org. Chem. 2023, 19, 864–872, doi:10.3762/bjoc.19.63

• supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via https://www.ccdc.cam.ac.uk/data_request/cif. Supramolecular assembly of TMeQ[6] and 1,2-bis(4-pyridyl)ethene (G). (a) UV–vis titration of G (3.0 × 10−5 mol·L−1, pH

• 6.5) in aqueous solution with the increase of TMeQ[6] concentration; (b) plots of n(TMeQ[6])/n(G) vs ultraviolet absorption of G. (a) Fluorescence spectra (U = 550 V, pH 6.5) of G (3.0 × 10−5 mol·L−1) in aqueous solution with increasing TMeQ[6] concentration; (b) plots of n(TMeQ[6])/n(G) vs

• solution; (b) fluorescence response (λmax,em = 380 nm) of G@TMeQ[6] (1:1, 3.0 × 10−5 mol·L−1) to metal cations in aqueous solution. (c(other metal cations) = 3.0 × 10−4 mol·L−1, U = 520 V, pH 6.5). Influence of coexisting ions on Hg2+ detection by G@TMeQ[6]. (a) Fluorescence titration curve (U = 500 V, pH

Eschenmoser coupling reactions starting from primary thioamides. When do they work and when not?

• Lukáš Marek,
• Jiří Váňa,
• Jan Svoboda and
• Jiří Hanusek

Beilstein J. Org. Chem. 2023, 19, 808–819, doi:10.3762/bjoc.19.61

• structurally related S-ethyl ethanimidothioate and S-ethyl benzimidothioate in aqueous solution, such reaction pathway begins to open [33] at pH > 6 and 8, respectively. The subsequent formation of imidothioates 6a,b''' and their base-catalyzed elimination (Scheme 3) takes place easily, especially in MeCN

• . Experiments as well as quantum calculations have shown that the acidifying effect of a solitary phenyl group (Z = Ph in Scheme 2 and in Figure 2) is not sufficient to enable a successful ECR. On the other hand, if the free rotation of phenyl group (Z) is restricted by its further bonding through a group Y

Construction of hexabenzocoronene-based chiral nanographenes

• Ranran Li,
• Di Wang,
• Shengtao Li and
• Peng An

Beilstein J. Org. Chem. 2023, 19, 736–751, doi:10.3762/bjoc.19.54

• glum of (P,P,M/M,M,P)-117 was measured as 2 × 10−4. Cyclooctatetraphenylene (COT-Ph) is a π-conjugated scaffold, whose three-dimensional (3D) geometry is based on its saddle shape. Martín and co-workers reported the 3D NG 121 by the introduction of four HBC units into COT-Ph [60]. As shown in Scheme 14

• , functionalized COT-Ph reacted with compound 50 through Sonogashira cross-coupling reaction affording compound 119 in a 73% yield. Then Diels–Alder reaction between 119 and 2 gave structure 120 as NG precursor. Compound 120 underwent intramolecular cyclodehydrogenation mediated by FeCl3, affording the final NG

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• , compounds 5a–c (Ar = Ph, 4-MeOC6H4, 4-CF3C6H4) were red-shifted by 18–39 nm relatively to the corresponding monomers. Their absorption maxima were rather close to those of butadiyne 1 end-capped by two DMAN residues. In doubly protonated tetrafluoroborate salts of the oligomers, conjugation between the aryl

Cassane diterpenoids with α-glucosidase inhibitory activity from the fruits of Pterolobium macropterum

• Sarot Cheenpracha,
• Ratchanaporn Chokchaisiri,
• Lucksagoon Ganranoo,
• Sareeya Bureekaew,
• Thunwadee Limtharakul and
• Surat Laphookhieo

Beilstein J. Org. Chem. 2023, 19, 658–665, doi:10.3762/bjoc.19.47

• according to experimental literature with slight modification [20]. α-Glucosidase (0.05 U/mL) and substrate, p-nitrophenyl-α-ᴅ-glucopyronoside (p-NPG) (1 mM) were dissolved in 0.1 M sodium phosphate buffer (pH 6.9). Fifty μL of sample (1 mg/mL in 10% DMSO) and 50 μL of α-glucosidase were preincubated at 37

pH-Responsive fluorescent supramolecular nanoparticles based on tetraphenylethylene-labelled chitosan and a six-fold carboxylated tribenzotriquinacene

• Nan Yang,
• Yi-Yan Zhu,
• Wei-Xiu Lin,
• Yi-Long Lu and
• Wen-Rong Xu

Beilstein J. Org. Chem. 2023, 19, 635–645, doi:10.3762/bjoc.19.45

• , PR China 10.3762/bjoc.19.45 Abstract We synthesized a new tetraphenylethylene-modified chitosan bioconjugate, CS-TPE, that shows the aggregation-induced emission effect. It can self-assemble into fluorescent polymeric nanoparticles in an aqueous solution at pH 5.3 either alone or with the water

• -soluble bowl-shaped six-fold carboxylated tribenzotriquinacene derivative TBTQ-C6 via host–guest binding. The spherical nanoparticles formed by CS-TPE amphiphiles or TBTQ-C6/CS-TPE supra-amphiphiles disintegrated under alkaline stimulation at pH 10.4 and the dispersion of the aggregates after the collapse

• in the presence of TBTQ-C6 was greatly improved. In addition, the fluorescence of CS-TPE was significantly enhanced by introducing TBTQ-C6, and remained relatively stable with variations in pH for both CS-TPE and TBTQ-C6/CS-TPE. Such pH-responsive supramolecular spherical nanoparticles with stable

Phenanthridine–pyrene conjugates as fluorescent probes for DNA/RNA and an inactive mutant of dipeptidyl peptidase enzyme

• Josipa Matić,
• Tana Tandarić,
• Marijana Radić Stojković,
• Filip Šupljika,
• Zrinka Karačić,
• Ana Tomašić Paić,
• Lucija Horvat,
• Robert Vianello and
• Lidija-Marija Tumir

Beilstein J. Org. Chem. 2023, 19, 550–565, doi:10.3762/bjoc.19.40

• a pH-dependent excimer formation that is significantly red-shifted relative to the pyrene and phenanthridine fluorescence. While the conjugate with a short linker showed negligible spectrophotometric changes due to the polynucleotide addition, the conjugate with a longer and more flexible linker

• combine to produce an excimer, which is identifiable by a certain fluorescence band [11][12]. Some of the pyrenes and phenanthridines exhibited meaningful biological activity. Several pyrene-guanidiniocarbonylpyrrole derivatives have been found to exhibit the affinity for ds-DNA that is strongly pH

• were moderately soluble in DMSO (up to c = 1 × 10−3 mol dm−3) and their stock solutions were stable during a few months. All measurements were recorded in the Na cacodylate buffer (Ic = 0.05 mol dm−3) both at pH 5.0 and pH 7.0 for comparison, since the phenanthridine heterocyclic nitrogen becomes