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

• the S0 → 1CS transition [52][53][54]. In addition, the aromatic ring attached to the NI unit changing it from an electron-pulling group to an electron-pushing group, leads to a blue shift of the absorption peak of the CS and the absorbance decreases (Figure S30 in Supporting Information File 1). For

• the oxidized molecules, the S0 → 1CS transition absorption peak is blue shifted to 360–420 nm (Figure 1b). These results indicate that upon oxidation of the PTZ unit, the electronic coupling between the donor and acceptor is reduced [55]. The fluorescence spectra of the compounds are studied (Figure 2

• attributed to a localized singlet excited state of 1NI* by comparison with the reported spectra of NI [58]. Within 155 fs, the system evolves to the second spectrum (blue line), for which both a sharp peak centered at 404 nm and a broad band in the range 600–750 nm were observed, which is identified as a

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

• work. X-ray crystal structure of CO2 bound to α-CD. TGA curve (blue) and dTGA curve (red) for CO2-1 crystals. Two lumps are seen with the former predominantly being CO2 and the second pre-dominantly water. Cell used to measure vis spectra under pressure (left), structure of 7 (middle) and spectrum of 7

• (40 μM) and 1 (2 mM) in citrate phospate buffer pH 3 (right) from 350–400 nm with 0 (blue), 2 (red), 4 (green), 6 (orange) and 8 (grey) bar of CO2. Binding of CO2 to 1 as a function of pressure. The results of crystallization of α-cyclodextrin from water in an atmosphere of CO2 carried out in a

Copper-catalyzed N-arylation of amines with aryliodonium ylides in water

• Kasturi U. Nabar,
• Bhalchandra M. Bhanage and
• Sudam G. Dawande

Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76

• , catalyzed by a copper catalyst [39]. Murphy and co-workers reported blue LED-mediated metal-free cyclopropanation of alkenes with iodonium ylides through a diradical intermediate [40]. However, iodonium ylides are relatively unexplored for the arylation of amines. So far only Spyroudis’s group reported N

Photoredox catalysis enabling decarboxylative radical cyclization of γ,γ-dimethylallyltryptophan (DMAT) derivatives: formal synthesis of 6,7-secoagroclavine

• Alessio Regni,
• Francesca Bartoccini and
• Giovanni Piersanti

Beilstein J. Org. Chem. 2023, 19, 918–927, doi:10.3762/bjoc.19.70

• compound 5 in hand, the required radical–radical coupling was investigated next, and some of the representative results are shown in Table S1 (see Supporting Information File 1). Irradiation from blue light-emitting diodes (LEDs) in the presence of 2 mol % of the photocatalyst [Ir(dF(CF3)ppy)2(dtbpy)]PF6

• , according to the Baldwin rules [92]. We began our investigation of the proposed decarboxylative cyclization by exposing the N-Boc derivative 8, Ir catalyst, and K2HPO4 in DMF to a 34 W blue LED lamp at room temperature (Table 1) [93][94][95][96][97]. To our delight, cyclization was observed under these

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

• molecules only in the organic phase but not in the aqueous phase. Therefore, the organic phase was concentrated under reduced pressure and the resulting residue was subjected to reversed-phase HPLC. Those fractions that showed a color change from blue to pink in the CAS assay were collected and purified in

• volume of 100 mL, hence yielding the blue CAS assay solution. To perform the assay, 1 mL of the CAS assay solution was pipetted into a cuvette followed by the addition of 0.2 mL of the substance to be tested. A color change from blue to yellow indicated the presence of metal-chelating molecules. Filter

Light-responsive rotaxane-based materials: inducing motion in the solid state

• Adrian Saura-Sanmartin

Beilstein J. Org. Chem. 2023, 19, 873–880, doi:10.3762/bjoc.19.64

• -crystal X-ray structure of rotaxane 1a (R1 = Me, R2 = R3 = H) showing two interlocked molecules of the crystalline array [44]. Colour key of the solid structure: light blue = carbon atoms; purple = nitrogen atoms; red = oxygen atoms; and orange = iron atoms. Hydrogen atoms are omitted for clarity. (a

• the solid structure of UMUMOF-(E)-3 showing a rhombohedral metallogrid; and (c) cartoon representation of the operation mode of UMUMOF-(E)-3 as a molecular nanodispenser [62]. Colour key of the solid structure: light blue = carbon atoms; purple = nitrogen atoms; red = oxygen atoms; and grey = copper

• array [63]. Colour key of the solid structure: light blue = carbon atoms; purple = nitrogen atoms; red = oxygen atoms; and magenta = uranium atoms. Acknowledgements All figures included in this article are original and have been redrawn based on the content of the referenced research articles by using

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• α-arylglycine motifs (highlighted in green and blue). The Petasis reaction – fundamental reactivities and recent developments. Observations from previous studies and mechanistic rationale. Initial experiments. Reaction scope – aryltrifluoroborates (yields and enantiomeric ratios in parentheses refer

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

• which although conjugated to a third unsaturated center are not conjugated to each other” [16]. It is easy to see that there are two π-conjugation paths in molecules 5: a donor–acceptor conjugation path (Figure 2, highlighted in blue) and the π-conjugation of naphthalene rings through a butadiyne linker

• nitro group. There are two types of independent non-equivalent dications, marked in blue and green, and two types of BF4− anions, marked in red and yellow, in the crystal structure of salt 11c (Figure S68 in Supporting Information File 1). Monomer fragments in both are identical (Table 2, Figure 5). The

• directions of electron density transfer are possible (Figure 7): between two DMAN fragments through the butadiyne linker (highlighted in green) and between the DMAN and aryl rings through the acetylene bridge (highlighted in blue). Obviously, the “butadiyne path” includes a longer conjugation chain

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

• Deepak Singh,
• Shyamal Pramanik and
• Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

• reaction was carried out between 1a and 2a in dry CH3CN as solvent under N2 atmosphere using 4CzIPN as the photocatalyst. Irradiating the reaction mixture for 10 h under blue LEDs (450 nm) led to the isolation of products 5 (54%) and 6 (28%) (Table 1, entry 1). However, the same reaction, under aerobic

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

• illustrated in Figure 4a, the measured ECD curve was compared to the predicted ECD curve of (5S,8R,9S,10R,14S)-1, indicating that the measured and predicted ECD spectra were similar except for a blue-shift in the ECD spectrum. Thus, the structure of 1 was characterized as shown. Compound 3 was obtained as a

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

• powders of CS-TPE exhibit a pale-yellow appearance under normal daylight conditions and emit intense green-blue light when exposed to UV irradiation (365 nm). This phenomenon differs greatly from the fluorescence properties of conventional ACQ fluorophores, which are typically nonfluorescent under UV

Direct C2–H alkylation of indoles driven by the photochemical activity of halogen-bonded complexes

• Martina Mamone,
• Giuseppe Gentile,
• Jacopo Dosso,
• Maurizio Prato and
• Giacomo Filippini

Beilstein J. Org. Chem. 2023, 19, 575–581, doi:10.3762/bjoc.19.42

• both UV–vis and nuclear magnetic resonance (NMR) spectroscopy [29]. In particular, the optical absorption spectra of substrate 2a (green dotted line), DABCO (red dotted line), and the solution containing both 2a and DABCO (blue line) were recorded in acetonitrile (Figure 2). Specifically, it was

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• are presented in different colors: the hydrogen bonding are labeled in blue color of the reduced density gradient isosurface; green color corresponds to the dispersion interactions (van der Waals interactions, the π-stacking); red color represents steric clashes. The interplay of these through-space

• protons. Low-gradient isosurfaces with low densities (blue color of the isosurface corresponds to the hydrogen bonding; the dispersion interactions (van der Waals interactions, the π-stacking) are marked in green color; red color indicates steric clashes) obtained for the ʟ- (left image) and ᴅ-alanine

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

• exhibited a micromolar and submicromolar binding affinity for ds-polynucleotides and inactivated a mutant of dipeptidyl peptidase enzyme E451A. Confocal microscopy revealed that the conjugate with the longer linker entered the HeLa cell membranes and blue fluorescence was visualized as the dye accumulated

• cellular uptake and intracellular distribution of Phen-Py-1 in HeLa cells by TCS SP8 X confocal microscopy. The results showed that the dye entered the HeLa cell membranes fast, and after 1 hour of incubation at 1 µM concentration, blue fluorescence was visualized as the dye accumulated in the cell

• dominant binding mode. The excimer fluorescence signal of Phen-Py-1 (longer linker between phenanthridine and pyrene unit) at 470 nm was quenched up to 30% upon the addition of polynucleotides combined with the significant hypsochromic (blue) shift of the emission maxima (10–20 nm). A similar fluorimetric

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

• Manuel Pedrón,
• Jana Sendra,
• Irene Ginés,
• Tomás Tejero,
• Jose L. Vicario and
• Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

• cyclohexanes. The resulting system is given in square brackets. In parentheses the integration over the volumes of −λ2·ρ2 representing the total integration data corresponding to the weak noncovalent van der Waals interactions (represented in green). Higher forces like H-bonds are indicated as blue discs. In

Discrimination of β-cyclodextrin/hazelnut (Corylus avellana L.) oil/flavonoid glycoside and flavonolignan ternary complexes by Fourier-transform infrared spectroscopy coupled with principal component analysis

• Nicoleta G. Hădărugă,
• Gabriela Popescu,
• Dina Gligor (Pane),
• Cristina L. Mitroi,
• Sorin M. Stanciu and
• Daniel Ioan Hădărugă

Beilstein J. Org. Chem. 2023, 19, 380–398, doi:10.3762/bjoc.19.30

• -cyclodextrin/Corylus avellana oil/hesperidin ternary complex at a 1:1:1 molar ratio (blue), β-cyclodextrin hydrate (red), C. avellana oil (pink), and hesperidin (green). Superposition of the FTIR spectra for the β-cyclodextrin/Corylus avellana oil/hesperidin ternary complex at a 3:1:1 molar ratio (blue), β

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

• Cécile Alleman,
• Charlène Gadais,
• Laurent Legentil and
• François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

• formation of the fused cyclobutane acid 162 as the desired precursor for the cyclooctane formation. The ring expansion was achieved in the presence of an iridium catalyst and under blue LED irradiation, via the trapping by TEMPO or O2 of the cyclobutyl radical resulting from decarboxylation, which allowed a

Investigation of cationic ring-opening polymerization of 2-oxazolines in the “green” solvent dihydrolevoglucosenone

• Solomiia Borova and
• Robert Luxenhofer

Beilstein J. Org. Chem. 2023, 19, 217–230, doi:10.3762/bjoc.19.21

• ≈ 1.65) (Supporting Information File 1, Figure S8, green), while the polymer obtained with EtOxMeOTf has a higher Mn and a more narrow molar mass distribution (Ð ≈ 1.10) (Figure S8, blue). Polymerization of 2-ethyl-2-oxazoline with MeOTf, MeOTs and EtOxMeOTf as an initiator at 60 °C To potentially

• resulting molar mass after initiation with EtOxMeOTf is closer to what is expected from [M]0/[I]0 ratio (Figure 6b, blue) and Ð remained below 1.2. 1H NMR analysis of the final product after precipitation and freeze-drying confirmed the presence of signals attributed to PEtOx, whereas the additional signals

• polymerization initiated with methyl triflate (black), methyl tosylate (red), 2-ethyl-3-methyl-2-oxazolinium triflate (blue), benzyl bromide (green) after 3 h of incubation and acyl chloride (dark red), propionyl chloride (purple) after 24 h of incubation in DLG. Peaks marked with asterisks originate from

Germacrene B – a central intermediate in sesquiterpene biosynthesis

• Houchao Xu and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

• ., by heating with sulphur, to the blue azulene derivative 62 (Scheme 16C) [121][122][124][125][126], but the structure elucidation of this compound was only completed in 1936 [127]. Based on a comparison of IR spectra of natural terpenes, their hydrogenation and dehydrogenation products, the correct

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• each cadinol-type. Orange: δ-cadinol; blue: τ-cadinol; red: amorph-4-en-10β-ol; violet: α-cadinol. Upper trace: (4S)-diastereomers; lower trace: (4R)-diastereomers. *Corresponding enantiomers. Coinjection of R-14 and S-14 with a gular gland extract of Hyperolius cinnamomeoventris performed with a

Preparation of β-cyclodextrin/polysaccharide foams using saponin

• Max Petitjean and
• José Ramón Isasi

Beilstein J. Org. Chem. 2023, 19, 78–88, doi:10.3762/bjoc.19.7

• carbon has been developed by Ma et al. [26], by the production of chitosan–saponin gels thanks to glutaraldehyde crosslinking. After adding potassium hydroxide, they freeze-dried the material and pyrolyzed the product. The resulting material possess a high absorption capacity of methylene blue, thanks to

• -cyclodextrin/polysaccharides (blue curves for chitosan, red for locust bean gum, green for xanthan gum) with saponin (yellow curves correspond to cyclodextrin matrices, without polysaccharide). Sorption of phenols (V, vanillin; Ph, phenol; m-c, m-cresol; 4eP, 4-ethylphenol; Eu, eugenol) in β-cyclodextrin

NaI/PPh₃-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

• Dan Liu,
• Yue Zhao and
• Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

• Discussion Key elements of reaction optimization are summarized in Table 1. With NaI (20 mol %) and PPh3 (20 mol %), acrylamide 1a and redox-active ester 2a were used as model substrates to react for 36 h in acetonitrile (MeCN) under blue LEDs irradiation and N2 atmosphere, delivering the desired oxindole

Combining the best of both worlds: radical-based divergent total synthesis

• Kyriaki Gennaiou,
• Antonios Kelesidis,
• Maria Kourgiantaki and
• Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

• platforms [66], the group considered a system in which a photoexcited catalyst oxidatively cleaves a siloxycyclopropane with endo selectivity [67], leading to aryl–nickel capture and reductive elimination. Thus, when substrates 121 and 122 were photoirradiated with blue LED light at 45 °C in the presence of

• chiral aldehyde 127 and Boc-protected amine 128, followed by zinc reduction of the nitro group and subsequent protection of the amine by a tosyl group in 27% overall yield. Irradiating 129 with blue light at 30 W in the presence of 1 mol % of [Ir(dtbbpy)(ppy)2]PF6 and 5 equiv of KHCO3 in THF resulted in

• radical reaction [87]. Indeed, when ʟ-tyrosine methyl ester (154), 1,4-cyclohexanedione monoethylene acetal (155), and dehydroalanine derivative 156 were allowed to react in the presence of TFA, molecular sieves, 1 mol % of fac-Ir(ppy)3, and Hantzsch ester under blue LED irradiation at 40 W, this resulted

Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements

• Alexios I. Vicatos,
• Zakiena Hoossen and
• Mino R. Caira

Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184

• to the cavities of the γ-CD molecules. The distinct packing arrangement of the repeat unit of the host molecules in γ-CD·PRO. The four-fold axis (blue line) runs through the centre of the channel, parallel to the c-axis. The water molecules are omitted for clarity. A stereoscopic view of γ-CD·PRO

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

• Elena R. Lopat’eva,
• Igor B. Krylov,
• Dmitry A. Lapshin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

• ][29] and specialized on the specific types of organophotoredox catalysts, such as quinone derivatives [30][31], carbon nitrides [32][33], eosin [34][35][36], 4CzIPN [37][38], Bodipy derivatives [39], methylene blue [40], pyrylium salts [41], and perylene diimides [42]. Photochemical processes

• , apparently, due to the interaction of NHPI with the TiO2 surface. It is noteworthy that NHPI or TiO2 alone demonstrated negligible activity compared to their simultaneous use. Upon the irradiation by blue LED, PINO radicals are formed on the TiO2 surface and diffuse in the volume of solution, where the