Dioxazolones as electrophilic amide sources in copper-catalyzed and -mediated transformations

• Seungmin Lee,
• Minsuk Kim,
• Hyewon Han and
• Jongwoo Son

Beilstein J. Org. Chem. 2025, 21, 200–216, doi:10.3762/bjoc.21.12

• approaches. Despite the synthetic strategies to generate the copper nitrenoid intermediates are gaining more attention [104][105], several limitations still remain. First, multiple steps are required to prepare dioxazolones, synthesized conventionally from carboxylic acids or acid chlorides over two steps

Quantifying the ability of the CF₂H group as a hydrogen bond donor

• Matthew E. Paolella,
• Daniel S. Honeycutt,
• Bradley M. Lipka,
• Jacob M. Goldberg and
• Fang Wang

Beilstein J. Org. Chem. 2025, 21, 189–199, doi:10.3762/bjoc.21.11

• exhibits slower acid dissociation [25] and different lipophilicity [19][20][26][27][28]. For these reasons, it is an attractive synthetic target [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] and an important bioisostere in drug design and biochemical studies [30][44][45][46]. Despite the

Recent advances in electrochemical copper catalysis for modern organic synthesis

• Yemin Kim and
• Won Jun Jang

Beilstein J. Org. Chem. 2025, 21, 155–178, doi:10.3762/bjoc.21.9

• co-workers reported Cu-catalyzed asymmetric electrochemical regiodivergent cross-dehydrogenative coupling of Schiff bases and hydroquinones (Figure 9) [58]. In this approach, a chiral copper complex was used as a Lewis acid catalyst, yielding various synthetic routes for synthesizing chiral amino

• (IV) species 113 coordinates with carboxylic acid and undergoes photoinduced ligand-to-metal charge transfer (LMCT) and regeneration of the Ce(III) species to produce a benzylic radical 115. The chiral Cu(II) catalyst 117 reacts with benzylic radical 115 to yield Cu(III) intermediate 118, which then

• boronic acid and disproportionation. Subsequently, the coupling product 120 is released through reductive elimination, and the resulting Cu(I) species 121 is either reoxidized or plated on the cathode. Despite the success of electrochemical Chan–Lam coupling for C–N bond formation, the electrooxidative

Nickel-catalyzed cross-coupling of 2-fluorobenzofurans with arylboronic acids via aromatic C–F bond activation

• Takeshi Fujita,
• Haruna Yabuki,
• Ryutaro Morioka,
• Kohei Fuchibe and
• Junji Ichikawa

Beilstein J. Org. Chem. 2025, 21, 146–154, doi:10.3762/bjoc.21.8

• coupling reactions of aromatic C–F and C–Br bonds with arylboronic acids. Keywords: arylboronic acid; benzofuran; C–F bond activation; cross-coupling; nickel; Introduction The metal-catalyzed activation of aromatic carbon–fluorine (C–F) bonds is widely recognized as a challenging task in synthetic

• activation of aromatic C–F bonds. Results and Discussion First, we explored optimal conditions for nickel-catalyzed defluorinative coupling using 2-fluoronaphtho[2,1-b]furan (1b) and m-tolylboronic acid (2b) as model substrates (Table 1). When 1b was reacted with 2b at 80 °C using Ni(cod)2 (10 mol %) as a

• -fluorobenzofuran (1a) when reacted with phenylboronic acid (2a) as well as arylboronic acids containing electron-donating groups, such as a methyl group at the 3-position (2b), two methyl groups at the 2- and 5-positions (2c), and a tert-butyl group at the 4-position (2d). The reaction with 3,5

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• emerged among copper catalysts because it can act as a precursor to triflic acid in addition to a powerful copper-catalytic effect. Indeed, Cu(OTf)2 has proven to be an excellent surrogate for triflic acid compared with other metal triflates because it is inexpensive and exhibits high activity with low

• dual activity as a metal catalyst as well as a Lewis acid [8][9][10][11]. However, in many cases, the role of copper is not clear and both activities often work synergistically. In all other cases, copper’s activity is due to the coordination/complexation with unsaturated systems, but it is rarely

• possible to exclude its action also as Lewis acid. Confirming this dual activity, it should be noted that copper triflate can rarely be replaced by other copper salts or complexes to obtain the same results. In general, catalyst switching does not work with copper triflate, thus supporting its unique

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

• compounds comprising a stereogenic plane or axis is much less developed. Axially chiral compounds are well known as chiral ligands in asymmetric catalysis, with notable examples of binaphthyl-based derivatives such as BINAP, SEGPHOS, or binaphthyl-based phosphoric acid derivatives, which are among the

• to NHC-catalyzed reactions. The major part is devoted to chiral Brønsted acid catalysis as it seems so far the most widely used activation principle for the generation of axially chiral compounds. Hydrogen-bond-donating catalysts and various other activation modes complete the discussion of recent

• activation, atroposelective aza-Michael addition, and intramolecular aldol reaction to form the cationic intermediate Int-6. Release of the catalyst C2, reduction with NaBH4, and dehydration with acetic acid leads to the desired product 6. Recently, an organocatalytic atroposelective intramolecular (4 + 2

Hot shape transformation: the role of PSar dehydration in stomatocyte morphogenesis

• Remi Peters,
• Levy A. Charleston,
• Karinan van Eck,
• Teun van Berlo and
• Daniela A. Wilson

Beilstein J. Org. Chem. 2025, 21, 47–54, doi:10.3762/bjoc.21.5

• have sought to address this issue by replacing the hydrophobic block with biodegradable alternatives, like polylactic acid, resulting in PEG-PDLLA block copolymers capable of forming vesicles that are able to undergo shape transformation towards stomatocytes [6]. Despite this progress, the persistence

Facile one-pot reduction of β-nitrostyrenes to phenethylamines using sodium borohydride and copper(II) chloride

• Laura D’Andrea and
• Simon Jademyr

Beilstein J. Org. Chem. 2025, 21, 39–46, doi:10.3762/bjoc.21.4

• that, up to 24 hours, this method shows some degree of functional group tolerance, as the amido and carboxylic acid functionalities of benzamide and benzoic acid, were left untouched, and the starting materials were finally fully recovered. 1-Bromo-4-nitrobenzene (8a) and 3-chlorophenol were used to

• reductive methods used to date for the synthesis of substituted phenethylamines from their α,β-unsaturated nitroalkene analogues. Furthermore, the NaBH4/CuCl2 system is effective at reducing nitro and ester functionalities on aromatic structures, while leaving intact benzoic acid, amido- and halogenated

• mm, 1.7 µm) operated at 40 °C, using a linear gradient of the binary solvent system of buffer A (Milli-Q H2O/MeCN/formic acid, 95:5:0.1 v/v) to buffer B (MeCN/formic acid, 100:0.1 v/v) from 0 to 100% B in 3.5 min, then 1 min at 100% B, flow rate: 0.8 mL/min. Data acquisition was controlled by

Emerging trends in the optimization of organic synthesis through high-throughput tools and machine learning

• Pablo Quijano Velasco,
• Kedar Hippalgaonkar and
• Balamurugan Ramalingam

Beilstein J. Org. Chem. 2025, 21, 10–38, doi:10.3762/bjoc.21.3

• chromatographic spectra and to automatically assign the peaks to reagents or products depending on the decrease or increase in peak intensity over time. In addition to monitoring the evolution of the reaction, the IR spectral data was processed in real time. This was to ensure the complete consumption of acid

• reactant and to feed this information back to the pump for immediate quenching of carbonyldiimidazole to prevent any side reactions. The entire process allows to control the acid activation and amide formation precisely to afford the desired final product in quantitative yield. Recently, Sagmeister et al

Synthesis, structure and π-expansion of tris(4,5-dehydro-2,3:6,7-dibenzotropone)

• Yongming Xiong,
• Xue Lin Ma,
• Shilong Su and
• Qian Miao

Beilstein J. Org. Chem. 2025, 21, 1–7, doi:10.3762/bjoc.21.1

• Barton–Kellogg reaction with 8b under similar conditions gave the episulfide intermediate, which, however, could not be desulfurized with triisopropyl phosphite, trimethyl phosphite or triphenylphosphine to give the corresponding triene. The subsequent Scholl reaction of 10 with DDQ and triflic acid at

Synthesis of acenaphthylene-fused heteroarenes and polyoxygenated benzo[j]fluoranthenes via a Pd-catalyzed Suzuki–Miyaura/C–H arylation cascade

• Merve Yence,
• Dilgam Ahmadli,
• Damla Surmeli,
• Umut Mert Karacaoğlu,
• Sujit Pal and
• Yunus Emre Türkmen

Beilstein J. Org. Chem. 2024, 20, 3290–3298, doi:10.3762/bjoc.20.273

• 1,8-diiodonaphthalene (12) and a broad range of arylboronic acids and esters to afford substituted fluoranthenes 13 in good to high yields (Scheme 1d) [43]. In that work, we had only one example of a heterocyclic fluoranthene analogue where the use of 4-pyridylboronic acid provided the corresponding

• -diiodonaphthalene (12) and thiophene-3-ylboronic acid and ester derivatives 17 under the optimized conditions reported in our previous work (Table 1) [43]. Gratifyingly, the reaction worked smoothly with the use of thiophene-3-ylboronic acid (17a) to give acenaphtho[1,2-b]thiophene (15a) in 76% yield when Pd(dppf

• ] or catechol [47] boronic esters as the final products. Therefore, it is important that they can be directly utilized with our methodology without further boronic ester interconversions. To this end, we first tested the reaction of thiophene-3-ylboronic acid pinacol ester (17b), and we were pleased to

Intramolecular C–H arylation of pyridine derivatives with a palladium catalyst for the synthesis of multiply fused heteroaromatic compounds

• Yuki Nakanishi,
• Shoichi Sugita,
• Kentaro Okano and
• Atsunori Mori

Beilstein J. Org. Chem. 2024, 20, 3256–3262, doi:10.3762/bjoc.20.269

• % yield. The yield is improved to 94% when the reaction is performed with PPh3 as a ligand of palladium. The reaction is examined with amides derived from unsubstituted picoline, 6-methylpicoline, and 2,6-pyridinedicarboxylic acid in a similar manner to afford the cyclized products in 70%, 77%, and 87

• extraction was found despite the similarities in the lanthanide series [23]. Chakravorty and co-workers reported that a similar arylation reaction gave access to the fused skeleton of the diamide of 2,6-pyridinedicarboxlic acid (Py-2,6-diamide) [29]. Our interest has thus turned to extend the substrate scope

• %, respectively. The highest yield of 2b was obtained in the presence of CyJohnPhos (L3) as ligand, while tricyclohexylphosphine (L2) gave the best yield in the reaction of 1c. Concerning the reaction of 1c, the use of tetra-n-butylammonium bromide and pivalic acid as additives and PCy3 (L2) as a ligand further

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• out IEDADA reactions has been a glowing field in recent years [11][12]. In particular, organocatalysis can provide different activation modes to promote enantioselective IEDADA reactions [13][14], based on three strategies (Figure 3): i) LUMO-lowering activation (Brønsted acid catalysis), ii) HOMO

• the squaramide moiety and a nucleophile through deprotonation as Brønsted base. On the other hand, a chiral phosphoric acid provides a confined chiral environment where the reactants are approached, activating both the azadiene by interaction with the acidic hydrogen and a dienophile bearing a

• acid as additive and a mixture of toluene and water provided the best results in terms of yield and enantioselectivity. A wide scope was explored, including electron-donating substituents and electron-withdrawing groups, as well as heterocycles, giving densely functionalized chiral azaspirocyclic

Discovery of ianthelliformisamines D–G from the sponge Suberea ianthelliformis and the total synthesis of ianthelliformisamine D

• Sasha Hayes,
• Yaoying Lu,
• Bernd H. A. Rehm and
• Rohan A. Davis

Beilstein J. Org. Chem. 2024, 20, 3205–3214, doi:10.3762/bjoc.20.266

• carbon signal. Although a downfield exchangeable CO2H proton was not observed in the 1H NMR spectrum of 5, a carboxylic acid moiety was assigned based on the 13C NMR shift value (δC 173.6) [17], and analysis of the HRESIMS ion at m/z 477.0022 [M + H]+, which confirmed the molecular formula to be

• /CH2Cl2 at room temperature (17% yield). Subjecting the methoxylated benzaldehyde intermediate 9 to a Doebner–Knoevenagel condensation with malonic acid and pyridine afforded the brominated cinnamic acid analogue 10 in 54% yield [19]. Amidation chemistry using carbonyldiimidazole (CDI) [18] and the

• (4-OCH3); LRESIMS (m/z): 293/295/297 [M + H]+. Doebner–Knoevenagel condensation of 3,5-dibromo-4-methoxybenzaldehyde with malonic acid 3,5-Dibromo-4-methoxybenzaldehyde (9, 80.0 mg, 0.27 mmol), malonic acid (56.0 mg, 0.54 mmol) and dry pyridine (1 mL) were refluxed at 100 °C for 5 h. The reaction

Germanyl triazoles as a platform for CuAAC diversification and chemoselective orthogonal cross-coupling

• John M. Halford-McGuff,
• Thomas M. Richardson,
• Aidan P. McKay,
• Frederik Peschke,
• Glenn A. Burley and
• Allan J. B. Watson

Beilstein J. Org. Chem. 2024, 20, 3198–3204, doi:10.3762/bjoc.20.265

• functional groups for subsequent product diversification (Scheme 1). For example, protected alkynylboron reagents can be employed [35][36][37], such as N-methyliminodiacetic acid (MIDA)boronate esters [38], potassium trifluoroborates [39], and others [40][41][42]. Similarly, organosilicon reagents have

• displaying an arylboronic acid and MIDA ester (22 and 23) gave no reaction, side reactions were observed with a dialkynyl germane (24), and the product derived from azide 25 was unstable to purification. To further demonstrate the compatibility and utility of germanyl alkynes in CuAAC reactions, we applied

• equiv), DMF, air, rt, 2 h. (iv) Pd(dtbpf)Cl2 (10 mol %), 2-acetylthiophen-3-ylboronic acid (1.2 equiv), K3PO4 (2.0 equiv), iPrOH/H2O 3:4, N2, 85 °C, 16 h. (v) Pd(dtbpf)Cl2 (2.0 mol %), 1-naphthylzinc bromide (1.2 equiv), THF, N2, 45 °C, 16 h. (vi) Cu(OAc)2·H2O (30 mol %), B(OH)3 (2.0 equiv), DBU (2.0

Synthesis of 2H-azirine-2,2-dicarboxylic acids and their derivatives

• Anastasiya V. Agafonova,
• Mikhail S. Novikov and
• Alexander F. Khlebnikov

Beilstein J. Org. Chem. 2024, 20, 3191–3197, doi:10.3762/bjoc.20.264

• chlorides have been developed. Keywords: azirine-2,2-dicarboxamides; azirine-2,2-dicarboxylic acids; isomerization; isoxazoles; Introduction The isomerization of isoxazoles, containing a heteroatomic substituent at C5, to 2H-azirines is a powerful method for the preparation of 2H-azirine-2-carboxylic acid

• derivatives [1]. In particular, the catalytic isomerization of 5-chloroisoxazoles allows the generation of azirine-2-carbonyl chlorides, which can be easily converted into a variety of azirine-2-carboxylic acid derivatives by reactions with nucleophilic reagents. Using this approach, numerous 2-(1H-pyrazol-1

• -carboxylic acid derivatives are not only valuable synthetic building blocks [3][4][5][6][7][8][9][10][11] but also show useful biological activities [12][13][14][15][16][17][18]. Although many 2,2-bifunctionalized azirines have been synthesized [3][4][5][6][7][8][9][10][11], the synthesis of only one 2H

Direct trifluoroethylation of carbonyl sulfoxonium ylides using hypervalent iodine compounds

• Radell Echemendía,
• Carlee A. Montgomery,
• Fabio Cuzzucoli,
• Antonio C. B. Burtoloso and
• Graham K. Murphy

Beilstein J. Org. Chem. 2024, 20, 3182–3190, doi:10.3762/bjoc.20.263

• ]. The most frequently used involves deprotonating the corresponding sulfoxonium salt with strong base, followed by the addition of an acylating agent (usually an acid chloride or chloroformate). Nevertheless, achieving a wide range of structural variations in sulfoxonium salts or ylides, particularly

Synthesis of extended fluorinated tripeptides based on the tetrahydropyridazine scaffold

• Thierry Milcent,
• Pascal Retailleau,
• Benoit Crousse and
• Sandrine Ongeri

Beilstein J. Org. Chem. 2024, 20, 3174–3181, doi:10.3762/bjoc.20.262

• tetrahydropyridazine scaffold is also found in numerous natural linear or cyclic peptides such as svetamycins or antrimycins as dehydropiperazic acid (Figure 2) [10]. Whereas many publications have been devoted to the synthesis and structure of piperazic acid derivatives (dehydro, chloro, hydroxy, …) [11][12], nothing

• than half a century [20]. In this context and in our ongoing effort to synthesize fluorinated non-proteinogenic linear or cyclic β-amino acids [21][22], it appeared attractive to build fluorinated β-analogs of dehydropiperazic acid (Figure 3). This novel fluorinated amino acid 1 will combine the

• electronic and structural properties of the fluorinated groups (CF3 or CF2H) and the geometric constraints due to its partially unsaturated cycle, which could help in the design of peptidomimetics. To our knowledge, only a few publications report the synthesis of tetrahydropyridazines with a carboxylic acid

Multicomponent reactions driving the discovery and optimization of agents targeting central nervous system pathologies

• Lucía Campos-Prieto,
• Aitor García-Rey,
• Eddy Sotelo and
• Ana Mallo-Abreu

Beilstein J. Org. Chem. 2024, 20, 3151–3173, doi:10.3762/bjoc.20.261

• other approaches such as visible light, microwaves, heterogeneous catalysis, and ultrasound [12][13][14][15]. Due to its versatility, one of the most prevalent of these MCRs is the Ugi reaction [16]. This reaction generally combines an isocyanide with an acid, an amine, and an aldehyde or ketone to

• obtain α-acylaminoamides. Innovation in recent years with alternative reagents, like N-hydroxyimides or nitric acid in place of an acid, N-alkylated hydrazines, or nitrobenzene derivatives (reduced in situ to anilines) instead of amines, and in situ-prepared isocyanides, makes it a versatile method for

• reaction (Scheme 1). A wide variety of isatins were suitable for performing the 4-center 3-component Ugi reaction (U4C-3CR), as well as isocyanides. Using 3-aminopropanoic acid (or β-alanine) and 4-aminobutanoic acid (or γ-aminobutyric acid), the corresponding β- and γ-lactam derivatives were obtained

Surprising acidity for the methylene of 1,3-indenocorannulenes?

• Shi Liu,
• Märt Lõkov,
• Sofja Tshepelevitsh,
• Ivo Leito,
• Kim K. Baldridge and
• Jay S. Siegel

Beilstein J. Org. Chem. 2024, 20, 3144–3150, doi:10.3762/bjoc.20.260

• description will follow. The pKa determinations in acetonitrile are based on the determinations of differences of pKa values of two acids. In this case one compound is a reference acid with a previously known pKa value and the other acid is either FIC or BFC. Both compounds, as well as the references are also

• separately titrated in order to obtain the UV–vis spectra of the acids in neutral as well as in deprotonated forms. Then, the same titration is done with a mixture of measured acid (FIC or BFC) and a reference acid. Using the spectral data from the titrations of mixtures the dissociation levels α = [A−]/([A

• titrations the moisture and oxygen contents in argon were always under 10 ppm during measurements. Triflic acid (Aldrich, 99+%) and phosphazene base P2-Et (165535-45-5, Aldrich, ≥98%) were used to prepare the acidic and basic titrant solutions, respectively. Acetonitrile (Romil 190 SpS far UV/gradient

Hypervalent iodine-mediated intramolecular alkene halocyclisation

• Charu Bansal,
• Oliver Ruggles,
• Albert C. Rowett and
• Alastair J. J. Lennox

Beilstein J. Org. Chem. 2024, 20, 3113–3133, doi:10.3762/bjoc.20.258

• C‒F bond to give predominantly the trans product, but this pathway competes with a less favourable SN2 nucleophilic attack by fluorine to form the cis product. However, a mechanism entirely mediated by the I(III) HVI reagent, with the Pd(OAc)2 only acting as a Lewis acid to activate the HVI reagent

• enough to displace the iodane to form the oxonium species A. When the carboxylic acid is used, the oxygen in the lactone intermediate is less reactive and so substitution of the iodane by fluoride is more favourable and the branched product is formed. In addition to aminofluorination, Szabó also reported

• fluoride forms the product. In 2017, Kitamura and co-workers reported the synthesis of fluorinated tetrahydrofurans 25 and butyrolactone 27 (Scheme 15) [33]. Unsaturated alcohols 23 and 3-butenoic acid (24) were competent starting materials, using PhI(OPiv)2 as an oxidant and pyridine·HF as a source of

Advances in the use of metal-free tetrapyrrolic macrocycles as catalysts

• Mandeep K. Chahal

Beilstein J. Org. Chem. 2024, 20, 3085–3112, doi:10.3762/bjoc.20.257

• other binding sites required for substrate binding and/or promotion of the catalytic activity. Past studies have shown that modifying the porphyrin core with urea functionalities and amino acid substituents leads to the formation of ureaporphyrins, which significantly enhance sugar binding in non-polar

• -free meso-tetra(pentafluorophenyl)porphyrin (67) as a HER electrocatalyst using TsOH (p-toluenesulfonic acid) as a proton donor in THF [111]. Macrocycle 67 undergoes two reversible one-electron reductions at E1/2 = −1.14 V and −1.54 V yielding radical anion [67]˙− and a dianion species [67]2−. Upon

• reduction to highly energetic dianion [67]2− (free energy of +36.3 kcal mol−1). Combining experimental and theoretical observations, the authors proposed the most favorable hydrogen generation mechanism to be E–P–E–P; where E stands for reduction and P means protonation (Figure 19). Acid protonates the

Enantioselective regiospecific addition of propargyltrichlorosilane to aldehydes catalyzed by biisoquinoline N,N’-dioxide

• Noble Brako,
• Sreerag Moorkkannur Narayanan,
• Amber Burns,
• Layla Auter,
• Valentino Cesiliano,
• Rajeev Prabhakar and
• Norito Takenaka

Beilstein J. Org. Chem. 2024, 20, 3069–3076, doi:10.3762/bjoc.20.255

• as an acid scavenger. The reactions with catalyst 3 in the presence of either N,N-diisopropylethylamine or 4 Å molecular sieves gave identical results (99% yield, 78:22 er), and thus we decided to proceed with molecular sieves (Scheme 4). It is often the case that the narrower the chiral pocket of a

Chemical structure metagenomics of microbial natural products: surveying nonribosomal peptides and beyond

• Thomas Ma and
• John Chu

Beilstein J. Org. Chem. 2024, 20, 3050–3060, doi:10.3762/bjoc.20.253

• (Figure 2b). The former analyzes nucleic acid sequences to prioritize BGCs that are worth exploring [20]. For example, it has been shown that tracking characteristic biosynthetic or self-resistance gene(s) can facilitate the discovery of new congeners of a natural product family [21][22]. Function

• corresponding nucleic acid sequence. Proteinaceous enzymes then go on to catalyze biosynthetic reactions that put together small molecule building blocks (BB) to generate natural products with extremely diverse chemical structures. Because the intricacy of this process is not fully understood, scientists still

• product. Specifically, it is now possible to predict the order and identity of the BBs in NRPs based solely on the nucleic acid sequences of its BGC [40][41][42][43][44][45][46][47][48][49]. These algorithms not only obviated the need for culture and gene expression, dereplication can now be done in

Tunable full-color dual-state (solution and solid) emission of push–pull molecules containing the 1-pyrindane moiety

• Anastasia I. Ershova,
• Sergey V. Fedoseev,
• Konstantin V. Lipin,
• Mikhail Yu. Ievlev,
• Oleg E. Nasakin and
• Oleg V. Ershov

Beilstein J. Org. Chem. 2024, 20, 3016–3025, doi:10.3762/bjoc.20.251

• acid both in solution and in the solid state. Keywords: dual-state emission; full-color emission; nitriles; push–pull molecules; pyrindane; stilbazole; Introduction Over the past decades, heteroaromatic push–pull molecules have attracted great attention due to their widespread use in materials

• ], positron emission tomography (PET) imaging [24], fluorescent probes and labels [25][26][27] detecting H2S in foodstuff, water, and living cells [28], Fe3+ ions [29], Hg2+ ions [30], and cyanide anions [31], for acid–base vapor sensing [32], and as candidate material for photonics devices, optical switches

• ) in tetrachloromethane (CTC) to 588 nm (orange) in formic acid. Therefore, it was found that compound 1c was characterized by a large Stokes shift upon increasing the solvent polarity, which reached 150 nm (5824 cm−1) in formic acid. This was associated with the bathochromic shift of the emission band