Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• the electronic nature of the compounds with and without AIEE properties. Keywords: acceptor–donor–acceptor; AIEE; low molecular weight; one-pot reaction; ((pyridin-2-yl)amino)maleimide; TD-DFT calculation; Introduction Fluorescent compounds have attracted considerable attention as functional

• -concentration solutions, and their emission efficiency, chromogenic properties, and light sensitivity decrease rapidly [5][6]. In recent years, contrary to conventional fluorescent compounds, aggregation-induced emission enhancement (AIEE)-based compounds that exhibit strong fluorescence in aggregate structures

• have been reported [7][8][9][10]. Because the aggregated state of AIEE-based compounds is affected by the external environment, these compounds have found use in clinical applications as chemical sensors or fluorescent probes [7][8][9][10]. Pyridine is a nitrogen-containing heterocyclic compound found

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• efficiency (EQE) exceeds the theoretical maximum of those with prompt fluorescent emitters. Most importantly, comparative study of the D–A molecule and its D–A–D counterpart from the viewpoints of the experiments and theoretical calculations revealed the effect of the number of the electron donor on the

• thermally activated delayed fluorescent behavior. Keywords: charge-transfer; dibenzophenazine; donor–acceptor; organic light-emitting diodes; thermally activated delayed fluorescence; Introduction Thermally activated delayed fluorescence (TADF), which was firstly reported in 1961 by Parker and Hatchard [1

• achieved a good EQE up to 11%, which exceeds the theoretical maximum (ca. 5%) of prompt fluorescent emitter-based OLEDs. The additional donor gave a better EQE of the OLED device than that fabricated with the D–A compound, due to a less efficient TADF process. Taken together the experimental and

Menadione: a platform and a target to valuable compounds synthesis

• Acácio S. de Souza,
• Ruan Carlos B. Ribeiro,
• Dora C. S. Costa,
• Fernanda P. Pauli,
• David R. Pinho,
• Matheus G. de Moraes,
• Fernando de C. da Silva,
• Luana da S. M. Forezi and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43

• source was made after preliminary studies demonstrated the occurrence of reactions with benzoquinones using the compact fluorescent lamp (Scheme 18). Reduction and acylation reactions Menadione reduction reactions are one of the most important types of reactions and are directly related to some of its

Four bioactive new steroids from the soft coral Lobophytum pauciflorum collected in South China Sea

• Di Zhang,
• Zhe Wang,
• Xiao Han,
• Xiao-Lei Li,
• Zhong-Yu Lu,
• Bei-Bei Dou,
• Wen-Ze Zhang,
• Xu-Li Tang,
• Ping-Lin Li and
• Guo-Qiang Li

Beilstein J. Org. Chem. 2022, 18, 374–380, doi:10.3762/bjoc.18.42

• value of 19.03 μM. The investigation of anti-inflammatory activities of lobophysterols E–H with classic transgenic fluorescent zebrafish models (Figure 5) showed that compound 1 exhibited moderate activity, with an inhibition rate of 32% (20 μM). Conclusion In conclusion, four new steroids

• were cultivated by Qilu University of Technology (Jinan, China). Transgenic zebrafish [Tg: zlyz-EGFP and Tg (vegfr2: GFP)] expressing enhanced green fluorescent protein (EGFP) was used in this article. The conditions of the maintenance complied with guidelines of the Organization for Economic Co

Recent developments and trends in the iron- and cobalt-catalyzed Sonogashira reactions

• Surendran Amrutha,
• Sankaran Radhika and
• Gopinathan Anilkumar

Beilstein J. Org. Chem. 2022, 18, 262–285, doi:10.3762/bjoc.18.31

• ) moiety since it can easily undergo aggregation-induced emission enhancement (AIEE). The self-assembly of the HPB derivative resulted in the formation of fluorescent aggregates, which can act as a stabilizer or as a reactor for the development of α-Fe2O3 nanoparticles at room temperature. The catalytic

• , Balla and co-workers discussed the scope of the reaction by the utilization of in-situ generated α-Fe2O3 nanoparticles with several activated and unactivated halides (Scheme 13) [30]. They also examined the effect of concentration of fluorescent aggregates of HPB, i.e., the size of the generated

Anomeric 1,2,3-triazole-linked sialic acid derivatives show selective inhibition towards a bacterial neuraminidase over a trypanosome trans-sialidase

• Peterson de Andrade,
• Sanaz Ahmadipour and
• Robert A. Field

Beilstein J. Org. Chem. 2022, 18, 208–216, doi:10.3762/bjoc.18.24

• , followed by addition of 0.5 mM MUNANA (20 μL, 0.1 mM final concentration) and incubated at 37 °C for 15 min. The fluorescent product released (MU) was measured with excitation and emission wavelengths of 360 and 460 nm, respectively. Neuraminidase (10 mU) assay was performed as described above without

First total synthesis of hoshinoamide A

• Haipin Zhou,
• Zihan Rui,
• Yiming Yang,
• Shengtao Xu,
• Yutian Shao and
• Long Liu

Beilstein J. Org. Chem. 2021, 17, 2924–2931, doi:10.3762/bjoc.17.201

• hoshinoamide A and other highly methylated polypeptide analogues. Our strategy was also helpful to further study its antimalarial activity. Structure-and-activity and functional studies with the fluorescent-labeled analogs are currently under investigation in our lab. Experimental General experimental

Synthesis of a novel aminobenzene-containing hemicucurbituril and its fluorescence spectral properties with ions

• Qingkai Zeng,
• Qiumeng Long,
• Jihong Lu,
• Li Wang,
• Yuting You,
• Xiaoting Yuan,
• Qianjun Zhang,
• Qingmei Ge,
• Hang Cong and
• Mao Liu

Beilstein J. Org. Chem. 2021, 17, 2840–2847, doi:10.3762/bjoc.17.195

• produced the desired amidobenzene-containing hemicucurbituril. As an original fluorescent chemosensor, it exhibited strong interactions with Fe3+ over other metal cations. The experimental evidence of fluorescence spectra suggested that a 1:1 complex was formed between this macrocycle and Fe3+ with an

Synthesis of phenanthridines via a novel photochemically-mediated cyclization and application to the synthesis of triphaeridine

• Songeziwe Ntsimango,
• Kennedy J. Ngwira,
• Moira L. Bode and
• Charles B. de Koning

Beilstein J. Org. Chem. 2021, 17, 2340–2347, doi:10.3762/bjoc.17.152

• captivated synthetic chemists and biologists alike since the 1960s due to their efficient DNA binding, antitumour and antiparasitic activities [1]. Such compounds include the DNA and RNA-fluorescent marker ethidium bromide (1), the cell viability probe propidium iodide (2) and the naturally occurring

Post-functionalization of drug-loaded nanoparticles prepared by polymerization-induced self-assembly (PISA) with mitochondria targeting ligands

• Janina-Miriam Noy,
• Fan Chen and
• Martina Stenzel

Beilstein J. Org. Chem. 2021, 17, 2302–2314, doi:10.3762/bjoc.17.148

• -((phenylcarbonothioyl)thio)pentanoic acid, but it was modified with ethylene glycol. During the polymerization of the water-soluble polymers, fluorescein O-methacrylate was added at a ratio of CTA to fluorescent monomer of 1:0.3. This means more that three out of ten polymer chains will be labelled, which is sufficient

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• used in pH-sensitive fluorescent materials [10] and laser technologies [11][12][13][14]. Moreover, xanthenes are present in some natural sources, such as santalin pigments found in many varieties of plants [15][16]. There have been many studies on the synthesis of xanthene derivatives to date because

• of their important biological and fluorescent uses. To summarize the main syntheses of these studies: in particular, transition metal-catalyzed cascade benzylation–cyclization [17], cyclization of polycyclic aryl triflate esters [18], reaction of β-naphthol and aldehydes [19][20] or inter- or

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• , respectively. The UV–vis absorption features of polymers 115 and 116 were altered upon protonation due to the formation of azulenium cations in the polymer backbone and they displayed a significant color change on protonation. None of these polymers were fluorescent in the neutral form, however, 115 and 116

Recent advances in the syntheses of anthracene derivatives

• Giovanni S. Baviera and
• Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

• [11][12], the 2,2’-bianthracene derivative 3 provides a green and fluorescent OLED [13], 2,2’-bianthracenyl (4) has been employed as an organic semiconductor in an OFET device [14], and di-n-alkoxyanthracenes have gelling properties with diverse solvents, mainly alkanes and alcohols [4]. Furthermore

• activity for iodoethynyl groups [63]. Intramolecular cyclization In 2009, Swager’s research group published the synthesis of fluorescent macrocycles based on 1,3-butadiyne-bridged dibenzo[a,j]anthracene subunits via a multistep route (Scheme 30) [64]. They synthesized substituted dibenzo[a,j]anthracenes

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• acetylcholinesterase inhibitors [11][12][13], being LSPN223 the most potent compound (Figure 2). Furthermore, coumarin derivatives have been used as fluorescent probes, laser dyes, fluorescent chemosensors, light absorbers for solar cells, optical brighteners, and organic light emitting diodes (OLEDs) [14][15]. From a

Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs

• Jongwoo Son

Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122

• adjacent directing group (see 31h). This manganese(I)-catalyzed late-stage glycosylation provides hexaglycopeptide conjugate 31m without epimerization. Moreover, the late-stage C–H diversification process enabled bioorthogonal access to glycosylated peptides, such as a fluorescent BODIPY-labeled tryptophan

• , fluorinations, allylations, alkynylations, alkenylations, and fluorescent labeling with BODIPY. Moreover, manganese catalysis exhibits excellent functional group tolerance in late-stage C–H functionalization, indicating a robust and versatile catalytic system. Several challenges still remain since there are

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

• recognition of C–G, G–C, and A–A base pairs, respectively [139][140]. While still in relatively early stages of development, the Janus-wedge triplex has already shown intriguing potential as a diagnostic or therapeutic approach for Huntington’s or related genetic diseases [139]. Fluorescent nucleobases in PNA

• : Because PNA has become a key component of many assays and diagnostics, development of fluorescent nucleobases as labels for PNA has attracted considerable attention. 2-Aminopurine (Figure 10), a fluorescent structural isomer of adenine [141], was one of the first fluorescent nucleobases used in PNA [142

• -aminopurine in PNA probes. Hudson and co-workers developed several fluorescent PNA nucleobases derived from phenylpyrrolocytosine [143][144][145]. One of the most promising analogues, mmguaPhpC (Figure 10), formed a stronger base pair with G than the native C–G pair which was followed by a 30–70% decrease of

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

• Premansh Dudhe,
• Mena Asha Krishnan,
• Kratika Yadav,
• Diptendu Roy,
• Krishnan Venkatasubbaiah,
• Biswarup Pathak and
• Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

• –c are shown to undergo a novel cascade imination-heterocylization in the presence of the organic base DIPEA to provide 1-indolyl-3,5,8-substituted γ-carbolines 3aa–ea in good yields. The γ-carbolines are fluorescent and exhibit anticancer activities against cervical, lung, breast, skin, and kidney

• traces of any β-carboline product were observed, which proves that the heterocyclization reaction is highly regiospecific. Optical properties of γ-carbolines Interestingly, the γ-carboline derivatives were found to be highly fluorescent under UV light irradiation. A systematic literature survey revealed

• that the structural core of carbolines had been widely exploited for the development of organic fluorescent entities, and in general, their UV absorbance ranges between 340 to 380 nm. For a deeper insight into the optical properties of the novel substituted γ-carbolines, absorption and emission studies

Double-headed nucleosides: Synthesis and applications

• Vineet Verma,
• Jyotirmoy Maity,
• Vipin K. Maikhuri,
• Ritika Sharma,
• Himal K. Ganguly and
• Ashok K. Prasad

Beilstein J. Org. Chem. 2021, 17, 1392–1439, doi:10.3762/bjoc.17.98

• nucleosides 151c,d and 154a,b when incorporated into oligonucleotides enabled fluorescent discrimination of targets with single nucleotide polymorphisms (SNPs) [24]. Nielsen and co-workers [15] synthesized a series of double-headed nucleosides 5-(1-phenyl-1H-1,2,3-triazol-4-yl)-2′-deoxyuridine (157a), 5-(1

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• applications ranging from organic thin‐film transistors (OTFTs), organic light-emitting diodes (OLEDs), dye‐sensitized solar cells (DSSCs), fluorescent probes, organic photovoltaics (OPVs) to the high hole mobility semiconductors, blue light-emitting materials, nonlinear optical materials and so forth [5][6][7

Photoinduced post-modification of graphitic carbon nitride-embedded hydrogels: synthesis of 'hydrophobic hydrogels' and pore substructuring

• Cansu Esen and
• Baris Kumru

Beilstein J. Org. Chem. 2021, 17, 1323–1334, doi:10.3762/bjoc.17.92

• –fluorescein isothiocyanate and fluorescein isothiocyanate–dextran fluorescent probes were subjected to HGCM and HGCM-vTA samples with a comparatively shorter releasing experiment than the one performed for RhB dye (Supporting Information File 1, Figure S4a). The static experiment principally relies on

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

Synthesis of 10-O-aryl-substituted berberine derivatives by Chan–Evans–Lam coupling and investigation of their DNA-binding properties

• Peter Jonas Wickhorst,
• Mathilda Blachnik,
• Denisa Lagumdzija and
• Heiko Ihmels

Beilstein J. Org. Chem. 2021, 17, 991–1000, doi:10.3762/bjoc.17.81

• , it has been found that berberine (1a) exhibits a selective cytotoxicity against cancer cells [12][13], which is mainly based on its DNA-binding properties [14]. Since the complexation with DNA leads to significant changes of the fluorescent quantum yields of the bound berberine, it can also be used

• as fluorescent probe in bioanalytical chemistry [15][16]. Because of these attractive properties of this lead structure, numerous berberine derivatives have been synthesized in order to further improve the biological activity [17][18][19][20][21][22][23][24][25][26]. Among those derivatives

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

• synthetic route being optimized over time [151][152]. The stability of these derivatives is similar to those of LNA [150][151][152], with the added advantage of additional coupling reactions to fluorescent groups [151], or small molecules being possible either during solid-phase synthesis (SPS) [153][154

Enhanced target cell specificity and uptake of lipid nanoparticles using RNA aptamers and peptides

• Roslyn M. Ray,
• Anders Højgaard Hansen,
• Maria Taskova,
• Bernhard Jandl,
• Jonas Hansen,
• Citra Soemardy,
• Kevin V. Morris and
• Kira Astakhova

Beilstein J. Org. Chem. 2021, 17, 891–907, doi:10.3762/bjoc.17.75

• a tight junction barrier has formed within these cells and can be used to determine the ability of the LNPs to pass through the BBB (Supporting Information File 1, Figure S3A). Additionally, we further confirmed our junctions using fluorescent microscopy on the barrier layers to confirm expression

• through direct addition by 1.6–1.8-fold (Figure 2B). Additionally, the mean fluorescent intensity (MFI) was found to be 2–2.3-fold higher in the target TZM-bl cells in both barrier and nonbarrier treatment groups compared to the control HeLa cells, indicating a higher accumulation of LNPs in the target

• (phosphate-buffered saline, PBS) conditions (Figure 4A). Additionally, we confirmed LNP uptake by the monocyte-derived macrophages (MDMs) using fluorescent microscopy (Figure 4B). We found that all LNPs containing the Cy5 oligonucleotide were observable under the microscope (Figure 4B) and that all

Manganese/bipyridine-catalyzed non-directed C(sp³)–H bromination using NBS and TMSN₃

• Kumar Sneh,
• Takeru Torigoe and
• Yoichiro Kuninobu

Beilstein J. Org. Chem. 2021, 17, 885–890, doi:10.3762/bjoc.17.74

• ][36][37][38][39][40][41][42][43]. Highly reactive and selective bromination reactions have been achieved using a stoichiometric amount of MnO2 [44] or a catalytic amount of Li2MnO3 [45] under fluorescent light irradiation in the presence of Br2 (Scheme 1d). Hill [46] and Groves [47][48][49] have