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

• +, and Mn2+ (nitrate salts were used as cation sources) in DMF resulted in different degrees of quenching of the fluorescence emission of host 4. The results are collected in Figure 3 as the corresponding fluorescence quenching efficiency which was quantified using the equation ΔI = (I0 − I), where I is

• halide ions, especially the heavier iodide ion, to the macrocyclic sensor, slightly enhanced the fluorescence emission in CH2Cl2/CH3OH 4:1 (v/v) at 298 K, instead of quenching the fluorescence as predicted by the classic heavy-atom effect. The corresponding fluorescence enhancement efficiency of selected

• −1. In another perspective, the presence of the coordination of selected anions to the macrocyclic sensor enhanced the fluorescence emission in various degree, extremely contrary to the classic heavy-atom effect caused by a heavy atom. In general, this macrocyclic sensor showed high fluorescence

Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

• Inaiá O. Rocha,
• Yuri G. Kappenberg,
• Wilian C. Rosa,
• Clarissa P. Frizzo,
• Nilo Zanatta,
• Marcos A. P. Martins,
• Isadora Tisoco,
• Bernardo A. Iglesias and
• Helio G. Bonacorso

Beilstein J. Org. Chem. 2021, 17, 2799–2811, doi:10.3762/bjoc.17.191

• coefficients of the derivatives studied here. All absorption spectra are listed in Supporting Information File 1 (Figures S2–S7). The steady-state fluorescence emission spectra of the Schiff base compounds from their absorption in the UV–vis region was carried out. Derivatives 3aa–fa and 3bb–be were analyzed

• in CHCl3, DMSO, and MeOH solutions by the emission and excitation spectra and exemplified in the Supporting Information File 1 (Figures S2–S7). For emission measurements, the maximum wavelength with the lowest absorption energy was used for excitation for the fluorescence measurements. The quantum

• fluorescence yields (Φf) were calculated in order to prove the quantum efficiency of these derivatives in terms of fluorescence emission and thus discuss the influence of the different solvents and substituents. Firstly, by comparing the selected solvents, compound 3aa (R = Ph, R1 = H) presented an emission in

Exfoliated black phosphorous-mediated CuAAC chemistry for organic and macromolecular synthesis under white LED and near-IR irradiation

• Azra Kocaarslan,
• Zafer Eroglu,
• Önder Metin and
• Yusuf Yagci

Beilstein J. Org. Chem. 2021, 17, 2477–2487, doi:10.3762/bjoc.17.164

• polymer has similar absorption characteristic to bare anthracene (Figure 4b). The fluorescence spectrum of diluted solution of PCL-Anth in THF excited at λexc = 350 nm showed the characteristic emission bands of the excited (singlet) anthracene at 595, 655, and 725 nm (Figure 4c). These observations

• the NMR tube. The reaction tube was irradiated by using a Philips 150 W PAR38E E27 halogen pressure glass type bulb with strong IR-A (NIR) emission. The light intensity inside the reaction tube was ≈200 mW·cm−2. The light bulb was attached to the top of a photoreactor setup equipped with a large air

• acetylene proton around 4.42 ppm. a) 1H NMR spectrum of chain end modified PCL-Anth; b) UV–vis spectra of (azidomethyl)anthracene (black) and PCL-Anth (red); c) fluorescence emission spectrum of PCL-Anth. a) GPC traces of PS-Az, PCL-Alk and block copolymer (Ps-b-PCL) b) 1H NMR spectrum of the block

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• and their optical and electrochemical properties investigation by the use of UV–vis and emission spectroscopy, CV measurements as well as DFT calculations. Results and Discussion Synthesis. At the beginning of this study, we synthesized 2,4-dibromo-9-chloro-5,6,7,8-tetrahydroacridine (2) by refluxing

• trifluoromethoxy group (OCF3), a longer reaction time of 6 hours was required to obtain the product 4c in decreased yield (57%). Photophysical properties. We studied the steady-state absorption and emission of selected tetrahydroacridines 4a–d to gain insights into their photophysical properties. The UV–vis

• was deduced to be around 3.37 eV. Derivatives 4b and 4d showed similar values of 3.20 eV and 3.18 eV, respectively. In contrast, compound 4c showed a decreased value of 3.09 eV. The emission spectra of tetrahydroacridines 4a–d were measured with an excitation line at 325 nm. They were dominated by

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

• Pieterjan Winant and
• Wim Dehaen

Beilstein J. Org. Chem. 2021, 17, 2315–2320, doi:10.3762/bjoc.17.149

• through oxidative quenching of the excited substrate. While an excited state of 1 could react in a similar fashion, the absorption maximum of 1 is centered around 280 nm, which is outside the emission spectrum of green LEDs. A recent study by Hashmi et al. [44], however, shed a completely different light

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

• displayed fluorescence emission at 385 nm in the protonated state. The electrochemical bandgap of these polymers was in the impressive range of 1.57–1.62 eV. In 2014, Hawker, Robb, and co-workers [35] also reported the synthesis of azulene-fluorene copolymers 117–121, containing varying ratios of 1,3-and

Towards new NIR dyes for free radical photopolymerization processes

• Haifaa Mokbel,
• Guillaume Noirbent,
• Didier Gigmes,
• Frédéric Dumur and
• Jacques Lalevée

Beilstein J. Org. Chem. 2021, 17, 2067–2076, doi:10.3762/bjoc.17.133

• in Figure 1. They are characterized by a sharp and intense absorption band in the NIR range. Remarkably, absorption of most of the dyes is excellent in the 700–850 nm spectral range, ensuring fairly good overlap with the emission spectrum of the laser diode used in this work (i.e., LD@785 nm

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

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• -fluorolactams 12-1, was synthesized by Sathyamurthy et al. in 1990 [55]. These compounds had already been prepared by Grakauskas and co-worker in 1970 [56], but in low yields and the N-fluorolactams were not recognized as fluorinating agents at that time. For positron emission tomography (PET), Sathyamurthy et

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

• radioisotope for positron emission tomography (PET) in clinical and preclinical research is 18F. Radiopharmaceuticals should be prepared at the late stage of the entire synthetic protocol because of the short half-lives of radioisotopes [26][27][28][29]. In their study, the authors used an aqueous 18F-fluoride

Volatile emission and biosynthesis in endophytic fungi colonizing black poplar leaves

• Christin Walther,
• Pamela Baumann,
• Katrin Luck,
• Beate Rothe,
• Peter H. W. Biedermann,
• Jonathan Gershenzon,
• Tobias G. Köllner and
• Sybille B. Unsicker

Beilstein J. Org. Chem. 2021, 17, 1698–1711, doi:10.3762/bjoc.17.118

• of the fungus-derived volatiles like 2-phenylethanol, 3-methyl-1-butanol and the sesquiterpene (E)-β-caryophyllene, are known to play a role in direct and indirect plant defense, the emission of volatiles from endophytic microbial species should be considered in future studies investigating tree

• known endophytic volatiles, sesquiterpenes have gained much attention in recent years as they can play an important role in plant–plant, plant–microbe, and microbe–microbe interactions [39][40]. Weikl et al., for instance, analyzed the volatile emission of Alternaria alternata and Fusarium oxysporum in

• their own TPS genes and how these fungal volatiles influence plant–insect interactions. Identification of fungal TPS genes is a useful tool to assess the impact of fungal terpene emission on plant volatile composition and on plant–insect interactions. In this study, we isolated and identified endophytic

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

• emission intensity (dependent on the sequence context) upon hybridization with complementary DNA and RNA [145]. Another analogue, 5,6-BenzopC (Figure 10) had high quantum yield and superior base pairing properties, but its fluorescence was completely quenched upon hybridization with DNA and RNA [146

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• properties. Herein, starting from readily available anthranilic acid, an efficient synthesis of 2,4-bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridine derivatives was accomplished via a one-pot double Sonogashira cross-coupling method. The UV-visible absorption and emission properties of the synthesized

• blue fluorescence was observed for the prepared tetrahydroacridine derivatives, their photophysical properties were investigated. Absorption and emission spectra were measured at room temperature in diluted dichloromethane solution and are depicted in Figure 2 and Figure 3. All spectroscopic data

• , including the maximum of absorption and emission, fluorescence quantum yield, stokes shift, onset of the absorption wavelengths and optical band gap are summarized in Table 3. Aiming to understand the impact of substituents at arylethynyl groups, spectra of diversely substituted tetrahydroacridines were

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

• 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

• absorption maximum (λmax) was observed at 230 nm for 3ac in DMSO (Figure 3, left side). The fluorescence studies carried out for 3ac in four different solvents revealed that the emission maxima shifted bathochromically by almost 40 nm upon changing the solvent polarity, for instance, from non-polar hexane to

• well followed by incubation for 20 minutes. The absorbance from each well proportional to the live cell was measured using a Synergy H1 multimode plate reader (BioTek Instruments, Inc., Winooski, VT, USA) at an excitation and emission wavelength of 530 nm and 590 nm, respectively. Dose–response curves

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

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

• properties (absorption and emission) for these versatile systems has been revealed. Keywords: Clauson–Kaas reaction; heterocycles; ring-closing metathesis; truxene; Ullmann-type coupling; Van Leusen reaction; Introduction The two-dimensional phenylene-based π-conjugated star-shaped architectures has

• ) furnished the triformyltruxene 24 (Scheme 7). Finally, the crude product 24 was directly treated with TosMIC under Van Leusen oxazole conditions to provide the required product 25 in 23% yield (two steps) as depicted in Scheme 7. Absorption and emission spectra The UV–vis absorption as well as fluorescence

• , compound 25 exhibited only a single broad band at ca. 339.10 nm as can be inspected from Figure 1. To our expectation, as can be seen from an inspection of Figure 1, emission spectra of all the synthesized truxenes lies at longer wavelengths as compared to the absorption spectra for the corresponding

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

• performed via inductively coupled plasma optical emission spectroscopy (ICP-OES Optima 8000). Scanning electron microscopy (SEM) and EDX elemental mapping were performed using a JSM-7500F (JEOL) microscope equipped with an Oxford Instruments X-Max 80 mm2 detector for the determination of both elemental

A new glance at the chemosphere of macroalgal–bacterial interactions: In situ profiling of metabolites in symbiosis by mass spectrometry

• Marine Vallet,
• Filip Kaftan,
• Veit Grabe,
• Fatemeh Ghaderiardakani,
• Simona Fenizia,
• Aleš Svatoš,
• Georg Pohnert and
• Thomas Wichard

Beilstein J. Org. Chem. 2021, 17, 1313–1322, doi:10.3762/bjoc.17.91

• (1024 × 1024) were acquired using a Zeiss cLSM 880 (Carl Zeiss AG, Oberkochen, Germany) with a Plan-Apochromat 20 × 0.8 and 488 nm Argon-laser excitation (5% transmission). Emission wavelengths for SYBR Gold (490–650 nm) and chlorophyll A (653–735 nm) were separated via the spectral detection unit

Synthetic accesses to biguanide compounds

• Oleksandr Grytsai,
• Cyril Ronco and
• Rachid Benhida

Beilstein J. Org. Chem. 2021, 17, 1001–1040, doi:10.3762/bjoc.17.82

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

• compounds 4a–f and 5a–e were identified and fully characterized by NMR-spectroscopic analysis (1H, 13C, COSY, HSQC, HMBC), mass spectrometric data and elemental analyses. Absorption and emission properties The absorption properties of the derivatives 5a–e resemble the ones of the berberine chromophore with

• long wavelength maxima between 403 nm (5e in aqueous buffer) and 426 nm (5d in CHCl3) (Table 1, Table S2, Figure S1, Supporting Information File 1) [40]. The emission intensity of all compounds is very low (Φfl << 0.01) and mostly not detectable in the series of tested solvents. To examine whether the

• significantly higher, but still relatively low emission quantum yields in glycerol at room temperature (Φfl = 0.009–0.031, 20 °C, η = 1412 cP) [41], whereas the emission intensity decreased with increasing temperature (Φfl = 0.001–0.002, 80 °C, η = 32 cP) [41]. Such a behavior usually indicates a radiationless

Synthesis of dibenzosuberenone-based novel polycyclic π-conjugated dihydropyridazines, pyridazines and pyrroles

• Ramazan Koçak and
• Arif Daştan

Beilstein J. Org. Chem. 2021, 17, 719–729, doi:10.3762/bjoc.17.61

• obtained gave absorbance and emission at long wavelengths. Keywords: dibenzosuberenone; inverse electron-demand Diels–Alder cycloaddition reactions; p-quinone methide; polycyclic π-conjugated dihydropyridazines; pyridazines; pyrroles; Inroduction Dibenzosuberone and dibenzosuberenone derivatives are

• exhibit photophysical properties such as photosensitization [13], fluorescence, and aggregation-induced emission (AIE) [14][15][16]. π-Conjugated polycyclic hydrocarbons (CPHs) containing polycyclic heteroaromatic molecules (PHAs) and aza-polycyclic aromatic hydrocarbons (aza-PAHs) have been attracting

• fluorescent dyes 3a,b in detail. In the present study, the effects of functional groups with different conjugations on maximum absorbance (λmax, abs) and emission (λmax, ems), and wavelengths of dihydropyridazines 3c–f and 3k were investigated. Compounds 3c,d, with high conjugation, show the highest

Synthesis, structural characterization, and optical properties of benzo[f]naphtho[2,3-b]phosphoindoles

• Mio Matsumura,
• Takahiro Teramoto,
• Masato Kawakubo,
• Masatoshi Kawahata,
• Yuki Murata,
• Kentaro Yamaguchi,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2021, 17, 671–677, doi:10.3762/bjoc.17.56

• approximately 50 nm longer than that of our oxide 3 [16]. The fluorescence wavelength, including the maximum emission (λem), and the quantum yield depend on the nature of the P-modification. Phosphine oxide 3, cation 5, and boron complex 6 emitted blue fluorescence in the visible-light region, with λem at 395

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

• material rather than the material itself, and it is usually achieved by combustion or incineration [61][62]. This method is generally used for plastics that cannot be economically recycled by other means [63][64]. However, it often entails the emission of toxic volatile compounds (furans, dioxins) [65

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

• Lucía Rossi-Fernández,
• Viviana Dorn and
• Gabriel Radivoy

Beilstein J. Org. Chem. 2021, 17, 519–526, doi:10.3762/bjoc.17.46

• confirming the heterogeneous nature of the catalytic method. The freshly prepared CoNPs/MgO catalyst was characterized by means of transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), X-ray diffraction (XRD) and

• , operated at an acceleration voltage of 100 kV. Approximately one hundred metal particles were measured to perform the particle size distribution. The cobalt content in the supported catalyst was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES), on a Spectro Arcos instrument

Helicene synthesis by Brønsted acid-catalyzed cycloaromatization in HFIP [(CF₃)₂CHOH]

• Takeshi Fujita,
• Noriaki Shoji,
• Nao Yoshikawa and
• Junji Ichikawa

Beilstein J. Org. Chem. 2021, 17, 396–403, doi:10.3762/bjoc.17.35

• manner [1][2][3][4][5][6]. Since helicenes possess chirality derived from their helical structure, optically active helicenes and their derivatives exhibit characteristic properties, such as huge optical rotation [7], nonlinear optical effects [8][9][10], and circularly polarized light emission [11