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

• ]helicenes was possible, in which no serious decrease in yield was observed in Suzuki–Miyaura coupling and cycloaromatization (see the Experimental section) [30]. Next, double helical compounds were set as synthetic targets, because their unique optical properties have recently attracted much attention [5

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• - and morphology-dependent properties arising from confinement effects and strong interactions between neighboring atoms [1][2][3]. The correlation between nanoparticle size and the related electronic and optical properties has extensively been studied, leading to applications in novel technologies and

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• alternating enantiomers form a screw along the a axis. Optical properties All helicenes 10 are well soluble in dichloromethane and chloroform. Solubility in other common solvents such as acetonitrile, DMSO, tetrahydrofuran, ethanol and hexane is markedly lower. Carbazole-based [6]helicene 12 was described as

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• of G on the optical properties of H, so an UV–vis spectroscopy experiment was carried out. We investigated the changes in the UV–vis absorption of the complex at different guest concentrations corresponding to 0.5 and 1 equiv. As shown in Figure 4, the concentration of G did not affect the absorption

Synthesis and investigation of quadruplex-DNA-binding, 9-O-substituted berberine derivatives

• Jonas Becher,
• Daria V. Berdnikova,
• Heiko Ihmels and
• Christopher Stremmel

Beilstein J. Org. Chem. 2020, 16, 2795–2806, doi:10.3762/bjoc.16.230

• bound to the G4-DNA, such as fluorescent light-up effects and the formation of ICD bands, which are mostly pronounced with linker length of n = 4 (with a2) and n = 5 (with 22AG). This significant influence of the complex structure on the optical properties of the ligand provides some evidence that each

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• . The extent of aggregation of AuNPs containing peripheral phosphate groups in the presence of an externally added low molecular weight bis(zinc(II)–DPA) complex could be controlled by diphosphate anions, which in turn allowed correlating the optical properties of the nanoparticle solution with the

• initially changed color at a certain limiting concentration, indicating that the anions induced crosslinking and the formation of aggregates in which individual AuNPs were electronically coupled. We did not observe a continuous shift of the optical properties with the anion concentration, however, because

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• nm for SN4'' 33 including molar extinction coefficients in the range from 30 500 M−1 cm−1 for TTA to 33 700 M−1 cm−1 for SN4'' derivative 33. In comparison to H-SN4 13, the influence of the hexyl side chain in Hex-SN4 9 on the optical properties is as expected marginal and the absorption maximum is

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• excess of PBA (more than 60-fold excess of PBA to dextran, in a glucose/PBA 1:1 molar ratio reaction) was employed. However, the resulting dextran functionalization was low (1.6 PBA units out of 60 glucose units). In our studies we used PBA-BODIPY (1), a dye which proved to show excellent optical

• properties for biofunctionalization [26] and that displays a PBA moiety conjugated to a BODIPY core. The mechanochemical synthesis avoids the use of a large excess of 1 in the reaction mixture. Accordingly, reactions following either mechanochemical or solution-based protocols were carried out using a

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• transfer systems, cation–π complexation, electron conductivity, optical properties and so on. Keeping the importance of this beautiful scaffold in mind, we compiled all the synthetic routes available for the construction of sumanene and its heteroatom derivatives including Mehta’s first unsuccessful effort

• -assembly, and optical properties of bowl-shaped π-conjugated systems [5][6][7][8][9]. The synthesis of π-bowls is an extremely challenging job due to the presence of unusual strain in these types of molecules, therefore, the first synthetic breakthrough in this arena came into the picture in the late

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• with significant Stokes shifts (+60 nm) and quantum yields of 10–32% (Table 1). Theoretical calculations To get insight into the electronic and optical properties of the 2-amino-6-chloro-substituted NDIs, we carried out computational investigations by using the Gaussian 09 program suite [32]. In

• vacuum. Bottom: The orientation of transition dipole moments (red arrow for 450–600 nm range) according to the calculations made for the spectra shown in Figure 2. Synthesis of water-soluble naphthalene diimides 3a,b, and 5. Optical properties of 3a,b, and 5 in cacodylate buffer (pH 5.0) at 23 °C. ∆Tm

Et₃N/DMSO-supported one-pot synthesis of highly fluorescent β-carboline-linked benzothiophenones via sulfur insertion and estimation of the photophysical properties

• Dharmender Singh,
• Vipin Kumar and
• Virender Singh

Beilstein J. Org. Chem. 2020, 16, 1740–1753, doi:10.3762/bjoc.16.146

• yields (ΦF) of up to 47%. Detailed studies to synthesize novel fluorophores with improved optical properties which can easily find application in materials science are underway in our laboratory Experimental General experimental procedure for the synthesis of β-carboline-based 2-nitrochalcone derivatives

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• mechanical calculations became a standard tool and even a decade before Lewis’ bonding model. At the other extreme is the purist quantum mechanical view exemplified by Figure 1. This “language” is able to reproduce structures, energies, reactivities, optical properties etc. of chemical compounds essentially

Synthesis of new fluorescent molecules having an aggregation-induced emission property derived from 4-fluoroisoxazoles

• Kazuyuki Sato,
• Akira Kawasaki,
• Yukiko Karuo,
• Atsushi Tarui,
• Kentaro Kawai and
• Masaaki Omote

Beilstein J. Org. Chem. 2020, 16, 1411–1417, doi:10.3762/bjoc.16.117

• fluorescent luminescence characteristics of 4-fluoroisoxazoles, the synthesis of α-fluorinated boron ketoiminates (F-BKIs), and their photochemical properties. Results and Discussion Synthesis and optical properties of 4-fluorinated isoxazoles Although there is a large number of fluorescent molecules

• ][38], their optical properties feature a large Stokes shift and high molar absorption coefficients (ε) that are similar to the corresponding boron diketonates. The synthesis and properties of BKIs have been reported recently and they are easily accessible either from the corresponding 1,3-diketones 1

• Et3N gave the desired F-BKIs 9 in moderate to good yields. Optical properties of boron ketoiminates and α-fluorinated boron ketoiminates Chujo and co-workers described that BKIs could be a promising structural motif for having AIE properties [36]. For the purpose of comparison with the photochemical

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• compounds 7a and 7b. The oxidation and reduction potentials and the HOMO–LUMO energy levels of both compounds are summarised in Table 2 and the energy levels are depicted in Figure 3. Optical properties The absorption properties of compounds 7a and 7b were investigated in dichloromethane using a Duetta

Synthesis and properties of tetrathiafulvalenes bearing 6-aryl-1,4-dithiafulvenes

• Aya Yoshimura,
• Hitoshi Kimura,
• Kohei Kagawa,
• Mayuka Yoshioka,
• Toshiki Itou,
• Dhananjayan Vasu,
• Takashi Shirahata,
• Hideki Yorimitsu and
• Yohji Misaki

Beilstein J. Org. Chem. 2020, 16, 974–981, doi:10.3762/bjoc.16.86

• ][15][16]. Considerable efforts have been devoted to the development of peripherally benzene- or thiophene-substituted TTFs. As for peripherally benzene-functionalized TTFs, some synthetic approaches, crystal and electronic structures, electrochemical and optical properties, and the nature of radical

Synthesis of C₇₀-fragment buckybowls bearing alkoxy substituents

• Yumi Yakiyama,
• Shota Hishikawa and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2020, 16, 681–690, doi:10.3762/bjoc.16.66

• and optical properties were investigated by single crystal X-ray analysis and UV–vis spectroscopy. In the synthesis of dioxole derivative 5b, the regioisomer 5c was also produced. The yield of 5c was increased by increasing the reaction temperature, indicating that the rearrangement might involve the

Regioselectively α- and β-alkynylated BODIPY dyes via gold(I)-catalyzed direct C–H functionalization and their photophysical properties

• Takahide Shimada,
• Shigeki Mori,
• Masatoshi Ishida and
• Hiroyuki Furuta

Beilstein J. Org. Chem. 2020, 16, 587–595, doi:10.3762/bjoc.16.53

• comparative NMR analysis and mass spectrometry (see Supporting Information File 1). Optical properties The α- and β-ethynyl-substituted BODIPYs exhibit large bathochromic shifts in the absorption and fluorescence spectra relative to the unsubstituted 1a with extended π-conjugation (Figure 4 and Figure 5). The

Efficient synthesis of 3,6,13,16-tetrasubstituted-tetrabenzo[a,d,j,m]coronenes by selective C–H/C–O arylations of anthraquinone derivatives

• Seiya Terai,
• Yuki Sato,
• Takuya Kochi and
• Fumitoshi Kakiuchi

Beilstein J. Org. Chem. 2020, 16, 544–550, doi:10.3762/bjoc.16.51

• the substituents in compounds 7 on their optical properties was studied by UV–vis spectroscopy (Figure 1). The UV–vis spectra of 7aa, 7bb, and 7ba were measured in chloroform, and the normalized UV–vis spectra are shown in Figure 1. These compounds showed similar peak patterns between 300 and 500 nm

Synthesis and circularly polarized luminescence properties of BINOL-derived bisbenzofuro[2,3-b:3’,2’-e]pyridines (BBZFPys)

• Ryo Takishima,
• Yuji Nishii,
• Tomoaki Hinoue,
• Yoshitane Imai and
• Masahiro Miura

Beilstein J. Org. Chem. 2020, 16, 325–336, doi:10.3762/bjoc.16.32

• condensed (hetero)acenes from rather simple polyarenes, in which several aromatic units are connected with each other through appropriate linker units [2][3][4][5][6][7][8][9][10][11]. Recently, we reported the synthesis and optical properties of a series of furan-fused aromatics via the formal

• BINOL derivatives [37][38][39]. In this context, we herein describe the synthesis of axially chiral BINOL-derived BBZFPys through the palladium-catalyzed oxidative coupling reaction. The optical properties of the synthesized polyaromatic compounds were systematically studied, and some of them displayed

• enantiomers in 10–36% yields. The higher yield of 4c was probably due to its better solubility. In order to systematically evaluate the optical properties of these coupling products, a simple benzofuran-fused 1,1’-binaphthyl 6 was also synthesized as a benchmark (Scheme 4). The parent ether 5 was obtained

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• (MeOH); the isolated compound Z-2 is stable in its free base form whereas its hydrochloride salt slowly decomposes. Optical properties and photoswitching in aqueous medium Hemi-indigo derivatives Z-1a–c display intense long-wavelength absorption bands, whose maxima are clearly dependent on the strength

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• examples clearly show that dye chemistry is a mature and essential topic in organic chemistry, it still constitutes a vibrant research area because of the continuous need for specifically designed dyes with custom-made optical properties for diverse topical applications. Hence, this special issue aimed at

Probing of local polarity in poly(methyl methacrylate) with the charge transfer transition in Nile red

• Aydan Yadigarli,
• Qimeng Song,
• Sergey I. Druzhinin and
• Holger Schönherr

Beilstein J. Org. Chem. 2019, 15, 2552–2562, doi:10.3762/bjoc.15.248

• particular, the spatial distribution of the dielectric constant measured for thin PMMA films was described using NR as a reported dye [15]. Because NR is (i) a photostable dye, (ii) possesses convenient optical properties, such as excitation with visible light, and fluorescence, which does not overlay with

Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

• A. Lennart Schleper,
• Mariano L. Bossi,
• Vladimir N. Belov and
• Stefan W. Hell

Beilstein J. Org. Chem. 2019, 15, 2344–2354, doi:10.3762/bjoc.15.227

• ]thiophene core. The structures of “thiophenylated” DAEs AsTh1, AsTh2, SyTh1, SyTh2, AsOTh1, AsOTh2, SyOTh1, and SyOTh2 prepared and studied in this work are given in Figure 1. Methyl esters of the thiophene carboxylic acids were chosen as model building blocks, because they possess optical properties

• the same on/off behavior. Conclusion We prepared eight 1,2-bis[(2-ethylbenzo[b]thiophene)-3-yl]perfluorocyclopentenes with oxidized and nonoxidized cores and decorated them with mono- and bithiophene rings in symmetric and asymmetric fashions. By studying the optical properties of the new compounds

• atmosphere, an emulsion of the starting compounds, Pd2(dba)3, P(Cy)3 stock solution, and aqueous K2CO3 in THF (see Supporting Information File 1 for details). Saponification of methyl ester groups in tetraester SyTh2 leading to tetracarboxylic acid SyTh2-H. Optical properties of the photochromic DAEs (in

Synthesis of a dihalogenated pyridinyl silicon rhodamine for mitochondrial imaging by a halogen dance rearrangement

• Jessica Matthias,
• Thines Kanagasundaram,
• Klaus Kopka and
• Carsten S. Kramer

Beilstein J. Org. Chem. 2019, 15, 2333–2343, doi:10.3762/bjoc.15.226

• optical properties for medical and bioimaging. As a compound with intrinsic mitochondria targeting ability, the radiolabelled analogue can be applied in multimodal (PET/OI) imaging of mitochondria for diagnostic and therapeutic use in, e.g., cancer patients. Keywords: halogen-dance reaction

• features with their optical properties and control the latter by rational dye design [15][24][25][26]. These investigations led to new silicon rhodamine dyes with enhanced and fine-tuned properties (quantum yield, lifetime, brightness, absorption and emission maxima). A recent review compared the

• HD reactions of nicotinic acids can be found in the literature. In fact, if 2,3-dihalogenated pyridines are used for the HD rearrangement as starting materials, only methyl groups are tolerated as carbon substituents. Optical properties of the pyridinyl silicon rhodamine 15 The dihalogenated

Synthesis and properties of sulfur-functionalized triarylmethylium, acridinium and triangulenium dyes

• Marco Santella,
• Eduardo Della Pia,
• Jakob Kryger Sørensen and
• Bo W. Laursen

Beilstein J. Org. Chem. 2019, 15, 2133–2141, doi:10.3762/bjoc.15.210

• functionalities were synthesized and their optical properties were studied. The sulfur functionalities were introduced by aromatic nucleophilic substitution of methoxy groups in triarylmethylium cations with ethanethiol followed by partial or full ring closure of the ortho positions with nitrogen or oxygen

• + PF6− (6) and the mono ring closed xanthenium 7. Synthesis of S2-TOTA+ PF6− (8) and S1-TOTA+ PF6− (9). Summary of absorption data of triarylmethylium ions in MeCN. Summary of absorption data of substituted TOTA dyes in CH2Cl2. Summary of optical properties of the fluorescent derivatives. Supporting