Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• ; inversion of CPL handedness; Tröger's base; Introduction Recently, much effort has been devoted to constructing luminescent materials with efficient high emission in the solid state [1][2][3]. More and more types of fluorophores with aggregation-induced emission (AIE) characteristics have been discovered

• construct CPL-active materials [19][20][21], so the fluorescent Tröger's base derivatives rac-TBPP fall into our sight as the candidate to construct CPL-active materials. Herein, we take two stratgies to construct rac-TBPP-based CPL material. One stratgy is to separate non-CPL emission rac-TBPP into CPL

• Cotton effect at the same wavelength, assigned to S2N-TBPP (Figure 1a) [23]. R2N-TBPP and S2N-TBPP were tested further by CPL spectroscopy, and the magnitude of the CPL emission was estimated by a luminescence dissymmetry factor (glum), defined as 2(IL − IR )/(IL + IR) where IL and IR are the intensity

The fluorescence of a mercury probe based on osthol

• Guangyan Luo,
• Zhishu Zeng,
• Lin Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

• irreversible nerve damage. Therefore, it is very important to develop a highly sensitive and selective method for mercury detection. At present, the detection of mercury mainly includes atomic absorption and atomic emission spectrometry [4], inductively coupled plasma mass spectrometry [5][6], and capillary

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

• ]helicenes 10 only weak fluorescence in the solution under UV irradiation was observed (Table 7, see also Supporting Information File 1, Figures S42–S45). Helicenes 10b and 10c exhibited blue emission with emission peaks at 481 and 440 nm, respectively. Quinoxaline-fused helicene 10a demonstrated a yellow

• emission with the highest in the series λem = 561 nm and Stokes shift 128 nm. Conclusion In summary, novel carbazole-based [6]helicenes fused with an azine ring (pyridine, pyrazine or quinoxaline) have been prepared from commercially available 2,3-dihaloazines via a five-step synthetic sequence. Two key

Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD^®/Olah’s reagent under solvent-free conditions

• Yumeng Liang,
• Akihito Taya,
• Zhengyu Zhao,
• Norimichi Saito and
• Norio Shibata

Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254

• the deoxyfluorination. FLUOLEAD® is a stable crystalline solid and has sufficient stability against moisture to be handled open to air without the emission of fumes, and it is available in quantities that can exceed 100 kg from Ube Industries, Ltd [31]. FLUOLEAD® is an attractive alternative to the

Metal-free synthesis of biarenes via photoextrusion in di(tri)aryl phosphates

• Hisham Qrareya,
• Lorenzo Meazza,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 3008–3014, doi:10.3762/bjoc.16.250

• phosphates examined were barely fluorescent in methanol, with an emission quantum yield (Φem) in the 0.005–0.06 range (see Table 2 and Supporting Information File 1 for further details). We thus focused on compounds 1e, 1h, 3a and 3c as the model substrates. In the case of compounds 1e and 1h, we observed

• that the fluorescence is significantly red shifted (about 30 nm) with respect to that of the corresponding diethyl aryl phosphates (see Figure 1 and Figure 2). On the other hand, when focusing on compound 3a, we noticed the presence of two emission bands located at 307 and 360 nm, respectively (see

• was observed with compound 3c, where a single emission band located at ca. 290 nm is observable in neat methanol, whereas the presence of TFE causes a lowering of that emission, in favor of a second band in the 330–350 nm region (Figure 4). These two emissions have been assigned, on the basis of our

Selected peptide-based fluorescent probes for biological applications

• Debabrata Maity

Beilstein J. Org. Chem. 2020, 16, 2971–2982, doi:10.3762/bjoc.16.247

• intensity, lifetime or excitation/emission maxima. The fluorescence turn-on response offers a bright signal against a dark background, which maximizes spatial resolution than the fluorescence turn-off signal [19]. A shift in the absorption/emission spectrum is also advantageous as the changes in ratio of

• intensities of absorption or emission at two wavelengths minimizes the error from the physical or chemical fluctuations in the sample. Conventional peptide probes based on environment-sensitive fluorophores [20][21][22], fluorescence resonance energy transfer (FRET) pairs [13] and pyrene excimer/monomer [23

• use of pyrene as a fluorophore has two major disadvantages such as poor quantum yield and an emission in the blue region, which is unfavorable for potential applications in biological systems. The Schmuck group successfully developed several peptide-based probes using these approaches for targeting

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• ) and CENIDE, University of Duisburg-Essen, Universitätsstraße 7, 45117 Essen, Germany 10.3762/bjoc.16.246 Abstract In this work, a series of γ-substituted diphenylnaphthalonitriles were synthesized and characterized. They show efficient emission in solution and in the aggregated state and their

• scattering (DLS). The steady-state and time-resolved photoluminescence spectroscopy studies revealed that all the molecules show intense fluorescence both in solution and in the aggregated state. In THF solutions, a blue emission was observed for the unsubstituted (H), methyl- (Me) and tert-butyl- (t-Bu

• ) substituted γ-diphenylnaphthalonitriles, which can be attributed to a weak π-donor capability of these groups. On the other hand, the methoxy- (OMe), methylsulfanyl- (SMe) and dimethylamino- (NMe2) substituted compounds exhibit a progressive red-shift in emission compared to H, Me and t-Bu due to a growing π

A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles

• Bingbing Lai,
• Meng Ye,
• Ping Liu,
• Minghao Li,
• Rongxian Bai and
• Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238

• results indicated that all prepared materials could remain stable in the system when used to catalyze organic reactions. FSEM (field emission scanning electron microscopy) and FTEM (field emission transmission electron microscopy) were used to observe the surface morphologies of different catalysts, and

Incorporation of a metal-mediated base pair into an ATP aptamer – using silver(I) ions to modulate aptamer function

• Marius H. Heddinga and
• Jens Müller

Beilstein J. Org. Chem. 2020, 16, 2870–2879, doi:10.3762/bjoc.16.236

• addition of 1q with a 90% decrease in emission. Upon the addition of AMP, the emission increases again almost sevenfold, indicating a dissociation of the quencher-labeled oligonucleotide and subsequent formation of the AMP-bound structure. Adding 1 equiv of Ag(I) leads to no significant further change, as

• was expected for the imidazole-free derivative 1af. Nevertheless, the addition of 10 equiv of Ag(I) leads to a slight decrease in the emission. The oligonucleotides 1bf, 1cf, and 1df all show less efficient quenching upon the addition of 1q, which can be attributed to the presence of the destabilizing

• mismatches involving imidazole. This effect is least pronounced for oligonucleotide 1df, which is quenched almost as effectively as 1af. All imidazole-containing aptamer derivatives show an increased emission upon the addition of AMP with an approximately threefold increase in the intensity. In contrast to

Using multiple self-sorting for switching functions in discrete multicomponent systems

• Amit Ghosh and
• Michael Schmittel

Beilstein J. Org. Chem. 2020, 16, 2831–2853, doi:10.3762/bjoc.16.233

• ), the silver(I) ions were tightly captured within the cavity of the triangular nanoswitch 35 (“catch”) while the luminophore 36 was left uncoordinated exhibiting emission at 554 nm (Figure 13). Due to the firm complexation of the silver(I) ions in [Ag(35)]+ any catalysis was switched OFF. Upon the

• addition of zinc(II), the silver(I) ions were translocated as a second messenger from the nanoswitch [Ag(35)]+ to the anthracene-appended crown ether 36 in a 2-fold completive self-sorting, i.e., furnishing [Zn(35)]2+ and [Ag(36)]+ (state SelfSORT-II). In this state, SelfSORT-II, the emission emerged at

• catalytic behavior showed a full reversibility up to three cycles and provided 45%, 43%, and 41% yield, respectively, in subsequent cycles. The small decrease of the yield over three release/capture cycles was explained by a minor degradation of silver(I), a phenomenon equally seen in the emission channel

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

• end of the titration. The compounds 4a–e have a very low intrinsic emission intensity that increased significantly upon the addition of the G4-DNA 22AG and a2 (Table 1, Figure 1B; cf. Supporting Information File 1, Figure S2). Thus, the characteristic emission band of berberine at 520 nm developed and

• titrations with 22AG and a2 clearly revealed the association of the derivatives 4a–e with G4-DNA (Figure 1). Specifically, the red shift and hypochromism of the absorption band along with the pronounced increase of the emission intensity are typical for quadruplex-bound ligands [17][18][19][20][21][22

• additional hydrophobic effect is the main contribution of the different substituents of 4a–e to the overall binding affinity. It is well known that the emission of the parent berberine increases strongly upon the accommodation in sterically constrained binding sites in, e.g., nucleic acids, cucurbiturils

Encrypting messages with artificial bacterial receptors

• Pragati Kishore Prasad,
• Naama Lahav-Mankovski,
• Leila Motiei and
• David Margulies

Beilstein J. Org. Chem. 2020, 16, 2749–2756, doi:10.3762/bjoc.16.225

• bacteria continuously divide, the emission pattern generated by the modified bacteria dynamically changes, enabling the system to produce encryption keys that change with time. Thus, this development indicates the potential contribution of live-cell-based encryption systems to the emerging area of

• labeled bacteria during cell division (Figure 2B). Another research direction in our group, which also involves the development of unconventional fluorescent probes, is the information protection at the molecular level [4][5][6]. In such studies [4][5][6], the emission patterns generated by the probes are

• security systems that can generate (pseudo) random fluorescence patterns [4][5][6]. Originally, the pattern-generating probes (or ID-probes [24]) were designed to detect multiple different analytes and their combinations [24][25][26]. In a later stage, we showed that the unique emission fingerprints

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• to an n-alkyl chain at the other, underwent self-assembly in aqueous media depending on the length of the alkyl segment. The amphiphilic derivatives having n-decyl or longer chains, formed nano-assemblies with cyanic–green emission resulting from the stacked pyrene chromophores in the aggregates. The

• presence of positive surface charges on the multivalent aggregates led to ATP binding which was accompanied by a significant increase in the excimeric emission intensity. This provided a convenient way of monitoring ATP binding in a “turn-on” mode and an efficient detection of ATP was achieved in aqueous

• buffer and produced nanoaggregates with surface exposed positive charges. Interestingly, the aggregates displayed cyanic green luminescence which originated from the excimeric emission of the stacked pyrenes [57][58][59]. In a recent work, we have demonstrated that self-assembled nanofibrous aggregates

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

• , gradually decreases with increasing number of pyrrole rings in the heteroacenes from 3.62 eV for TTA to 3.50 eV for 33 (Figure 2, left). The SN4-heteroacenes fluoresce, if at all, only very weakly and emission maxima lay in between 356 nm for TTA and 388 nm for 22 with the most extended conjugated π-system

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• exhibits an emission maximum peak at 329 nm upon excitation at 294 nm. This emission band is probably due to the formation of the ground-state dimer by interaction between the benzene rings upon excitation or excimer emission caused by the interaction between the aromatic rings [41][43]. As the

• concentration of the fullerenes C60 and C70 increase, the emission is significantly quenched, indicating the photoinduced energy transfer from TBTQ-(OG)6 to the fullerenes [47][48]. Molar ratio plots (see Figure S16, Supporting Information File 1) on the basis of the fluorescence titration experiments suggested

Synthesis of 1,4-benzothiazinones from acylpyruvic acids or furan-2,3-diones and o-aminothiophenol

• Ekaterina E. Stepanova,
• Maksim V. Dmitriev and
• Andrey N. Maslivets

Beilstein J. Org. Chem. 2020, 16, 2322–2331, doi:10.3762/bjoc.16.193

• potential Cu2+ chemosensors [14], and their BF2 chelates, as multicolor fluorescence complexes, some of which exhibited aggregation-induced emission (AIE) properties [15]. In addition, enaminones I and II proved themselves to be versatile and available building blocks for the synthesis of various

Chan–Evans–Lam N1-(het)arylation and N1-alkеnylation of 4-fluoroalkylpyrimidin-2(1H)-ones

• Viktor M. Tkachuk,
• Oleh O. Lukianov,
• Mykhailo V. Vovk,
• Isabelle Gillaizeau and
• Volodymyr A. Sukach

Beilstein J. Org. Chem. 2020, 16, 2304–2313, doi:10.3762/bjoc.16.191

• pyrimidin-2(1H)-ones 5a–e exhibit fluorescence properties with emission of λmax = 490–532 nm in CH2Cl2 solution. In order to analyze the effect exerted on the Chan–Evans–Lam arylation by 4-, 5-, and 6-substituents on the pyrimidine ring and also aiming at the further functionalization of pyrimidin-2(1H)-one

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• with different polarities and showed absorption in the visible region and green-red emission with low quantum yields. The absorption and the emission maxima were shifted bathocromically by increasing the solvent’s polarity. However, there was no correlation with the polarity parameters of the solvents

• comprising of electron-donating and accepting groups in a donor–π–acceptor (D–π–A) system. The dyes exhibit strong absorption and emission properties in solution and in the solid state [1][2][3]. One important feature of these molecules is an exceptional polarizability which is a crucial criterion for NLO

• ][12][13][14]. Among dyestuffs classes, the push-pull fluorescent dyes are renowned to own such special behaviors. The push-pull dyes generate higher charge delocalization upon excitation, thus enhance both polarizability and fluorescence emission [12][13][14][18]. The charge delocalization upon

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

• conjugate (milled reaction) compared to a 0.61% w/w of 1 in the Dex-1a conjugate (conventional solution reaction) was obtained. The loading of 1 in both conjugates was also confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis which showed in Dex-1b a boron content roughly

• emission bands were at λem = 524 nm (λexc = 380 nm) and λem = 523 nm (λexc = 460 nm, see Supporting Information File 1, Figure S2). Then, a Stokes shift of 16 nm could be appreciated in agreement with data previously reported for PBA-BODIPY (1) [26][35]. Dynamic light scattering (DLS) measurements were

• assemblies of the conjugate Dex-1b a simple experiment with pyrene was conducted. It is well known that the fluorescence spectrum of pyrene is very sensitive to the polarity of the environment [37]. Indeed, the ratio (I1/I3) between the first (I1 = 372 nm) and the third bands (I3 = 383 nm) in the emission

Tools for generating and analyzing glycan microarray data

• Akul Y. Mehta,
• Jamie Heimburg-Molinaro and
• Richard D. Cummings

Beilstein J. Org. Chem. 2020, 16, 2260–2271, doi:10.3762/bjoc.16.187

• on detecting reagents (e.g., labeled GBP, antibody or streptavidin). The emission wavelength of the fluorophore determines the filter used by the scanner before the intensities are measured by a photomultiplier tube (PMT) or by CCD camera. Currently, CCD camera systems are less sensitive as compared

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

• reaction yielded 92 (Scheme 21). As can be seen from the literature, pyrene-based compounds remain among the highest beautiful and fascinating classes of molecules because of their extremely characteristic (“fingerprint”) optical absorption as well as emission behavior. Keeping in mind the uniqueness of

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• chiral properties of the DNA or RNA helical structures [12][13], could also take advantage of induced CD spectrum (ICD) in the visible spectrum range of small achiral dyes, which they show only upon binding to DNA/RNA [14]. Moreover, with recent advances in fluorescence emission-based polarisation

• not observe any emission, neither for single dye binding to DNA, nor in crowding conditions (excess of dye over DNA binding sites) at which eventually fluorescent excimers could be formed. Interactions with DNA/RNA Because of significant differences in the protonation states of compound 4, studies

Photosensitized direct C–H fluorination and trifluoromethylation in organic synthesis

• Shahboz Yakubov and
• Joshua P. Barham

Beilstein J. Org. Chem. 2020, 16, 2151–2192, doi:10.3762/bjoc.16.183

• isotopes for positron emission tomography (PET) due to their suitable half-life (t1/2 = 110 min) and low positron energy, which allows the production of high-resolution images [23]. Therefore, radiopharmaceuticals that contain fluorine substituents are in high demand. Fluorine enhances important properties

• out of reach of even the lowest emission wavelength range of the CFL bulb. Ir(ppy)3 also gave no reaction. This was interesting, considering that its triplet energy (T1 = 57.8 kcal⋅mol−1) was similar to Selectfluor® (T1 = 61.4 kcal⋅mol−1). Benzophenone (T1 = 69.1 kcal⋅mol−1) and 9-fluorenone (T1

Clustering and curation of electropherograms: an efficient method for analyzing large cohorts of capillary electrophoresis glycomic profiles for bioprocessing operations

• Ian Walsh,
• Matthew S. F. Choo,
• Sim Lyn Chiin,
• Amelia Mak,
• Shi Jie Tay,
• Pauline M. Rudd,
• Yang Yuansheng,
• Andre Choo,
• Ho Ying Swan and
• Terry Nguyen-Khuong

Beilstein J. Org. Chem. 2020, 16, 2087–2099, doi:10.3762/bjoc.16.176

• Capillary electrophoresis of the released and APTS-labelled antibody N-glycans was performed on a CESI8000 CE instrument (Sciex) equipped with a solid state laser-induced fluorescent detector (excitation 488 nm, emission 520 nm). Separations were made across a 20 cm effective length (30 cm total length), 50

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

• interacted with ds-DNA/RNA by threading intercalation. Different from a reference NDI dye with identical visible range absorbance (520–540 nm) and Stokes shifts in emission (+60 nm, quantum yield > 0.2), only these amino acid–NDI conjugates showed selective fluorimetric response for GC-DNA in respect to AT(U

• both, the minor and major groove of the polynucleotide. Such bulky groups positioning requires the DNA double helix to shortly open at a binding site and close upon threading intercalator insertion. Also, the chosen NDI chromophore is characterised by easily tuneable emission wavelengths [23], and

• we took advantage of the fluorescence of 3a,b, and 5. Since suspected threading intercalation usually requires longer incubation times, the time required for reaching equilibrium was checked by repeatedly collecting emission spectra upon additions of DNA or RNA aliquots to the dye solution