Recent advances in phosphorescent platinum complexes for organic light-emitting diodes

• Cristina Cebrián and
• Matteo Mauro

Beilstein J. Org. Chem. 2018, 14, 1459–1481, doi:10.3762/bjoc.14.124

• corresponds to purely fluorescent-based devices from a first approximation spin statistics, up to 100%. Nonetheless, EQEs are typically upper limited to values of ca. 20–25% owing to differences in the refractive index of organic materials commonly employed and suboptimal light outcoupling. In spite of that

Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions

• Anja Gronewold,
• Mareike Horn and
• Ines Neundorf

Beilstein J. Org. Chem. 2018, 14, 1378–1388, doi:10.3762/bjoc.14.116

• , Supporting Information File 1), not even after a longer incubation period of two hours (data not shown). For NrTP alone, a slight fluorescent signal was visible in the nucleoli of MCF-7 cells (Figure S6, Supporting Information File 1). Notably, N50-sC18* was distributed within the whole cell cytosol, and

• to be fluorescent [42] and this property was used to test if the peptides were able to enhance the intracellular uptake of the drug. Therefore, solutions out of DOX and the sequences N50-sC18* and NrTP-sC18* were incubated with HeLa and MCF-7 cells, respectively, and observed for red fluorescence

• in triplicate. Cells treated with medium only served as negative control and their fluorescent signal was subtracted from all other samples in each set of experiment. Circular dichroism spectra of the novel peptides solved in 10 mM phosphate buffer (pH 7) (A), or phosphate buffer with the addition of

An overview of recent advances in duplex DNA recognition by small molecules

• Sayantan Bhaduri,
• Nihar Ranjan and
• Dev P. Arya

Beilstein J. Org. Chem. 2018, 14, 1051–1086, doi:10.3762/bjoc.14.93

• by reducing aggregation and also helps to conduct a detailed thermodynamic study for the 8-ring HP polyamides for the very first time. Recently, Hartley et al. designed and synthesized a hybrid fluorescent HP polyamide conjugate 22 (Figure 6) by attaching the A·T recognizing fluorophore, p

• challenging tandem hairpin Py/Im polyamides which could recognize >10 base pairs with flexible linker conjugated with a fluorescent dye (either Texas Red (TR) or Cyanine 3 (Cy3)) using a Fmoc-based solid phase synthetic approach; two of the representative conjugates 23 and 24 are shown in the Figure 8 [86][87

• telomere foci clearly because of their fluorescent nature. Later on, the authors successfully designed tandem tetramer Py–Im polyamides with 4 hairpins and 3 hinges targeting 24 bp of the human telomere sequences [88]. Thus, the authors set the new record for the longest binding site of synthetic, non

Hypervalent iodine(III)-mediated decarboxylative acetoxylation at tertiary and benzylic carbon centers

• Kensuke Kiyokawa,
• Daichi Okumatsu and
• Satoshi Minakata

Beilstein J. Org. Chem. 2018, 14, 1046–1050, doi:10.3762/bjoc.14.92

• scale at a 0.2 or 0.4 M concentration on the benchtop with a fluorescent light on the ceiling. Yields are for isolated products. aPhI(OAc)2 (3 equiv) was used. bI2 (1 equiv) was used. cI2 (0.75 equiv) was used. Hydrolysis of acetates. Mechanistic investigations. Proposed reaction pathway. Effect of

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

Development of novel cyclic NGR peptide–daunomycin conjugates with dual targeting property

• Andrea Angelo Pierluigi Tripodi,
• Szilárd Tóth,
• Kata Nóra Enyedi,
• Gitta Schlosser,
• Gergely Szakács and
• Gábor Mező

Beilstein J. Org. Chem. 2018, 14, 911–918, doi:10.3762/bjoc.14.78

• the smallest active Dau containing metabolite Dau=Aoa-Gly-OH. No significant difference in degradation speed of the conjugates was observed. Therefore, the replacement of Lys has no influence on the biological activity through the lysosomal degradation. Cellular uptake Daunomycin is fluorescent

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• made to selectively recognize and detect these analytes, especially ATP using small-molecule fluorescent chemosensors. Despite the various solutions, the selective detection of ATP is still challenging due to the structural similarity of various nucleotides. In this paper, we report the conjugation of

• . Conclusions: The first, uracil-containing fluorescent ATP probe based on a hydroxyflavone fluorophore was synthesized and evaluated. A selective complexation with ATP was observed and a ratiometric response in the excitation spectrum. Keywords: ATP sensing; base-pairing; fluorescent probes; 3-hydroxyflavone

• recognition and sensing of ATP has therefore paramount importance in the understanding of biological processes. Amongst the numerous solutions [5][6][7][8][9], fluorescent chemosensors using either indicator displacement assays [10][11][12][13][14][15], cation-based recognition units [16][17][18][19][20

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• exciton utilization of TADF materials. Importantly, OLEDs based on 2 exhibited a maximum external quantum efficiency of 8.9%, which is higher than the theoretical efficiency of the OLEDs based on conventional fluorescent materials. Keywords: fluorenone acceptor; orange light emission; organic light

• previously limited by the statistic rule of spin multiplicity. For conventional fluorescent materials, only singlet excitons are involved in electroluminescence, leading to a theoretical maximal internal quantum efficiency (IQEmax) of 25% and a theoretical maximal external quantum efficiency (EQEmax) of 5

• increase the cost of the final OLEDs. Alternatively, a thermally activated delayed fluorescence (TADF) material is a kind of noble-metal-free fluorescent material able to transform triplet excitons into singlet excitons through reverse intersystem crossing (RISC) to achieve 100% IQEmax in theory [4]. On the

Synthesis of a sucrose-based macrocycle with unsymmetrical monosaccharides "arms"

• Karolina Tiara,
• Mykhaylo A. Potopnyk and
• Sławomir Jarosz

Beilstein J. Org. Chem. 2018, 14, 634–641, doi:10.3762/bjoc.14.50

• V4.1 software package (Waters Inc). Thin-layer chromatography (TLC) was performed on silica gel plates coated with fluorescent indicator. Column chromatography was performed on silica gel (Merck, 230–400 mesh). Organic solutions were dried over anhydrous MgSO4. Procedure for the synthesis of nitro

Continuous multistep synthesis of 2-(azidomethyl)oxazoles

• Thaís A. Rossa,
• Nícolas S. Suveges,
• Marcus M. Sá,
• David Cantillo and
• C. Oliver Kappe

Beilstein J. Org. Chem. 2018, 14, 506–514, doi:10.3762/bjoc.14.36

• ]. Sulfamoxole is a broad-spectrum antibiotic for the treatment of bacterial infections (Figure 1b) [8]. In addition, ongoing studies show the potential of amino and amido-oxazoles to act as fluorescent dipeptidomimetics (Figure 1c) [9]. Due to their diene character, oxazoles find also use as intermediates in

• dilution was necessary to avoid clogging of the reactor. Examples of naturally occurring oxazoles (a); some drugs containing oxazole as the active moiety (b); general structure of fluorescent dipeptidomimetics derived from trisubstituted oxazoles (c); reactivity of the oxazole system as an azadiene (d

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• the light-emitting ability of the emitter, which is directly related to the nature, and the photoluminescence quantum yield (PLQY) of the emitter. Based on spin statistics, upon electrical excitation, singlet and triplet excitons are formed in a 1:3 ratio [4]. In the case of fluorescent materials

• , only singlet excitons can be utilized for light emission, limiting the internal quantum efficiency (IQE) of fluorescent OLEDs to 25%. Conversely, phosphorescent materials can both harvest singlet and triplet excitons for emission by intersystem crossing (ISC), enabling to reach a theoretical IQE of 100

• ). TADF materials can also be metal-free, addressing the fabrication cost and environmental issues. Therefore, TADF emitters retain the high efficiency of the second generation of emitters (triplet emitters), the stability of the first generation of fluorescent materials while eliminating the different

Fluorogenic PNA probes

• Tirayut Vilaivan

Beilstein J. Org. Chem. 2018, 14, 253–281, doi:10.3762/bjoc.14.17

• vivo. For nucleic acids, the latter valuable information cannot be obtained by sequencing despite the tremendous advances in the field in recent years [1]. Accordingly, fluorescent oligonucleotide probes are still one of the most important tools not only for the detection of nucleic acids, but also

• proteins and other non-nucleic acid targets by employing aptamer technology [2]. However, ordinary fluorescent oligonucleotide probes generally show indistinguishable signals between the free and target-bound states. This means that additional treatments are required in order to separate the bound and

• developments in the areas of fluorogenic PNA probes. Some examples of PNA probes for nucleic acid hybridization and detection that may not be strictly fluorogenic by definition have been included where deemed suitable. Overview of PNA and fluorescent PNA probes Peptide nucleic acids (PNA) are a unique class of

Fluorescent nucleobase analogues for base–base FRET in nucleic acids: synthesis, photophysics and applications

• Mattias Bood,
• Sangamesh Sarangamath,
• Moa S. Wranne,
• Morten Grøtli and
• L. Marcus Wilhelmsson

Beilstein J. Org. Chem. 2018, 14, 114–129, doi:10.3762/bjoc.14.7

• . Keywords: B-to-Z-DNA transition; fluorescent base analogues; FRET; netropsin; nucleic acid structure and dynamics; quadracyclic adenines; tricyclic cytosines; Z-DNA; Review Introduction The importance of nucleic acid structure and dynamics in the understanding of vital processes in living organisms has

• . In this review we will focus on the FRET between fluorescent base analogues, i.e., base–base FRET, the theory behind it, the increased accuracy in orientation factor κ2 as an effect of their position inside the base-stack, other advantages and disadvantages compared to FRET in nucleic acids using

• external fluorophores like Cy-, Alexa- and ATTO-dyes as well as finally summarize some of its recent applications. The field started less than a decade ago with the introduction of the first fluorescent nucleobase analogue FRET pair, tCO–tCnitro, and we divide this review into three parts: the first one

Polarization spectroscopy methods in the determination of interactions of small molecules with nucleic acids – tutorial

• Tamara Šmidlehner,
• Ivo Piantanida and
• Gennaro Pescitelli

Beilstein J. Org. Chem. 2018, 14, 84–105, doi:10.3762/bjoc.14.5

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• synthetic lipid A derivative had a bias towards MyD88- or TRIF-dependent immune responses [78]. 1.3. Synthesis of fluorescent-labeled lipid A analogues For studying the structural basis and the dynamics of TLR4-lipid A interplay, the application of labeled synthetic lipid A derivatives as versatile probes

• for tracking ligand–receptor interactions was exploited. However, the hydrophobic character and the large size of most fluorescent labels which could potentially compete with lipid A for the LPS binding site at the TLR4 complex, posed an additional challenge. The only optional hydroxyl group which

• could qualify as the site of attachment of a fluorescent label without hindering the biological activity would be position 6’ of the diglucosamine backbone of lipid A. When attached to position 6’ via a linker molecule, the fluorescent label would not interfere with the binding of lipid A to the MD-2

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• L·mol−1·cm−1). All investigated dyes from the series are either not fluorescent or their fluorescence is quite low, but they become strongly fluorescent after binding to dsDNA. The influence of the substituents attached to the chromophores was investigated by combination of spectroscopic (UV–vis and

• ]. Hybridization-sensitive fluorescent probes in which TO is tethered to a nucleic acid: DNA [22][23][33][34][35][36], RNA [20][36] or PNA [18][19][21][31]) strands have been constructed by several research groups (the Krull, Kubista, Seitz and Wagenknecht groups). The continued scientific and commercial interest

• twice as high as that of TO-7Cl, which can be ascribed to the effect of the benzyl substituent. While the chloro substituent itself leads to a decrease of the relative fluorescent quantum yield (62% for TO-7Cl compared to TO), the benzyl group in 5a increases it two fold, making 5a almost 30% brighter

Synthetic mRNA capping

• Fabian Muttach,
• Nils Muthmann and
• Andrea Rentmeister

Beilstein J. Org. Chem. 2017, 13, 2819–2832, doi:10.3762/bjoc.13.274

• showing that N7-ethyl and N7-benzyl-modified cap analogues are still substrates for GlaTgs [98]. This allowed us to enzymatically prepare cap analogues with different combinations of functional moieties (Figure 5B) [95]. A 4-vinylbenzyl/azido dual modification allowed appending two different fluorescent

Development of a fluorogenic small substrate for dipeptidyl peptidase-4

• Futa Ogawa,
• Masanori Takeda,
• Kanae Miyanaga,
• Keita Tani,
• Ryuji Yamazawa,
• Kiyoshi Ito,
• Atsushi Tarui,
• Kazuyuki Sato and
• Masaaki Omote

Beilstein J. Org. Chem. 2017, 13, 2690–2697, doi:10.3762/bjoc.13.267

• , Kashiwara, Osaka 582-8582, Japan 10.3762/bjoc.13.267 Abstract A series of aniline and m-phenylenediamine derivatives with electron-withdrawing 3,3,3-trifluoropropenyl substituents were synthesized as small and chemically stable fluorescent organic compounds. Their fluorescence performances were evaluated

• by converting 2,4-disubstituted aniline 1 to the non-fluorescent dipeptide analogue H-Gly-Pro-1 for the use as a fluorogenic substrate for dipeptidyl peptidase-4 (DPP-4). The progress of the enzymatic hydrolysis of H-Gly-Pro-1 with DPP-4 was monitored by fluorometric determination of 1 released into

• the reaction medium. The results suggest that 1 could be used as fluorophore in OFF–ON-type fluorogenic probes. Keywords: dipeptidyl peptidase-4; fluorogenic substrate; fluorometry; small fluorescent molecule; Introduction Fluorescent organic probes have become indispensable for bio-imaging or

Metal-mediated base pairs in parallel-stranded DNA

• Jens Müller

Beilstein J. Org. Chem. 2017, 13, 2671–2681, doi:10.3762/bjoc.13.265

• a non-canonical DNA structure [9][66]. Pyrrolocytosine (PC) represents a fluorescent analogue of cytosine that still retains the base pairing properties of its parent nucleobase [67]. Accordingly, its application in metal-mediated base pairing was probed, too. An initial report on the MePC–Ag(I)–C

Pyrene–nucleobase conjugates: synthesis, oligonucleotide binding and confocal bioimaging studies

• Artur Jabłoński,
• Yannic Fritz,
• Hans-Achim Wagenknecht,
• Rafał Czerwieniec,
• Tytus Bernaś,
• Damian Trzybiński,
• Krzysztof Woźniak and
• Konrad Kowalski

Beilstein J. Org. Chem. 2017, 13, 2521–2534, doi:10.3762/bjoc.13.249

• Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki and Wigury 101, 02-089 Warszawa, Poland 10.3762/bjoc.13.249 Abstract Fluorescent pyrene–linker–nucleobase (nucleobase = thymine, adenine) conjugates with carbonyl and hydroxy functionalities in the linker were synthesized and

• characterized environment-dependent fluorescence. This property, together with the facile synthetic accessibility, makes it and its derivatives useful for a number of applications, e.g., as materials for organic electronics [1], dyes for mechanochromic materials [2], and fluorescent monomers for polymer

• synthesis [3]. Pyrenyl derivatives have also attracted considerable attention as fluorescent probes in nucleic acid chemistry and closely related research areas. In particular the pyrene scaffold has been utilized for the construction of abiotic oligopyrenotides with nucleic acid-like structural properties

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• derivatives were measured in 1,4-dioxane with excitation under wavelength corresponding to the absorption maxima (Table 2, see also Supporting Information File 2). All examined compounds except 5b showed fluorescent behavior. The measured fluorescence spectra show a vibrational structure and are mirror images

One-pot syntheses of blue-luminescent 4-aryl-1H-benzo[f]isoindole-1,3(2H)-diones by T3P^® activation of 3-arylpropiolic acids

• Melanie Denißen,
• Alexander Kraus,
• Guido J. Reiss and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 2340–2351, doi:10.3762/bjoc.13.231

• -emitting diodes (OLEDs) [2][3][4][5]. As a consequence efficient and efficacious syntheses of fluorescent molecules can be most advantageously addressed by diversity-oriented syntheses [6][7][8], namely by multicomponent [9][10][11][12][13][14][15][16][17][18][19][20][21] and domino reactions [22][23][24

• class particularly attractive for the development of novel sensors and fluorescent dyes [38], for instance 6-chloro-2,3-naphthaleneimide derivatives were successfully used for labeling amino acids, and for studying peptide protein interactions [39]. Even the superficial attachment to a binding domain

• comparing the relative intensities of the emission maxima at identical concentrations, reveals that only the methoxy derivative 4b (Table 6, entry 2) is substantially fluorescent (Figure 5). With this exception all qualitatively determined emission spectra reveal a broad unstructured maximum followed by a

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• corresponding vibronic band was seen in the absorption spectrum at 330–340 nm. Density functional theory (DFT) calculations [38] were carried out at the B3LYP/LanL2DZ level of theory. The HOMO and LUMO energies of the selected compounds are given in Table 3. For fluorescent compounds 3, 4, 7, and 9, the HOMO

• center. Because of the cationic nature of the phosphorus center, the energy levels in cationic phospholium 7 are significantly stabilized. In contrast to the fluorescent phospholes, calculations show that the HOMO and HOMO−1 of nonfluorescent phosphole sulfide 5 and selenide 6 have a large contribution

Curcuminoid–BF₂ complexes: Synthesis, fluorescence and optimization of BF₂ group cleavage

• Henning Weiss,
• Jeannine Reichel,
• Helmar Görls,
• Kilian Rolf Anton Schneider,
• Mathias Micheel,
• Michael Pröhl,
• Michael Gottschaldt,
• Benjamin Dietzek and
• Wolfgang Weigand

Beilstein J. Org. Chem. 2017, 13, 2264–2272, doi:10.3762/bjoc.13.223

• .13.223 Abstract Eight difluoroboron complexes of curcumin derivatives carrying alkyne groups containing substituents have been synthesized following an optimised reaction pathway. The complexes were received in yields up to 98% and high purities. Their properties as fluorescent dyes have been

• attention regarding their properties as fluorescent dyes with fluorescence quantum yields of up to 60% and Stokes shifts of up to 5000 cm−1 [9]. Additionally, the incorporation of the BF2 group forces the β-diketone unit into the enol form, which leads to increased rigidity and enhanced photostability of

• spectroscopy To investigate their properties as fluorescent dyes we measured the UV–vis absorption and fluorescence spectra of the BF2 complexes 2a–h. Measurements were carried out in dichloromethane at room temperature and under ambient atmosphere. The results are shown in Figure 2. All BF2 complexes show

Superstructures with cyclodextrins: Chemistry and applications IV

• Gerhard Wenz

Beilstein J. Org. Chem. 2017, 13, 2157–2159, doi:10.3762/bjoc.13.215

• magnetic resonance imaging (MRI) [22]. Well-defined fluorescent polyrotaxanes with alternating, threaded cucurbit[6]uril and CD rings were assembled by Fraser Stoddart’s group via an alkyne–azide click reaction exploiting supramolecular catalysis [23][24]. The concurrent radical copolymerization of 1,3