Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• media. Except for the derivative 2a the arylethynylbenzoquinolizinium derivatives have low emission quantum yields (Table 2, Figure 4). The derivative 2a has a moderate to high fluorescence intensity with slight deviations of the emission maxima in different solvents (Table 2, Figure 4A). In chloroform

• was also observed in polar solvents though with less intensity (Figure 4), which indicates that the emission from the LC state can compete with the charge shift and solvent relaxation, leading to dual emission. Remarkably, the emission quantum yields of the methoxy- and amino-substituted derivatives

Synthesis and photophysical studies of a multivalent photoreactive Ru^II-calix[4]arene complex bearing RGD-containing cyclopentapeptides

• Sofia Kajouj,
• Lionel Marcelis,
• Alice Mattiuzzi,
• Adrien Grassin,
• Damien Dufour,
• Pierre Van Antwerpen,
• Didier Boturyn,
• Eric Defrancq,
• Mathieu Surin,
• Julien De Winter,
• Pascal Gerbaux,
• Ivan Jabin and
• Cécile Moucheron

Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150

• ). Emission quantum yields were determined by integrating the corrected emission spectra over the frequencies. [Ru(bpy)3]2+ in water under air was chosen as the standard luminophore (quantum yield of 0.042 under argon). The luminescence lifetimes were measured by the time-correlated single photon counting (TC

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

• state. Nevertheless, Che and co-workers demonstrated that extending the π-conjugation of the cyclometalated ligand led to enhanced phosphorescence quantum yields [51][52]. Indeed, the increased conjugation resulted in a modification of the frontier molecular orbitals and prevention of Jahn–Teller

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

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

• high photoluminescence (PL) quantum yields [13][14][15]. The calculated ΔEST of 1 and 2 are 0.33 and 0.27 eV, which are small enough to achieve TADF behavior. As shown in Figure 1c, the twisting angle (θ’) of 1 in S1 is 63.74°, which is much smaller than its θ in S0, meanwhile, the conformation of the

Enhanced quantum yields by sterically demanding aryl-substituted β-diketonate ancillary ligands

• Rebecca Pittkowski and
• Thomas Strassner

Beilstein J. Org. Chem. 2018, 14, 664–671, doi:10.3762/bjoc.14.54

• weak emission, to mesityl (mes) or duryl (dur) substituted acetylacetonates. The new complexes show very efficient emission with quantum yields >70% in the sky-blue spectral region (480 nm) and short decay times (<3 μs). Keywords: ancillary ligand; β-diketonates; photoluminescence; platinum(II

• challenging [7][8]. Tetradentate [9][10][11], terdentate [12][13][14][15], and bidentate [16][17][18][19][20] cyclometalated Pt(II) complexes were recently shown to be promising phosphorescent triplet emitters in OLEDs (PhOLEDs), which emit light with high quantum yields in the blue spectral region. The

• of duryl complex 3 mostly remains structurally unresolved. For both complexes, very high quantum yields of 82% (2) and 73% (3) at ambient temperatures as well as short decay times around 3 μs (Table 1) were measured. The complexes show no aggregation behavior at higher concentrations (10 wt % in PMMA

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

• contribution of the delayed component in PL with emission quantum yields for the delayed component of luminescence in the 38–44% range. These molecules also exhibit high reverse intersystem crossing rates (kRISC > 15 × 104 s−1). Conversely, CN-P2 and CN-P4 show larger ∆EST (0.180 − 0.190 eV) than CN-P3, CN-P5

• and CN-P6 and lower TADF contributions in PL with smaller quantum yields for the delayed component of luminescence (19–23%). Smaller RISC were also determined (kRISC of < 8 × 104 s−1). Finally, TADF contribution on the total luminescence of CN-P7 and CN-P8 was the weakest of the series (≤1%) as a

Fluorogenic PNA probes

• Tirayut Vilaivan

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

• significant fractions of TO that are back-bound to the PNA probe (molar ratio between 0.7 to almost 1.0 at 30 °C) [159]. The smallest fraction was observed in probes with homopyrimidine sequences. In addition, the fluorescence quantum yields of the probe in the back-bound conformation were lowest in

• analogue of cytosine [182]. The tC exhibits decent quantum yields of ≈0.2 both in free form and when incorporated into DNA or aegPNA [183], and forms specific base pairs with dG, but does not show appreciable fluorescence change upon the base pairing. While this could be advantageous for several

Synthesis and spectroscopic properties of β-meso directly linked porphyrin–corrole hybrid compounds

• Baris Temelli and
• Hilal Kalkan

Beilstein J. Org. Chem. 2018, 14, 187–193, doi:10.3762/bjoc.14.13

• characters, high fluorescence quantum yields and favorable electronic properties. Porphyrin–corrole conjugates have been successfully used as donor–acceptor systems in photoinduced charge separation processes. It was shown that derivatives of these conjugates could be potentially used in photovoltaic

• same effect was also observed in the emission spectra. Fluorescence spectra of the compounds gave split emission bands except for 4c. Fluorescence life times and quantum yields were further determined for the hybrid compounds (Table 2). Measured fluorescence life times (4–9 ns), and fluorescence

• quantum yields are in agreement with the literature data [35][36]. Strong electron-withdrawing pentafluorophenyl-substituted 4e and Zn–porphyrin complex 4f gave higher quantum yields compared to reported literature values for meso–meso-linked porphyrin–corrole dyads [34] and traids [35]. High fluorescence

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

• , tC shows high and stable quantum yields (around 20%) both in monomeric form, in single- as well as in double-stranded DNA [29][30]. The quantum yield of tCO in different environments is even higher than those of tC [31]. While slightly dependent on the neighboring base environment they are still very

• in single fluorescence lifetimes (3–5 ns) [31]. High and stable quantum yields and single lifetimes in duplexes along with firm stacking are properties that make tC and tCO excellent FRET donors. In order to make evaluation of FRET data more exact, through a high precision in the orientation factor

• sensitive to the direct surroundings [55]. Once incorporated into DNA strands, qAN1 specifically base-pairs to the complementary base, thymine, and allows formation of stable B-form DNA [25]. Moreover, the quantum yields inside DNA are significantly increased compared to those of qA. However, the quantum

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

• solution. TFPE-anilines 1 and 2 gave moderate fluorescence quantum yields of 0.31 and 0.30, respectively. In comparison with these, the fluorescence quantum yields of TFPE-phenylenediamine 3 was slightly lower, namely 0.25. The introduction of one more TFPE group into 3, to give 4, further decreased the

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

• carbonyls 2 and 3 show distinctly weaker fluorescence than the pyrene alcohols 4 and 5. The quantum yields at ambient temperature are at least 20 times lower than for 4 and 5. The decay times drop to below 2 ns (Table 1). Similar trends were already observed for 1-acetylpyrene [31]. In the latter case, low

• . An X-ray crystal structure analysis of derivative 2 shows dimers stabilized by thymine–thymine hydrogen bonds. Conjugates 2 and 3 with the carbonyl function in the linker moiety are characterized by short emission decay times and low quantum yields. The reduction of the carbonyl function in 2 and 3

• afforded products 4 and 5 that display long fluorescence decay times (ca. 150 ns) and high emission quantum yields (ca. 40%). The interactions between the adenine derivatives (3 and 5) and the single-stranded oligonucleotide templates, (dA)10, T10 and the double-stranded template (dA)10-T10 were

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

• longest-wavelength absorption/emission maxima (λmaxA/F), terminal absorptions (λend), Stokes shifts, and quantum yields of fluorescence (qF). The absorption spectra consist of two intense low-energy charge-transfer bands located within the range of 550–650 nm accompanied by weak high-energy bands found

• effect. The measured quantum yields of fluorescence are within the range of 0.17–0.35 with no direct trends. However, a slight decrease of qF can be found when going from the chromophores bearing weaker donors (e.g., 2a/b) to chromophores with strong donors such as NMe2 or ferrocene (e.g., 1a/b or 5b

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

• -benzo[f]isoindole-1,3(2H)-diones 4. Variation of the amine 3 in pseudo three-component syntheses of 1H-benzo[f]isoindole-1,3(2H)-diones 4. Selected photophysical properties (absorption and emission maxima,a,b fluorescence quantum yields (Φf [53]),c and Stokes shifts Δd) of compounds 4a–g,m,n,s, 5, and 6

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 phosphole derivatives with different electronic properties [10][11][12][13][14][15][16][17]. Phosphole-based ladder-type π-conjugated heteroacenes were shown to exhibit a high charge mobility and/or fluorescence quantum yields [18][19][20][21][22][23][24]. For example, dibenzo-fused phospholo[3,2

• may be associated with the low fluorescence quantum yields. Conclusion A series of novel indole-fused phospholes were synthesized by simple chemical modifications at the trivalent phosphorus center. These organophosphorus compounds generated a whole series of derivatives from only one precursor. The X

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

• 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

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. The fluorescence quantum yields were experimentally determined for some of the synthesized chromophores; e.g., 1-(5-arylthiophen-2-yl)ethanones quantum yields were

• solvatochromism is inherent to the chromophores of the chalcone group, whereas chromophores of 2-aminopyrimidine group exhibit both positive and negative solvatochromism. For some of the compounds, the fluorescence quantum yields were experimentally determined, which values for 1-(5-arylthiophen-2-yl)ethanones

Energy down converting organic fluorophore functionalized mesoporous silica hybrids for monolith-coated light emitting diodes

• Markus Börgardts and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2017, 13, 768–778, doi:10.3762/bjoc.13.76

• synthesized materials with the corresponding dye loading and solid state quantum yields are summarized in Table 1. Especially for the Nile red-functionalized hybrid materials the highest quantum yield of 23% was obtained at a low dye loading of 1.5 μmol·g−1 (8@MCM-2). A further increase of Nile red loading

• causes a drop of quantum yields, presumably due to self-quenching effects. Based on the assumption that energy transfer typically occurs at distances of less than 10 nm between two dye molecules, self-quenching should be observed if more than one molecule is found in an area of 10 × 10 nm [29]. If dye

• furnishing optima of their solid-state fluorescence quantum yields Φf (Figure 4). The optical properties of the dye-functionalized hybrid materials differ slightly from the properties of their precursor molecules in solution. For all hybrid materials a broad band can be observed in the spectra, which can be

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• biological studies due to their well-established synthesis and functionalisation strategies, tuneable emission profiles and high quantum yields of fluorescence (QYs) [8][9][10][11]. However, the presence of heavy metals like Cd2+, and the associated concerns surrounding heavy metal toxicity has meant that

Novel β-cyclodextrin–eosin conjugates

• Gábor Benkovics,
• Damien Afonso,
• András Darcsi,
• Szabolcs Béni,
• Sabrina Conoci,
• Éva Fenyvesi,
• Lajos Szente,
• Milo Malanga and
• Salvatore Sortino

Beilstein J. Org. Chem. 2017, 13, 543–551, doi:10.3762/bjoc.13.52

• preservation of the photophysical properties of the dye. In fact, this molecular hybrid exhibits satisfactory fluorescence and 1O2 photogeneration quantum yields making it a suitable candidate for biomedical research studies in the field of imaging and PDT applications. The possibility to exploit the CD cavity

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• the case of 15f,g (Figure 2). The measured photoluminescence quantum yields decrease in the following order: 15b (0.84) > 15d (0.49) > 15g (0.29) > 15e (0.25) > 15c (0.20) ≈ 15f (0.18), indicating that for larger substituents the non-radiative rate constant increases. Such phenomena are frequently

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• experiments in different solvents, a fraction from the stock solution was evaporated and redissolved in e-Pure™ water (resistivity ≤ 18 MΩ cm), Britton–Robinson buffer (H3PO4, H3BO3, NaOAc, 0.04 M each) [58], or acetonitrile (spectral grade). The fluorescence quantum yields were determined by standard methods

A postsynthetically 2’-“clickable” uridine with arabino configuration and its application for fluorescent labeling and imaging of DNA

• Heidi-Kristin Walter,
• Bettina Olshausen,
• Ute Schepers and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2017, 13, 127–137, doi:10.3762/bjoc.13.16

• , 76344 Eggenstein-Leopoldshafen, Germany 10.3762/bjoc.13.16 Abstract The arabino-configured analog of uridine with a propargyl group at the 2’-position was synthesized and incorporated into DNA by solid-phase chemistry. The fluorescence quantum yields of DNA strands that were postsynthetically modified

• determination of quantum yields and emission color contrasts. Results and Discussion The synthesis of the phosphoramidite 7 (Scheme 2) was straightforward and includes mainly protecting group chemistry since it starts with the commercially available arabino-configured uridine analog 3. The 3’- and 5’-hydroxy

• show a unique combination of optical properties [25], including suitable brightness and fluorescence quantum yields, large Stokes’ shifts compared to conventionally applied Cy3 and Cy5, and most importantly, excellent photostabilities. D1–D4 were representatively chosen since they will serve as energy

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

• Lukas J. Patalag and
• Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

• isomerization are presented. The absorption properties are modulated by the number of conjugated C=C double bonds of the oligoene chain ranging from one to three. Large Stokes shifts of about 4900–5700 cm−1 and fluorescence quantum yields of up to 0.44 were observed. Keywords: fatty acid; fluorescence; lipid

• fluorescence quantum yields are known to be quite modest. For comparison, a prototypical pentaene motif exhibits a fluorescence quantum yield of 0.06 in EtOH [23]. Our fatty acids 11c and 11d, however, which can be regarded as terminally substituted pentaene derivatives, can still reach values of 0.18 in THF

• = 412 nm (three double bonds) which matches the requirements for modern laser equipments to trigger efficient excitation. All three variants show remarkably large Stokes shifts ranging from 4900–5700 cm−1 and fluorescence quantum yields in the range of 0.18 to 0.44. As a set of geometrically similar

Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

• Dominik Urselmann,
• Konstantin Deilhof,
• Bernhard Mayer and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2016, 12, 2055–2064, doi:10.3762/bjoc.12.194

• proceeds with lower oxidation potentials and consistently reversible oxidations can be identified. The Stokes shifts are large and substantial fluorescence quantum yields can be measured. Computational chemistry indicates lowest energy conformers with sigmoidal and helical structure, similar to

• state [57][79]. Also the fluorescence quantum yields Φf with 15 to 18% essentially remain constant within this series, although, the increasing number of sulfur-containing heterocycles suggests an increase in fluorescence deactivating spin–orbit coupling. In comparison to the consanguineous

• oligophenothiazines [45] the compounds 3 display considerable lower fluorescence quantum yields. Computations and electronic structure The electronic properties of the three thienyl-bridged oligophenothiazines 3 were further investigated by computational studies on the DFT level of theory. First the ground state