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

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• shows a strong hypsochromic shift for both transitions with the emission wavelengths at 427 nm and 522 nm, respectively (Figure 5, Table 3). Moreover, the fluorescence quantum yields of these compounds were greatly affected by the azulenyl substitution. While, 4′-azulenylterpyridine showed a medium

A flow reactor setup for photochemistry of biphasic gas/liquid reactions

• Josef Schachtner,
• Patrick Bayer and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2016, 12, 1798–1811, doi:10.3762/bjoc.12.170

• the need for filters and allows high quantum yields by the correct matching of lamp emission and chromophore absorption bands (Figure 4 and Figure 5). The absence of UV emission bands regarding the used red and warm white LEDs enhances the selectivity of many organic reactions by suppression of

Synthesis, fluorescence properties and the promising cytotoxicity of pyrene–derived aminophosphonates

• Jarosław Lewkowski,
• Maria Rodriguez Moya,
• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Renata Kontek and
• Gabriela Gajek

Beilstein J. Org. Chem. 2016, 12, 1229–1235, doi:10.3762/bjoc.12.117

• concentrations (1 μM). We have found that all compounds under study were emissive albeit emission quantum yields varied from ≈0.01 to ≈0.7 (Table 1). The typical absorption and emission spectrum (those of compound 3Aj), compared with the spectra of pyrene are shown in Figure 1. The spectra are closely similar

• band I). IC50 values of studied compounds. Synthesis of aminophosphonates 3Aa–j, 3Ba–e, 3Ca–d, 3Cg, aminophosphonic acids 4a, 4c and hydroxyphosphonate 5A. Absorption and emission maxima and fluorescence quantum yields (ΦF) for the synthesized compounds in chloroform solution (c = 1 μM). IC50 values on

Biradical vs singlet oxygen photogeneration in suprofen–cholesterol systems

• Fabrizio Palumbo,
• Francisco Bosca,
• Isabel M. Morera,
• Inmaculada Andreu and
• Miguel A. Miranda

Beilstein J. Org. Chem. 2016, 12, 1196–1202, doi:10.3762/bjoc.12.115

• singlet oxygen was assessed by time-resolved near infrared emission studies in dichloromethane using perinaphthenone as standard. The quantum yields (ΦΔ) were 0.52 for 1 and 2 and 0.56 for 3. In conclusion, SP-α-Ch dyads are unique in the sense that they can be used to photogenerate both biradicals and

Synthesis and fluorosolvatochromism of 3-arylnaphtho[1,2-b]quinolizinium derivatives

• Phil M. Pithan,
• David Decker,
• Manlio Sutero Sardo,
• Giampietro Viola and
• Heiko Ihmels

Beilstein J. Org. Chem. 2016, 12, 854–862, doi:10.3762/bjoc.12.84

• solvent. For the derivatives 6a–d the quantum yields were the highest in MeOH and the lowest in CHCl3. The phenanthrenyl-substituted derivative 6e exhibits the highest fluorescence quantum yields in 2-PrOH and 1-BuOH (ΦF = 0.34) and the lowest in CHCl3 (ΦF = 0.071). Discussion In most of the tested

• quinolizinium derivatives 6a–e. Supporting Information The Supporting Information contains the experimental section (synthesis, determination of fluorescence quantum yields); absorption and emission spectra of 6b; 1H NMR spectra of compounds 6a–e; plots of emission energies of 6e versus selected solvent

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• blue emitters and the trans isomers exhibited significantly higher fluorescence quantum yields (relative to 9,10-diphenylanthracene) as compared to the corresponding cis isomers. The solid-state fluorescence spectra revealed an important red shift of λmax due to intermolecular interactions in the

• groups have been found to exhibit good solvatochromism properties and high quantum yields in the solid state why they are considered as important precursors for the fabrication of fluorescent materials [20]. Owing to their exciting photophysical properties many dicyanomethylene pyran-containing

• process that occurs when an electron is transferred from a singlet energy level into a triplet energy level [36]. The derivatives 2a–d are blue emitters, displaying maximum-emission bands at around 370–393 nm. Remarkably, the fluorescence quantum yields calculated relative to 9,10-diphenylanthracene are

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

• Anna Wrona-Piotrowicz,
• Janusz Zakrzewski,
• Anna Gajda,
• Tadeusz Gajda,
• Anna Makal,
• Arnaud Brosseau and
• Rémi Métivier

Beilstein J. Org. Chem. 2015, 11, 2451–2458, doi:10.3762/bjoc.11.266

• photophysical properties of 3a–d and 4 and, for comparison, those of N-alkylamide 5 (Figure 1). The steady-state spectroscopic data for 3a–d, 4 and 5, along with fluorescence quantum yields in chloroform solutions, are presented in Table 1 (although it was recently reported that pyrene undergoes

• practically did not influence the electronic absorption and emission spectra. Structured emission bands were observed showing only a small effect of solvent polarity (Figure 1). However, the fluorescence quantum yields of 3a–d and 4 were significantly higher than that of 5. In order to explain this phenomenon

• into the corresponding fluorescent amidoalkylphosphonates. It is worthy to note that this class of compounds offers numerous possibilities of chemical transformations [35][36]. The pyrenyl amidoalkylphosphonates emit fluorescence with quantum yields ca. 2 times higher than simple N-substituted pyrene-1

2-Hetaryl-1,3-tropolones based on five-membered nitrogen heterocycles: synthesis, structure and properties

• Yury A. Sayapin,
• Inna O. Tupaeva,
• Alexandra A. Kolodina,
• Eugeny A. Gusakov,
• Vitaly N. Komissarov,
• Igor V. Dorogan,
• Nadezhda I. Makarova,
• Anatoly V. Metelitsa,
• Valery V. Tkachev,
• Sergey M. Aldoshin and
• Vladimir I. Minkin

Beilstein J. Org. Chem. 2015, 11, 2179–2188, doi:10.3762/bjoc.11.236

• –f, which indicates that irradiation of solutions of 11a–f in heptane at 293 K initiates the ESIPT O−H···N → O···H−N responsible for the ASS-fluorescence. It should be noted that the quantum yields of the ASS-fluorescence of compounds 11a,c,e (R1 = H) (0.15–0.18) and 11b,d,f (R1 = Cl) (0.19–0.22) are

Effective ascorbate-free and photolatent click reactions in water using a photoreducible copper(II)-ethylenediamine precatalyst

• Redouane Beniazza,
• Natalia Bayo,
• Florian Molton,
• Carole Duboc,
• Stéphane Massip,
• Nathan McClenaghan,
• Dominique Lastécouères and
• Jean-Marc Vincent

Beilstein J. Org. Chem. 2015, 11, 1950–1959, doi:10.3762/bjoc.11.211

• efficient photoinduced electron transfer process leading to a fast Cu(II) to Cu(I) reduction, the final electron source being the solvent. The photoreduction process was extremely efficient, photoreduction quantum yields (Фred) ranging from 0.17 up to around 1 being measured in good H-atom donating solvents

Design, synthesis and photochemical properties of the first examples of iminosugar clusters based on fluorescent cores

• Mathieu L. Lepage,
• Antoine Mirloup,
• Manon Ripoll,
• Fabien Stauffert,
• Anne Bodlenner,
• Raymond Ziessel and
• Philippe Compain

Beilstein J. Org. Chem. 2015, 11, 659–667, doi:10.3762/bjoc.11.74

• . Difluoroboradiaza-s-indacenes, commonly named boron-dipyrromethene dyes (F-BODIPY), were logically selected for the construction of the probes. These compounds indeed combine high fluorescence quantum yields and high molar extinction coefficients, strong chemical and photochemical stability in solution and in solid

• properties of those multivalent dyes in aqueous media (glycine buffer at pH 10.7), are interesting, providing high quantum yields, 24% for 13a and 43% for 15a, and well-defined spectroscopic features. Altogether, these results augur well for a new class of molecular tools dedicated to rationalize the mode of

A facile synthesis of functionalized 7,8-diaza[5]helicenes through an oxidative ring-closure of 1,1’-binaphthalene-2,2’-diamines (BINAMs)

• Youhei Takeda,
• Masato Okazaki,
• Yoshiaki Maruoka and
• Satoshi Minakata

Beilstein J. Org. Chem. 2015, 11, 9–15, doi:10.3762/bjoc.11.2

• –430 nm), while π–π* transitions (300–340 nm) were red-shifted. On the other hand, diluted dichloromethane solutions (10−5 M) of diazahelicenes 2 did not show photoluminescence (Φf < 0.02, for the detailed values of quantum yields, see the Supporting Information File 1). Due to the presence of the

A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

• Stefanie Wolfram,
• Hendryk Würfel,
• Stefanie H. Habenicht,
• Christine Lembke,
• Phillipp Richter,
• Eckhard Birckner,
• Rainer Beckert and
• Georg Pohnert

Beilstein J. Org. Chem. 2014, 10, 2470–2479, doi:10.3762/bjoc.10.258

• transilluminator whereas BPT (1) offers a very good absorbance at 365 nm, a standard UV excitation wavelength. We then recorded fluorescence spectra of all fluorophores and determined fluorescence quantum yields Φ (Table 1). To characterize BPT (1) in a non-interacting solvent we used cyclohexane resulting in an

• was emitted by NBD/DDY/catalase, which is probably due to very low fluorescence quantum yields reported for NBD derivatives of primary amines in water [39]. Furthermore, NBD (9) is not suitable for standard SDS-PAGE (12% gels) as the dye smears and therefore potentially covers fluorescent signals of

• with a GENESYS™ 10 S spectrophotometer (Thermo Fischer Scientific Inc., Waltham, MA, USA) with 10 mm quartz cells. Quantum yields were obtained as described in [43] using quinine sulfate in 0.05 M sulfuric acid as fluorescent standard with a Varian Cary 500 spectrophotometer (Varian Inc., Palo Alto, CA

Synthesis and optical properties of pyrrolidinyl peptide nucleic acid carrying a clicked Nile red label

• Nattawut Yotapan,
• Chayan Charoenpakdee,
• Pawinee Wathanathavorn,
• Boonsong Ditmangklo,
• Hans-Achim Wagenknecht and
• Tirayut Vilaivan

Beilstein J. Org. Chem. 2014, 10, 2166–2174, doi:10.3762/bjoc.10.224

• the fluorescence quantum yields (50% MeCN: λabs 564 nm, λem 641 nm, ΦF 0.29; 20% MeCN: λabs 587 nm, λem 651 nm; ΦF 0.14). In aqueous phosphate buffer (10 mM, pH 7.0), the Nile red-labeled acpcPNA 10mer-Nr exhibited a broad absorption peak centered at 575 nm and a fluorescence emission at 656 nm

• maxima (647 nm) compared to the single-stranded PNA (656 nm) as well as a small fluorescence increase (1.36 fold at 643 nm) (Figure 3a,b). The blue-shifted fluorescence maxima and increased quantum yields of Nile red suggest that the Nile red chromophore in complementary PNA–DNA duplexes was placed in a

• , 11merCC-Nr, 11merGG-Nr, 11merTT-Nr) were synthesized. These four Nile red-labeled acpcPNA sequence exhibited differences only at the bases flanking the Nile red label, For single-stranded PNA, the order of fluorescence quantum yields was AA > TT ~ CC > GG. This suggests a more efficient quenching of the

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

• Sanjeewa N. Senadheera,
• Abraham L. Yousef and
• Richard S. Givens

Beilstein J. Org. Chem. 2014, 10, 2038–2054, doi:10.3762/bjoc.10.212

• bioactivity. The desirable properties of any new PPG candidate are 1) absorption at wavelengths near or above 400 nm, 2) enhanced chemical and photochemical quantum yields and 3) improved rate of release, ideally in the range of ps to ns time constants; all three are useful properties for applications in

• ) and comparison with an independently synthesized sample obtained from Friedel–Crafts alkylation of 1-methoxynaphthalene (11) with methyl bromoacetate and ferric oxide [27]. Quantum yields for disappearance and percentage conversions for 14a are higher than that of 14b as indicated in Table 1. After

• aq MeOH (Φdis = 0.028, Table 1 and Table 2) but the product mixture was more complex (vide infra). Interestingly, quantum yields for the disappearance for 14a are enhanced three-fold (Φdis = 0.067) when the photolysis solution was purged free of oxygen (Table 2). The quantum yield of 14a for the

Synthesis of new, highly luminescent bis(2,2’-bithiophen-5-yl) substituted 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole

• Anastasia S. Kostyuchenko,
• Vyacheslav L.Yurpalov,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2014, 10, 1596–1602, doi:10.3762/bjoc.10.165

• synthesis, efficient ring closure reaction affording a 4H-1,2,4-triazole unit is presented. All target ambipolar compounds display strong photoluminescence with measured quantum yields up to 0.59. Modification of the demonstrated synthetic routes may be exploited for the preparation of longer, specifically

• photoluminescence quantum yields are indicated together with the formulae of the corresponding compounds. In the case of 18 (4-phenyl-4H-1,2,4-triazole ring) the photoluminescence quantum yield is almost three times higher than that measured for 15 (1,3,4-thiadiazole ring). The obtained results clearly demonstrate

• dichloromethane. Optimum fluorescence excitation wavelengths (given in the legends) have been selected based on fluorescence emission profiles. Photoluminescence quantum yields measured for 13, 15 and 18 together with their formulae. Synthesis of ethyl 3-decyl-2,2'-bithiophene-5-carboxylate (3). Synthesis of

Pyrene-modified PNAs: Stacking interactions and selective excimer emission in PNA₂DNA triplexes

• Alex Manicardi,
• Lucia Guidi,
• Alice Ghidini and
• Roberto Corradini

Beilstein J. Org. Chem. 2014, 10, 1495–1503, doi:10.3762/bjoc.10.154

• fluorescence properties of these PNA in the absence and in the presence of DNA. The evaluation of the pyrene quantum yields showed that these probes are much less fluorescent than the 1-pyreneacetic acid precursor in water (23 times lower quantum yield for PNA2, see Supporting Information File 1, Figure S16

Multichromophoric sugar for fluorescence photoswitching

• Stéphane Maisonneuve,
• Rémi Métivier,
• Pei Yu,
• Keitaro Nakatani and
• Juan Xie

Beilstein J. Org. Chem. 2014, 10, 1471–1481, doi:10.3762/bjoc.10.151

• fluorescence quantum yields were determined by using quinine sulfate dihydrate in sulfuric acid (0.5 N) as a standard at λexc = 325 nm (ΦF = 0.546) and coumarin 540A in ethanol as a standard at λexc = 450 nm (ΦF = 0.544). Photochromic reactions were induced in situ by a continuous irradiation Hg–Xe lamp