Application of Cu(I)-catalyzed azide–alkyne cycloaddition for the design and synthesis of sequence specific probes targeting double-stranded DNA

• Svetlana V. Vasilyeva,
• Vyacheslav V. Filichev and
• Alexandre S. Boutorine

Beilstein J. Org. Chem. 2016, 12, 1348–1360, doi:10.3762/bjoc.12.128

• absorption spectra in the interval 300–700 nm do not change upon DNA titration (data not shown), which means that increase in fluorescence emission is due to the increase of the quantum yield of fluorescence. Studies of interaction of the probes with fixed and live mouse cells are under investigation in the

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

• ratio of intensities of III/I vibronic bands on the medium polarity) [26]. The highest emission quantum yield (0.68) was found for aminophosphonic acid 4a in aqueous buffer (pH 7.4). A similar phenomenon of higher emission efficiency of 1-(pyrene-1-carboxamido)methylphosphonic acid in comparison to a

• corresponding aminophosphonate was earlier reported [29]. The aforementioned data suggest possible application of compound 3Aj (and other exhibiting similar emission quantum yield) as molecular probes monitoring micropolarity of the fluorophore environment. On the other hand, water-soluble 4a might be used for

• fluorescence properties of the obtained compounds were investigated and N-benzylamino(pyren-1-yl)methylphosphonic acid showed a quantum yield of 68%, while dimethyl tert-butylamino(pyren-1-yl)methylphosphonate (3Aj) gave 11% quantum yield. The influence of a series of derivatives on two colon cancer cell lines

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

• and the cell. The photodiode output current was amplified and fed into a TDS-640A Tektronix oscilloscope via a Co-linear 150 MHz, 20 dB amplifier. The output signal from the oscilloscope was transferred to a personal computer for study. Thus, the singlet oxygen quantum yield (ΦΔ) of the dyads was

• determined in dichloromethane solutions using the same absorbance value (0.30) at 308 nm for each compound. A singlet oxygen quantum yield (ΦΔ) of 0.95 for perinaphthenone in dichloromethane was used as standard [22]. Chemical structure of the photosensitizing chromophores benzophenone (BZP) and 2

• luminescence at 1270 nm, using a germanium diode as detector. The singlet oxygen lifetime (Figure 7A) was found to be ca. 70 μs in all cases (in agreement with the1O2 lifetime reported in the literature [20] for the same solvent). The photosensitized singlet oxygen production was established with a quantum

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

• ][7]. In this context, fluorosolvatochromic probes appear to be especially attractive as indicators for the surrounding medium, because emission spectroscopy is a highly sensitive method that allows to determine three different physical quantities, namely emission quantum yield, emission energy and

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

• revealed that all compounds are blue emitters. The calculated fluorescence quantum yield relative to 9,10-diphenylanthracene is significantly higher for the trans isomers when compared to the corresponding cis isomers. The solid-state fluorescence investigations revealed in the case of the regioisomers 2 a

Syntheses of dibenzo[d,d']benzo[2,1-b:3,4-b']difuran derivatives and their application to organic field-effect transistors

• Minh Anh Truong and
• Koji Nakano

Beilstein J. Org. Chem. 2016, 12, 805–812, doi:10.3762/bjoc.12.79

• quantum yield (Φ = 61% in CHCl3 solution). To investigate the structure–property relationship of DBBDFs and DNBDFs, the optical properties of syn-DBBDF 5 and syn-DNBDF 6 were compared with those of anti-DBBDF 3 and anti-DNBDF 4. The UV–vis spectra of anti-DBBDF 3 and anti-DNBDF 4 were reported to show

Interactions between 4-thiothymidine and water-soluble cyclodextrins: Evidence for supramolecular structures in aqueous solutions

• Vito Rizzi,
• Sergio Matera,
• Paola Semeraro,
• Paola Fini and
• Pinalysa Cosma

Beilstein J. Org. Chem. 2016, 12, 549–563, doi:10.3762/bjoc.12.54

• several clinical diseases [12][21]. One of the most commonly used thiobase for PDT applications is S4TdR, whose triplet state is generated upon photoexcitation with a quantum yield of one [22][23][24][25][26]. Under these conditions the production of reactive oxygen species (ROS), well-known toxic agents

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

• approximately two-fold increase in solution fluorescence quantum yield in comparison with that of a model N-alkyl pyrene-1-carboxamide. This effect was tentatively explained by stiffening of the amidophosphonate lateral chain which was caused by the interaction (intramolecular hydrogen bond) of phosphonate and

• species. Table 2 shows that 3a displays a slightly shorter excited state lifetime (10.6 ns) than its alkyl analogue 5 (12.3 ns). The higher emission quantum yield of 3a results from a ≈2.3 times higher value of kr and a concomitant ca. 1.8 times lower value of knr. Notably, compound 4 displays a kr value

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

• solution at 293 K. Ф – Quantum yield of the fluorescence. Supporting Information Supporting Information File 519: Experimental section, crystallographic data for compounds 5g, 6e, 11b, 13; optimized geometries of the intermediates and transition states involved in the routes of the formation of 1,3

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

• shown by UV–vis spectroscopy (Figure 2). This rate is comparable to that observed previously with the analogous complex 2, for which a photoreduction quantum yield close to unity has been determined in THF [14]. Because of such a high efficiency, the photoreduction proceeded well under direct sunlight

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

• influence of both triazole rings. The second transition at 386 nm is assigned in light of previous studies to the S0→S2 of the BODIPY subunit [39][65][66][67]. The triazole rings absorb below 250 nm for the π–π* transition [68]. Excitation at 510 nm affords a relatively intense emission with a quantum yield

• -methylumbelliferone displays a strong absorption at 360 nm and a broad emission around 446 nm (Figure 4a). The fluorescence quantum yield is high (fluo = 81%) as previously determined under similar conditions [74]. In order to record the efficiency of the fluorescence quenching of the anion of 4-methylumbelliferone

Synthesis and chemosensing properties of cinnoline-containing poly(arylene ethynylene)s

• Natalia A. Danilkina,
• Petr S. Vlasov,
• Semen M. Vodianik,
• Andrey A. Kruchinin,
• Yuri G. Vlasov and
• Irina A. Balova

Beilstein J. Org. Chem. 2015, 11, 373–384, doi:10.3762/bjoc.11.43

• at the optimal excitation wavelength of 425 nm which corresponds to the absorption bands at ≈425 nm in UV–vis spectra of both samples (Figure 6). An additional ethynyl moiety in the repeating unit of olygomer 10b led to the increase in quantum yield from 1% for 10a to 2% for 10b, while qualitative

• properties and Pd2+-sensing ability of PAEs obtained suggested that the incorporation of an additional triple bond into a cinnoline ring offers a more significant improvement to the fluorescence quantum yield and the Pd2+dependent quenching efficiency than increasing of the polymerization degree. Recent

Solution processable diketopyrrolopyrrole (DPP) cored small molecules with BODIPY end groups as novel donors for organic solar cells

• Diego Cortizo-Lacalle,
• Calvyn T. Howells,
• Upendra K. Pandey,
• Joseph Cameron,
• Neil J. Findlay,
• Anto Regis Inigo,
• Tell Tuttle,
• Peter J. Skabara and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2683–2695, doi:10.3762/bjoc.10.283

• films from a 20 mg mL−1 solution, respectively. Film thicknesses were measured using a Dektak 150 M stylus profiler. Absorption and emission spectra of compounds 9 and 10 were obtained with a Varian Cary 300 UV–visible spectrophotometer and a Photoluminescence Quantum Yield (PLQY) measurement system

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

• emission maximum of 444 nm and a quantum yield of Φ = 0.96. In an aqueous solution containing 20% THF (v/v) the maximum of emission (λem,max) is shifted to 455 nm (Figure 4). The quantum yield of BPT (1) in this solution is Φ = 0.87 which makes it convenient for fluorescence detection in aqueous media, e.g

• ., for biological applications. In contrast, the quantum yield of BNS (6) in 80% water/20% THF (v/v) was below 0.03 and rendering it inappropriate for this purpose. The UV properties allow UV detection after LC separation as could be shown by ultra-performance liquid chromatography (UPLC) coupled to a

• chloride (7) and subsequently treated with 3-azidopropan-1-amine to provide the fluorescence/MS tag 6. Characterization of BPT (1) and comparison with other azide modified fluorophores We characterized the new thiazole reporter BPT (1) regarding its absorption and emission properties as well as its quantum

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

• label that can change its fluorescence in response to its altered micro-environment [7][8][9]. Nile red is a member of the benzophenoxazine dye family which exhibits several interesting features including a high photostability, high fluorescence quantum yield, broad working pH range, long excitation and

• purification. All Nile red-labeled acpcPNAs are freely soluble in water (>1 mM), providing a bright blue solution. The UV–vis spectrum of the free propargyl Nile red label 1 in acetonitrile (Figure 2a) showed absorption and fluorescence emission maxima at 538 nm and 620 nm, with a fluorescence quantum yield

• red in the acpcPNA 10mer-Nr was not quenched as indicated by the quantum yield value being similar to that of the free label (10mer-Nr: ΦF = 0.16; 1: ΦF = 0.14 in 20% MeCN). Unfortunately, the value can only be compared in an acetonitrile:water mixture as compound 1 is essentially insoluble in water

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• the fit was estimated by the parameter χ2 (0.90 ≤ χ2 ≤ 1.10) and the symmetrical distribution of the residuals about the zero axis. All measurements were performed at room temperature. The fluorescence quantum yield was determined by using the FLS 980 fluorospectrometer with an integrating sphere and

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

• esters were excellent, resulting in quantitative release of DEP based on conversion. The quantitative conversion and apparent good efficiency of the 1,4-derivative 14a prompted further investigation. The quantum yield for disappearance of 14a in 1% aq MeCN (Φdis = 0.021) is comparable to that observed in

• 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

• . Irradiation of 2,6-HNA DEP (10) at 350 nm in 1% aq MeCN under conditions comparable to those employed with 14a,b also released phosphate. The disappearance quantum yield for 10 (Φdis = 0.031) was nearly the same as that obtained for 14a but the conversion after a 10 min irradiation was only 67%. Unlike 14a,b

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• RF preparations in order to alter the quantum yield of the photoreaction without quenching the fluorescence of RF [81]. Ascorbic acid and sodium azide are the two most studied external quenchers for RF photoreactions. Both these compounds reduce the photodegradation of RF with different quenching

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

• quinquethiophene by 1,3,4-oxadiazole leads to a substantial increase of the fluorescence quantum yield and a hypsochromic shift of the emission band [14], both features being technologically advantageous. They are, however, difficult to solution process due to strong intermolecular interactions, associated with

• completive heteroatom. Moderate to high fluorescence quantum efficiency yields are also observed, ranging from 0.59 for 18 to 0.21 for 15. Here, a clear heteroatom effect is observed, while the influence of the thiophene substituent seems negligible. The observed trend of decreasing quantum yield with

• crossing channels as well, making the thermal decay pathway accessible. The hindering of these decay modes in the oxadiazole derivatives 13 and 14 doubles their quantum yield. For the triazole derivative 18 the quantum yield is even nearly triple that of 15, but this enhancement should also be traced to

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

• ), associated with a fluorescence quantum yield ΦF = 0.12. These spectroscopic characteristics are rather comparable to the absorption and fluorescence features of the fluorophore 5 [4]. The photophysical properties of the photochromic model compound 9 have been described in a previous report [4]. Briefly, the

On the mechanism of photocatalytic reactions with eosin Y

• Michal Majek,
• Fabiana Filace and
• Axel Jacobi von Wangelin

Beilstein J. Org. Chem. 2014, 10, 981–989, doi:10.3762/bjoc.10.97

• of such processes. The magnitude of quantum yields Φ also describes how much energy is wasted into thermal dissipation in such systems, which is an especially critical parameter for the evaluation of sustainability of a photocatalytic process. The quantum yield is defined as the efficiency of a

• photochemical reaction in the studied system: Φ = (rate of substrate conversion)/(absorbed photon flux) Theoretically, if a simple photocatalytic process is considered, the quantum yield would be in the range 0 < Φ ≤ 1. It approaches unity as the efficiency of the photocatalytic step increases. In reality

• ][18][19][20][21]. For more details on the actinometry experiments and quantum yield determinations, see Supporting Information File 1. The observed quantum yields Φ of the studied reactions varied by almost two orders of magnitude, between 4.7 and 0.075. This already indicates the operation of

Tailoring of organic dyes with oxidoreductive compounds to obtain photocyclic radical generator systems exhibiting photocatalytic behavior

• Christian Ley,
• Julien Christmann,
• Ahmad Ibrahim,
• Luciano H. Di Stefano and
• Xavier Allonas

Beilstein J. Org. Chem. 2014, 10, 936–947, doi:10.3762/bjoc.10.92

• dye (see insert Figure 1). It should be noted that in the same conditions, no photolysis occurs for an acetonitrile solution of neat RB. To quantify the consumption of the PS, the photolysis quantum yield (Φphotolysis) was determined. Φphotolysis is defined by the ratio of the initial number of

• photolysis quantum yield of 0.19 for RB/TA is obtained. Photocyclic initiating system A typical photocyclic initiating system (PCIS) consists of a light absorbing dye (PS), an electron acceptor (A) and an electron donor (D) (Scheme 3). In such systems, upon irradiation photoinduced electron transfer reaction

• compare clearly Type II and PCIS, the quantum yield of dye photolysis (Φphotolysis) was also determined for RB/TA/EDB. The total concentration of absorbed photons for the PCIS is 0.0139 mol·L−1. Dividing the initial RB concentration by this value leads to a photolysis quantum yield of 4.7·10−3. This

Columnar/herringbone dual crystal packing of pyrenylsumanene and its photophysical properties

• Binod Babu Shrestha,
• Shuhei Higashibayashi and
• Hidehiro Sakurai

Beilstein J. Org. Chem. 2014, 10, 841–847, doi:10.3762/bjoc.10.80

• emission with high quantum yield (0.82) was observed for pyrenylsumanene in solution, while excimer-type red-shifted emission was evident in the crystalline phase. Keywords: carbon nanomaterials; columnar crystal packing; fluorescence; herringbone; pyrenylsumanene; Introduction Buckybowls – bowl-shaped

• in the crystal is also assigned to the excimer state. The quantum yields of pyrene in solution and in the solid state are almost equal (0.64 and 0.68). In contrast, the quantum yield of 1 in the solid state (0.10) is decreased significantly from that in solution (0.82). This exciton quenching may be

• due to the effect of the sumanene moiety, since the quantum yield of 3 is low both in solution and in the solid state. Conclusion The ability to predict the crystal packing of organic molecules is important in the design of functional organic compounds but remains challenging. In this regard, the

Rapid pseudo five-component synthesis of intensively blue luminescent 2,5-di(hetero)arylfurans via a Sonogashira–Glaser cyclization sequence

• Fabian Klukas,
• Alexander Grunwald,
• Franziska Menschel and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2014, 10, 672–679, doi:10.3762/bjoc.10.60

• quantum yield Φf. The same holds true for the comparison of the constitutional isomers 2i and 2j. Therefore, the twisted structure of 2j causes a larger Stokes shift and a much lower fluorescence quantum yield Φf. The huge Stokes shift originates from a considerable planarization in the excited state [42

• quantum yield Φf. This finding correlates well with the planar ground state structure and an associated low Stokes shift. All studied representatives are potentially interesting singlet bluelight emitters. In addition, the electronic properties of the furans 2 have been studied by cyclic voltammetry

• in a one-pot fashion, which opens a ready access to biologically active furan derivatives. In addition the investigation of the photophysical properties of these compounds reveals an intense blue luminescence in solution approaching unity for the fluorescence quantum yield Φf of distinct derivatives