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

The effect of cyclodextrin complexation on the solubility and photostability of nerolidol as pure compound and as main constituent of cabreuva essential oil

• Joyce Azzi,
• Pierre-Edouard Danjou,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2017, 13, 835–844, doi:10.3762/bjoc.13.84

• susceptibility to degradation limit its application. The aim of our study was to improve the solubility and photostability of Ner through its encapsulation in different cyclodextrins (CDs). The formation constants of cis-, trans-Ner and their commercial mixture with various CDs (α-CD, β-CD, γ-CD, HP-β-CD, RAMEB

• solid complexes was assessed by HPLC. The structural characterization of CD/trans-Ner inclusion complex was then conducted by NMR spectroscopy followed by molecular modelling studies. The effect of encapsulation on the Ner photostability was also carried out over time under UVB irradiation. AL-type

• concentration of CD increased. These findings suggested that CDs are promising encapsulating carriers for Ner by enhancing its solubility and stability and thereby its application in food industry. Keywords: cabreuva essential oil; cyclodextrins; nerolidol; photostability; solubility; Introduction Nerolidol

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

• employing of inorganic luminophores. Further optimization of the dye loadings of these monoliths as well as fine tuning of the correlated color temperatures and determination of their luminescence efficiencies is currently under way. Additionally, studies on the photostability of the hybrid materials are in

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

• probing biological interactions and in biomedical applications [2][3][4][5][6]. Among these novel type of probes, luminescent semiconductors, quantum dots (QDs), which possess a narrow emission spectra and common excitation, superior photostability and electron density when compared to organic

• their remarkable photostability too, as long exposure times lead to no obvious photobleaching. Fructose and maltose combinations have also been used as an alternative to glucose as the carbon source. The Ostrikov team developed a room temperature preparation of weakly emissive CDs (QY 2%) by mixing a

The role of alkyl substituents in deazaadenine-based diarylethene photoswitches

• Christopher Sarter,
• Michael Heimes and
• Andres Jäschke

Beilstein J. Org. Chem. 2016, 12, 1103–1110, doi:10.3762/bjoc.12.106

• opening by vis irradiation only for pyridyl switch 1b, which had shown the highest photostability (Figure 2). These measurements revealed almost complete loss of photoswitchability over 7 cycles, whereas the compound 2b showed only slight deterioration (Figure 3). The more electron-rich two-methyl

• indeed show photochromicity; in the case of a naphthyl substituent even to a significant extent. In all cases, however, the absorption cross-section was much smaller than for the 2-methyl compounds. More importantly, the one-methyl derivatives showed lower photostability, thermal stability, reversibility

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

• evaluate the photostability of 4-thiothymidine (S4TdR) in the presence of CDs, the formation of inclusion complexes involving aqueous solutions of S4TdR and five CDs (namely 2-HP-α-CD, 2-HP-β-CD, 2-HP-γ-CD, DIMEB CD, and TRIMEB CD) were investigated by different spectroscopic techniques (UV–vis, FTIR–ATR

Synthesis and properties of novel star-shaped oligofluorene conjugated systems with BODIPY cores

• Clara Orofino-Pena,
• Diego Cortizo-Lacalle,
• Joseph Cameron,
• Muhammad T. Sajjad,
• Pavlos P. Manousiadis,
• Neil J. Findlay,
• Alexander L. Kanibolotsky,
• Dimali Amarasinghe,
• Peter J. Skabara,
• Tell Tuttle,
• Graham A. Turnbull and
• Ifor D. W. Samuel

Beilstein J. Org. Chem. 2014, 10, 2704–2714, doi:10.3762/bjoc.10.285

• ,4a-diaza-s-indacene unit has attracted much attention due to the properties it imparts to the compounds that contain it, such as efficient luminescence, high absorptivity, good photostability and solubility in common solvents [1][2][3][4]. Due to these properties, BODIPY-containing conjugated systems

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

• used in the active layer of OPV devices as they show high absorption coefficients, good photostability and chemical robustness. Although the BODIPY unit has been incorporated in conjugated polymers [35][36][37] and tested in OPVs with moderate PCEs [38][39], several small molecules containing BODIPY

Encapsulation of biocides by cyclodextrins: toward synergistic effects against pathogens

• Véronique Nardello-Rataj and
• Loïc Leclercq

Beilstein J. Org. Chem. 2014, 10, 2603–2622, doi:10.3762/bjoc.10.273

• diameter of the capped particles was smaller than uncapped ones (up to 3-fold). Moreover, these nanoparticles have superior photostability to intense ultraviolet radiation and significantly higher antibacterial activity (up to 3.5-fold) were obtained against E. coli, P. aeruginosa and S. aureus. As the β

An integrated photocatalytic/enzymatic system for the reduction of CO₂ to methanol in bioglycerol–water

• Michele Aresta,
• Angela Dibenedetto,
• Tomasz Baran,
• Antonella Angelini,
• Przemysław Łabuz and
• Wojciech Macyk

Beilstein J. Org. Chem. 2014, 10, 2556–2565, doi:10.3762/bjoc.10.267

• the chemical stability and photostability of photocatalysts, are also under continuous investigation for their further improvement and bring the whole reaction closer to a potential application. Conclusion Titanium dioxide modified with chromium(III) complex, [CrF5(H2O)]2−@TiO2, exhibits great ability

• investigation together with other parameters, such as the optimization of the photosystem for a more efficient NAD+ reduction, the improvement of the reaction selectivity, the increase of the absorption coefficient, and the increase of the chemical stability and photostability of photocatalysts. The

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

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

• intersystem crossing in the 2,6-HNA platform and strong fluorescence of the 2,6-HNA chromophore (Figure 2) also diminishes formation of the triplet and, thus, its participation in a photo-Favorskii rearrangement. Finally, an indication of the photostability of the 2,6-HNA derivatives had earlier precedence in

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

• two major coenzymes, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), account for the vitamin activity in human nutrition [13]. RF is among the most widely studied compounds in terms of photostability and degradation in aqueous and organic solvents. It shows strong absorption at 223

• diketo compound at around pH 10–12. The latter two photoproducts are formed by the isoalloxazine ring cleavage on alkaline hydrolysis of RF [20][24][32][34][75][76][77]. The pH of the solution has a significant effect on the photostability of RF. Under acidic and neutral pH conditions, RF is

• viscosity The rate of RF photolysis is affected by solvent polarity, which causes changes in the conformation of the ribityl side chain to undergo degradation [83]. RF shows higher photostability in less polar solvents [96]. When RF was irradiated anaerobically in alcohols and alcohol/water mixtures, a

From porphyrin benzylphosphoramidate conjugates to the catalytic hydrogenation of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin

• Marcos C. de Souza,
• Leandro F. Pedrosa,
• Géssica S. Cazagrande,
• Vitor F. Ferreira,
• Maria G. P. M. S. Neves and
• José A. S. Cavaleiro

Beilstein J. Org. Chem. 2014, 10, 628–633, doi:10.3762/bjoc.10.54

• recently synthesized porphyrin diisopropylphosphoramidate conjugates derived from 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPF20). Such compounds showed a high photostability and a good capacity to generate singlet oxygen, but their solubility in water is moderate [4]. Additionally, we tried to

Studies on the photodegradation of red, green and blue phosphorescent OLED emitters

• Susanna Schmidbauer,
• Andreas Hohenleutner and
• Burkhard König

Beilstein J. Org. Chem. 2013, 9, 2088–2096, doi:10.3762/bjoc.9.245

• understanding of the processes at work and to examine whether the photostability in solution and in a solid organic matrix would show a similar behavior. We therefore selected four well-known phosphorescent emitters for a detailed investigation of their photodegradation behavior in solution and in thin polymer

• , though only as a side product, while no indication of halogen abstraction was found for the other two complexes. The influence of dioxygen As cyclometalated Ir-complexes are very efficient singlet oxygen sensitizers we investigated the influence of oxygen on the photostability of the compounds. 1O2 is

• states [14][16][21]. Supposed the molecule is not susceptible to an attack of 1O2, it would be expected that the presence of oxygen in this case actually increases the photostability of the material. This is due to the very fast quenching of the excited state by O2 [22], leading to a significantly

Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features

• Laura Bekere,
• David Gachet,
• Vladimir Lokshin,
• Wladimir Marine and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2013, 9, 1311–1318, doi:10.3762/bjoc.9.147

• patterns. Keywords: fluorescence; hydrogen bond; 1,8-naphthalimide; one- and two-photon absorption; zinc oxide; Introduction 1,8-Naphthalimide derivatives are useful for a variety of applications owing to their strong fluorescence, electroactivity and photostability. These compounds can be employed as

Electron and hydrogen self-exchange of free radicals of sterically hindered tertiary aliphatic amines investigated by photo-CIDNP

• Martin Goez,
• Isabell Frisch and
• Ingo Sartorius

Beilstein J. Org. Chem. 2013, 9, 437–446, doi:10.3762/bjoc.9.46

• presaturation [31], thus the displayed signal intensities correspond to the pure polarizations. Furthermore, NMR spectra taken after a full series of time-resolved CIDNP measurements gave no indication of product formation; the remarkable photostability of the BP/DABCO system has already been reported in the

Hydrophobic analogues of rhodamine B and rhodamine 101: potent fluorescent probes of mitochondria in living C. elegans

• Laurie F. Mottram,
• Safiyyah Forbes,
• Brian D. Ackley and
• Blake R. Peterson

Beilstein J. Org. Chem. 2012, 8, 2156–2165, doi:10.3762/bjoc.8.243

• ) are renowned for their red-shifted fluorescence, photostability, and high quantum yields over a wide range of pH values (i.e., pH 4–10). These fluorophores penetrate cells more readily than analogous fluorescein derivatives, because the negative plasma membrane potential within the cytoplasm of cells

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• step in high yield by the reaction of benzonitrile (or other aromatic nitriles) with succinic acid diesters. Numerous DPP derivatives have since been synthesized, their colours ranging from orange yellow via red to purple. Many DPP derivatives exhibit a high photostability in the solid state, weather