Characterization of the synthetic cannabinoid MDMB-CHMCZCA

• Carina Weber,
• Stefan Pusch,
• Dieter Schollmeyer,
• Sascha Münster-Müller,
• Michael Pütz and
• Till Opatz

Beilstein J. Org. Chem. 2016, 12, 2808–2815, doi:10.3762/bjoc.12.279

• kcal/mol were selected from this set, the structures were confirmed as local minima (no imaginary frequencies), and the geometries were used for the excited-state calculations. ECD spectra were calculated using TD-DFT (number of states: 75) at the TD- and TDA-B3LYP/6-311++G** [23][24][25][26][27][28

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

• moment of the electronic shift additionally. However, the large displacement of electron density from one part of the π-system to another enforces a geometrical equilibration of the nuclei which triggers the emission event to take place from a considerably relaxed excited state. As a consequence, the

Copper-catalyzed asymmetric sp³ C–H arylation of tetrahydroisoquinoline mediated by a visible light photoredox catalyst

• Pierre Querard,
• Inna Perepichka,
• Eli Zysman-Colman and
• Chao-Jun Li

Beilstein J. Org. Chem. 2016, 12, 2636–2643, doi:10.3762/bjoc.12.260

• , entries 7 and 8). A tentative reaction mechanism has been proposed in Scheme 3, in order to rationalize this arylation reaction. Upon visible light irradiation, [Ir(ppy)2(dtbbpy)]PF6 I was converted into an excited state II, Ir(III)* [11][33][34][35][36][37]. The THIQ undergoes a single electron transfer

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

• oligophenothiazines [45]. However, the lack of a systematic trend with the numbers of phenothiazinyl units indicates that the excited state property is strongly affected by local conformational biases arising from the planarization of electronic ground state butterfly conformation of phenothiazines in the excited

• 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

Enantioconvergent catalysis

• Justin T. Mohr,
• Jared T. Moore and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2016, 12, 2038–2045, doi:10.3762/bjoc.12.192

• visible light (Scheme 4) [27]. Although the mechanism continues to be studied, it is hypothesized that irradiation of the copper–carbazole complex leads to an excited-state adduct that is capable of generating achiral tertiary alkyl radical intermediates through electron transfer with a racemic alkyl

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

• exhibit S1→S0 fluorescence under low excitation intensity, azulene shows fluorescence predominantly from the S2 excited state and only very weakly from S1 [18]. The control of the optical and electronic properties of the azulene-based materials can be finely tuned by careful selection of the substitution

• the second excited state localized in the azulene-fused ring. The shorter wavelength absorption is assigned to the transition to the fourth excited state comprised of excitation occurring on the azulene ring mixed with some azulene→terpy charge transfer. Emission spectra The observed S2→S0 emission

• . Orbital origin of spectra The most important Kohn–Sham orbitals (ψi) playing an active role in the calculated electronic transitions are shown in Figure 6 along with their energies. The nature of the excited state(s) accessed through electronic transitions are listed in Table 4 is a contribution of

Synthesis and characterization of benzodithiophene and benzotriazole-based polymers for photovoltaic applications

• Desta Gedefaw,
• Marta Tessarolo,
• Margherita Bolognesi,
• Mario Prosa,
• Renee Kroon,
• Wenliu Zhuang,
• Patrik Henriksson,
• Kim Bini,
• Ergang Wang,
• Michele Muccini,
• Mirko Seri and
• Mats R. Andersson

Beilstein J. Org. Chem. 2016, 12, 1629–1637, doi:10.3762/bjoc.12.160

• the first case ionized states are generated, while after light absorption the excited state is based on electrons and holes electrostatically bound [30]. Moreover, an energetic barrier between the electrode surface and the polymer film can further contribute to increase the electrochemically derived

Star-shaped and linear π-conjugated oligomers consisting of a tetrathienoanthracene core and multiple diketopyrrolopyrrole arms for organic solar cells

• Hideaki Komiyama,
• Chihaya Adachi and
• Takuma Yasuda

Beilstein J. Org. Chem. 2016, 12, 1459–1466, doi:10.3762/bjoc.12.142

• , and associated oscillator strengths (f) for TTA-DPP4 and TTA-DPP2 calculated at the B3LYP/6-31G(d,p) level. The arrows indicate the first singlet–excited state (S1) transition. The alkyl chains are modified to methyl groups to simplify the calculations. TGA curves of TTA-DPP4 and TTA-DPP2 at a heating

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

• nonsteroidal anti-inflammatory drug that contains the 2-benzoylthiophene (BZT) chromophore and has a π,π* lowest triplet excited state. In the present work, dyads (S)- and (R)-SP-α-Ch (1 and 2), as well as (S)-SP-β-Ch (3) have been prepared from β- or α-Ch and SP to investigate the possible competition between

• significantly more photoreactive than 1 indicating a clear stereodifferentiation in the photochemical behavior. Transient absorption spectra obtained for 1–3 were very similar and matched that described for the SP triplet excited state (typical bands with maxima at ca. 350 nm and 600 nm). Direct kinetic

• singlet oxygen, thus being able to initiate Ch oxidation from their triplet excited states following either of the two competing mechanistic pathways. Keywords: aryl ketones; hydrogen abstraction; lipid peroxidation; photoproducts; triplet excited state; Introduction Among the constituents of cell

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

• by a charge shift (CS) in the excited state and subsequent solvent relaxation. Furthermore, the polarity of protic polar and aprotic polar solvents affects the emission energy to different extent, which indicates a major influence of hydrogen bonding on the stabilization of the ground and excited

• emission lifetime. Notably, a considerable number of solvatochromic molecules is based on charge-transfer (CT) processes in the excited state resulting from a pronounced donor–acceptor interplay within the fluorophore [8]. Thus, upon excitation of such compounds, a CT – or in charged species a charge shift

• (CS) – takes place that results in a significantly different electron distribution of the molecule in the excited state as compared to the ground state. As a consequence, the solvent molecules reorganize to re-establish an optimal stabilization of the molecules in the excited state, which is usually

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

• , ROS (namely singlet oxygen, superoxide ions and hydrogen peroxide), generated via the excited state of the PS, destroy the PS itself. Because of this, the effort to preserve the PS is one of main issues. Regarding S4TdR, as a result of its photodynamic activity, the thiobase can be destroyed by a

Bright molecules for sensing, computing and imaging: a tale of two once-troubled cities

• A. Prasanna de Silva

Beilstein J. Org. Chem. 2015, 11, 2774–2784, doi:10.3762/bjoc.11.298

• compete for the deactivation of the same excited state, it was equally clear that a luminescence signal could be switched ‘on’ by chemical command. Therefore, we were fortunate to be able to introduce a general design tool of luminescent PET sensing/switching [11][12][13][14][15], which even handled

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

• 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

• that is comparable to that of 3a (kr = 5.3–6.4 × 107 s−1 for the two species), but its non-radiative deactivation pathway is almost entirely suppressed. Therefore, it may be concluded that the phosphonato group exerts a significant influence on the excited state deactivation kinetics of 3a. This

• influence may be attributed to the highly polar nature of the phosphonato group (electrostatic interaction between C=O and P=O dipoles may hamper rotations in the lateral chain responsible for non-radiative deactivation of the excited state). Another factor to be taken into consideration is the possibility

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

• diffraction. 2-(2-Benzoxa(thia)zolyl)-6-alkoxycarbonylphenols display intense green fluorescence with anomalous Stokes shifts caused by the excited state intramolecular proton transfer (ESIPT) effects. Keywords: β-tropolones; fluorescence; intramolecular hydrogen bond; tautomerism; X-ray analysis

• which has attracted much attention due to the applications in various molecular probes and luminescent materials because of the remarkable photophysical properties of the ESIPT (excited state intramolecular proton transfer) chromophores [33][34]. UV-irradiation of solutions of these compounds in

Photoinduced 1,2,3,4-tetrahydropyridine ring conversions

• Baiba Turovska,
• Henning Lund,
• Viesturs Lūsis,
• Anna Lielpētere,
• Edvards Liepiņš,
• Sergejs Beljakovs,
• Inguna Goba and
• Jānis Stradiņš

Beilstein J. Org. Chem. 2015, 11, 2166–2170, doi:10.3762/bjoc.11.234

• potential of excited molecules is shifted to negative values (ΔE = ~2 V) compared to their ground state [21][22][23]. For example the oxidation potential of 9,10-dihydro-10-methylacridine is +0.80 V [23], which is shifted to −3.10 V in the singlet excited state [23]. The recorded UV–vis spectrum of 1

• the sunlight in summer at 300 nm is sufficient to initiate the photooxygenation of 1. Direct reactions of dioxygen with organic substrates in the absence of a catalyst are usually slow, unless the substrate is a particularly good reducing agent. Excited state species are easier to oxidize than the

Probing multivalency in ligand–receptor-mediated adhesion of soft, biomimetic interfaces

• Stephan Schmidt,
• Hanqing Wang,
• Daniel Pussak,
• Simone Mosca and
• Laura Hartmann

Beilstein J. Org. Chem. 2015, 11, 720–729, doi:10.3762/bjoc.11.82

• (Scheme 1). It is known that benzophenone can absorb the energy of photons to excite the electron in its carbonyl group from ground state (S0) to the excited state (S1) or (S2) depending on the wavelength used. Subsequently, the excited electron can go to the triple state (T1) through intersystem crossing

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

• of 24% (in aqueous glycine buffer at pH 10.7), the profile of the band mirrors the absorption with a maximum at 558 nm which is in keeping with little reorganization in the excited state and characteristic of a singlet emitter. The modest Stokes shift (Δss = 1020 cm−1) and the short excited state

• large Stokes shift of 6850 cm−1 and a longer excited state life time (τ = 71.7 ns) [72]. Again the excitation spectrum matches the absorption one proving that aggregation is unlikely under the used aqueous conditions. From a general point of view, fluorescent probes have been used for the detection of

Photocatalytic nucleophilic addition of alcohols to styrenes in Markovnikov and anti-Markovnikov orientation

• Martin Weiser,
• Sergej Hermann,
• Alexander Penner and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2015, 11, 568–575, doi:10.3762/bjoc.11.62

• photoirradiation by both sunlight and green light-emitting diodes. Furthermore, based on Ered(PDI/PDI●−) = −0.28 V (measured by cyclic voltammetry, vs SCE, see Supporting Information File 1) and E00 = 2.35 eV (see Supporting Information File 1), PDI is an electron deficient chromophore with an excited state

Fluoride-driven ‘turn on’ ESPT in the binding with a novel benzimidazole-based sensor

• Kai Liu,
• Xiaojun Zhao,
• Qingxiang Liu,
• Jianzhong Huo,
• Bolin Zhu and
• Shihua Diao

Beilstein J. Org. Chem. 2015, 11, 563–567, doi:10.3762/bjoc.11.61

• is important to human health (for example, dental care, osteoporosis and osteosarcoma). To realize the high selectivity and sensitivity to fluoride, many anion fluorescent sensors have been designed based upon numerous signal mechanisms [4][8][9][10]. However, excited-state intra/intermolecular

• atom is transferred to an electronegative atom at the excited state [2][17][18]. By regulating the proton acidity of the H-bond donor which plays a vital role in the ESPT process, the biologically and chemically important anion would be distinguished by the different optical outputs for the interaction

Eosin Y-catalyzed visible-light-mediated aerobic oxidative cyclization of N,N-dimethylanilines with maleimides

• Zhongwei Liang,
• Song Xu,
• Wenyan Tian and
• Ronghua Zhang

Beilstein J. Org. Chem. 2015, 11, 425–430, doi:10.3762/bjoc.11.48

• form N,N-dimethylanilines 1 and maleimides 2 is depicted in Scheme 3. On absorption of visible light, the ground state of Eosin Y (EY) is induced to its single excited state (1EY*), which moves to its more stable triplet excited state (3EY*) through inter system crossing (ISC) [46][47]. 3EY* may

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

• and n = 6 for 10b) contribute considerably to the interaction between the palladium and oligomer molecules in the ground (non-excited) state. However, at the same time, the fluorescence quenching efficiency exhibited almost a two fold increase for the PAE 10b (Q = 47) in comparison with the PAE 10a (Q

• = 26). This illustrates the significant contribution of the aforementioned triple bond to the interaction of Pd2+ with oligomer molecules in the excited state (Figure 10 and Figure 11). Moreover, the increased quenching efficiency of the PAE 10b with shorter chains and an additional ethynyl moiety in

Articulated rods – a novel class of molecular rods based on oligospiroketals (OSK)

• Pablo Wessig,
• Roswitha Merkel and
• Peter Müller

Beilstein J. Org. Chem. 2015, 11, 74–84, doi:10.3762/bjoc.11.11

• these types should therefore facilitate very interesting applications for ARs. As mentioned above, compound 32a can serve as a probe for this equilibrium owing to the pyrene moieties. As many polyaromatic hydrocarbons pyrene possess a marked tendency to form excimers in the excited state [23]. The broad

An improved procedure for the preparation of Ru(bpz)₃(PF₆)₂ via a high-yielding synthesis of 2,2’-bipyrazine

• Danielle M. Schultz,
• James W. Sawicki and
• Tehshik P. Yoon

Beilstein J. Org. Chem. 2015, 11, 61–65, doi:10.3762/bjoc.11.9

• )32+) [10] has emerged as one of the most useful transition metal photocatalysts for oxidatively induced organic transformations (Figure 1). Due to the electron-deficient nature of its bipyrazyl ligands, the excited state redox potential of 2 is quite positive (+1.45 V vs SCE) [11]. Consequently, it

Visible-light-induced bromoetherification of alkenols for the synthesis of β-bromotetrahydrofurans and -tetrahydropyrans

• Run Lin,
• Hongnan Sun,
• Chao Yang,
• Youdong Yang,
• Xinxin Zhao and
• Wujiong Xia

Beilstein J. Org. Chem. 2015, 11, 31–36, doi:10.3762/bjoc.11.5

• upon the above results, the mechanism is proposed as shown in Scheme 2. Firstly, oxidative quenching of the visible-light-induced excited state Ru(bpy)32+* by CBr4, generates Br− along with the Ru(bpy)33+ complex. Then bromine was generated in situ through the oxidation of Br− by Ru(bpy)33+ [16

One-pot functionalisation of N-substituted tetrahydroisoquinolines by photooxidation and tunable organometallic trapping of iminium intermediates

• Joshua P. Barham,
• Matthew P. John and
• John A. Murphy

Beilstein J. Org. Chem. 2014, 10, 2981–2988, doi:10.3762/bjoc.10.316

• accessing the excited state [18][34][36]. The ability to adjust oxidising power through photocatalyst choice renders the transformation substrate-tunable. Thus, we selected photoredox catalysis as an oxidative functionalisation whose substrate scope might be extended (by catalyst selection) in future