Reversible photoswitching of the DNA-binding properties of styrylquinolizinium derivatives through photochromic [2 + 2] cycloaddition and cycloreversion

• Sarah Kölsch,
• Heiko Ihmels,
• Jochen Mattay,
• Norbert Sewald and
• Brian O. Patrick

Beilstein J. Org. Chem. 2020, 16, 111–124, doi:10.3762/bjoc.16.13

• accomplished. However, it is well known that [2 + 2] photodimerizations can also be performed in the solid state or with a thoroughly stirred suspension [37][43][78]. Therefore, suspensions of 3b und 3c in water were irradiated with an LED lamp at 450–470 nm to give the 2,2'-(2,4-diphenyl-1,3-cyclobutanediyl

• reminiscent of the high stereoselectivity observed for [2 + 2] photodimerizations in organized media or in the solid state [37][38][39][40][41]. Considering the pronounced donor–acceptor interplay in 3b and 3c and the resulting strong dipole moment, it may be proposed that these compounds form dimeric

• aggregates in the solid state and even in solution through dipole–dipole interactions and directional π stacking (Scheme 2), as observed, for example, with donor-substituted benzoquinolizinium derivatives [79] or donor-substituted styrylpyridinium derivatives [80][81][82]. Hence, an ideal overlap of the π

Synthesis and optoelectronic properties of benzoquinone-based donor–acceptor compounds

• Daniel R. Sutherland,
• Nidhi Sharma,
• Georgina M. Rosair,
• Ifor D. W. Samuel,
• Ai-Lan Lee and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2019, 15, 2914–2921, doi:10.3762/bjoc.15.285

• photoluminescence quantum yield (ΦPL) of 3 is poor at 4%. We next investigated the solid-state PL behavior of 3 in a 10 wt %-doped thin film using PMMA as host matrix. The PL spectrum of 3 exhibited two bands, one at 550 nm, corresponding to the emission of 3 and a second high-energy band at 450 nm that was

• attributed to the PMMA host matrix [39]. The narrower emission profile of 3 in the solid state than in DCM solution could be due to the suppression of various nonradiative vibrational modes in the inert host matrix PMMA. Compound 3 showed a low ΦPL of 6% under nitrogen atmosphere. Time-resolved PL

Carbazole-functionalized hyper-cross-linked polymers for CO₂ uptake based on Friedel–Crafts polymerization on 9-phenylcarbazole

• Dandan Fang,
• Xiaodong Li,
• Meishuai Zou,
• Xiaoyan Guo and
• Aijuan Zhang

Beilstein J. Org. Chem. 2019, 15, 2856–2863, doi:10.3762/bjoc.15.279

• ) were similar to the ones for P1–P5. P1–P11 are polymers with very similar chemical structure, which have been proved by FTIR. In addition, we performed solid state 1H NMR and solid state 13C NMR on P3 as a representative sample. The solid state 1H NMR showed peaks in the range of 1.5–3.5 ppm for the

• saturated protons (Supporting Information File 1, Figure S2). Also, the solid state 13C NMR (Figure 2) showed peaks between 25–50 ppm, indicating sp3 carbons [9][16]. The peaks about 139 ppm belong to the substituted aromatic carbon, the peaks about 128 ppm were attributed to the unsubstituted aromatic

• carbon. Based on the above peaks in the solid state NMR, the Friedel–Crafts polymerization product was confirmed. TGA analysis The thermal stability of HCPs was investigated by TGA tests (Figure 3 and Supporting Information File 1, Figure S3). A slight weight loss at 100 °C was observed for P2, P4, P5

One-pot synthesis of substituted pyrrolo[3,4-b]pyridine-4,5-diones based on the reaction of N-(1-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-2-oxo-2-arylethyl)acetamide with amines

• Valeriya G. Melekhina,
• Andrey N. Komogortsev,
• Boris V. Lichitsky,
• Vitaly S. Mityanov,
• Artem N. Fakhrutdinov,
• Arkady A. Dudinov,
• Vasily A. Migulin,
• Yulia V. Nelyubina,
• Elizaveta K. Melnikova and
• Michail M. Krayushkin

Beilstein J. Org. Chem. 2019, 15, 2840–2846, doi:10.3762/bjoc.15.277

• fragments proceeds first, followed by intramolecular cyclization (Scheme 4B). The structure of the 4-chloro-substituted pyrrolopyrimidinone 1e was proven by single crystal X-ray analysis (Figure 1). Despite the unambiguous dominance of the pyridone-based conformation in the solid state of 1e, two tautomers

A combinatorial approach to improving the performance of azoarene photoswitches

• Joaquin Calbo,
• Aditya R. Thawani,
• Rosina S. L. Gibson,
• Andrew J. P. White and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2019, 15, 2753–2764, doi:10.3762/bjoc.15.266

• calculations, the E-isomer of 4pzMe-F2 possesses a fully coplanar structure. Unexpectedly, for 4pzMe-OMe2 the pyrazole and benzene rings occupy two separate planes. Thus, in the solid state, the structure of the E-isomer 4pzMe-OMe2 becomes even more twisted (calculated dihedral angle of 49° versus 78° in the

• crystal structure). We attribute this to a packing effect in the solid state. To the best of our knowledge, an E-isomer azo photoswitch with this type of solid state packing is unprecedented and may open new possibilities in solid state photoswitchable materials applications. The benzene ring in 4pzH-F2

• fluorine atoms, sterics are unlikely to play a role for 4pzH-F2 and we would expect a planar E-isomer, as noted by Hecht and co-workers in their o‑fluoroazobenzenes [13][14]. Thus, once again, solid state packing of these derivatives is surprising. The experimental photoswitching performance of the

Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

• Natascha Breuer,
• Irina Gruber,
• Christoph Janiak and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2019, 15, 2684–2703, doi:10.3762/bjoc.15.262

• well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular

• , dimethylamino-substituted α-pyrones, as donor–acceptor systems, display remarkable photophysical properties, such as strongly red-shifted absorption and emission maxima with daylight fluorescence and fluorescence quantum yields up to 99% in solution and around 11% in the solid state, as well as pronounced

• increasingly used in OLEDs [6][7][8][9][10] and LCDs [11][12][13] of mobile phones [14]. Fluorescent compounds often intensively emit in solution but only weakly or not in the solid state [15]. Dyes which fluoresce both in the solid state and in solution are still relatively rare, due to the fact that often

Synthesis of aryl-substituted thieno[3,2-b]thiophene derivatives and their use for N,S-heterotetracene construction

• Nadezhda S. Demina,
• Nikita A. Kazin,
• Nikolay A. Rasputin,
• Roman A. Irgashev and
• Gennady L. Rusinov

Beilstein J. Org. Chem. 2019, 15, 2678–2683, doi:10.3762/bjoc.15.261

• transfer because of their tendency to π-stack, with non-bonded sulfur–sulfur interactions in the solid state, which results in large intermolecular orbital coupling of HOMOs and, as a consequence, enhanced carrier transport properties [10]. However, there is a problem of poor solubility of a number of S

AgNTf₂-catalyzed formal [3 + 2] cycloaddition of ynamides with unprotected isoxazol-5-amines: efficient access to functionalized 5-amino-1H-pyrrole-3-carboxamide derivatives

• Ziping Cao,
• Jiekun Zhu,
• Li Liu,
• Yuanling Pang,
• Laijin Tian,
• Xuejun Sun and
• Xin Meng

Beilstein J. Org. Chem. 2019, 15, 2623–2630, doi:10.3762/bjoc.15.255

• %) in DCE (2.0 mL) at 80 °C, unless otherwise noted. Isolated yields are provided. Scope with regard to the 5-aminoisoxazole 8 (see Figure 2). aReaction conditions: 2.0 equiv of 8e, 100 °C. Molecular structure in the solid state of compound 10ad. Two modes of reactions of alkynes by silver catalysis

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• vinylogues of recently reported acylphosphonium zwitterions [25]. Structural studies The solid-state molecular structures of betaines E-3a, E-3b, E-3e and Z-3e were determined by single-crystal X-ray diffraction analysis and are shown in Figures 2–5. Some data characterizing the bonding geometry of the P+–C1

• triflamide anion departs, remain to be answered. Phosphonium betaines 3 prepared. An E:Z ratio of 100:0 means that only the E-isomer was observed in the NMR spectra. Solid-state structure of E-3a (ORTEP plot), two symmetry-independent molecules in the triclinic unit cell. Solid-state structure of E-3b·CH2Cl2

• (ORTEP plot); CH2Cl2 solvate molecule not shown. Solid-state structure of E-3e·H2O·CH2Cl2 (ORTEP plot). The CH2Cl2 solvate molecule is disordered. Hydrogen-bonded H2O molecule: O1···O2 2.907(2) Å, angle O1···H–O2 169(3)°. Solid-state structure of Z-3e (ORTEP plot). Stable betaines I–IV. Reactions of N

Anion-driven encapsulation of cationic guests inside pyridine[4]arene dimers

• Anniina Kiesilä,
• Jani O. Moilanen,
• Anneli Kruve,
• Christoph A. Schalley,
• Perdita Barran and
• Elina Kalenius

Beilstein J. Org. Chem. 2019, 15, 2486–2492, doi:10.3762/bjoc.15.241

• "through-wall" electrostatic interactions. Results and Discussion We have previously shown that tetraisobutylpyridine[4]arene forms hydrogen-bonded dimers with eight intermolecular N–H···O(amide) hydrogen bonds in the solid state, in solution and in the gas phase [11]. Resorcinarene capsules of similar

• similar affinity towards the Me4N+ cation as 2. Also, all our attempts to obtain a solid-state single crystal structure of 1 with a cationic guest were unsuccessful. It is possible that the observation of such complexes requires special conditions present in the ESI source. To obtain more detailed

Experimental and computational electrochemistry of quinazolinespirohexadienone molecular switches – differential electrochromic vs photochromic behavior

• Eric W. Webb,
• Jonathan P. Moerdyk,
• Kyndra B. Sluiter,
• Benjamin J. Pollock,
• Amy L. Speelman,
• Eugene J. Lynch,
• William F. Polik and
• Jason G. Gillmore

Beilstein J. Org. Chem. 2019, 15, 2473–2485, doi:10.3762/bjoc.15.240

• the solid state [21]), in solution showed the expected 3a chemical shifts but also smaller peaks (ca. 20% relative to 3a) with similar splitting and chemical shifts as those for photogenerated 4a (to which we initially erroneously attributed them [21]). However, the frequencies for this solvatochromic

Self-assembled coordination thioether silver(I) macrocyclic complexes for homogeneous catalysis

• Zhen Cao,
• Aline Lacoudre,
• Cybille Rossy and
• Brigitte Bibal

Beilstein J. Org. Chem. 2019, 15, 2465–2472, doi:10.3762/bjoc.15.239

• . These silver(I) complexes adopted similar structures in solution and in the solid state. As each sulfur atom in the ligand is prochiral, macrocycles L2M2 were obtained as mixtures of diastereoisomers, depending on the configurations of the sulfur atoms coordinated to silver cations. The X-ray structures

• the coordinated ligands (head-to-head or head-to-tail) resulting into different spatial arrangements. In solution, the architectures of silver(I) complexes with ligand syn-1 seemed to be similar to the solid-state structures. The silver(I) complexes were evaluated as homogeneous catalysts in two

Ultrafast processes triggered by one- and two-photon excitation of a photochromic and luminescent hydrazone

• Alessandro Iagatti,
• Baihao Shao,
• Alberto Credi,
• Barbara Ventura,
• Ivan Aprahamian and
• Mariangela Di Donato

Beilstein J. Org. Chem. 2019, 15, 2438–2446, doi:10.3762/bjoc.15.236

• -photon excitation (i.e., near infrared (NIR) light), which is also maintained in serum and solid state, has a very high photochemical stability and excellent fatigue resistance. Although the main photochemical properties of this molecule have been recently reported [29], a detailed analysis of its

Photochromic diarylethene ligands featuring 2-(imidazol-2-yl)pyridine coordination site and their iron(II) complexes

• Andrey G. Lvov,
• Max Mörtel,
• Anton V. Yadykov,
• Frank W. Heinemann,
• Valerii Z. Shirinian and
• Marat M. Khusniyarov

Beilstein J. Org. Chem. 2019, 15, 2428–2437, doi:10.3762/bjoc.15.235

• at the iron(II) ion at room temperature (rt) in solution via ligand photocyclization [19]. More recently, the remarkable photoswitching between high-spin and low-spin states at rt in the solid state and thin films was demonstrated [20][21][22]. Kawai et al. obtained a luminescent complex of europium

Reversible switching of arylazopyrazole within a metal–organic cage

• Anton I. Hanopolskyi,
• Soumen De,
• Michał J. Białek,
• Yael Diskin-Posner,
• Liat Avram,
• Moran Feller and
• Rafal Klajn

Beilstein J. Org. Chem. 2019, 15, 2398–2407, doi:10.3762/bjoc.15.232

• arylazopyrazoles, that 2 would similarly encapsulate E-1. Results and Discussion Arylazopyrazole E-1 has a very low solubility in water and its encapsulation in cage 2 was attempted from the solid state. Encouragingly, when a colorless aqueous solution of 2 was stirred with an excess of solid E-1, it turned to

Thermal stability of N-heterocycle-stabilized iodanes – a systematic investigation

• Andreas Boelke,
• Yulia A. Vlasenko,
• Mekhman S. Yusubov,
• Boris J. Nachtsheim and
• Pavel S. Postnikov

Beilstein J. Org. Chem. 2019, 15, 2311–2318, doi:10.3762/bjoc.15.223

• Federation Department of Solid State Engineering, University of Chemistry and Technology, 16628 Prague, Czech Republic 10.3762/bjoc.15.223 Abstract The thermal stability of pseudocyclic and cyclic N-heterocycle-stabilized (hydroxy)aryl- and mesityl(aryl)-λ3-iodanes (NHIs) through thermogravimetric analysis

Small anion-assisted electrochemical potential splitting in a new series of bistriarylamine derivatives: organic mixed valency across a urea bridge and zwitterionization

• Keishiro Tahara,
• Tetsufumi Nakakita,
• Alyona A. Starikova,
• Takashi Ikeda,
• Masaaki Abe and
• Jun-ichi Kikuchi

Beilstein J. Org. Chem. 2019, 15, 2277–2286, doi:10.3762/bjoc.15.220

• . Such N–H···F hydrogen-bond formation was also reported for other urea derivatives with PF6− as counteranion in the solid state [54][55]. The N···F distance of 2.85 Å in 1b+–PF6− is slightly longer than that observed in the crystal structure of a silver complex having a pyridyl urea ligand (2.67 and

Aggregation-induced emission effect on turn-off fluorescent switching of a photochromic diarylethene

• Luna Kono,
• Yuma Nakagawa,
• Ayako Fujimoto,
• Ryo Nishimura,
• Yohei Hattori,
• Toshiki Mutai,
• Nobuhiro Yasuda,
• Kenichi Koizumi,
• Satoshi Yokojima,
• Shinichiro Nakamura and
• Kingo Uchida

Beilstein J. Org. Chem. 2019, 15, 2204–2212, doi:10.3762/bjoc.15.217

• , fluorescence switching for molecular level recording [4], multiple-fluorescence for logic circuits [5] as well as biological applications [6] and super-resolution microscopy for bio-imaging [7][8]. The fluorescence switching in solid state is attracting much attention from both scientific and technological

• mm quartz cell, which was then placed in the integral sphere. The quantum yield was calculated using an installed software. The solid-state absorption spectrum was obtained by Kubelka–Munk conversion of a diffractive reflectance spectrum of the above mixture measured on a JASCO FP-6600

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• the solid state the movement of the molecules is restricted because of charge-transfer complexes between NDI and Cl−, Br− or I−. Because macrocycle 13 precipitated in less polar organic solvents upon addition of halides, the binding affinities were studied in DMSO in which the binding constants for Cl

1,2,3,4-Tetrahydro-1,4,5,8-tetraazaanthracene revisited: properties and structural evidence of aromaticity loss

• Arnault Heynderickx,
• Sébastien Nénon,
• Olivier Siri,
• Vladimir Lokshin and
• Vladimir Khodorkovsky

Beilstein J. Org. Chem. 2019, 15, 2059–2068, doi:10.3762/bjoc.15.203

• the presence of two H-donor (N–H) and two H-acceptor (N=C) sites that can lead to well organized H-bonded arrangements in the solid state. Moreover, the presence of two different types of nitrogen atoms affords the possibility to be selectively substituted at the desired position. Here we revisited

• bond lengths. The dominant motive seen for 3 in the solid state is the formation of infinite chains based on N–H···N=C hydrogen bonds (N···N distances 3.011–3.047 Å, Figure 9). The crystal lattice of 6a (Figure 10) also exhibits the presence of the infinite chains >N–H···Cl−···H–N+: the Cl−···N and Cl

• supramolecular array generated by 3 in the solid state. Color coding: nitrogen, blue; carbon, grey. View of the supramolecular array generated by 6a in the solid state. Color coding: nitrogen, blue; carbon, grey, chloride, green. View of the supramolecular array generated by 7a in the solid state. Color coding

Fluorinated azobenzenes as supramolecular halogen-bonding building blocks

• Esther Nieland,
• Oliver Weingart and
• Bernd M. Schmidt

Beilstein J. Org. Chem. 2019, 15, 2013–2019, doi:10.3762/bjoc.15.197

• building blocks both in solution and in the solid state in combination with neutral halogen bonding acceptors, such as lutidines. Therefore, we investigate the photochemistry of a series of azobenzene photoswitches. Upon introduction of iodoethynyl groups, the halogen bonding donor properties are

• noncovalent interaction between a polarized halogen atom (the halogen bond donor) and a Lewis base (the halogen bond acceptor) [1][2]. A prominent example regarding the origin of halogen bonding can be found in inorganic solid-state chemistry. The structurally diverse group of polyiodides, with its rich

• ) and E-4,4’-di(iodoethynyl)perfluoroazobenzene (A3) halogen bond donors can be combined with rigid u-shaped anthracene building blocks, bearing two 3,5-lutidine acceptors in 1 and 8 positions, to form self-assembled boxes of 25–30 Å length in solution and in the solid state [35]. We chose azobenzene

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• appeared that the product was unstable, which was unexpected since Albrecht has reported that their complexes were stable for months in both solution and the solid state. Even our own model study showed that the complex was easy to work with and manipulate, but we needed to concede that the calix[4]arene

Synthesis and anion binding properties of phthalimide-containing corona[6]arenes

• Meng-Di Gu,
• Yao Lu and
• Mei-Xiang Wang

Beilstein J. Org. Chem. 2019, 15, 1976–1983, doi:10.3762/bjoc.15.193

• conveniently by means of a macrocyclic condensation reaction between N-functionalized 3,6-dihydroxyphthalimides and 3,6-dichlorotetrazine under mild conditions in a one-pot reaction manner. The novel macrocycles exist as a mixture of rapidly interconvertible conformers in solution while in the solid state they

• adopt the conformation in which three phthalimide units are cis,trans-orientated. Acting as electron-deficient macrocyclic hosts, the synthesized O6-corona[3]arene[3]tetrazines self-regulated conformational structures to complex anions in the gas phase and in the solid state owing to the anion–π

• -corona[6]arenes in the solid state, high quality single crystals of 3a were grown at room temperature from diffusion of diethyl ether vapor into the solution of 3a in acetonitrile. X-ray diffraction analysis revealed that the macrocycle 3a adopted an interesting conformation. As depicted in Figure 1, it

Halide metathesis in overdrive: mechanochemical synthesis of a heterometallic group 1 allyl complex

• Ross F. Koby,
• Nicholas R. Rightmire,
• Nathan D. Schley,
• Timothy P. Hanusa and
• William W. Brennessel

Beilstein J. Org. Chem. 2019, 15, 1856–1863, doi:10.3762/bjoc.15.181

• ]∞, enable an otherwise unfavorable halide metathesis to proceed with mechanochemical assistance. From this result, we demonstrate that ball milling and unexpected solid-state effects can permit seemingly unfavored reactions to occur. Keywords: caesium; entropy; intermolecular forces; mechanochemistry

• likely to be isolated. The high concentration of reagents in a solid-state reaction may influence product formation as well. The possibility of partial exchange also needs to be considered. If the caesium iodide were insufficiently reactive, a starting ratio of 3:1 for [KA']:CsI could give rise to

• kJ mol−1; Table 1, entries 3 and 4). Of course, these are calculations on isolated monomers, and the energetics of formation of the solid-state polymeric forms [30] would be expected to change these values, but not necessarily in a way that would clearly favor the formation of [CsA'] over [KA']. If

Complexation of 2,6-helic[6]arene and its derivatives with 1,1′-dimethyl-4,4′-bipyridinium salts and protonated 4,4'-bipyridinium salts: an acid–base controllable complexation

• Jing Li,
• Qiang Shi,
• Ying Han and
• Chuan-Feng Chen

Beilstein J. Org. Chem. 2019, 15, 1795–1804, doi:10.3762/bjoc.15.173

• both 1,1′-dimethyl-4,4'-bipyridinium salts and protonated 4,4'-bipyridinium salts in solution and in the solid state. Especially, the helic[6]arene and its derivatives containing 2-hydroxyethoxy or 2-methoxyethoxy groups exhibited stronger complexation with the guests than the other helic[6]arene

• protonated 4,4'-bipyridinium salts (Figure 1) in both solution and in the solid state. We found that the helic[6]arene and its derivatives containing 2-hydroxyethoxy or 2-methoxyethoxy groups showed stronger complexation with the guests than the other helic[6]arene derivatives. This result can be explained

• ·G3−2PF6]2+, [H5·G3−2PF6]2+, [H1·G4−2BArF]2+, [H2·G4−2BArF]2+, [H4·G4−2BArF]2+, [H5·G4−2BArF]2+ were observed, which further confirmed the formation of the 1:1 host–guest complexes (Supporting Information File 1, Figures S41–S55). Host–guest complexation in the solid state The single crystal of