Multiswitchable photoacid–hydroxyflavylium–polyelectrolyte nano-assemblies

• Alexander Zika and
• Franziska Gröhn

Beilstein J. Org. Chem. 2021, 17, 166–185, doi:10.3762/bjoc.17.17

• particles, and information on the molecular structure was gained by UV–vis spectroscopy. Isothermal titration calorimetry (ITC) provided information on the thermodynamics and interaction forces in the supramolecular assembly formation. Keywords: electrostatic self-assembly; hydroxyflavylium

• nanoscale structure, as indicated in Scheme 3. To gain fundamental understanding on these possibilities, different trigger paths and the dependency on the assembly composition were studied with regard to the effect on the nano-assembly characteristics by dynamic and static light scattering, UV–vis

• followed with UV–vis spectroscopy to monitor the differences between the states. As can be seen in Figure 1, the different forms of Flavy vary in the light absorption. While the forms A and AH+ show an absorption at λ = 500 and λ = 550 nm, respectively, due to their expanded electronic system, the

Insight into functionalized-macrocycles-guided supramolecular photocatalysis

• Minzan Zuo,
• Krishnasamy Velmurugan,
• Kaiya Wang,
• Xueqi Tian and
• Xiao-Yu Hu

Beilstein J. Org. Chem. 2021, 17, 139–155, doi:10.3762/bjoc.17.15

• authenticated by isothermal calorimetric titration or fluorescence titration and stopped-flow analysis. Furthermore, the quantum yield and reaction velocity of the photocatalysis can be verified by actinometry and UV–vis measurements. Therefore, with the aid of various analytical and spectroscopic studies, we

Tuning the solid-state emission of liquid crystalline nitro-cyanostilbene by halogen bonding

• Subrata Nath,
• Alexander Kappelt,
• Matthias Spengler,
• Bibhisan Roy,
• Jens Voskuhl and
• Michael Giese

Beilstein J. Org. Chem. 2021, 17, 124–131, doi:10.3762/bjoc.17.13

• assemblies by UV–vis and fluorescence spectroscopy. The NO2-Cn building blocks are moderately fluorescent in the solid state and F4St as well as F4Az show no significant fluorescence. However, upon formation of the halogen-bonded assemblies the fluorescence of the materials is significantly changed. Since

Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies

• Cheng Qian,
• Yuan Chen,
• Qian Zhao,
• Ming Cheng,
• Chen Lin,
• Juli Jiang and
• Leyong Wang

Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6

• carboxyl groups in DGG. Moreover, the morphologies of rac-TBPP/DGG co-gels might be different due to the changing stoichiometric ratios. In order to get an indepth understanding on the inversion of CPL handedness, rac-TBPP/DGG co-gels at molar ratios of 1:16 and 1:80 were explored further by UV–vis and

• FTIR (fourier transform infrared) spectra. UV–vis absorption spectra of rac-TBPP/DGG co-gels exhibited a strong absorption band at 333 nm, assigned to the conjugated structure of benzene and pyridine in the rac-TBPP (Figure 3a). However, a red-shift broaden absorption band situated at 372 nm appears in

• spectra of rac-TBPP/DGG co-gel (red line) and rac-TBPP/LGG (blue line) co-gel at the molar ratio of 1:80. (a) UV–vis absorption spectra of rac-TBPP and rac-TBPP/DGG co-gel (rac-TBPP/DGG = 1:80). (b) FTIR spectra of DGG and rac-TBPP/DGG co-gels at molar ratios of 1:80 and 1:16, respectively. SEM images of

Control over size, shape, and photonics of self-assembled organic nanocrystals

• Chen Shahar,
• Yaron Tidhar,
• Yunmin Jung,
• Haim Weissman,
• Sidney R. Cohen,
• Ronit Bitton,
• Iddo Pinkas,
• Gilad Haran and
• Boris Rybtchinski

Beilstein J. Org. Chem. 2021, 17, 42–51, doi:10.3762/bjoc.17.5

• , followed by the immediate evaporation of THF in a high-vacuum and adding water to reach a 1 × 10−4 M concentration. The self-assembly is instantaneous, as indicated by a color change from bright orange to pink in all systems. UV–vis spectra of compound 1 in aqueous medium exhibit a 0-0/0-1 vibronic band

• applicability of organic nanocrystals. Experimental General information The 1H and 13C NMR spectra were recorded at 20 °C on a 300 MHz NMR spectrometer (Bruker). Electrospray ionization (ESI) mass spectrometry was performed using a Micromass Platform instrument. UV–vis absorption and fluorescence measurements

• ) and Origin 7.5 (OriginLab) softwares. Chemical structure of compound 1 and UV–vis spectra in an aggregating aqueous medium and in the disaggregating solvent THF. Transmission electron microscopy (TEM) images (left, zoomed-out and zoomed-in; 1 × 10−4 M solutions of 1 deposited on TEM grids) and crystal

The fluorescence of a mercury probe based on osthol

• Guangyan Luo,
• Zhishu Zeng,
• Lin Zhang,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2021, 17, 22–27, doi:10.3762/bjoc.17.3

• fluorescence, UV–vis spectrophotometry, mass spectrometry, and 1H NMR spectroscopy, and the recognition mechanism is discussed. The results showed that OST and Hg2+ can form a complex with a stoichiometric ratio of 1:1. The binding constant was 1.552 × 105 L∙mol−1, having a highly efficient and specific

• to a higher field. Because Hh is located in the central area of the shield and Hi is at the edge of the shield, the Δδ value of Hh is relatively large, and finally both moved to δ 1.35. Based on the 1H NMR and mass spectrometry data, combined with the analysis of the UV–vis spectrum, the interaction

Synthesis, crystal structures and properties of carbazole-based [6]helicenes fused with an azine ring

• Daria I. Tonkoglazova,
• Anna V. Gulevskaya,
• Konstantin A. Chistyakov and
• Olga I. Askalepova

Beilstein J. Org. Chem. 2021, 17, 11–21, doi:10.3762/bjoc.17.2

• were used as starting materials. To discern the effect of merging an azine moiety within a helical skeleton, the X-ray structures, UV–vis absorption and fluorescence spectra of the helicenes were investigated and compared to that of the parent carbazole-based [6]helicene (7H-phenanthro[3,4-c]carbazole

• absorption of quinoxaline-fused [6]helicene 10a was red-shifted by 19 nm (Table 7). Compounds 10 exhibited almost a solvent independence of UV–vis absorption spectra (Supporting Information File 1, Figure S41). The optical band gaps (Egopt), estimated from the onset point of the absorption spectra, for [6

• ]helicenes 10. Supporting Information Supporting Information File 76: Experimental procedures and analytical data, copies of 1H and 13C NMR spectra of all new compounds, X-ray data for 9c and 10a–c, HPLC spectra of helicenes 10a–c, UV–vis and fluorescence spectra of 10a–c. Acknowledgements The authors

Naphthalonitriles featuring efficient emission in solution and in the solid state

• Sidharth Thulaseedharan Nair Sailaja,
• Iván Maisuls,
• Jutta Kösters,
• Alexander Hepp,
• Andreas Faust,
• Jens Voskuhl and
• Cristian A. Strassert

Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246

• monomeric species in dilute solutions The UV–vis absorption spectra of the six samples in THF are shown in Figure 3. The p-substituents on the phenyl group at the γ-position of the naphthalonitrile cause drastic changes in the electronic properties of the compounds. For H, Me, t-Bu, OMe, SMe and NMe2, the

Construction of pillar[4]arene[1]quinone–1,10-dibromodecane pseudorotaxanes in solution and in the solid state

• Xinru Sheng,
• Errui Li and
• Feihe Huang

Beilstein J. Org. Chem. 2020, 16, 2954–2959, doi:10.3762/bjoc.16.245

• , which agreed with the formation of the complexation; the alkyl chains of G were encapsulated in the cavity of H. This further indicated that the interactions between H and G were weak. UV–vis absorption properties of the complex in solution Based on the UV–vis properties of H, we wondered the influence

• of G on the optical properties of H, so an UV–vis spectroscopy experiment was carried out. We investigated the changes in the UV–vis absorption of the complex at different guest concentrations corresponding to 0.5 and 1 equiv. As shown in Figure 4, the concentration of G did not affect the absorption

• between H and G were weak and that there was a complexation competition with solvent molecules. Furthermore, the addition of G did not change the maximum UV–vis absorption wavelength of H. The bromine atoms at the periphery of the guest molecule provide convenience for the further capping of the

UV resonance Raman spectroscopy of the supramolecular ligand guanidiniocarbonyl indole (GCI) with 244 nm laser excitation

• Tim Holtum,
• Vikas Kumar,
• Daniel Sebena,
• Jens Voskuhl and
• Sebastian Schlücker

Beilstein J. Org. Chem. 2020, 16, 2911–2919, doi:10.3762/bjoc.16.240

• choosing the laser wavelength in electronic resonance and the enhanced Raman spectrum involving only vibrational modes of the molecular subunit is selectively detectable. Since the GCP exhibits electronic resonances in the ultraviolet region with an absorption maximum at ca. 298 nm (see UV–vis absorption

• pyrrole ring, which leads to different optical absorption properties in the UV–visible range (see Figure 1). Based on the UV–vis absorption spectrum, we expect a stronger resonance enhancement for GCI than GCP at 244 nm excitation due to its higher absorbance. Again, a 244 nm excitation is necessary for

• form a laminar liquid column in air at the laser focus. The laser radiation was focused by two cylindrical lenses to create a line focus along the sample liquid column and a 90° scattering geometry was used for collecting the Raman scattered light. The UV–vis absorption spectra were acquired with a UV

Incorporation of a metal-mediated base pair into an ATP aptamer – using silver(I) ions to modulate aptamer function

• Marius H. Heddinga and
• Jens Müller

Beilstein J. Org. Chem. 2020, 16, 2870–2879, doi:10.3762/bjoc.16.236

• washing with buffer. The elution was quantified by UV–vis spectroscopy. In the absence of Ag(I), the aptamer derivatives bearing imidazole residues show a lower affinity to ATP than the unmodified aptamer (Figure 9). While only 17% of the DNA is eluted in the five washing fractions of 1af, the amount of

Selective recognition of ATP by multivalent nano-assemblies of bisimidazolium amphiphiles through “turn-on” fluorescence response

• Rakesh Biswas,
• Surya Ghosh,
• Shubhra Kanti Bhaumik and
• Supratim Banerjee

Beilstein J. Org. Chem. 2020, 16, 2728–2738, doi:10.3762/bjoc.16.223

• . Sodium chloride, 28% ammonia solution and all the solvents were purchased from Merck. Milli-Q water was used for all the experiments. UV–vis spectroscopic measurements were carried out in Agilent Cary 8454 spectrophotometer. Emission spectroscopic measurements were carried out in a Horiba Fluoromax 4

A heterobimetallic tetrahedron from a linear platinum(II)-bis(acetylide) metalloligand

• Matthias Hardy,
• Marianne Engeser and
• Arne Lützen

Beilstein J. Org. Chem. 2020, 16, 2701–2708, doi:10.3762/bjoc.16.220

• diastereomers. The new complexes were characterized by NMR and UV–vis spectroscopy and ESI mass spectrometry. Using GFN2-xTB we generated energy-minimized models of the diastereomers of this cage that further corroborated the results from analytical findings. Keywords: cage compounds; heterobimetallic

• UV–vis spectroscopy. The spectrum of tetrahedron 4 in acetonitrile solution revealed multiple absorption maxima. The most prominent maxima are located at 200 and 294 nm with a shoulder at 360 nm, probably corresponding to π–π* transitions from the aromatic systems and the triple bonds. Finally, a

• , correlation of the proton. Low- and high-resolution electrospray ionization mass spectrometry (ESIMS) spectra were recorded on a Bruker Daltonic LTQ Orbitrap XL. The UV–vis spectrum was recorded on a Specord 200 spectrometer (Analytik Jena AG) at ambient temperature. 4-Ethynylaniline (1) [50], trans-[Pt(PBu3

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• signals of the immobilized ligand molecules but no sharp signals, showing that the nanoparticles were not contaminated with unbound ligands or residual citrate. According to transmission electron microscopy (TEM), NPrac-1 had an average diameter of 9.1 ± 2.4 nm and a maximum of the SPR band in the UV–vis

• sensing, even when simultaneously present at concentrations significantly higher than the actual analyte. The effects of the phosphate salts on the solutions of all four nanoparticles were then followed in a more precise fashion by using UV–vis spectroscopy. To this end, the solutions of the four

• nanoparticles NP4-Zn, NP10-Zn, NP25-Zn, and NP35-Zn (0.25 mg/mL) in water/methanol 1:2 (v/v) were treated with increasing amounts of either Na2HPO4, Na4P2O7, or Na5P3O10, and the UV–vis spectra of the resulting solutions were recorded between 350 and 800 nm to assess the effects of the salts on the position and

Synthesis and characterization of S,N-heterotetracenes

• Astrid Vogt,
• Florian Henne,
• Christoph Wetzel,
• Elena Mena-Osteritz and
• Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

• ). Optical spectroscopy of the various SN4-heteroacenes was performed in THF solutions. UV–vis absorption spectra of TTA, SN4 9, and SN4'' 33 are shown in Figure 2, left, those of heteroacenes 13, 19, and 22 in Figure S6 (Supporting Information File 1) and data is listed in Table 1. In general, the

• ', and SN4''. UV–vis absorption spectra of TTA, Hex-SN4 9, Pr-SN4'' 33 and fluorescence spectrum of 33 in THF at rt (left) and corresponding cyclic voltammograms in dichloromethane/tetrabutylammonium hexafluorophosphate (0.1 M), 100 mV/s (right). Energy diagram of the frontier molecular orbitals of

• benzofused S,N-heteroacenes 19 and 22. Supporting Information Supporting Information File 561: Synthetic procedures, 1H, 13C NMR, HRMS, and UV–vis spectra as well as cyclic voltammograms. Supporting Information File 562: Crystallographic data. Acknowledgements We gratefully acknowledge B. Müller, Institute

Anion exchange resins in phosphate form as versatile carriers for the reactions catalyzed by nucleoside phosphorylases

• Julia N. Artsemyeva,
• Ekaterina A. Remeeva,
• Tatiana N. Buravskaya,
• Irina D. Konstantinova,
• Roman S. Esipov,
• Anatoly I. Miroshnikov,
• Natalia M. Litvinko and
• Igor A. Mikhailopulo

Beilstein J. Org. Chem. 2020, 16, 2607–2622, doi:10.3762/bjoc.16.212

• ), except where otherwise indicated. TLC was performed on TLC glass plates covered with silica gel 60 F254 (Merck, Germany). The TLC control of the PF-1Pis synthesis and conversions was tested first by UV light then by heating of the plates. UV–vis spectra were recorded with a Shimadzu UV-Mini 1240

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• and 1j because of paramagnetic line broadening and overlapping signals. To circumvent these problems, UV–vis spectroscopy was performed at very low concentrations (Table 1). The porphyrin Soret bands are different for the diamagnetic (λmax ≈ 406 nm) and the paramagnetic species (λmax ≈ 423 nm). The

• File 1. “Record player” approach for molecular spin switching. a) General principle b) Variation of the substituent R in 4-position of the pyridine unit. Record player molecules synthesized in this work (1f–j) are highlighted. Hammett plot of the investigated pyridine substituents [36]. UV–vis spectra

Thermodynamic and electrochemical study of tailor-made crown ethers for redox-switchable (pseudo)rotaxanes

• Henrik Hupatz,
• Marius Gaedke,
• Hendrik V. Schröder,
• Julia Beerhues,
• Arto Valkonen,
• Fabian Klautzsch,
• Sebastian Müller,
• Felix Witte,
• Kari Rissanen,
• Biprajit Sarkar and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2020, 16, 2576–2588, doi:10.3762/bjoc.16.209

• properties of the rotaxane NDIRot were investigated by UV–vis–NIR spectroelectrochemistry in a CH2Cl2/CH3CN 1:1 mixture and compared to NDIC8 and NDIC7 (Figure 4 and Table S3 in Supporting Information File 1). In the neutral state, the rotaxane displays the typical absorption pattern of an N,N’-disubstituted

• clarity), b) NDIC7 (CH3CN molecule omitted for clarity) and c) NDIC8. a) Synthesis of the [2]rotaxane NDIRot. b) Stacked 1H NMR spectra (700 MHz, CDCl3, 298 K) of NDIC8 (top), NDIRot (middle), and A1·BArF24 (bottom). The signal assignment was done by 2D NMR spectroscopy. UV–vis–NIR spectra obtained by

Water-soluble host–guest complexes between fullerenes and a sugar-functionalized tribenzotriquinacene assembling to microspheres

• Si-Yuan Liu,
• Xin-Rui Wang,
• Man-Ping Li,
• Wen-Rong Xu and
• Dietmar Kuck

Beilstein J. Org. Chem. 2020, 16, 2551–2561, doi:10.3762/bjoc.16.207

• with fullerenes (Figure 1). All these TBTQ-based hosts were found to bind fullerenes in organic solvents with different strengths, as indicated by UV–vis or 1H NMR titration experiments. Moreover, easily accessible C3v-symmetrical sixfold hydroxy-functionalized TBTQ derivatives gain increasing

• affinity of C70-fullerene may be attributed to its larger size and surface area as compared to C60-fullerene [50]. The complexation between TBTQ-(OG)6 and fullerenes was also examined by UV–vis spectroscopy in both toluene/DMSO 1:1 (v/v) and water. Figure 3a shows the UV–vis spectra of TBTQ-(OG)6, C60 and

• NMR spectra were recorded on a 400 MHz Bruker NMR spectrometer and chemical shifts were reported in ppm (δ). The fluorescence spectra were measured on a F97Pro fluorescence spectrophotometer (LengGuang Tech, Shanghai, China) and UV–vis spectra were measured on a UV-3300PC spectrometer (Mapada

Host–guest interaction of cucurbit[8]uril with oroxin A and its effect on the properties of oroxin A

• Zhishu Zeng,
• Jun Xie,
• Guangyan Luo,
• Zhu Tao and
• Qianjun Zhang

Beilstein J. Org. Chem. 2020, 16, 2332–2337, doi:10.3762/bjoc.16.194

• –guest interactions between oroxin A (OA) and cucurbit[8]uril (Q[8]) using 1H NMR, MS, UV–vis and IR spectroscopy. The results showed that OA and Q[8] formed an inclusion compound (OA@Q[8]) with a molar ratio of 1:1 and a binding constant of 1.299 × 107 L·mol−1. In addition, the effect of Q[8] on the

• containing 10% DMSO by volume, OA (500 μmol·L−1) upon the addition of different molar equivalents of Q[8]: (a) 0, ( b ) 0.35, (c) 0.44, (d) 1.03, (e) 1.60 and (f) neat Q[8]. (A) The UV–vis absorption spectra recorded for OA in the presence of Q[8] (c(Q[8]), labeled a–k: 0, 0.2, 0.4, 0.6, ..., 2.0 × 10–5

Styryl-based new organic chromophores bearing free amino and azomethine groups: synthesis, photophysical, NLO, and thermal properties

• Anka Utama Putra,
• Deniz Çakmaz,
• Nurgül Seferoğlu,
• Alberto Barsella and
• Zeynel Seferoğlu

Beilstein J. Org. Chem. 2020, 16, 2282–2296, doi:10.3762/bjoc.16.189

• all dyes 3–7 and 8–12 were recorded in the same solvents of various polarities that were used in the UV–vis studies, and the results are summarized in Table 1 and Table S1 (Supporting Information File 1). All dyes showed fluorescence properties and there was no direct correlation of the increase of

• maximum absorption wavelengths of these dyes were in the range of 374–386 nm and 377–385 nm. Moreover, almost the same trends which were obtained from the UV–vis absorption spectra were also observed in the emission maxima. The photophysical properties of dyes 3–7 were similar to those of the

• . An interaction between the dyes and hydroxide anion was investigated in DMSO as the solvent. The presence of hydroxide led to small changes in the UV–vis absorption spectra of the dyes. As presented in Figure 5, the interaction of dye 12 with the hydroxide anion, led to a small hyperchromic effect in

The B & B approach: Ball-milling conjugation of dextran with phenylboronic acid (PBA)-functionalized BODIPY

• Patrizia Andreozzi,
• Lorenza Tamberi,
• Elisamaria Tasca,
• Gina Elena Giacomazzo,
• Marta Martinez,
• Mirko Severi,
• Marco Marradi,
• Stefano Cicchi,
• Sergio Moya,
• Giacomo Biagiotti and
• Barbara Richichi

Beilstein J. Org. Chem. 2020, 16, 2272–2281, doi:10.3762/bjoc.16.188

• by UV–vis spectroscopy (λmax = 508–511 nm). The DMSO/ethanol mixtures and ethanol solutions were dried under vacuum, the recovered dye was solubilized in DMSO, and the UV–vis spectra were recorded. The amount of recovered PBA-BODIPY (1) was estimated (Figure 2A), using the molar extinction

• by means of UV–vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and transmission electron microscopy (TEM) analysis (see Supporting Information File 1). Concerning the chemical structure of the conjugate, the data reported in the literature were

• -BODIPY-dextran conjugate Dex-1b were studied in water. The UV–vis spectra of Dex-1b reported in Figure 3A shows the same absorption pattern of the PBA-BODIPY (1, see Supporting Information File 1) [26]. The main absorption band corresponding to the transition S0 → S1, is observed at λabs = 508 nm. The

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• palladium(II) was carried out in the presence of PdCl2(MeCN)2 in a stepwise manner, confirmed by UV–vis spectroscopic technique. The cyclopentadienyl (Cp) ligand has its own identity in the field of organometallic chemistry as a plethora of transition metal complexes contain this moiety in their structures

Naphthalene diimide bis-guanidinio-carbonyl-pyrrole as a pH-switchable threading DNA intercalator

• Poulami Jana,
• Filip Šupljika,
• Carsten Schmuck and
• Ivo Piantanida

Beilstein J. Org. Chem. 2020, 16, 2201–2211, doi:10.3762/bjoc.16.185

• charges, while at pH 5 both GCP moieties are also protonated, yielding 4 with four positive charges [18]. The concentration dependence of 4 according to its UV–vis spectrum at both, pH 5 and 7, was linear up to 2 × 10−5 M (Supporting Information File 1), supporting the presence of single, non-aggregated 4

• molecules in water. The absorption maxima and corresponding molar extinction coefficients (ε) are given in Table S1 (Supporting Information File 1). Heating of the aqueous solution of 4 up to 90 °C did not yield any significant changes in its UV–vis spectrum, suggesting that the chromophores are not

• involved in intra- or intermolecular stacking interactions. The excellent reproducibility of the UV–vis spectrum upon cooling back to room temperature (Figure S2, Supporting Information File 1) verified the chemical stability of the compound. The aqueous solution of the studied compound 4 was non

Synthesis of 6,13-difluoropentacene

• Matthias W. Tripp and
• Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

• HOMO–LUMO gap of 6,13-difluoropentacene was determined via UV–vis spectroscopy and compared to other fluorinated pentacenes. Keywords: fluorinated acenes; Friedel–Crafts reaction; ortho-lithiation; synthesis; Introduction Pentacenes are a prototype in the field of organic semiconductors due to their

• degradation in degassed C6D6 was slow enough to obtain a clean 1H NMR spectrum (see Supporing Information File 1) [17]. Next, the HOMO–LUMO gap of 5 was investigated via UV–vis spectroscopy in solution (Figure 2). The λmax was determined to be at 597 nm, which corresponds to a HOMO–LUMO gap of ΔE = 2.08 eV

• -difluoroanthracene. This strategy could be applicable for the synthesis of differently substituted 6,13-difluoropentacenes as well. Structures of pentacene and fluorinated pentacenes. UV–vis spectrum of F2PEN 5 in CH2Cl2. Retrosynthetic analysis of F2PEN 5. Synthesis of F2PEN 5. Decomposition of diol 13 in solution