Aryl-substituted acridanes as hosts for TADF-based OLEDs

• Naveen Masimukku,
• Dalius Gudeika,
• Oleksandr Bezvikonnyi,
• Ihor Syvorotka,
• Rasa Keruckiene,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 989–1000, doi:10.3762/bjoc.16.88

• accompanied by intermolecular CT state relaxation. Such emission is evidenced by solvatochromic effects, i.e., a bathochromic shift of the emission peak due to the change of the environment to a more polar one. By replacement of the solvent toluene with THF, the solution of 4 exhibited a bathochromic shift of

Cation-induced ring-opening and oxidation reaction of photoreluctant spirooxazine–quinolizinium conjugates

• Phil M. Pithan,
• Sören Steup and
• Heiko Ihmels

Beilstein J. Org. Chem. 2020, 16, 904–916, doi:10.3762/bjoc.16.82

• photodegradation of the substrate (Figure S2A, Supporting Information File 1). For 3b, the irradiation at 420 nm led to a decrease of the absorption and a bathochromic shift of the long-wavelength absorption band, and after an irradiation time of 60 min, the spectrum showed distinct absorption bands with maxima at

Bipyrrole boomerangs via Pd-mediated tandem cyclization–oxygenation. Controlling reaction selectivity and electronic properties

• Liliia Moshniaha,
• Marika Żyła-Karwowska,
• Joanna Cybińska,
• Piotr J. Chmielewski,
• Ludovic Favereau and
• Marcin Stępień

Beilstein J. Org. Chem. 2020, 16, 895–903, doi:10.3762/bjoc.16.81

• . Pairs of lactam rings present in cNMI2O and cNMI3O form a quinoidal substructure, which produces a very significant bathochromic shift of their lowest-energy absorption bands (up to 176 nm in toluene) in comparison to the of α-unsubstituted analogues. Lactam bipyrroles cNDAnO and cNMInO show noticeable

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• reflected the characteristics of PAHs including triphenylene derivatives (Table 1, entries 5 and 6) [32][33][34], rather than the 2,3-dialkylbenzo[b]phosphole core (Table 1, entry 4). As expected, the absorption of 8c showed a bathochromic shift compared to 8a and 8b as a result of π-extension (Table 1

Photophysics and photochemistry of NIR absorbers derived from cyanines: key to new technologies based on chemistry 4.0

• Bernd Strehmel,
• Christian Schmitz,
• Ceren Kütahya,
• Yulian Pang,
• Anke Drewitz and
• Heinz Mustroph

Beilstein J. Org. Chem. 2020, 16, 415–444, doi:10.3762/bjoc.16.40

• helped to understand the function and formation H and J-aggregates [46][47][48][49] being aligned parallel or in series, respectively. The capability of cyanines to form J-aggregates exhibiting a huge bathochromic shift, which was reported for the first time by Scheibe [50] and Jelley in 1937 [51

• bathochromic shift of the absorption of about 100 nm [3]. Substitution of the terminal groups comprising by either substituted indolium, benzo[e]indolium or benzo[c,d]indolium patterns helps to finetune the absorption wavelength with respect to the light source used. Furthermore, different substituents at the

Six-fold C–H borylation of hexa-peri-hexabenzocoronene

• Mai Nagase,
• Kenta Kato,
• Akiko Yagi,
• Yasutomo Segawa and
• Kenichiro Itami

Beilstein J. Org. Chem. 2020, 16, 391–397, doi:10.3762/bjoc.16.37

• calculations. The spectra revealed a bathochromic shift of absorption bands compared with unsubstituted HBC under the effect of the σ-donation of boryl groups. Keywords: C–H borylation; hexa-peri-hexabenzocoronene; iridium catalyst; X-ray crystallography; Introduction Polycyclic aromatic hydrocarbons (PAHs

• its LUMO and LUMO+1 are degenerate. The HOMO and LUMO energies of 1 increase under the influence of the σ-donation of the boryl groups, resulting in a decrease of the HOMO–LUMO energy gap. This is in line with the bathochromic shift observed in the absorption spectrum of 1 from that of HBC. Conclusion

Potent hemithioindigo-based antimitotics photocontrol the microtubule cytoskeleton in cellulo

• Alexander Sailer,
• Franziska Ermer,
• Yvonne Kraus,
• Rebekkah Bingham,
• Ferdinand H. Lutter,
• Julia Ahlfeld and
• Oliver Thorn-Seshold

Beilstein J. Org. Chem. 2020, 16, 125–134, doi:10.3762/bjoc.16.14

• strength of groups in the hemistilbene para-position of HTIs correlates to (a) a bathochromic shift of the S0 → S1 absorption band (up to λmax ≈ 500 nm with julolidine substitution) and (b) decreased thermal stability of the metastable E-isomer, i.e., faster thermal relaxation [30]. However, they also

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

• wavelength maxima appear at around 255 nm. The unsubstituted α-pyrone 6a exhibits its longest wavelength maximum at 381 nm (Table 8, entry 1). A p-methoxyphenyl substituent in the 6-position causes a bathochromic shift (Table 8, entry 2), whereas the same substituent in 4-position leads to a hypsochromic

• , entry 6). The introduction of a more strongly electron-donating substituent, such as N,N-dimethylaminophenyl, causes a significant bathochromic shift (Table 8, entries 3 and 5). Donor–acceptor substitution in positions 4 and 6 causes a further bathochromic shift (Table 8, entry 7). In solution only N,N

• (540 nm) and 6d (489 nm) appear at quite different energies, similar to their corresponding absorption maxima in solution. In comparison to α-pyrone 6a the introduction of two methoxy substituents in derivative 6f results in a bathochromic shift to 526 nm. The solid-state emission of N,N

Arylisoquinoline-derived organoboron dyes with a triaryl skeleton show dual fluorescence

• Vânia F. Pais,
• Tristan Neumann,
• Ignacio Vayá,
• M. Consuelo Jiménez,
• Abel Ros and
• Uwe Pischel

Beilstein J. Org. Chem. 2019, 15, 2612–2622, doi:10.3762/bjoc.15.254

• moiety [37][38], while the donor is related to the electronically variable aryl residue. Comparing the emission maxima of the dyes in the less polar dichloromethane with those in the highly polar dimethyl sulfoxide, additional trends can be seen. Thus, dye 17 shows only a slight bathochromic shift of the

A toolbox of molecular photoswitches to modulate the CXCR3 chemokine receptor with light

• Xavier Gómez-Santacana,
• Sabrina M. de Munnik,
• Tamara A. M. Mocking,
• Niels J. Hauwert,
• Shanliang Sun,
• Prashanna Vijayachandran,
• Iwan J. P. de Esch,
• Henry F. Vischer,
• Maikel Wijtmans and
• Rob Leurs

Beilstein J. Org. Chem. 2019, 15, 2509–2523, doi:10.3762/bjoc.15.244

• , Supporting Information File 1) and the photoisomerization are observed. When the substituent Y is a halogen atom, we observe a slight bathochromic shift of the π–π* band to higher wavelengths with increasing size of the heteroatom, from 323 nm for Y = H (3e) to 339 nm for Y = I (6e) (Table 3, Figure 4A

• intrinsic activity (α) of the cis-isomers (Figure 4C). This capacity of the Y substituent to alter the electron density is conceivably also related to its capacity to induce a bathochromic shift of the π–π* band of the trans-isomer. Potential evidence for this can be extracted from the significant

• correlation between the bathochromic shift and intrinsic activity of PSS360 (Figure 4D) for the subseries 3e, 4d, 6b and 6d–h, which only differ in the nature of Y group (Figure 4C, Table 4). Conclusion We report a toolbox of 31 photochromic small-molecule CXCR3 receptor ligands based on the modeling-assisted

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

• are in the 310–323 nm range. Interestingly, the carbocycle size and the presence/absence of carbonyl group are weakly reflected in the position of absorption maxima of open-ring isomers. For example, the reduction of carbonyl group in 3 (compared to 4) leads to insignificant bathochromic shift of the

• 504 nm in toluene, while a hypsochromic shift of 14 nm was observed in acetonitrile. This influence of solvent polarity was detected for all ligands [39]. The carbonyl group in the ethene bridge of 3 causes a significant bathochromic shift (68 nm in toluene) of the closed-ring isomer maximum in

Click chemistry towards thermally reversible photochromic 4,5-bisthiazolyl-1,2,3-triazoles

• Chenxia Zhang,
• Kaori Morinaka,
• Mahmut Kose,
• Takashi Ubukata and
• Yasushi Yokoyama

Beilstein J. Org. Chem. 2019, 15, 2161–2169, doi:10.3762/bjoc.15.213

• (R = OMe, 570 nm) and 6c (R = CN, 570 nm) in hexane (Scheme 3) [36]. In triazoles, while the introduction of electron-donating methoxy groups had little effect on the absorption maximum wavelengths, the introduction of electron-withdrawing cyano groups induced a large bathochromic shift. This

An overview of the cycloaddition chemistry of fulvenes and emerging applications

• Ellen Swan,
• Kirsten Platts and
• Anton Blencowe

Beilstein J. Org. Chem. 2019, 15, 2113–2132, doi:10.3762/bjoc.15.209

• , this can result in a bathochromic shift [2][42]. Consideration of frontier molecular orbital theory allows the electronic nature and general reactivity patterns of fulvenes to be interpreted. Fulvene cycloadditions The multiple cycloaddition pathways observed for fulvenes provides access to a diverse

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

• significantly strengthened in solution. However, the bathochromic shift of the π→π* band leads to a partial overlap with the n→π* band, making it slightly more difficult to address. The introduction of iodine substituents is furthermore accompanied with a diminishing thermal half-life. A series of three

• , which is very desirable for application in supramolecular systems [12][13][35]. Tetra- and octafluorinated A1 and A2 show clear spectral separation of the n→π* bands, whereas the extended π-system of iodoethynyl A3 lead to a bathochromic shift of the π→π* band by 24 nm, now partially overlapping with

• iodoethynyl group, as trade-off, photophysical properties are changing. The bathochromic shift of the π→π* band leads to an overlap with the n→π* excitation, making it more difficult to address, together with a diminishing thermal half-life. Both effects can be qualitatively reproduced and understood with the

Functional panchromatic BODIPY dyes with near-infrared absorption: design, synthesis, characterization and use in dye-sensitized solar cells

• Quentin Huaulmé,
• Cyril Aumaitre,
• Outi Vilhelmiina Kontkanen,
• David Beljonne,
• Alexandra Sutter,
• Gilles Ulrich,
• Renaud Demadrille and
• Nicolas Leclerc

Beilstein J. Org. Chem. 2019, 15, 1758–1768, doi:10.3762/bjoc.15.169

• spacer [14][21][23][24]. Introduction of such units on those positions is known to lead to a larger bathochromic shift of the S0→S1 absorption band than the same substitution on its 2nd and 6th positions [25]. A thiophene-triphenylamine unit was selected among the reported electron-donating units, due to

• Table 1 and Figure 5a). This suggests no self-aggregation of the alkylated dye occurs on the oxide surface, which can be explained by the presence of the co-adsorbent CDCA, and of the multiple alkyl chain substitution of the TPA units. On the other hand, a bathochromic shift of the absorption profile of

Synthesis, photophysical and electrochemical properties of pyridine, pyrazine and triazine-based (D–π–)₂A fluorescent dyes

• Keiichi Imato,
• Toshiaki Enoki,
• Koji Uenaka and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2019, 15, 1712–1721, doi:10.3762/bjoc.15.167

• , the three dyes showed a bathochromic shift of the fluorescence band with increasing solvent polarity from toluene to DMF (i.e., positive fluorescence solvatochromism). Thus, the Stokes shift (SS) values of the three dyes increase with increasing solvent polarity. Compared with OUY-2, OUK-2 and OUJ-2

• -2, 592 nm for OUK-2, and 557 nm for OUJ-2, which showed a significant bathochromic shift by 97 nm, 112 nm, and 48 nm, respectively, compared with those in toluene. The solid-state Φf value is below 0.02 for OUY-2 and OUK-2 and 0.09 for OUJ-2, which are much lower than those in toluene. It is well

• electron-withdrawing ability of the azine ring lowers the LUMO energy level of the (D–π–)2A fluorescent dyes. Consequently, the fact revealed that the bathochromic shift of the ICT-based photoabsorption band in the order of OUY-2 < OUK-2 < OUJ-2 is attributed to the stabilization of the LUMO energy level

Synthesis, enantioseparation and photophysical properties of planar-chiral pillar[5]arene derivatives bearing fluorophore fragments

• Guojuan Li,
• Chunying Fan,
• Guo Cheng,
• Wanhua Wu and
• Cheng Yang

Beilstein J. Org. Chem. 2019, 15, 1601–1611, doi:10.3762/bjoc.15.164

• at the ground state. Similar results were observed for P5A-Py except for a slight bathochromic shift of the absorption compared with Py-6. The fluorescence spectrum of P5A-DPA is very similar to that of DPA-6 (Figure 1b). P5A-DPA showed an intense fluorescence in the visible light region, peaked at

• further investigated by dynamic light scattering (DLS) analyses, and revealed the formation of nanoparticles with 615 nm in average diameter after the addition of 50% water (Figure 4d). Increasing the amount of water to 70% or 90% led to a bathochromic shift of the UV–vis absorption and a raise of the

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• the first title compound 3 in 71% yield. Due to the electron-withdrawing amide group, the chromophore is relatively electron deficient (absorption at 420 nm and emission at 495 nm). In order to achieve a bathochromic shift of absorption and emission bands, the DAT and ALA moieties should be

• primary amine 8 was coupled with ALA in the presence of COMU–DIPEA to furnish the second title compound 7 in 68% yield. Indeed, a bathochromic shift of the spectral data was observed (absorption at 514 nm and emission at 566 nm). Spectroscopy. Being typical push–pull aromatic systems, all DAT derivatives

• NH2 and NHBoc group is the most electron-deficient one with absorption and emission wavelength at 408 nm and 487 nm, respectively (Stokes shift ca. 80 nm). A bathochromic shift of 16 nm of both, absorption and emission wavelengths, is achieved by introduction of a benzyl residue at one nitrogen atom

Coordination chemistry and photoswitching of dinuclear macrocyclic cadmium-, nickel-, and zinc complexes containing azobenzene carboxylato co-ligands

• Jennifer Klose,
• Tobias Severin,
• Peter Hahn,
• Alexander Jeremies,
• Jens Bergmann,
• Daniel Fuhrmann,
• Jan Griebel,
• Bernd Abel and
• Berthold Kersting

Beilstein J. Org. Chem. 2019, 15, 840–851, doi:10.3762/bjoc.15.81

• −) frequencies are significantly red-shifted by 78–103 cm−1 to lower wavenumbers. A bathochromic shift of 14–32 cm−1 is also clearly observed for the νs(RCO2–) frequencies. Notice that Δ = νas(RCO2−) − νs(RCO2−) is invariably larger than 180 cm−1, a clear indication that the co-ligand is in the bridging mode [7

Synthesis and fluorescent properties of N(9)-alkylated 2-amino-6-triazolylpurines and 7-deazapurines

• Andrejs Šišuļins,
• Jonas Bucevičius,
• Yu-Ting Tseng,
• Irina Novosjolova,
• Kaspars Traskovskis,
• Ērika Bizdēna,
• Huan-Tsung Chang,
• Sigitas Tumkevičius and
• Māris Turks

Beilstein J. Org. Chem. 2019, 15, 474–489, doi:10.3762/bjoc.15.41

• development does not allow yet to introduce arylamino moieties at C(2) due to the diminished nucleophilicity of anilines. The 7-deazapurine derivatives were characterized with a somewhat larger Stokes shift and bathochromic shift of the lowest energy absorption band in comparison to purine derivatives, but

N-Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes

• Fabienne Speck,
• David Rombach and
• Hans-Achim Wagenknecht

Beilstein J. Org. Chem. 2019, 15, 52–59, doi:10.3762/bjoc.15.5

• of the π-donating dimethylamino substituent in 2 induces a hypsochromic shift of the absorption maximum by 7 nm to 313 nm, while the mesityl group present in 5 as a σ-donor causes a bathochromic shift of about 8 nm. The detailed structure of the alkyl group attached to the amino part in the

Bioinspired cobalt cubanes with tunable redox potentials for photocatalytic water oxidation and CO₂ reduction

• Zhishan Luo,
• Yidong Hou,
• Jinshui Zhang,
• Sibo Wang and
• Xinchen Wang

Beilstein J. Org. Chem. 2018, 14, 2331–2339, doi:10.3762/bjoc.14.208

• charge-transfer transitions from μ-O atoms to the Co centers, which leads to a modest bathochromic shift from 355 (R = H) to 365 nm, however, with a remarkably enhanced intensity. In addition, the highest energy band between 220–260 nm is believed to be of ligand origin, most probably originating from

Synthesis of new p-tert-butylcalix[4]arene-based polyammonium triazolyl amphiphiles and their binding with nucleoside phosphates

• Vladimir A. Burilov,
• Guzaliya A. Fatikhova,
• Mariya N. Dokuchaeva,
• Ramil I. Nugmanov,
• Diana A. Mironova,
• Pavel V. Dorovatovskii,
• Victor N. Khrustalev,
• Svetlana E. Solovieva and
• Igor S. Antipin

Beilstein J. Org. Chem. 2018, 14, 1980–1993, doi:10.3762/bjoc.14.173

• sensing purposes. Thereby, premicellar concentrations of calixarenes 10a,b (6 and 4 µM, respectively) and 12a,b (4 and 2 µM, respectively) were selected to design a receptor system based on the principle of competitive EY displacement by the guests. At these concentrations, a bathochromic shift

• packaging density of aggregates and their general lipophilicity. To reveal this, absorbance spectra of the 10b–EY system in the presence of ADP and ATP were recorded (Figure 5a and b). The addition of small amounts of nucleotides leads to a bathochromic shift of the EY adsorption due to a deeper penetration

Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

• Siva Sankar Murthy Bandaru,
• Darinka Dzubiel,
• Heiko Ihmels,
• Mohebodin Karbasiyoun,
• Mohamed M. A. Mahmoud and
• Carola Schulzke

Beilstein J. Org. Chem. 2018, 14, 1871–1884, doi:10.3762/bjoc.14.161

• derivatives 2a–d with ct DNA and G4-DNA 22AG [d(AG3T2AG3T2AG3T2AG3)] were investigated with photometric and fluorimetric titrations (Figures 6–9, Table 3). In general, a hypochromic effect and a bathochromic shift were observed by the addition of DNA. For example, the addition of ct DNA and G4-DNA 22AG to

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• X-ray crystallography (Figure 1). Remarkably, the presence of OH and Cl substituents in products 4i–l results in a bathochromic shift of UV–vis absorptions. The crystal structure of 4k is that of the regioisomer proposed on the basis of reactivity considerations. Since the space group is