Using the phospha-Michael reaction for making phosphonium phenolate zwitterions

• Matthias R. Steiner,
• Max Schmallegger,
• Larissa Donner,
• Johann A. Hlina,
• Christoph Marschner,
• Judith Baumgartner and
• Christian Slugovc

Beilstein J. Org. Chem. 2024, 20, 41–51, doi:10.3762/bjoc.20.6

• and exhibit a negative solvatochromism. An analysis of the kinetics of the zwitterion formation was performed for three Michael acceptors (acrylonitrile, methyl acrylate, and acrylamide) in two different solvents (chloroform and methanol). The results revealed the proton transfer step necessary to

• modular synthesis of stable phosphonium phenolate zwitterions bearing additional functional groups. The bonding situation in the zwitterions was studied by NMR and UV–vis spectroscopies and single-crystal X-ray analysis of selected representatives. The zwitterions exhibit negative solvatochromism and

Quinoxaline derivatives as attractive electron-transporting materials

• Zeeshan Abid,
• Liaqat Ali,
• Sughra Gulzar,
• Faiza Wahad,
• Raja Shahid Ashraf and
• Christian B. Nielsen

Beilstein J. Org. Chem. 2023, 19, 1694–1712, doi:10.3762/bjoc.19.124

• -phenylindoloquinoxaline (PhIQ) derivatives, shown in Figure 6 as Qx50 series, by chemically modifying the PhIQ groups. In particular, substituents at the 2- and 3-positions of PhIQs were introduced, allowing regulation of the reduction–oxidation potentials of the compounds. The PhIQs exhibited fluorescent solvatochromism

• , including solvatochromism and AIE enhancement. These characteristics enable tunable emission and enhanced luminescence efficiency. The potential application of tripodal derivatives in white OLEDs indicates the versatility of quinoxaline-based materials in achieving diverse emission colors [67]. Figure 7

• functionalities, and optimizing the π-conjugated backbone structure of Qxs, significant advancements have been made. These approaches effectively address key concerns and obstacles, resulting in red-shifted absorption and emission maxima, improved nonlinear optical properties, solvatochromism, mechanical

A deep-red fluorophore based on naphthothiadiazole as emitter with hybridized local and charge transfer and ambipolar transporting properties for electroluminescent devices

• Suangsiri Arunlimsawat,
• Patteera Funchien,
• Pongsakorn Chasing,
• Atthapon Saenubol,
• Taweesak Sudyoadsuk and
• Vinich Promarak

Beilstein J. Org. Chem. 2023, 19, 1664–1676, doi:10.3762/bjoc.19.122

• and emission behaviors were investigated in several solvents as illustrated in Figure 3a. The results showed that, while the UV–vis absorption spectra were nearly unaffected by the nature of the solvent due to the LE nature, the emission spectra exhibited a noticeable positive solvatochromism, with

Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation

• Ashish Kumar Mazumdar,
• Gyana Prakash Nanda,
• Nisha Yadav,
• Upasana Deori,
• Upasha Acharyya,
• Bahadur Sk and
• Pachaiyappan Rajamalli

Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122

• solvatochromism in solution. The Lippert–Mataga plot and DFT calculations indicated that BPy-p3C had more excited-state CT properties than BPy-pTC due to the bulkier donor group. Both compounds displayed strong emission in the aggregated state in a highly polar medium (80–90 vol % water/THF mixtures). As compared

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• ). Solvatochromic studies for DICzTRZ show that the PDM of the ground state structure is small and so the absorption spectrum is essentially not affected by changes in polarity, while the excited state shows the characteristic positive solvatochromism associated with an emission from a CT state (λPL going from 462

• spectrum of DICzTRZ in 10−5 M toluene solution. c) Ground and excited state solvatochromism study of DICzTRZ (excitation wavelength, λexc, = 340 nm, * = second harmonic of the excitation source); d) emission spectra of DICzTRZ in 10−5 M toluene solution (cyan), 20 wt % CzSi film (blue), and 10 wt % PMMA

Mesoionic tetrazolium-5-aminides: Synthesis, molecular and crystal structures, UV–vis spectra, and DFT calculations

• Vladislav A. Budevich,
• Sergei V. Voitekhovich,
• Alexander V. Zuraev,
• Vadim E. Matulis,
• Vitaly E. Matulis,
• Alexander S. Lyakhov,
• Ludmila S. Ivashkevich and
• Oleg A. Ivashkevich

Beilstein J. Org. Chem. 2021, 17, 385–395, doi:10.3762/bjoc.17.34

• solvatochromism, that is discussed in more detail in the theoretical section. The 13C NMR shift of the C5 endocyclic atom for aminides 8 is observed at 162.1–163.1 ppm in DMSO-d6. For the parent 5-aminotetrazolium salts, this chemical shift is found at 156.5–158.3 ppm in the same solvent. The TGA/DSC data show

• –c show solvatochromism. The experimental UV–vis spectra of compound 8a in different solvents are presented in Figure 3a. As can be seen, the experimental spectra in n-hexane and THF, being similar, differ significantly from those in chloroform, methanol, and water. This difference may be due to the

Synthesis and properties of quinazoline-based versatile exciplex-forming compounds

• Rasa Keruckiene,
• Simona Vekteryte,
• Ervinas Urbonas,
• Matas Guzauskas,
• Eigirdas Skuodis,
• Dmytro Volyniuk and
• Juozas V. Grazulevicius

Beilstein J. Org. Chem. 2020, 16, 1142–1153, doi:10.3762/bjoc.16.101

• excited (1LE) state at 450 nm was observed. In contrast, compound 2 bearing dimethyldihydroacridine as the donor moiety, possessed the most sensitive 1CT. A positive solvatochromism was observed resulting in bathochromic shifts of the PL spectra in the solvents with increasing polarizability indexes

Synthesis of novel multifunctional carbazole-based molecules and their thermal, electrochemical and optical properties

• Nuray Altinolcek,
• Ahmet Battal,
• Mustafa Tavasli,
• William J. Peveler,
• Holly A. Yu and
• Peter J. Skabara

Beilstein J. Org. Chem. 2020, 16, 1066–1074, doi:10.3762/bjoc.16.93

• , respectively. Keywords: carbazole; electrochemistry; fluorescence; formyl group; solvatochromism; Introduction Carbazole derivatives have found many different applications in a variety of technologically important areas, such as organic light emitting diodes (OLEDs), organic photovoltaics (OPVs), dye

• the compounds are given in Figure 4. Solvatochromism In general, ICT-based absorption and emission bands show solvent dependency. This is better known as solvatochromism. The ICT behaviour of compounds 7a and 7b was further investigated in different solvents. Normalised UV–vis spectra of compounds 7a

• transport properties with positive solvatochromism. Whilst 7a showed very low emission intensity, 7b showed very high emission intensity. It is noted that the conjugation in compound 7b encompasses the N atom of the carbazole ring and the formyl functionality (viz. the donor/acceptor units of the ICT

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

• 6 are relatively small, and their LE emissions are mainly ultraviolet. There was practically no positive solvatochromism observed for the dilute solutions of compounds 3, 5, and 6. Only tails related to CT can be observed in the PL spectra of these compounds. Quenching of internal molecular motion

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

• up to 67%, while their bandgaps and chiroptical responses could be tuned by twisting the bipyrrole chromophore. The solvatochromism and apparent superradiance of these chromophores indicated a potential involvement of solvent-induced symmetry-breaking charge transfer in the excited state [34]. Here

• solvatochromism which is stronger for n = 2 and is always negative. In contrast, the solvatochromism of α-free boomerangs is positive and even more pronounced. On going from toluene to acetonitrile, the onset of the lowest-energy band of cNMI2H is shifted to longer wavelengths by 25 nm. The cNMI2H and cNMI3H

Dyes in modern organic chemistry

• Heiko Ihmels

Beilstein J. Org. Chem. 2019, 15, 2798–2800, doi:10.3762/bjoc.15.272

• theoretical and computational chemistry [20]. In the same way, essential dye properties, such as aggregation [21][22] or solvatochromism [23], are still in the focus of current physical organic research. The analytical sciences also depend very much on the availability of appropriate dyes with characteristic

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

• emission solvatochromism. Also a donor-substituted α-pyrone shows pronounced aggregation-induced emission enhancement. Keywords: cyclocondensation; DFT calculations; fluorescence; heterocycles; 1H-pyridines; α-pyrones; Introduction A high sensitivity and precise tuneability of fluorescence colors are

• %. Furthermore, the N,N-dimethylaminophenyl-derivative 6c shows a pronounced emission solvatochromism (Figure 11, Table 9). While the polarity effect on the absorption maximum is only minor within a range of the longest wavelength maximum between 469 and 490 nm, the emission maximum is shifted bathochromically

• with increasing solvent polarity in a range from green fluorescence (529 nm) in toluene to red fluorescence in DMSO (638 nm) (Figure 12). The observed positive emission solvatochromism is a consequence of a significant change in the dipole moment from the electronic ground to the vibrationally relaxed

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

• (ethanol) (ε ≈ 20,000). Whereas a 5 nm shift between the absorption maximum in toluene and acetone evidences the presence of slight positive solvatochromism, the band shapes in water and ethanol are irregular and reflect rather specific interaction with these solvents. The shoulder extending from 450 till

• substituent (N–H), absorbs at about the same wavelength as 3 and exhibits a weak positive solvatochromic shift of about 7 nm, absorption of bis-acylated derivative 10a is strongly blue shifted and shows no solvatochromism. As noted in [5], both 3 and 5 undergo rapid photoreactions in solution in the presence

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

• polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots for OUY-2, OUK-2 and OUJ-2 indicate that the Δμ (= μe − μg) value, which is the difference in the dipole moment of the dye between the excited (μe) and the ground (μg) states, increases in the order of OUY-2 < OUK-2 < OUJ-2

• , 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

• with increasing solvent polarity (i.e., positive fluorescence solvatochromism). The Lippert–Mataga plots revealed that the difference in the dipole moment of the dye between the excited state and the ground state increases in the order of OUY-2 < OUK-2 < OUJ-2. Thus, the fact explains our findings that

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

• as cell imaging tools [31][32], biosensors and sensors for detection of heavy metals [33]. The tendency of these structures to form hydrogen bonds, to respond to medium effects (solvatochromism) [34] and to certain impurities (e.g., coordination complexes with metal ions) make these compound classes

Rational design of boron-dipyrromethene (BODIPY) reporter dyes for cucurbit[7]uril

• Mohammad A. Alnajjar,
• Jürgen Bartelmeß,
• Robert Hein,
• Pichandi Ashokkumar,
• Mohamed Nilam,
• Werner M. Nau,
• Knut Rurack and
• Andreas Hennig

Beilstein J. Org. Chem. 2018, 14, 1961–1971, doi:10.3762/bjoc.14.171

• state of the amine lone pair with the BODIPY chromophore. In accordance with this hypothesis, a positive solvatochromism with varying contents of ACN was observed (Figure S18, Supporting Information File 1). The fluorescence quantum yields of the unprotonated BODIPY dyes were determined in 30% (v/v) ACN

Synthesis and application of trifluoroethoxy-substituted phthalocyanines and subphthalocyanines

• Satoru Mori and
• Norio Shibata

Beilstein J. Org. Chem. 2017, 13, 2273–2296, doi:10.3762/bjoc.13.224

• the oxygen atom directly connected to the phthalocyanine macrocycle. The phenomenon of solvatochromism [45][46] is defined by the polarity of the solvent, and the Q band is shifted to a shorter wavelength region in a highly polar solvent. In addition to the Q band, in solvatochromism, a small

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

• strong absorption bands with absorption maxima between 475 and 503 nm resulting from π–π* transitions [9]. Extinction coefficients range from roughly 9500 to over 50000 M−1 cm−1 (Table 4). All absorption curves show secondary maxima or shoulders at slightly shorter wavelengths. As solvatochromism is a

• known property for curcumin and its derivatives [32][33], we investigated the solvatochromism of 2b as an example compound in five different solvents (Figure 3). Solvents were chosen by their ET(30) values of polarity as determined by Reichardt [34]. With rising solvent polarity, the vibrational

• structure of the absorption band is being lost. In toluene, THF and dichloromethane the compound shows only weak solvatochromism. Interestingly, a positive solvatochromism relative to the more nonpolar solvents is appearing in DMSO, while the absorption band is slightly being shifted hypsochromically in

New electroactive asymmetrical chalcones and therefrom derived 2-amino- / 2-(1H-pyrrol-1-yl)pyrimidines, containing an N-[ω-(4-methoxyphenoxy)alkyl]carbazole fragment: synthesis, optical and electrochemical properties

• Daria G. Selivanova,
• Alexei A. Gorbunov,
• Olga A. Mayorova,
• Alexander N. Vasyanin,
• Igor V. Lunegov,
• Elena V. Shklyaeva and
• Georgii G. Abashev

Beilstein J. Org. Chem. 2017, 13, 1583–1595, doi:10.3762/bjoc.13.158

• -methoxyphenoxy)alkyl]carbazole fragment. Such readily functionalizable heterocycle as carbazole was used as a main starting compound for their preparation. The investigation of the optical properties has shown that the positive solvatochromism is inherent to the chromophores containing an electron-withdrawing

• prop-2-en-1-one fragment, while the compounds containing a 2-aminopyrimidine moiety exhibit both positive and negative solvatochromism. The fluorescence quantum yields were experimentally determined for some of the synthesized chromophores; e.g., 1-(5-arylthiophen-2-yl)ethanones quantum yields were

• ; electrochemical oxidation; pyrimidine; solvatochromism; Introduction Nowadays a great number of research projects concerning the synthesis of organic conjugated systems with a wide scope of their applications, primarily as materials for organic electronic devices such as light-emitting diodes, field-effect

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

• attributed to an inhomogeneous line broadening in the solid state. As benzofurazane and Nile red dyes exhibit solvatochomism, their spectral properties are clearly affected by incorporation into the polar silica environment. A detailed study of the spectral properties and solvatochromism of the Nile red

Interactions between photoacidic 3-hydroxynaphtho[1,2-b]quinolizinium and cucurbit[7]uril: Influence on acidity in the ground and excited state

• Jonas Becher,
• Daria V. Berdnikova,
• Darinka Dzubiel,
• Heiko Ihmels and
• Phil M. Pithan

Beilstein J. Org. Chem. 2017, 13, 203–212, doi:10.3762/bjoc.13.23

• ]. Notably, the chromophore of the oxyanion-substituted quinolizinium derivative 2cB resembles the well-established solvatochromic pyridinium-N-phenolate betaine dyes that are employed as polarity probes [53]. Correspondingly, the derivative 2cB shows a similar positive solvatochromism, i.e., a blue shift of

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

• states. Keywords: fluorescence; heterocycles; quinolizinium; solvatochromism; Introduction Dyes that change their absorption and emission properties, especially their color, in different media are considered as helpful optical probes, because they may be applied for the characterization and

• consistent picture of the solvatochromism of this class of compounds turned out to be rather difficult. Specifically, different cationic biaryl derivatives (Figure 6) show significantly varying trends regarding the influence of the solvent on the steady-state emission. For example, it was reported that the

• interplay in the ground and excited state, specifically the resulting delocalization of the charge. Unfortunately, detailed investigations of the steady-state solvatochromism of this class of compounds are rather scarce, so far, as most photophysical studies of 9-aryl-9-methylacridinium or 4-aryl-N

Indenopyrans – synthesis and photoluminescence properties

• Andreea Petronela Diac,
• Ana-Maria Ţepeş,
• Albert Soran,
• Ion Grosu,
• Anamaria Terec,
• Jean Roncali and
• Elena Bogdan

Beilstein J. Org. Chem. 2016, 12, 825–834, doi:10.3762/bjoc.12.81

• groups have been found to exhibit good solvatochromism properties and high quantum yields in the solid state why they are considered as important precursors for the fabrication of fluorescent materials [20]. Owing to their exciting photophysical properties many dicyanomethylene pyran-containing

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• slightly larger nanophase separation in 31. It is worth noting that the self-aggregation of TTF-annulenes results in the appearance of solvatochromism and thermochromism [68]. As shown in Figure 10, 30 exhibits a supramolecular thermochromism in toluene, and the color at −10 °C is reddish purple, whereas

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

• insertion are suggestive of different interactions between the Nile red label and the duplexes. Keywords: click chemistry; deoxyribonucleic acid; DNA bulge; fluorescence; nucleic acids; solvatochromism; Introduction Fluorescent labels are important tools for investigating the structure and dynamics of