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

• charge transport. The copolymers, Qx2, Qx3, and Qx4, formed by combining QxCN with different aryl groups showed down-shifting of lowest unoccupied molecular orbital (LUMO) levels and enhanced electron injection and transport. Furthermore, the dipole moment introduced by the CN groups improved charge

• importance of specific substitutions. While Qx44b demonstrated favorable properties such as a superior dipole moment, narrow bandgap, and red-shifted absorption, the reduced charge transfer rate presented a challenge. This analysis emphasizes the need for a delicate balance between desirable electronic

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

• interactions between the solvent and dipole moment of the chromophore (Figure 3b). The Lippert–Mataga plot showed two linear slopes indicating the presence of two different excited states in the molecule. In the high-polarity region, the excited-state dipole moment (μe) was 19.04 D, which was close to that of

• a typical CT molecule 4-(N,N-dimethylamino)benzonitrile (μe = 23 D) [55], suggesting a CT state-dominated character in high-polarity solvents. Besides, in the low-polarity region, the μe value was 5.49 D, which is slightly higher than the ground-state dipole moment (μg = 1.30 D) estimated using

A series of perylene diimide cathode interlayer materials for green solvent processing in conventional organic photovoltaics

• Kathryn M. Wolfe,
• Shahidul Alam,
• Eva German,
• Fahad N. Alduayji,
• Maryam Alqurashi,
• Frédéric Laquai and
• Gregory C. Welch

Beilstein J. Org. Chem. 2023, 19, 1620–1629, doi:10.3762/bjoc.19.119

• and acceptor molecules (N···F and N···H bonding when using the acceptor Y6), as well as an induced dipole moment in the molecule for increased work function tuning of the cathode. The use of benzyl and pentafluorobenzyl substituents was to evaluate the impact of H vs F on the electrochemical

Organic thermally activated delayed fluorescence material with strained benzoguanidine donor

• Alexander C. Brannan,
• Elvie F. P. Beaumont,
• Nguyen Le Phuoc,
• George F. S. Whitehead,
• Mikko Linnolahti and
• Alexander S. Romanov

Beilstein J. Org. Chem. 2023, 19, 1289–1298, doi:10.3762/bjoc.19.95

• experience a very weak solvatochromic effect with increasing solvent polarity from cyclohexane to dichloromethane. This indicates only minor change of the dipole moment upon vertical excitation from S0 (6.4 D) to S1 (7.2 D) excited states according to the TD-DFT theoretical calculations (Table S2, Supporting

Polymer and small molecule mechanochemistry: closer than ever

• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1225–1235, doi:10.3762/bjoc.18.128

• material, which induced a nonzero dipole moment in the crystal lattice. As a consequence, a strain-induced charge potential of at least 1.23 eV was produced on the surface of the material, leading to the conversion of mechanical energy into chemical energy. Mechanistically, the ZnO and BaTiO3 participated

Continuous flow synthesis of azobenzenes via Baeyer–Mills reaction

• Jan H. Griwatz,
• Anne Kunz and
• Hermann A. Wegner

Beilstein J. Org. Chem. 2022, 18, 781–787, doi:10.3762/bjoc.18.78

• only the geometry is altered from the planar (E)-AB to its twisted (Z)-AB form, but also its properties change (e.g., dipole moment and polarity) [13][14]. Furthermore, the (Z)-AB can be reversibly switched back by visible light or thermally [15]. To synthesize ABs a variety of reactions can be chosen

Comparative study of thermally activated delayed fluorescent properties of donor–acceptor and donor–acceptor–donor architectures based on phenoxazine and dibenzo[a,j]phenazine

• Saika Izumi,
• Prasannamani Govindharaj,
• Anna Drewniak,
• Paola Zimmermann Crocomo,
• Satoshi Minakata,
• Leonardo Evaristo de Sousa,
• Piotr de Silva,
• Przemyslaw Data and
• Youhei Takeda

Beilstein J. Org. Chem. 2022, 18, 459–468, doi:10.3762/bjoc.18.48

• between the dipole moment of the host and the excited state dipole moment of the TADF molecule [19]. The activation energy for the TADF process of the D–A compound 1 is as low as 15 meV. Nevertheless, the TADF efficiency of the D–A compound in CBP is much lower when compared to that in Zeonex® and its D–A

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

• ) of the device. A compound will emit light perpendicular to its transition dipole moment (TDM), quantified by the anisotropy factor, a. Controlling the orientation of the TDM to lie horizontally in the film (where 1 − a is the fraction of horizontally aligned TDMs) will lead to a maximized amount of

• increased spin-vibronic coupling [28][29][30][31][32][33]. The permanent dipole moment (PDM) of DICzTRZ is substantial increased to 2.1 Debye compared to that in ICzTRZ (0.3 Debye); however, both the transition dipole moment (TDM) and oscillator strength (f) are slightly smaller (TDM = 7.6 Debye and f

Chemical syntheses and salient features of azulene-containing homo- and copolymers

• Vijayendra S. Shetti

Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139

• Vijayendra S. Shetti Department of Chemistry, National Institute of Technology Karnataka, Surathkal 575025, India 10.3762/bjoc.17.139 Abstract Azulene is a non-alternant, aromatic hydrocarbon with many exciting characteristics such as having a dipole moment, bright color, stimuli responsiveness

• ). The striking feature of azulene is its permanent dipole moment (1.08 D) and blue color unlike its colorless isomer naphthalene [4]. Azulene possesses an unequal distribution of electron density between its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO

2,4-Bis(arylethynyl)-9-chloro-5,6,7,8-tetrahydroacridines: synthesis and photophysical properties

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli,
• Noureddine Chaaben,
• Kamel Alimi,
• Stefan Jopp and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 1629–1640, doi:10.3762/bjoc.17.115

• polarity difference. In fact, derivative 4f shows the highest dipole moment of 4.276 D as compared to 4a (0.698 D). As shown in Table 5, the ionization potential (IP) and electron affinity (EA) of tetrahydroacridines are almost identical. In addition, EHOMO and ELUMO do not change notably and the

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

• the n-hexane and water solutions, the calculated CT distances are 1.5 and 2.0 Å, respectively. The change in the dipole moment, caused by the excitation, is greater in water being 6.1 D vs 4.9 D in n-hexane. Moreover, the calculated τ index is much greater in the case of the water solution (0.520 Å in

Amine–borane complex-initiated SF₅Cl radical addition on alkenes and alkynes

• Audrey Gilbert,
• Pauline Langowski,
• Marine Delgado,
• Laurent Chabaud,
• Mathieu Pucheault and
• Jean-François Paquin

Beilstein J. Org. Chem. 2020, 16, 3069–3077, doi:10.3762/bjoc.16.256

• CF3 substituent [3][4][5][6][7][8]. Furthermore, it induces a stronger dipole moment, which can dramatically affect the properties of the neighboring functional groups on a molecule [3][4][5][6][7][8]. Considering the wide range of trifluoromethylated compounds of interest, the synthesis of their SF5

Regioselective synthesis of heterocyclic N-sulfonyl amidines from heteroaromatic thioamides and sulfonyl azides

• Vladimir Ilkin,
• Vera Berseneva,
• Tetyana Beryozkina,
• Tatiana Glukhareva,
• Lidia Dianova,
• Wim Dehaen,
• Eugenia Seliverstova and
• Vasiliy Bakulev

Beilstein J. Org. Chem. 2020, 16, 2937–2947, doi:10.3762/bjoc.16.243

• sulfonyl azides. Due to the high dipole moment, the presence of electronegative heteroatoms bearing electron lone pairs, one could propose alternative reactions which might make it difficult to find a general regioselective procedure for the synthesis of the target molecules in good yields. To the best of

Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose

• Danny Lainé,
• Vincent Denavit,
• Olivier Lessard,
• Laurie Carrier,
• Charles-Émile Fecteau,
• Paul A. Johnson and
• Denis Giguère

Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237

• destabilize the adjacent carbocation center [41][42][43], avoiding 1,2-alkyl shift, and thus formation of byproduct 20. Similarly, the large dipole moment of the C–F bond at C2 influences the outcome of the deoxyfluorination at C4 [3]. For triflates 16 and 17, both dipoles (green arrows, Figure 3a) are

Conformational preferences of fluorine-containing agrochemicals and their implications for lipophilicity prediction

• Daniela Rodrigues Silva,
• Joyce K. Daré and
• Matheus P. Freitas

Beilstein J. Org. Chem. 2020, 16, 2469–2476, doi:10.3762/bjoc.16.200

• lipophilicity with the molecular conformation. Keywords: dipole moment; fluorinated compounds; gauche effect; herbicides; log P; Introduction Whilst in the last years the agrochemical industry has encountered a period of downturn affected by new regulations, low crop prices, biochemical resistance, among

• employed to describe lipophilicity. It has been previously established that the lipophilicity of a compound depends greatly on the overall molecular polarity [15], which is often expressed as the molecular dipole moment (μ). In turn, the orientation of polar bonds also influences the overall polarity of an

• polar solvent (e.g. water), however, decreases the difference in energy among conformers and Igg becomes the most stable conformer in solution, i.e., a double gauche effect takes place (see data in parentheses in Figure 2). This is not surprising, since Igg has the highest dipole moment (data shown in

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

• of ICT for electronic state modification in the excited state of the molecules [45]. In this state, all dyes have a notably higher dipole moment and a lower LUMO energy level as compared to their ground state [46][47][48][49]. Increasing the electron-donating strength of the various heterocyclic

• scalar product, μβ(2ω), of the vector component of the first hyperpolarizability tensor, β, and the dipole moment vector [58][59][60][61]. This product is derived according to Equation 1 considering γ0(−2ω,ω,ω,0), the third-order term, as negligible for the push-pull dyes under consideration. This

• exhibited a higher NLO response than their analogs 3–7. In order to obtain an insight into the NLO properties of the studied dyes, the first-order hyperpolarizability (β) and dipole moment (µ) were calculated at the B3LYP/6-31+G(d,p) level of theory in CHCl3. In general, a high NLO response for a typical

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

• absence of ICD bands within the naphthalene diimide absorption range (350–420 nm) suggested that the NDI transition dipole moment associated with the higher energy transition (NDI longer axis) was not well-oriented in respect to the DNA chiral axis [14]. At variance to ds-DNA, the addition of compound 4

Naphthalene diimide–amino acid conjugates as novel fluorimetric and CD probes for differentiation between ds-DNA and ds-RNA

• Annike Weißenstein,
• Myroslav O. Vysotsky,
• Ivo Piantanida and
• Frank Würthner

Beilstein J. Org. Chem. 2020, 16, 2032–2045, doi:10.3762/bjoc.16.170

• ). The transition dipole moment associated with the HOMO-to-LUMO transition in the visible range (red arrow) and with the higher energy transition (blue arrow) are respectively shown superimposed on the minimised structure. Interactions of 3a,b, and 5 with ds-DNA/RNA For a study of interactions with

• transition dipole moment with respect to the DNA chiral axis [50]. A positive sign observed for 3a suggests that the long axis of the NDI chromophore is perpendicular to the longitudinal axis of the base pairs (red arrow in Figure 8, for 3a), while a negative one observed for 3b suggests a parallel

• ). b) The molecular ground state dipole moment is indicated by the black arrow. The transition dipole moments calculated by TD-DFT (at the B3LYP/6-31+G** level of theory) for the lowest transitions in the visible range of the spectrum (indicated in the spectra by the red and blue arrows) are shown

Polarity effects in 4-fluoro- and 4-(trifluoromethyl)prolines

• Vladimir Kubyshkin

Beilstein J. Org. Chem. 2020, 16, 1837–1852, doi:10.3762/bjoc.16.151

• . The existence of the minor conformations will also be relevant in the explanation of the amide-rotation barriers (vide infra). It should be noted that calculation of the net dipole is of little aid when accessing polarity of the model compounds 1–4 [77]. For example, the dipole moment calculated for

Models of necessity

• Timothy Clark and
• Martin G. Hicks

Beilstein J. Org. Chem. 2020, 16, 1649–1661, doi:10.3762/bjoc.16.137

• how well the results fit with the user’s own preferences and prejudices. Take, for instance, the concepts of polarization and charge transfer. Of these two closely related concepts, polarization is real and observable (e.g., through a change in dipole moment), whereas charge transfer is a qualitative

• net atomic charges) and of the bond. Physically, both result in the same change in dipole moment. Objectively, they are not distinguishable, as has been pointed out many times [33]. Quantum mechanics to Lewis or the reverse? The preceding section could easily be expanded into a complete book but

• . Conceptual distinction between polarization and charge transfer. The distinction depends entirely on the definition of the atoms, and even the bond. In both cases, the result is the same increase in dipole moment. The vertical dashed lines indicate notional borders between atoms. The two phenomena are

Rearrangement of o-(pivaloylaminomethyl)benzaldehydes: an experimental and computational study

• Csilla Hargitai,
• Györgyi Koványi-Lax,
• Tamás Nagy,
• Péter Ábrányi-Balogh,
• András Dancsó,
• Gábor Tóth,
• Judit Halász,
• Angéla Pandur,
• Gyula Simig and
• Balázs Volk

Beilstein J. Org. Chem. 2020, 16, 1636–1648, doi:10.3762/bjoc.16.136

• close dielectric constant (ε = 4.7 for CHCl3 and 8.9 for DCM) [28], the similar polarity index (P = 2.7 for CHCl3 and 3.1 for DCM) [29][30][31], and the very close dipole moment (1.15 for CHCl3, 1.14 for DCM) [32], the conformation of the compounds should be almost the same in the NMR solvent and in the

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• small molecular volume increases the pharmacokinetic abilities of the compounds. In addition, 3 and 4 have a greater dipole moment compared to 5 and 6. The hydrogen-bond formation and the noncovalent interactions are influenced by the dipole moment. This means that an increased dipole moment can improve

• the binding properties of a molecule. Besides the dipole moment, 3 and 4 have the greatest chemical hardness of the bisphosphonates. This descriptor is related to the chemical susceptibility to an external potential. Therefore, the antiinflammatory activity of these compounds can be related to the

• size (volume), solvation (dipole moment), and chemical reactivity (hardness; probably related to a minor metabolic biotransformation). These descriptors can be associated with the better pharmacokinetic profile of the derivatives 3 and 4 by oral administration. Molecular docking As a second

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• , and its dipole moment in the benzene solution was measured (2.90 D). Besides the mentioned sterically hindered iminoxyl radicals 8 and 16, iminoxyl radicals with electron-withdrawing substituents at the C=NO• fragment also demonstrate increased stability compared to ordinary alkyl and aryl iminoxyl

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

• . This indicates that the excited state dipole moment is much greater than the ground state dipole moment. Quantum yields The relative fluorescent quantum yields (ϕFL) of compounds 7a and 7b were determined in dichloromethane by using rhodamine B (ϕFL = 49% at λexc=355 nm) in ethanol as reference [45

Synthesis of organic liquid crystals containing selectively fluorinated cyclopropanes

• Zeguo Fang,
• Nawaf Al-Maharik,
• Peer Kirsch,
• Matthias Bremer,
• Alexandra M. Z. Slawin and
• David O’Hagan

Beilstein J. Org. Chem. 2020, 16, 674–680, doi:10.3762/bjoc.16.65

• the requirements for different LCD technologies. For the traditional twisted nematic (TN) LCD technology, devices require liquid crystals with display positive dielectric anisotropy by which the molecular dipole moment is oriented parallel to the long axis of the molecule, while for the current

• adopt conformations with low overall molecular polarities. A comparison of the Δε for 8 and 9 illustrates that incorporation of the third alpha-fluorine lowers the overall Δε value. This is presumably due to a resulting decrease in the overall molecular dipole moment () along the minor axis. When an

• structure to the more rigid spiro structure 11a, brought about a dramatic enhancement of the molecular dipole moment (μ||), resulting in a much more positive and increased parameter value (Δε = 4.8). This experimental value was close to the predicted calculated value (Δε = 4.3) as shown in Table 2. It is