Enhanced host–guest interaction between [10]cycloparaphenylene ([10]CPP) and [5]CPP by cationic charges

• Eiichi Kayahara,
• Yoshiyuki Mizuhata and
• Shigeru Yamago

Beilstein J. Org. Chem. 2024, 20, 436–444, doi:10.3762/bjoc.20.38

• sp2 carbon of [10]CPP within 0.30 nm. HOMO−1, HOMO, LUMO, and LUMO+1 orbitals of [10]CPP⊃[5]CPP2+ (1), [5]CPP2+, and [10]CPP. X-ray crystal structure of [10]CPP⊃[5]CPP2+[B(C6F5)4]2. a) Side and b) top views of ORTEP drawings. The thermal ellipsoids are scaled at the 50% probability level. All hydrogen

Synthesis of π-conjugated polycyclic compounds by late-stage extrusion of chalcogen fragments

• Aissam Okba,
• Pablo Simón Marqués,
• Kyohei Matsuo,
• Naoki Aratani,
• Hiroko Yamada,
• Gwénaël Rapenne and
• Claire Kammerer

Beilstein J. Org. Chem. 2024, 20, 287–305, doi:10.3762/bjoc.20.30

• -resolution STM and AFM images, revealing the linear fusion of benzene rings with a zigzag edge (Figure 3), and their electronic properties were investigated at the single-molecule scale, with a particular attention devoted to the evolution of the HOMO–LUMO gap along the incremental series of acenes

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• -chromophores” after the shape of the main structural fragment resembling the Latin letter “H” (Figure 4) [19]. The small HOMO–LUMO gap and, thus, the long-wavelength absorption are responsible for the purple color of indigo in vapors, which changes into deep blue color in the crystalline state due to formation

Multi-redox indenofluorene chromophores incorporating dithiafulvene donor and ene/enediyne acceptor units

• Christina Schøttler,
• Kasper Lund-Rasmussen,
• Line Broløs,
• Philip Vinterberg,
• Ema Bazikova,
• Viktor B. R. Pedersen and
• Mogens Brøndsted Nielsen

Beilstein J. Org. Chem. 2024, 20, 59–73, doi:10.3762/bjoc.20.8

• bifluorenylidene motif [32] obtained by dimerizing two pyrrolo-annelated IF-DTF units. Notably, the dimer 13 underwent a first oxidation more readily (by as much as 0.14 V) than the corresponding fluorene-DTF donor 17 (both containing the same N-tosylated pyrrolo-DTF unit). The low electrochemical HOMO–LUMO gap of

• absorb strongly in the visible region and undergo one reversible oxidation, while no reductions were observed for these compounds. Systematic studies show that by small structural modifications, the optical and electrochemical HOMO–LUMO gaps can be finely tuned – with first oxidations and reductions that

Charge carrier transport in perylene-based and pyrene-based columnar liquid crystals

• Alessandro L. Alves,
• Simone V. Bernardino,
• Carlos H. Stadtlober,
• Edivandro Girotto,
• Giliandro Farias,
• Rodney M. do Nascimento,
• Sergio F. Curcio,
• Thiago Cazati,
• Marta E. R. Dotto,
• Juliana Eccher,
• Leonardo N. Furini,
• Hugo Gallardo,
• Harald Bock and
• Ivan H. Bechtold

Beilstein J. Org. Chem. 2023, 19, 1755–1765, doi:10.3762/bjoc.19.128

• . In 1-iso, only the two hexagonal imide groups affect the HOMO/LUMO localization, whereas the pentagonal central imide group is little affected. In 2-iso, both pentagonal are relevant to the HOMO/LUMO localization, whereas the two terminal benzene rings are little affected. The cartesian coordinates

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

• energy gap between HOMO/LUMO hybrid orbits and drive fluorescence emission to longer wavelengths [48][49]. In this molecular design, the strong electron-deficient naphtho[2,3-c][1,2,5]thiadiazole (Nz) [13][50][51] as an acceptor and the strong electron-donating carbazole [52] as a donor unit were used in

• , 129.14, 128.16, 127.87, 127.81, 127.72, 127.43, 126.78, 126.71, 126.63, 126.22, 126.17, 123.56, 123.35, 123.21, 120.53, 120.11, 110.03, 109.89; HMRS–MALDI–TOF (m/z): [M]+ calcd for C86H56N4S, 1176.4226; found, 1176.4221. a) The optimized structure and HOMO/LUMO distributions calculated by B3LYP/6-31G(d,p

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

• respective HOMO/LUMO level energies determined from CV E1/2 values. b) Corresponding CVs for PDIN-FB, PDIN-B, CN-PDIN-FB, and CN-PDIN-B with E1/2 values. a) Chemical structures of BHJ donor material PM6 and acceptor material Y6, b) conventional OPV device structure used in this study, and c) the work

Cyclization of 1-aryl-4,4,4-trichlorobut-2-en-1-ones into 3-trichloromethylindan-1-ones in triflic acid

• Vladislav A. Sokolov,
• Andrei A. Golushko,
• Irina A. Boyarskaya and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2023, 19, 1460–1470, doi:10.3762/bjoc.19.105

• temperature. Then, we carried out DFT calculations of cations Aa–Da derived from protonation of compounds 1a and 2a. Thermodynamics of their formation, as Gibbs energies ΔG298 of the corresponding reactions, energies of HOMO/LUMO, electrophilicity indices ω [22][23], charge distribution, and contribution of

Application of N-heterocyclic carbene–Cu(I) complexes as catalysts in organic synthesis: a review

• Nosheen Beig,
• Varsha Goyal and
• Raj K. Bansal

Beilstein J. Org. Chem. 2023, 19, 1408–1442, doi:10.3762/bjoc.19.102

• on C1 enhancing its nuceophilicity (Figure 9). The Mulliken charge, obtained from the NBO calculations, was found to be almost double at the C–H atom in the complexed alkyne (−0.294) as compared to the free alkyne (−0.129). Furthermore, as depicted in Figure 10, the HOMO–LUMO energy gap in the NHC–Cu

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

• HOMO–LUMO overlap integrals were calculated using Multiwfn program [30]. The molecular structures of the title compound 4BGIPN and the benchmark TADF emitter 4CzIPN. Crystal structure for compound 4BGIPN in monoclinic form ((a) top view and (b) side view) where black arrows show opposite orientation of

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• weakening in the host/donor R–X bond, and an accompanied decrease in the HOMO–LUMO gap which may be experimentally observed as a red-shift in the vibrational frequency [46][47][64][65]. 1.2 Halogen bonding in monovalent iodine The σ-holes expressed by both molecular iodine and other organoiodine compounds

• absorption spectra of various ylides were generated both computationally and experimentally, and these revealed that ylide excitation should occur in the blue light region, inducing a HOMO–LUMO excitation within the ylide. The LUMO was a molecular orbital situated primarily on iodine, and its natural

The effect of dark states on the intersystem crossing and thermally activated delayed fluorescence of naphthalimide-phenothiazine dyads

• Liyuan Cao,
• Xi Liu,
• Xue Zhang,
• Jianzhang Zhao,
• Fabiao Yu and
• Yan Wan

Beilstein J. Org. Chem. 2023, 19, 1028–1046, doi:10.3762/bjoc.19.79

• . Thus, the HOMO/LUMO energy gap increases upon oxidation of the PTZ moiety. This is supported by the blue-shifted fluorescence of the dyads with the oxidized PTZ moieties as compared to the dyads containing the native PTZ moiety (Figure 2). Since the NI moiety is intact, the 3CS state becomes much

Synthesis, structure, and properties of switchable cross-conjugated 1,4-diaryl-1,3-butadiynes based on 1,8-bis(dimethylamino)naphthalene

• Semyon V. Tsybulin,
• Ekaterina A. Filatova,
• Alexander F. Pozharskii,
• Valery A. Ozeryanskii and
• Anna V. Gulevskaya

Beilstein J. Org. Chem. 2023, 19, 674–686, doi:10.3762/bjoc.19.49

• (for 5a and 5b) to 2.09 eV (for 5e). Thus, the HOMO–LUMO gap is significantly reduced by the introduction of the electron-withdrawing substituent, while the introduction of a donor substituent, e.g., a OMe group, does not change this value. Previously, using the example of diphenylpolyynes containing a

• phenyl and p-methoxyphenyl derivatives) to 2.09 eV (for p-nitrophenyl derivative). Thus, the HOMO–LUMO gap is significantly reduced by the introduction of the electron-withdrawing substituent, while the introduction of a donor substituent, e.g., a OMe group, does not change this value. On the other hand

A new oxidatively stable ligand for the chiral functionalization of amino acids in Ni(II)–Schiff base complexes

• Alena V. Dmitrieva,
• Oleg A. Levitskiy,
• Yuri K. Grishin and
• Tatiana V. Magdesieva

Beilstein J. Org. Chem. 2023, 19, 566–574, doi:10.3762/bjoc.19.41

• assuming that the HOMO/LUMO localization is not significantly influenced by the tert-butyl group. Indeed, the HOMO is a combination of the π-orbitals of the substituted phenylene fragment, the p-orbital of the amide nitrogen and the Ni d-orbitals (see Supporting Information File 1). Although the phenylene

Naphthalimide-phenothiazine dyads: effect of conformational flexibility and matching of the energy of the charge-transfer state and the localized triplet excited state on the thermally activated delayed fluorescence

• Kaiyue Ye,
• Liyuan Cao,
• Davita M. E. van Raamsdonk,
• Zhijia Wang,
• Jianzhang Zhao,
• Daniel Escudero and
• Denis Jacquemin

Beilstein J. Org. Chem. 2022, 18, 1435–1453, doi:10.3762/bjoc.18.149

• increases up to 84° in NI-PhMe2-PTZ. In NI-Ph-PTZ, the dihedral angle between the NI and the PTZ is ca. 55°, and it increases up to 87° in NI-PhMe2-PTZ. As shown in Table S1 (Supporting Information File 1), for all compounds, S1 corresponds to a HOMO→LUMO electronic transition (see the molecular orbitals

• involves a HOMO-2-to-LUMO electronic excitation (see Figure 10 for the orbitals). For the same compound, T2 corresponds to a HOMO→LUMO transition with a predominant 3CT character. The computed triplet energies (see Table S2) are in reasonable agreement with the experimental ones. More in details, the

Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

• Merve Karaman,
• Abhishek Kumar Gupta,
• Subeesh Madayanad Suresh,
• Tomas Matulaitis,
• Lorenzo Mardegan,
• Daniel Tordera,
• Henk J. Bolink,
• Sen Wu,
• Stuart Warriner,
• Ifor D. Samuel and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2022, 18, 1311–1321, doi:10.3762/bjoc.18.136

• emitters possess a smaller HOMO–LUMO gap. The HOMO is more strongly affected by the incorporation of donor units [28]. For instance, in the case of Cz-DiKTa and DMAC-DiKTa the HOMO is destabilized by 0.47 eV and 0.94 eV, respectively, compared to DiKTa [28]. The lowest unoccupied molecular orbital (LUMO

• and the HOMO energy between the two emitters. For DiKTa-DPA-OMe, the HOMO is mainly localized on the DPA unit but with some delocalization onto the DiKTa core, resulting in a destabilization of this orbital from −5.91 eV in DiKTa-OMe to −5.19 eV in DiKTa-DPA-OMe. The HOMO–LUMO gap, ΔEg, thus decreases

Synthesis, optical and electrochemical properties of (D–π)₂-type and (D–π)₂Ph-type fluorescent dyes

• Kosuke Takemura,
• Kazuki Ohira,
• Taiki Higashino,
• Keiichi Imato and
• Yousuke Ooyama

Beilstein J. Org. Chem. 2022, 18, 1047–1054, doi:10.3762/bjoc.18.106

• units (Figure 3). Consequently, the fact reveals that compared to the (D–π)2Ph-type structure, the (D–π)2-type structure can cause not only the stabilization of the LUMO energy level but also the delocalization of the HOMO and LUMO over the whole molecule, leading to a narrower HOMO–LUMO band gap of OTT

• properties both in solution and the solid state, but also can cause delocalization of the HOMO and the LUMO over the whole molecule as well as the stabilization of the LUMO energy level, leading to a narrower HOMO–LUMO band gap of OTT-2 than OTK-2, that is, the bathochromic shift of photoabsorption band from

Electrochemical and spectroscopic properties of twisted dibenzo[g,p]chrysene derivatives

• Tomoya Imai,
• Ryuhei Akasaka,
• Naruhiro Yoshida,
• Toru Amaya and
• Tetsuo Iwasawa

Beilstein J. Org. Chem. 2022, 18, 963–971, doi:10.3762/bjoc.18.96

• . Conversely, the LUMO level of the highly twisted DBC-H(56°)-2 was 0.05 eV lower than the less twisted DBC-H. As a result, the HOMO–LUMO gap of DBC-H(56°)-2 becomes smaller than that of DBC-H. This is consistent with the trend reported for twisted acenes [57]. The conformational effect of the MeO group was

• HOMO to LUMO and HOMO-1 to LUMO+1 (see Tables S1–S6 in Supporting Information File 1). The trend for the order of optical band gap is roughly consistent with that of the HOMO–LUMO gap obtained from DFT calculation [52]. In the photoluminescence spectra, the luminescence of DBC-Br was very weak. On the

Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials

• Valentin H. K. Fell,
• Joseph Cameron,
• Alexander L. Kanibolotsky,
• Eman J. Hussien and
• Peter J. Skabara

Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94

• , which extends the degree of π-conjugation [1]. In this way, the HOMO–LUMO gap can be narrowed [2]. Low HOMO–LUMO gaps are desirable for organic solar cells as the maximum photoflux density of the sun is at ca. 700 nm, corresponding to 1.77 eV [3]. However, fused systems have the drawback of being prone

• to poor solubility as a consequence of strong π–π interactions between the planar molecules [4]. Thus, attaching solubilising alkyl chains is necessary [5]. A common way to further decrease the HOMO–LUMO gap is attaching electron-donating and electron-accepting groups. Electron-rich units raise the

• EHOMO of the molecule closer to vacuum level, whilst electron-withdrawing units lower the ELUMO away from vacuum, leading to smaller HOMO–LUMO gaps [3]. A central aspect of the development of modern technology is the improvement of semiconductors. Semiconductors are, for example, applied in transistors

Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons

• Hengjia Liu and
• Guohua Xie

Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83

• permission from Elsevier. This content is not subject to CC BY 4.0. Pyrazine-containing polymers 19 and 20 investigated by Li et al. (a) HOMO/LUMO orbitals and energy levels (unit: eV) and (b) electrostatic potential surface (EPS) maps calculated by Gaussian 09 at the B3LYP/6-31G(d,p) level of theory. (c

• ) Cyclic voltammetry curves of the four compounds and HOMO/LUMO energy level diagram and (d) estimated from the CV tests. Figure 11a–d were reproduced from [45] with permission from The Royal Society of Chemistry. This content is not subject to CC BY 4.0. (a) UV–vis absorbance and (b) PL spectra (excited

Syntheses of novel pyridine-based low-molecular-weight luminogens possessing aggregation-induced emission enhancement (AIEE) properties

• Masayori Hagimori,
• Tatsusada Yoshida,
• Yasuhisa Nishimura,
• Yukiko Ogawa and
• Keitaro Tanaka

Beilstein J. Org. Chem. 2022, 18, 580–587, doi:10.3762/bjoc.18.60

• fractions. Fluorescence spectral changes of (a) 4a (10−5 M, Exmax = 413 nm) and (b) 4e (10−5 M, Exmax = 415 nm) upon addition of 0.1 M HCl. Protonation of N-methyl-4-((pyridin-2-yl)amino)-substituted maleimides 4 by 0.1 M HCl. Frontier molecular orbitals and HOMO–LUMO energy gaps of compounds 3a, 4a, and 4e

Substituent effect on TADF properties of 2-modified 4,6-bis(3,6-di-tert-butyl-9-carbazolyl)-5-methylpyrimidines

• Irina Fiodorova,
• Tomas Serevičius,
• Rokas Skaisgiris,
• Saulius Juršėnas and
• Sigitas Tumkevicius

Beilstein J. Org. Chem. 2022, 18, 497–507, doi:10.3762/bjoc.18.52

• were of similar molecular geometry with partially twisted carbazole units (in the order of 45–47°). The steric hindrance between the carbazole fragments and the pyrimidine core was enhanced by introducing a methyl group in position 5 of the latter [29], enabling sufficient HOMO–LUMO decoupling. Single

• pyrimidine ring and nearby phenyl groups, resulting in a lower HOMO–LUMO overlap. A similar LUMO localization is observed for compound 4 with a 2-cyano group. The energies of the HOMO level were in the range from −5.50 eV to −5.70 eV with lower values for those compounds bearing electron-withdrawing groups

• the larger conjugation length of the acceptor unit (also evidenced by a deeper LUMO), followed by lower oscillator strengths of S0→S1 transition due to more evident HOMO–LUMO decoupling (≈0.04 vs ≈0.4). Lower singlet–triplet energy gaps were estimated for compounds with stronger acceptor units (down

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

• . OLED fabrication and characterization The OLED device was fabricated and characterized in the CBP host (Figure 4). The HOMO–LUMO values obtained from the electrochemical measurement (Figure S5 in Supporting Information File 1) were used to evaluate whether the emitter works in a previously analyzed

Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines

• Najeh Tka,
• Mohamed Adnene Hadj Ayed,
• Mourad Ben Braiek,
• Mahjoub Jabli and
• Peter Langer

Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162

• their HOMO/LUMO energy levels were estimated by cyclic voltammetry measurements. Besides, density functional theory calculations were carried out for further exploration of their electronic properties. Keywords: catalysis; cross-coupling; cyclization; fluorescence; palladium; Introduction π-Conjugated

• values of HOMO, LUMO, and the band gap energies of compounds 4a–d at the B3LYP level of theory with 6-31G(d) basis set using dichloromethane as a continuum solvent model are given in Figure 9. The energy gap values are affected by the type and the position of the substituent located at the phenyl groups

• 4f. Calculated energy levels for compounds 4a–d and their spatial distribution of the HOMO–LUMO frontier molecular orbitals from DFT calculations. Visualization of MEP for compounds 4a–d calculated by B3LYP method with 6-31G(d) basis set. Cyclic voltammogram for 4c in 0.1 M (n-Bu)4NBF4/acetonitrile

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

• , anti-Kasha photophysics, and a small HOMO–LUMO gap when compared to its isomer, naphthalene. These properties make azulene-containing polymers an intriguing entity in the field of functional polymers, especially for organic electronic applications like organic field-effect transistors (OFET) and

• ) resulting in a relatively small electron repulsion energy in the first singlet excited state and thus, a small HOMO–LUMO (S0–S1) gap compared to naphthalene. The large energy gap between its S2 and S1 states (up to 15000 cm−1) makes internal conversion less probable, making azulene emit from the S2 state

• protonation of 17 and 18 by TFA resulted in a large red-shifted broad absorption band in the 500–900 nm region due to the formation of azulenium cations in the polymer backbone unlike the 1,3-polyazulene 5, which had no significant effect on its absorption spectrum upon protonation. The HOMO–LUMO gap for the