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

• characteristics of the derivatives 1–9 were analyzed and compared (Figure 3). The parent compound N-phenylphenothiazine (1) shows an absorption maximum at 320 nm. Substitution of the arene moiety results in a shift of the absorption maxima due to a change in the HOMO–LUMO gaps. It turned out that the introduction

Oxidative and reductive cyclization in stiff dithienylethenes

• Michael Kleinwächter,
• Ellen Teichmann,
• Lutz Grubert,
• Martin Herder and
• Stefan Hecht

Beilstein J. Org. Chem. 2018, 14, 2812–2821, doi:10.3762/bjoc.14.259

• approximation reflecting the HOMO–LUMO gap. The sole exception to this trend is the only derivative with an H-substituted double bond ethene-Me, which exhibit the expected behavior of a less facile oxidation of the Z-isomer due to its somewhat twisted π-system leading to less pronounced π-conjugation and

• line with the largely reduced HOMO–LUMO gap of the colored closed isomers implying an energetically higher and thus more accessible HOMO level. The first and second oxidation potential are shifted depending on the electron-donating or electron-withdrawing character of the attached substituents

Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

• Hendrik V. Schröder and
• Christoph A. Schalley

Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190

• the TTF derivative 2 in the neutral, radical-cation, and dication state are shown in Figure 2. The spectrum of 2 shows only weak absorption above 350 nm which results in a pale yellow solution. The lowest-energy band is the HOMO→LUMO transition of the molecule. The radical-cation 2●+ exhibits two

[3 + 2]-Cycloaddition reaction of sydnones with alkynes

• Veronika Hladíková,
• Jiří Váňa and
• Jiří Hanusek

Beilstein J. Org. Chem. 2018, 14, 1317–1348, doi:10.3762/bjoc.14.113

• energies between the dipole and dipolarophile. While for type I (HOMO-controlled) combining a high-lying dipole HOMO with a dipolarophile LUMO the reaction is accelerated by electron-donating substituents on the dipole and electron-withdrawing substituents on the dipolarophile (both lowering the HOMO–LUMO

• HOMO are possible – due to similar energy gaps – both electron-rich as well as electron-poor dipolarophiles/dipoles react more quickly than parent (unsubstituted) ones. Using semi-empirical quantum calculations (CNDO/2), Houk et al. [58] calculated average HOMO/LUMO energies for azomethine-imines

• with alkyl propiolates (cf. Table 4, entries 6, 7, 23–29, 33, 34, 50–55, 58, 118, 141) and acylalkynes (Table 4, entry 142). Other terminal alkynes, for which the calculated lower HOMO–LUMO energy gaps correspond to the type III mechanism (especially phenylacetylenes, alkylacetylenes

D–A–D-type orange-light emitting thermally activated delayed fluorescence (TADF) materials based on a fluorenone unit: simulation, photoluminescence and electroluminescence studies

• Lin Gan,
• Xianglong Li,
• Xinyi Cai,
• Kunkun Liu,
• Wei Li and
• Shi-Jian Su

Beilstein J. Org. Chem. 2018, 14, 672–681, doi:10.3762/bjoc.14.55

• simulated EQE by employing the TTA model. Molecular structures of isomers 1 and 2. Thermal and electrochemical properties of the investigated compounds 1 and 2. The calculated HOMO, LUMO, twisting angles (θ, θ’), bond lengths (l, l’), ΔEST and dipole moment in gas phase for S0 and in solution for S1, from

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

• singlet–triplet energy splitting is one of the key elements for controlling the RISC efficiency, that the dihedral angle between the donor and the acceptor can be difficultly anticipated and that an overlap of both the HOMO/LUMO energy levels could adversely affect the color purity and ΔEST, it has to be

• with the azasiline donor, OLEDs displaying the unprecedented EQE of 22.3% were obtained [46]. As specificity, azasiline is a 6-membered heterocycle comprising a silicon atom introduced instead of a carbon atom to enlarge the HOMO–LUMO gap and lower the HOMO level. Due to the sp3 hybridization of the

Halogen-containing thiazole orange analogues – new fluorogenic DNA stains

• Aleksey A. Vasilev,
• Meglena I. Kandinska,
• Stanimir S. Stoyanov,
• Stanislava B. Yordanova,
• David Sucunza,
• Juan J. Vaquero,
• Obis D. Castaño,
• Stanislav Baluschev and
• Silvia E. Angelova

Beilstein J. Org. Chem. 2017, 13, 2902–2914, doi:10.3762/bjoc.13.283

• in the range of 0.137–0.862 and for dyes 5b–d these transitions are predicted to be more intense than the HOMO–LUMO ones. The HOMO–LUMO gaps are similar and range from 3.14 eV to 3.27 eV for the compounds in methanol. The frontier orbital energy difference for TO is the highest, thus confirming the

• presence of dsDNA, calculated fluorescence enhancement factor () and relative fluorescence quantum yield in presence of dsDNA with respect to TO. TDDFT/PBE0 excitation energies (eV), wavelengths (nm) (in parentheses), oscillator strength f, HOMO and LUMO energies and energy differences (HOMO–LUMO gap) (eV

Structure–property relationships and third-order nonlinearities in diketopyrrolopyrrole based D–π–A–π–D molecules

• Jan Podlesný,
• Lenka Dokládalová,
• Oldřich Pytela,
• Adam Urbanec,
• Milan Klikar,
• Numan Almonasy,
• Tomáš Mikysek,
• Jaroslav Jedryka,
• Iwan V. Kityk and
• Filip Bureš

Beilstein J. Org. Chem. 2017, 13, 2374–2384, doi:10.3762/bjoc.13.235

• substituent shifts the EHOMO to more positive values, slightly deepened ELUMO, and reduces the ΔE within the order of 1 (dimethylanilino) > 2 (4-methoxyphenyl) > 4 (5-methoxythiophen-2-yl) > 3 (thiophen-2-yl). The organometallic ferrocene in 5b caused reduction of the HOMO–LUMO gap up to 1.47 eV and proved to

• be the strongest electron donor within the studied series of compounds. This is in accordance with our previous observations [9][35]. Except for chromophores 3a,b, insertion of an additional acetylene linker rather extended the electrochemical HOMO–LUMO gap (series a vs b). Linear optical properties

• straightforward. Whereas in series b chromophore 1b showed larger THG than 2b, the situation is completely opposite in series a. Attaching ferrocene donors as in 5b has a very detrimental effect on the NLO response. Despite the THG efficiency usually increases with narrowing HOMO–LUMO gap, in the present series

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• from the lone-pair orbitals on the S and Se atoms, respectively, and the HOMO−2 is delocalized over the conjugated π-system (Figure 5). According to the time-dependent DFT calculations for 5 and 6, the S0 → S1 transitions are mainly dominated by the dipole-forbidden HOMO–LUMO (lp–π*) transition; this

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

• (right of Figure 10). This result is consistent with a decrease in the HOMO–LUMO gap due to the conjugate expansion of each dimer, and it can be said that Pc-subPc is a dye showing intermediate spectroscopic properties between Pc-Pc and subPc-subPc. Conclusion This review is a summary of research on

Molecular-level architectural design using benzothiadiazole-based polymers for photovoltaic applications

• Vinila N. Viswanathan,
• Arun D. Rao,
• Upendra K. Pandey,
• Arul Varman Kesavan and
• Praveen C. Ramamurthy

Beilstein J. Org. Chem. 2017, 13, 863–873, doi:10.3762/bjoc.13.87

• endeavored to obtain a series of low band gap polymers, P1, P2, and P3, with matching HOMO–LUMO energy levels with the acceptor moiety, without sacrificing the planarity of the molecule. Benzothiadiazole and fluorene, which are commonly used moieties in D–A–D-type polymers, have been chosen as the acceptor

• experimental values obtained by UV–vis spectroscopy. Here it is observed that both the HOMO–LUMO values and the electronic transition wavelengths of the polymers showed promising results for OPV applications. The HOMO–LUMO energy levels of the polymers were determined by cyclic voltammetry, using non-aqueous

• Ag/AgCl as the reference electrode in acetonitrile with 0.1 M tetrabutylammonium hexafluorophosphate as electrolyte at a scan rate of 100 mV/s. The instrument was calibrated with ferrocene/ferrocenium and was found to be ≈0.11 V. The HOMO–LUMO energy levels were calculated using the following

Synthesis and optical properties of new 5'-aryl-substituted 2,5-bis(3-decyl-2,2'-bithiophen-5-yl)-1,3,4-oxadiazoles

• Anastasia S. Kostyuchenko,
• Tatyana Yu. Zheleznova,
• Anton J. Stasyuk,
• Aleksandra Kurowska,
• Wojciech Domagala,
• Adam Pron and
• Alexander S. Fisyuk

Beilstein J. Org. Chem. 2017, 13, 313–322, doi:10.3762/bjoc.13.34

• the quantum-chemical predictions and the experiment. According to the theoretical results the observed transition is solely connected with the HOMO–LUMO transition. A careful analysis of frontier molecular orbitals disclosed a notable charge transfer from the central part to the terminal substituents

• involved in this process, but the main contribution (estimated by coefficients of the wave function for each excitation) comes from the HOMO–LUMO (predominantly) and HOMO−1–LUMO+1 transitions. For thiophene-substituted derivatives, the HOMO is delocalized over the whole molecule, while the LUMO is mostly

• -oxadiazole fragment (Figure 4). The peculiarity of the HOMO–LUMO localization for thiophene and phenyl substituents can be rationalized taking into account the fact that the thiophene core is electron rich and therefore can donate electron density to the core. It has to be mentioned that together with

Regiochemistry of cyclocondensation reactions in the synthesis of polyazaheterocycles

• Patrick T. Campos,
• Leticia V. Rodrigues,
• Andrei L. Belladona,
• Caroline R. Bender,
• Juliana S. Bitencurt,
• Fernanda A. Rosa,
• Davi F. Back,
• Helio G. Bonacorso,
• Nilo Zanatta,
• Clarissa P. Frizzo and
• Marcos A. P. Martins

Beilstein J. Org. Chem. 2017, 13, 257–266, doi:10.3762/bjoc.13.29

• other hand, the reaction of glyoxalates with amidines did not lead to the formation of imidazolones, but rather N-acylated products were obtained. All the products were isolated in good yields. DFT-B3LYP calculations provided HOMO/LUMO coefficients, charge densities, and the stability energies of the

• regiochemistry of the products [11]. Saiz et al. [14] synthesized 2-hydrazolyl-4-thiazolidinones with the aid of semi-empirical calculations (PM3 method). Through HOMO/LUMO energies, orbital coefficients, and charge distribution, a mechanism was proposed explaining the products observed. The authors claimed that

• the HOMO/LUMO energy gap is small and that the reaction between thiosemicarbazone and benzyl is kinetically favored, probably controlled by the frontier orbital component. Furthermore, calculations of HOMO and LUMO frontier orbital coefficients were used to prove the regiochemistry in cycloaddition

Spectral and DFT studies of anion bound organic receptors: Time dependent studies and logic gate applications

• Srikala Pangannaya,
• Neethu Padinchare Purayil,
• Shweta Dabhi,
• Venu Mankad,
• Prafulla K. Jha,
• Satyam Shinde and
• Darshak R. Trivedi

Beilstein J. Org. Chem. 2017, 13, 222–238, doi:10.3762/bjoc.13.25

• ]. The molecular geometry was fully optimized by using Berny’s optimization algorithm, which uses redundant internal coordinates. Molecular orbitals (HOMO, LUMO) were plotted using the GaussView software. In a second step the time-dependent DFT (TD-DFT) method was used considering the same B3LYP exchange

Benzothiadiazole oligoene fatty acids: fluorescent dyes with large Stokes shifts

• Lukas J. Patalag and
• Daniel B. Werz

Beilstein J. Org. Chem. 2016, 12, 2739–2747, doi:10.3762/bjoc.12.270

• (d,p)) reveal that the HOMO is predominantly located at the oligoene chain while the LUMO is rather spread over the BTD terminus (Figure 3). Indeed, further TD-DFT calculations (not shown) assign the longest wavelength absorptions of all three compounds to a high contribution of a HOMO–LUMO

High performance p-type molecular electron donors for OPV applications via alkylthiophene catenation chromophore extension

• Paul B. Geraghty,
• Calvin Lee,
• Jegadesan Subbiah,
• Wallace W. H. Wong,
• James L. Banal,
• Mohammed A. Jameel,
• Trevor A. Smith and
• David J. Jones

Beilstein J. Org. Chem. 2016, 12, 2298–2314, doi:10.3762/bjoc.12.223

• (PESA), and UV–vis to determine approximate energy HOMO–LUMO energy levels, and the data are summarized in Table 3. From the UV–vis absorption onsets, determined from the as-cast thin films, we determined the Eg(opt) levels, which demonstrate a clear trend in the reduction of Eg(opt) on increasing the

• to −5.02 eV for BPR (see Figures S10.1–S10.5). There is a good correlation between the HOMO energy levels measured by CV and PESA. DFT calculations. To further understand the impact on varying the conjugation length of the oligothiophene bridging arm on the distribution of the HOMO/LUMO energy levels

• LUMO decreases. The HOMO of the BXR series extends as the number of the thiophene rings increases. In contrast, the LUMO becomes more localized towards the N-hexylrhodamine acceptor moiety as the conjugation length increases. The calculated HOMO values and HOMO–LUMO energy difference follows the same

Synthesis and characterization of fluorinated azadipyrromethene complexes as acceptors for organic photovoltaics

• Forrest S. Etheridge,
• Roshan J. Fernando,
• Sandra Pejić,
• Matthias Zeller and
• Geneviève Sauvé

Beilstein J. Org. Chem. 2016, 12, 1925–1938, doi:10.3762/bjoc.12.182

• evaporator. The devices were characterized using a Oriel Sol2A solar simulator and a Keithley 2400 SourceMeter. The active area of each solar cell is 0.20 cm2. a) Azadipyrromethene ligand labeling positioning; b and c) chelates; d) estimated HOMO/LUMO energy levels [9]. Chemical structures of the fluorinated

Experimental and theoretical investigations on the high-electron donor character of pyrido-annelated N-heterocyclic carbenes

• Michael Nonnenmacher,
• Dominik M. Buck and
• Doris Kunz

Beilstein J. Org. Chem. 2016, 12, 1884–1896, doi:10.3762/bjoc.12.178

• conjugated π-system leads to an energy increase of the highest occupied π-orbital and a smaller HOMO–LUMO gap. Analyzing the molecular orbitals of the free carbenes I–III and dipiy reveals that in dipiy the carbene σ-orbital is no longer the highest occupied orbital, but it is found stabilized by 0.58 eV as

Synthesis and properties of fluorescent 4′-azulenyl-functionalized 2,2′:6′,2″-terpyridines

• Adrian E. Ion,
• Liliana Cristian,
• Mariana Voicescu,
• Masroor Bangesh,
• Augustin M. Madalan,
• Daniela Bala,
• Constantin Mihailciuc and
• Simona Nica

Beilstein J. Org. Chem. 2016, 12, 1812–1825, doi:10.3762/bjoc.12.171

• strength of I is too weak to play a role in absorption, however, it is responsible for the S1→S0 emission. Close lying electronic excited states resulting from transitions II and III are dominated by HOMO→LUMO+1 excitation (azulene-centered valence transition, accompanied by some charge transfer (CT) from

• the azulene to the central pyridine ring), with relatively minor contribution from HOMO→LUMO+2 excitation (CT from the azulene to the terpyridine moiety). The transitions II and III are responsible for the lower energy absorption around 377 nm (4a) and 381 nm (4b) and for S2→S0 emission in the

Effect of the π-conjugation length on the properties and photovoltaic performance of A–π–D–π–A type oligothiophenes with a 4,8-bis(thienyl)benzo[1,2-b:4,5-b′]dithiophene core

• Ni Yin,
• Lilei Wang,
• Yi Lin,
• Jinduo Yi,
• Lingpeng Yan,
• Junyan Dou,
• Hai-Bo Yang,
• Xin Zhao and
• Chang-Qi Ma

Beilstein J. Org. Chem. 2016, 12, 1788–1797, doi:10.3762/bjoc.12.169

• the CV results are also listed in Table 1. The frontier molecular orbital energy levels (HOMO/LUMO) and also the energy band gaps of these compounds were calculated according to the method reported in our previous paper [20], where the ferrocene/ferrocenium couple (Fc+/Fc) was used as the standard

Experimental and theoretical insights in the alkene–arene intramolecular π-stacking interaction

• Valeria Corne,
• Ariel M. Sarotti,
• Carmen Ramirez de Arellano,
• Rolando A. Spanevello and
• Alejandra G. Suárez

Beilstein J. Org. Chem. 2016, 12, 1616–1623, doi:10.3762/bjoc.12.158

• , represents the destabilizing interactions between the occupied orbitals (steric repulsion), ΔEoi shows the interaction between orbitals (including all electron-pair bondings, HOMO–LUMO charge-transfer processes, polarization interactions, etc.), and ΔEdisp refers to the effect exerted by dispersion forces

Ring-whizzing in polyene-PtL₂ complexes revisited

• Oluwakemi A. Oloba-Whenu,
• Thomas A. Albright and
• Chirine Soubra-Ghaoui

Beilstein J. Org. Chem. 2016, 12, 1410–1420, doi:10.3762/bjoc.12.135

• ; density functional theory (DFT); hapototropic rearrangements; HOMO–LUMO interactions; polyene-ML2 complexes; ring-whizzing; Introduction Polyene–transition metal complexes were found to undergo fluxional rearrangements as early as 1956 with the preparation of Cp2Fe(CO)2 [1]. The migration of an MLn unit

3,6-Carbazole vs 2,7-carbazole: A comparative study of hole-transporting polymeric materials for inorganic–organic hybrid perovskite solar cells

• Wei Li,
• Munechika Otsuka,
• Takehito Kato,
• Yang Wang,
• Takehiko Mori and
• Tsuyoshi Michinobu

Beilstein J. Org. Chem. 2016, 12, 1401–1409, doi:10.3762/bjoc.12.134

• summary, highly electron-rich donor–donor type polymers with the different carbazole connectivity patterns, i.e., 3,6-Cbz-EDOT and 2,7-Cbz-EDOT, were synthesized by the Pd-catalyzed Stille polycondensation. The HOMO/LUMO energy levels of these polymers were determined from the onset oxidation potentials

Syntheses of dibenzo[d,d']benzo[2,1-b:3,4-b']difuran derivatives and their application to organic field-effect transistors

• Minh Anh Truong and
• Koji Nakano

Beilstein J. Org. Chem. 2016, 12, 805–812, doi:10.3762/bjoc.12.79

• the π-conjugated skeleton than syn-DBBDF 5, it should possess an extended π-conjugation length, resulting in a red-shifted absorption spectrum. The HOMO–LUMO energy gaps estimated from the absorption edges were 3.72 eV and 3.32 eV for syn-DBBDF 5 and syn-DNBDF 6, respectively. Their photoluminescence

• showed one oxidation wave with an onset potential of 0.56 eV (vs Fc/Fc+, HOMO = −5.36 eV). The lower oxidation potential and higher HOMO energy level of syn-DNBDF 6 should reflect its longer π-conjugation length than syn-DBBDF 5. Based on their HOMO energy levels and HOMO−LUMO energy gaps, syn-DBBDF 5

Versatile deprotonated NHC: C,N-bridged dinuclear iridium and rhodium complexes

• Albert Poater

Beilstein J. Org. Chem. 2016, 12, 117–124, doi:10.3762/bjoc.12.13

• transformation also follows the principle of maximum hardness [70][71], i.e., the chemical hardness evolves from 39.6 to 46.7 kcal/mol bearing a H-T type of coordination. This increase of chemical hardness is a consequence of the increased stability of the HOMO, which results in a larger HOMO–LUMO gap [61][65