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

Hydroquinone–pyrrole dyads with varied linkers

• Hao Huang,
• Christoffer Karlsson,
• Maria Strømme,
• Martin Sjödin and
• Adolf Gogoll

Beilstein J. Org. Chem. 2016, 12, 89–96, doi:10.3762/bjoc.12.10

• substantial changes in the HOMO–LUMO gap that correlated with the extent of conjugation found experimentally. The results of this work are expected to open up for use of the investigated compounds as components of redox-active materials in sustainable, organic electrical energy storage devices. Keywords

• reference compound spectra (Figure 5). According to DFT calculations (see Supporting Information File 2 for details), the HOMO–LUMO transition is allowed for all compounds and has π–π* character. The HOMO of DMB couples strongly to the pyrrole HOMO, resulting in increased HOMO energy in 1, cis-3c, trans-3c

• therefore a measure of the charge delocalization in the molecule. This effect can be viewed as an increased delocalized system that results in a lowering of the HOMO–LUMO gap, which can be traced by the red shifts of the highest wavelength absorption in UV–vis spectra (Table 1). The extent of conjugation

Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

• Diego M. Andrada,
• Nicole Holzmann,
• Thomas Hamadi and
• Gernot Frenking

Beilstein J. Org. Chem. 2015, 11, 2727–2736, doi:10.3762/bjoc.11.294

• coefficient at the Ccarb atom that makes it suitable for π-backdonation. The LUMOs of compounds 1, and 7–10 which are not displayed in Figure 2 are also π-orbitals which have a node at the Ccarb atom. The HOMO–LUMO energy difference varies considerably between 4.58 eV (4) and 1.55 eV (15). The small HOMO–LUMO

• gap of the diamidocarbene 15 comes from the very low lying LUMO which has been noted before [42]. There is clearly a correlation between the HOMO–LUMO energy difference and the calculated singlet–triplet gap of the compounds which are given at the bottom of Figure 2. The largest singlet–triplet (S/T

Synthesis and photophysical characteristics of polyfluorene polyrotaxanes

• Aurica Farcas,
• Giulia Tregnago,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert and
• Franco Cacialli

Beilstein J. Org. Chem. 2015, 11, 2677–2688, doi:10.3762/bjoc.11.288

• reported [20]. Furthermore, these results suggest that the reduction process of 3·TM-βCD displays a semi-reversible behavior. The HOMO/LUMO energy levels in combination with the electronic potentials of the anodic indium tin oxide (ITO) glass substrate (−4.75 eV) and cathodic aluminum (−2.2 eV), prove that

• mg∙mL−1 in CHCl3 (a), and normalized emission spectra at 10−1 mg∙mL−1 and 10−3 mg∙mL−1 in CHCl3, (b) and (c), respectively. CV of 3 (a), 3·TM-βCD (b) and 3·TM-γCD (c) in 0.1 M tetrabutylammonium perchlorate (TBAClO4)/ACN solution at scan rate 20 mV∙s−1 and HOMO/LUMO energetic levels in addition to

Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics

• Alexander L. Kanibolotsky,
• Neil J. Findlay and
• Peter J. Skabara

Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191

• units into a conjugated network is a standard way to narrow the HOMO/LUMO band gap and examples of such units include dioxopyrrolopyrrole (DPP) [17][18][19], benzodifuranone [20] and boron-dipyrromethene (BODIPY) [21][22]. As a different class of electroactive materials, TTF derivatives are well-known

• -acceptor into the conjugated backbone led to a polymer with a narrow optical band gap (Egopt = 1.32 eV in CH2Cl2 solution), with the expected lower value of Egopt = 1.26 eV in the film due to π–π stacking interactions. The value of the HOMO/LUMO levels (−5.13/−3.49 eV) in the film were noticeably different

• solution, hence an interpretable 1H NMR spectrum was only obtained in a mixture of CDCl3 with CS2. In CH2Cl2 solution, the chemically synthesised product showed a π–π* transition peak at 443 nm, with a HOMO–LUMO gap of 2.32 eV, a value very similar to that of the parent sexithiophene 53 [91]. For the

Synthesis and spectroscopic properties of β-triazoloporphyrin–xanthone dyads

• Dileep Kumar Singh and
• Mahendra Nath

Beilstein J. Org. Chem. 2015, 11, 1434–1440, doi:10.3762/bjoc.11.155

• attractive building blocks for supramolecular arrays. These molecules provide various desirable properties such as a rigid planar geometry, highly conjugated structures, intense electronic absorption and emission properties and small HOMO–LUMO energy gaps [1][2]. Additionally, the electronic properties of

Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

• Awatef Ayadi,
• Aziz El Alamy,
• Olivier Alévêque,
• Magali Allain,
• Nabil Zouari,
• Mohammed Bouachrine and
• Abdelkrim El-Ghayoury

Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149

• . Packing diagram of L1 showing the orientation of the columns of head to tail dimers. UV–visible absorption spectra of ligands L1 and L2 (c 2.5 × 10−5 M in (dichloromethane/acetonitrile, 9:1, v/v)), room temperature. HOMO–LUMO Frontier orbitals representation for ligands L1 and L2. Cyclic voltammograms of

Surprisingly facile CO₂ insertion into cobalt alkoxide bonds: A theoretical investigation

• Willem K. Offermans,
• Claudia Bizzarri,
• Walter Leitner and
• Thomas E. Müller

Beilstein J. Org. Chem. 2015, 11, 1340–1351, doi:10.3762/bjoc.11.144

• state and the HOMO–LUMO gap of these complexes [53]. Penta-coordinated cobalt(III)–salen complexes are high-spin complexes and spin-restricted calculations are insufficient to describe their electron configuration. In the hexa-coordinated [(2-hydroxyethoxy)CoIII(salen)(trichloroacetate)] complex, the

Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F₄TCNQ

• Raúl García,
• M. Ángeles Herranz,
• Edmund Leary,
• M. Teresa González,
• Gabino Rubio Bollinger,
• Marius Bürkle,
• Linda A. Zotti,
• Yoshihiro Asai,
• Fabian Pauly,
• Juan Carlos Cuevas,
• Nicolás Agraït and
• Nazario Martín

Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120

• procedure explained in Supporting Information File 1. The corresponding transmission curves are shown in Figure 9. Notice that the molecular HOMO–LUMO gap was corrected, following the procedure previously reported [37]. The HOMO and all other occupied orbital energies were shifted by Σocc=−IP − εH +Δocc

• , while the LUMO and all other unoccupied orbital levels were shifted by Σvirt=−EA − εL +Δvirt. Here, Δocc (Δvirt) is the image charge correction for the occupied (unoccupied) states, εH (εL) is the Kohn–Sham energy of the gas phase HOMO (LUMO), and IP(EA) is the gas phase ionization potential (electron