scholarly journals Predicting the substituent effects in the optical and electrochemical properties of N,N′-substituted isoindigos

2021 ◽  
Author(s):  
Ferdinand L. Kiss ◽  
Brian P. Corbet ◽  
Nadja A. Simeth ◽  
Ben L. Feringa ◽  
Stefano Crespi
Keyword(s):  
Electrochemical Properties ◽  
Bulk Heterojunction ◽  
Substituent Effects ◽  
Dft Method ◽  
Structural Isomer ◽  
Visible Range ◽  
Broad Absorption Band ◽  
Td Dft ◽  
Organic Photovoltaic Materials ◽  
Electron Deficiency

AbstractIsoindigo, the structural isomer of the well-known dye indigo, has seen a major revival recently because of the increasing interest of its use as a potential drug core structure and for the development of organic photovoltaic materials. Highly beneficial for diverse applications are its facile synthesis, straightforward functionalisation and the broad absorption band in the visible range. Moreover, its intrinsic electron deficiency renders isoindigo a promising acceptor structure in bulk heterojunction architectures. Here we present new insights into the substituent effects of N-functionalised isoindigos, developing a reliable and fast in silico screening approach of a library of compounds. Using experimental UV–Vis and electrochemical data increased the accuracy of the TD-DFT method employed. This procedure allowed us to accurately predict the optical and electrochemical properties of N-functionalised isoindigos and the elucidation of the relationship between substituent effects and electronic properties. Graphic abstract

scholarly journals Radiation Induced One-Electron Oxidation of 2-Thiouracil in Aqueous Solutions

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4402
Author(s):  
Skotnicki ◽  
Taras-Goslinska ◽  
Janik ◽  
Bobrowski
Keyword(s):  
Absorption Band ◽  
Absorption Spectra ◽  
Sulfur Atom ◽  
Density Functional ◽  
Transient Absorption ◽  
Dft Method ◽  
Broad Absorption Band ◽  
Transient Absorption Spectra ◽  
Td Dft ◽  
Type Radical

Oxidative damage to 2-thiouracil (2-TU) by hydroxyl (•OH) and azide (N3) radicals produces various primary reactive intermediates. Their optical absorption spectra and kinetic characteristics were studied by pulse radiolysis with UV-vis spectrophotometric and conductivity detection and by time-dependent density functional theory (TD-DFT) method. The transient absorption spectra recorded in the reactions of •OH with 2-TU depend on the concentration of 2-TU, however, only slightly on pH. At low concentrations, they are characterized by a broad absorption band with a weakly pronounced maxima located at λ = 325, 340 and 385 nm, whereas for high concentrations, they are dominated by an absorption band with λmax ≈ 425 nm. Based on calculations using TD-DFT method, the transient absorption spectra at low concentration of 2-TU were assigned to the ●OH-adducts to the double bond at C5 and C6 carbon atoms (3●, 4●) and 2c-3e bonded ●OH adduct to sulfur atom (1…●OH) and at high concentration of 2-TU also to the dimeric 2c-3e S-S-bonded radical in neutral form (2●). The dimeric radical (2●) is formed in the reaction of thiyl-type radical (6●) with 2-TU and both radicals are in an equilibrium with Keq = 4.2 × 103 M−1. Similar equilibrium (with Keq = 4.3 × 103 M−1) was found for pH above the pKa of 2-TU which involves admittedly the same radical (6●) but with the dimeric 2c-3e S-S bonded radical in anionic form (2●−). In turn, ●N3-induced oxidation of 2-TU occurs via radical cation with maximum spin location on the sulfur atom which subsequently undergoes deprotonation at N1 atom leading again to thiyl-type radical (6●). This radical is a direct precursor of dimeric radical (2●).

scholarly journals Experimental and theoretical study on solvent and substituent effects on the intramolecular charge transfer in 3-[(4-substituted)phenylamino]isobenzofuran-1(3H)-ones

2018 ◽  
Vol 83 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Nevena Prlainovic ◽  
Milica Rancic ◽  
Ivana Stojiljkovic ◽  
Jasmina Nikolic ◽  
Sasa Drmanic ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Density Functional ◽  
Energy Gap ◽  
Intramolecular Charge Transfer ◽  
Substituent Effects ◽  
Dft Method ◽  
Electronic Excitations ◽  
Functional Theory ◽  
Td Dft

The substituent and solvent effects on solvatochromism in 3-[(4-substituted) phenylamino]isobenzofuran-1(3H)-ones were studied using experimental and theoretical methodologies. The effect of specific and non-specific solvent?solute interactions on the shifts of UV?Vis absorption maxima were evaluated using the Kamlet?Taft and Catal?n solvent parameter sets. The experimental results were studied by density functional theory (DT) and time-dependent density functional theory (TD-DFT). The HOMO/LUMO energies (EHOMO/ELUMO) and energy gap (Egap) values, as well as the mechanism of electronic excitations and the changes in the electron density distribution in both ground and excited states of the investigated molecules were studied by calculation in the gas phase. The electronic excitations were calculated by the TD-DFT method in the solvent methanol. It was found that both substituents and solvents influence the degree of ?-electron conjugation of the synthesized molecules and affect the intramolecular charge transfer character.

Quantum-Chemical Ab Initio Calculations on Inda- and Thallabenzene (C5H5In and C5H5Tl) and their Structural Isomers η5-C5H5In and η5-C5H5Tl

2018 ◽  
Vol 71 (3) ◽  
pp. 102
Author(s):  
Emma Persoon ◽  
Yuekui Wang ◽  
Gerhard Raabe
Keyword(s):  
Ab Initio ◽  
Quantum Chemical ◽  
Density Functional ◽  
Single Point ◽  
Normal Modes ◽  
Dft Method ◽  
Basis Sets ◽  
Triplet States ◽  
Structural Isomers ◽  
Td Dft

Quantum-chemical ab initio, time-independent, as well as time-dependent density functional theory (TD-DFT) calculations were performed on the so far elusive heterocycles inda- and thallabenzene (C5H5In and C5H5Tl), employing several different methods (MP2, CISD, CCSD, CCSD(T), BD, BD(T), QCISD, QCISD(T), CASSCF, DFT/B3LYP), effective core potentials, and different basis sets. While calculations on the MP2 level predict the ground states of the title compounds to be singlets with the first triplet states between 13 and 15 kcal mol−1 higher in energy, single point calculations with the QCISD(T), CCSD(T), and BD(T) methods at CCSD-optimized structures result in energy differences between the singlet and the triplet states in the range between 0.3 and 2.1 kcal mol−1 in favour of the triplet states. According to a CASSCF(8,8) calculation the triplets are also more stable by about 2.5–2.9 kcal mol−1. Calculations were also performed for the C5v-symmetric η5 structural isomers (cyclopentadienylindium, CpIn, and cyclopentadienylthallium, CpTl, Cp = C5H5) of the title compounds. At the highest level of theory employed in this study, C5H5In is between 79 and 88 kcal mol−1 higher in energy than CpIn, while this energy difference is even larger for thallabenzene where C5H5Tl is energetically between 94 and 102 kcal mol−1 above CpTl. In addition we report on the UV/vis spectra calculated with a TD-DFT method as well as on the spectra of the normal modes of C5H5In and C5H5Tl. Both types of spectra might facilitate identification of the title compounds eventually formed in photolysis or pyrolysis experiments.

Substituent Effects on the Electrochemical Properties of Pyrroles and Small Oligopyrroles

1997 ◽  
Vol 9 (3) ◽  
pp. 723-729 ◽  
Author(s):  
C. P. Andrieux ◽  
P. Hapiot ◽  
P. Audebert ◽  
L. Guyard ◽  
M. Nguyen Dinh An ◽  
...  
Keyword(s):  
Electrochemical Properties ◽  
Substituent Effects

scholarly journals TD-DFT Prediction of the Intermolecular Charge-Transfer UV-Vis Spectra of Viologen Salts in Solution

2020 ◽  
Vol 10 (22) ◽  
pp. 8108
Author(s):  
Giacomo Saielli
Keyword(s):  
Charge Transfer ◽  
Solvent Effects ◽  
Polar Solvent ◽  
Essential Feature ◽  
Visible Range ◽  
Absorption Bands ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Td Dft ◽  
Very High

The absorption spectrum of viologen salts in a medium or low polar solvent is an essential feature that influences all its “chromic” applications, whether we are considering thermochromic, electrochromic, photochromic or chemochromic devices. The prediction by quantum chemical methods of such absorption bands, typically observed in the visible range and due to charge transfer (CT) phenomena, is a very challenging problem due to strong solvent effects influencing both the geometry and the electronic transitions. Here we present a computational protocol based on DFT to predict with very high accuracy the absorption maxima of the CT bands of a series of viologen salts in solvents of low and medium polarity. The calculations also allow a clear dissection of the solvent effects, direct and indirect, and orbital contributions to the CT band.

Investigating the photolysis of NO2 and influencing factors by using a DFT/TD-DFT method

2020 ◽  
Vol 230 ◽  
pp. 117559
Author(s):  
Xiaoxiang Wang ◽  
Lei Zhou ◽  
Yifan Liu ◽  
Kun Zhang ◽  
Guangli Xiu
Keyword(s):  
Influencing Factors ◽  
Dft Method ◽  
Td Dft

Étude structurale des systèmes dissymétriques de structure D-π-A à base de thiénopyrazine destinés aux cellules solaires organiques de type « bulk heterojunction » (BHJ)

2019 ◽  
Vol 97 (10) ◽  
pp. 745-755 ◽  
Author(s):  
Mohamed Bourass ◽  
Mohammed Bouachrine
Keyword(s):  
Bulk Heterojunction ◽  
Td Dft ◽  
Homo Lumo

Onze nouvelles molécules organiques de structure donneurs-espaceur-accepteurs (D-π-A) utilisées pour les cellules solaires organiques (OSC) basées sur la thiénopyrazine et le thiophène ont été étudiées par la théorie de la densité fonctionnelle (DFT) et la théorie de la densité fonctionnelle dépendante de temps DFT (TD-DFT), pour expliquer comment l’ordre de conjugaison influe sur les performances des cellules solaires. Le groupe accepteur d’électrons (ancrage) était composé de 2-cyanoacrylique pour tous les composés, tandis que l’unité donneuse d’électrons était variée et que son influence fut étudiée. Les résultats théoriques ont montré que les calculs TD-DFT, avec une fonction hybride d’échange – corrélation utilisant la méthode d’atténuation de Coulomb (CAM-B3LYP) en conjonction avec un modèle de solvatation à cycle continu polarisable (modèle de continuum polarisable, PCM) combinée avec la base 6-31G(d,p), était raisonnablement capable de prédire les énergies d’excitation, les spectres d’absorption et d’émission des molécules étudiées. Les niveaux d’énergie des orbitales moléculaires frontières (orbitale moléculaire occupée de plus haute énergie (HOMO) et orbitale moléculaire inoccupée de plus basse énergie (LUMO) de ces composés peuvent avoir un effet positif sur le processus d’injection et de régénération d’électrons. La tendance des lacunes calculées HOMO-LUMO se compare bien avec les données spectrales. En outre, les valeurs estimées de photovoltage en circuit ouvert (Voc) pour ces composés ont été présentées. L’étude des propriétés structurelles, électroniques et optiques de ces composés pourrait aider à concevoir des matériaux organiques photovoltaïques fonctionnels plus efficaces.

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