scholarly journals OS100: A Benchmark Set of 100 Digitized UV-Visible Spectra and Derived Experimental Oscillator Strengths

2021 ◽  
Author(s):  
Astrid Tarleton ◽  
Jorge Garcia-Alvarez ◽  
Anah Wynn ◽  
Cade Awbrey ◽  
Tomas Roberts ◽  
...  
Keyword(s):  
Density Functional ◽  
Oscillator Strengths ◽  
Learning Approaches ◽  
Excitation Energies ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Plain Text ◽  
Solvent Model ◽  
Visible Spectra ◽  
Uv Visible

Excited-state quantum chemical calculations typically report excitation energies and oscillator strengths, ƒ, for each electronic transition. On the other hand, UV-visible spectrophotometric experiments report energy-dependent molar extinction/attenuation coefficients, ε(v), that determine the absorption band line shapes. ε(v) and ƒ are related, but this relation is complicated by various broadening and solvation effects. We fit and integrated experimental UV-visible spectra to obtain ƒexp values for absorption bands and estimated the uncertainty in the fitting. We derived 164 ƒexp values from 100 organic molecules ranging in size from 6-34 atoms. The corresponding computed oscillator strengths (ƒcomp) were obtained with time-dependent density functional theory and a polarizable continuum solvent model. By expressing experimental and computed absorption strengths using a common quantity, we directly compared ƒcomp and ƒexp. While ƒcomp and ƒexp are well correlated (linear regression R2=0. 921), ƒcomp in most cases significantly overestimates ƒexp (regression slope=1.34). The agreement between absolute ƒcomp and ƒexp values was substantially improved by accounting for a solvent refractive index factor, as suggested in some derivations in the literature. The 100 digitized UV-visible spectra are included as plain text files in the supporting information to aid in benchmarking computational or machine-learning approaches that aim to simulate realistic UV-visible absorption spectra.

scholarly journals OS100: A Benchmark Set of 100 Digitized UV-Visible Spectra and Derived Experimental Oscillator Strengths

2021 ◽  
Author(s):  
Astrid Tarleton ◽  
Jorge Garcia-Alvarez ◽  
Anah Wynn ◽  
Cade Awbrey ◽  
Tomas Roberts ◽  
...  
Keyword(s):  
Density Functional ◽  
Oscillator Strengths ◽  
Learning Approaches ◽  
Excitation Energies ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Plain Text ◽  
Solvent Model ◽  
Visible Spectra ◽  
Uv Visible

The scientific method involves validating computational theories and methods against experimental results. However, the comparison between theory and experiments is not always straightforward; in UV-visible spectroscopy, experiments provide a plot of wavelength-dependent molar extinction/attenuation coefficients (ε) while computations typically provide single-valued excitation energies and oscillator strengths (ƒ) for each band. ε and ƒ are related, but this relation is complicated by various broadening and solvation effects. We describe a protocol to fit and integrate experimental UV-visible spectra to obtain ƒexp values for absorption bands and to estimate the uncertainty in the fitting. We apply this protocol to derive 164 ƒexp values from 100 organic molecules ranging in size from 6-34 atoms. The corresponding computed oscillator strengths (ƒcomp) are obtained with time-dependent density functional theory and a polarizable continuum solvent model. By expressing experimental and computed absorption strengths using a common quantity, we directly compare ƒcomp and ƒexp. While ƒcomp and ƒexp are well correlated (linear regression R2=0. 914), ƒcomp in most cases significantly overestimates ƒexp (regression slope=1.31). The agreement between absolute ƒcomp and ƒexp values is substantially improved by accounting for a solvent refractive index factor, as suggested in some derivations in the literature. The 100 digitized UV-visible spectra are included as plain text files in the supporting information to aid in benchmarking computational or machine-learning approaches that aim to simulate realistic UV-visible absorption spectra.

Role of heteroatoms and substituents on the structure, reactivity, aromaticity, and absorption spectra of pyrene: a density functional theory study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Bapan Saha ◽  
Pradip Kumar Bhattacharyya
Keyword(s):  
Density Functional Theory ◽  
Absorption Spectra ◽  
Density Functional ◽  
Structural Parameters ◽  
Visible Absorption ◽  
Functional Theory ◽  
Solvent Phase ◽  
Visible Spectra ◽  
Td Dft ◽  
Uv Visible

Abstract Effect of heteroatoms viz. BN and substituents viz. –Me (methyl), –OH (hydroxyl), –NH2 (amine), –COOH (carboxyl), and –CN (cyano) on the structural parameters, global reactivity, aromaticity, and UV-visible spectra of pyrene are studied with the help of density functional theory (DFT). Global reactivity parameters such as global hardness (η) and electrophilicity (ω) are calculated using density functional reactivity theory (DFRT). Time dependent density functional theory (TD-DFT) is explored for interpreting the UV-visible absorption spectra. Aromaticity of the pyrene rings are predicted from the nucleus independent chemical shift (NICS) values. Presence of BN unit and substituent induces reasonable impact on the studied parameters. The observed absorption spectra lie predominantly within the UV-region (both blue and red shifts are observed in presence of BN and substituent). HOMO energy and absorption spectra are affected nominally in solvent phase.

scholarly journals Theoretical Study of the Absorption Spectrum and the Thermochemistry of the CF3OSO3 Radical

2010 ◽  
Vol 65 (8-9) ◽  
pp. 720-724 ◽  
Author(s):  
Carlos J. Cobos ◽  
Adela E. Croce
Keyword(s):  
Absorption Spectrum ◽  
Density Functional ◽  
Basis Set ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Functional Theory ◽  
Dissociation Enthalpy ◽  
The Density Functional Theory ◽  
Uv Visible ◽  
Experimental Absorption

The UV-visible absorption spectrum of the recently reported CF3OSO3 radical has been studied by using the time-dependent generalization of the density functional theory (TDDFT). For this a set of eleven hybrid functionals combined with the 6-311+G(3df) basis set were employed. The main features of the three experimental absorption bands of CF3OSO3 recorded over the 220 - 530 nm range are well reproduced by the calculations. A dissociation enthalpy for the CF3O-SO3 bond of 19.1 kcal mol−1 is predicted at the BAC-G3MP2//B3LYP/6-311+G(3df) level of theory

Meso-aryl-ß-pyrrolic positions interactions in meso-tetraarylporphyrins: Flat arylporphyrins and building blocks for oligoporphyrins

2004 ◽  
Vol 08 (02) ◽  
pp. 111-119 ◽  
Author(s):  
Henry J. Callot ◽  
Romain Ruppert ◽  
Christophe Jeandon ◽  
Sébastien Richeter
Keyword(s):  
Building Blocks ◽  
Absorption Bands ◽  
Visible Absorption ◽  
Aryl Ring ◽  
Porphyrin Macrocycle ◽  
Uv Visible

Aryl groups bound to the meso positions of porphyrins often react with neighboring groups, in particular ß-acyl groups to give highly diversified monomeric and dimeric new functionalized porphyrins. The products, whose meso-aryl ring approaches coplanarity with the porphyrin macrocycle, show large shifts of UV-visible absorption bands and various potentialities for building external chelating moieties and assembling oligoporphyrins.

scholarly journals Unraveling the Effects of Co-Crystallization on the UV/Vis Absorption Spectra of an N-Salicylideneaniline Derivative. A Computational RI-CC2 Investigation

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4512
Author(s):  
Jean Quertinmont ◽  
Tom Leyssens ◽  
Johan Wouters ◽  
Benoît Champagne
Keyword(s):  
Optical Properties ◽  
Crystal Field ◽  
Indirect Effects ◽  
Density Functional ◽  
Crystal Packing ◽  
Density Functional Theory Method ◽  
Oscillator Strengths ◽  
Excitation Energies ◽  
Keto Form ◽  
Cell Parameters

This work aims at unraveling the effects of co-crystallization on the optical properties of an N-salicylideneaniline-derived molecular switch transforming between an enol and a keto form. This is achieved by way of a two-step multi-scale method where (i) the molecular geometry and unit cell parameters are optimized using a periodic boundary conditions density functional theory method and (ii) the optical properties are computed for a selection of clusters embedded in an array of point-charges that reproduce the crystal field electronic potential. The optical properties (vertical excitation energies and oscillator strengths) are obtained at the RI-CC2/def2-TZVPD level of approximation. This method allows us to decompose the effects of co-crystallization into (i) indirect effects, the geometry changes of the chromophore due to crystal packing with the coformer, and (ii) direct ones, the polarization due to the interacting coformer and to the crystal field. For the former effects, variations of a crucial torsion angle lead to modification of the π-conjugation and therefore to the decrease or increase of the excitation energies. About the latter, they are antagonistic: (i) the coformer is not directly involved in the excitations but its polarization decreases the excitation energies while (ii) the crystal field has the opposite effect. For the co-crystals with succinic and fumaric acids, combining these direct and indirect effects leads to a hypsochromic shift of the first absorption band with respect to the reference crystal, in agreement with experimental data.

scholarly journals Novel acridine-based thiosemicarbazones as ‘turn-on' chemosensors for selective recognition of fluoride anion: a spectroscopic and theoretical study

2018 ◽  
Vol 5 (7) ◽  
pp. 180646 ◽  
Author(s):  
Ibanga Okon Isaac ◽  
Iqra Munir ◽  
Mariya al-Rashida ◽  
Syed Abid Ali ◽  
Zahid Shafiq ◽  
...  
Keyword(s):  
Density Functional ◽  
Theoretical Study ◽  
Fluoride Anion ◽  
Metal Fluoride ◽  
Visible Absorption ◽  
Functional Theory ◽  
H Nmr ◽  
Tetrabutylammonium Fluoride ◽  
Uv Visible ◽  
Nickel Fluoride

New thiosemicarbazide-linked acridines 3a–c were prepared and investigated as chemosensors for the detection of biologically and environmentally important anions. The compounds 3a–c were found selective for fluoride (F − ) with no affinity for other anions, i.e. − OAc, Br − , I − , HSO 4 − , SO 4 2− , PO 4 3− , ClO 3 − , ClO 4 − , CN − and SCN − . Further, upon the gradual addition of a fluoride anion (F − ) source (tetrabutylammonium fluoride), a well-defined change in colour of the solution of probes 3a–c was observed. The anion-sensing process was studied in detail via UV–visible absorption, fluorescence and 1 H-NMR experiments. Moreover, during the synthesis of acridine probes 3a–c nickel fluoride (NiF 2 ), a rarely explored transition metal fluoride salt, was used as the catalyst. Theoretical studies via density functional theory were also carried out to further investigate the sensing and anion (F − ) selectivity pattern of these probes.

scholarly journals Hunting for Organic Molecules with Artificial Intelligence: Molecules Optimized for Desired Excitation Energies

2018 ◽  
Author(s):  
Masato Sumita ◽  
Xiufeng Yang ◽  
Shinsuke Ishihara ◽  
Ryo Tamura ◽  
Koji Tsuda
Keyword(s):  
Artificial Intelligence ◽  
Density Functional ◽  
Excitation Energies ◽  
Visible Absorption ◽  
Functional Theory ◽  
Materials Development ◽  
Creative Commons ◽  
Computational Resources ◽  
Android Robot ◽  
Absorption Measurements

<p><a></a>This work presents a proof-of-concept study in artificial-intelligence-assisted (AI-assisted) chemistry where a machine-learning-based molecule generator is coupled with density functional theory (DFT) calculations, synthesis, and measurement. Although deep-learning-based molecule generators have shown promise, it is unclear to what extent they can be useful in real-world materials development. To assess the reliability of AI-assisted chemistry, we prepared a platform using the ChemTS molecule generator and a DFT simulator, and attempted to generate novel photo-functional molecules whose lowest excited states lie at desired energetic levels. A ten-day run on 12 cores discovered 86potential photo-functional molecules around target lowest excitation levels, designated as 200, 300, 400, 500, and 600 nm. Among the molecules discovered, six were synthesized and five were confirmed to reproduce DFT predictions in ultraviolet visible absorption measurements. This result shows the potential of AI-assisted chemistry to discover ready-to-synthesize novel molecules with modest computational resources.<br></p><p><br></p><div>The Android robot is reproduced or modified from work created and shared by Google and used </div><div>according to terms described in the Creative Commons 3.0 Attribution License.</div>

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