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.

scholarly journals A New Benchmark Set for Excitation Energy of Charge Transfer States: Systematic Investigation of Coupled-Cluster Type Methods

2020 ◽  
Author(s):  
Balázs Kozma ◽  
Attila Tajti ◽  
Baptiste Demoulin ◽  
Róbert Izsák ◽  
Marcel Nooijen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excitation Energy ◽  
Systematic Investigation ◽  
Coupled Cluster ◽  
Excitation Energies ◽  
Chemical Methods ◽  
Valence States ◽  
Quantum Chemical Methods ◽  
Material Physics ◽  
Cluster Methods

There are numerous publications on benchmarking quantum chemistry methods for excited states. These studies rarely include Charge Transfer (CT) states although many interesting phenomena in e.g. biochemistry and material physics involve transfer of electron between fragments of the system. Therefore, it is timely to test the accuracy of quantum chemical methods for CT states, as well. In this study we first suggest a set benchmark systems consisting of dimers having low-energy CT states. On this set, the excitation energy has been calculated with coupled cluster methods including triple excitations (CC3, CCSDT-3, CCSD(T)(a)* ), as well as with methods including full or approximate doubles (CCSD, STEOM-CCSD, CC2, ADC(2), EOM-CCSD(2)). The results show that the popular CC2 and ADC(2) methods are much more inaccurate for CT states than for valence states. On the other hand, CCSD seems to have similar systematic overestimation of the excitation energies for both valence and CT states. Concerning triples methods, the new CCSD(T)(a)* method including non-iterative triple excitations preforms very well for all type of states, delivering essentially CCSDT quality results.<br>

SPECTROSCOPIC AND QUANTUM-CHEMICAL INVESTIGATION OF TESTOSTERONE PROPIONATE, A COMMONLY MISUSED ANABOLIC STEROID

2021 ◽  
Author(s):  
Nikola Ristivojević ◽  
◽  
Dušan Dimić ◽  
Marko Đošić ◽  
Stefan Mišić ◽  
...  
Keyword(s):  
Quantum Chemical ◽  
Density Functional ◽  
Testosterone Propionate ◽  
Anabolic Steroids ◽  
Chemical Methods ◽  
Dft Methods ◽  
Functional Theory ◽  
Quantum Chemical Methods ◽  
Td Dft ◽  
Ir And Raman

Anabolic steroids are a group of commonly counterfeit substances used by individuals who want to gain weight and muscles. Testosterone propionate (TP), an ester analog of testosterone, belongs to this group and its spectroscopic analysis is important especially when it is improperly labeled and misused. In this contribution quantum chemical methods, at the B3LYP/6- 311++G(d,p) level of theory, were applied for the prediction of the vibrational (IR and Raman) and UV-VIS spectra of TP. The applicability of the chosen level of theory was proven based on the comparison between experimental and theoretical bond lengths and angles. The most prominent bands in the IR and Raman spectra were assigned and correlated with the calculated ones. The electronic spectra were also analyzed and the assignments were made based on the Time-Dependent Density Functional Theory (TD-DFT) calculations. The orbitals included in the most intense transitions were visualized and possible solvent effects were discussed. The presented results proved the applicability of the DFT methods for the prediction of spectra that could lead to the counterfeit substances determination.

scholarly journals One-pot three-component synthesis and photophysical characteristics of novel triene merocyanines

2014 ◽  
Vol 10 ◽  
pp. 599-612 ◽  
Author(s):  
Christian Muschelknautz ◽  
Robin Visse ◽  
Jan Nordmann ◽  
Thomas J J Müller
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Sonogashira Coupling ◽  
Absorption Bands ◽  
One Pot ◽  
Red Emission ◽  
Long Wavelength ◽  
Dft Computations ◽  
Td Dft ◽  
Intense Absorption

Novel triene merocyanines, i.e. 1-styryleth-2-enylidene and 4-(1,3,3-trimethylindolin-2-ylidene)but-2-en-1-ylideneindolones are obtained in good to excellent yields in a consecutive three-component insertion Sonogashira coupling–addition sequence. The selectivity of either series is remarkable and has its origin in the stepwise character of the terminal addition step as shown by extensive computations on the DFT level. All merocyanines display intense absorption bands in solution and the film spectra indicate J-aggregation. While 1-styryleth-2-enylideneindolones show an intense deep red emission in films, 4-(1,3,3-trimethylindolin-2-ylidene)but-2-en-1-ylideneindolones are essentially nonemissive in films or in the solid state. TD-DFT computations rationalize the charge-transfer nature of the characteristic broad long-wavelength absorptions bands.

STRUCTURAL, ELECTRONIC AND OPTICAL PROPERTIES OF THIOPHENE AND THIENOTHIOPHENE CONTAINING DIKETO-PYRROLO-PYRROLES (DPPs) IN POLAR APROTIC SOLVENTS

2013 ◽  
Vol 01 (01) ◽  
pp. 1250003 ◽  
Author(s):  
HONGJUN LIU ◽  
ERIC ASSEN B. KANTCHEV ◽  
HUEI SHUAN TAN ◽  
TYLER B. NORSTEN
Keyword(s):  
Optical Properties ◽  
Density Functional ◽  
Chemical Methods ◽  
Functional Theory ◽  
Molecular Conformations ◽  
Quantum Chemical Methods ◽  
Td Dft ◽  
Ct Complex ◽  
New Compounds ◽  
C Nmr

Thiophene (T) and thienothiophene (TT) containing 2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) compounds were prepared according to the succinic ester route from the corresponding heterocyclic nitrile precursors. As is typical of most DPP pigments, the new compounds showed high thermal stability and could be obtained in pure form as determined by elemental analysis. The bulk properties and molecular structure of the compounds were further characterized by thin film, powder XRD and solid state CP-MAS 13 C NMR. Density functional theory (DFT) and time-dependent (TD) DFT were employed to study the geometric and electronic structures of these molecules in the ground state. The optical properties were investigated by UV-Vis absorption and fluorescence spectroscopies in dimethylsulfoxide (DMSO) and N,N-dimethylacetamide (DMA), which revealed that the absorption maximum of the thiophene diketo-pyrrolo-pyrroles (TDPP) and thienothiophene diketo-pyrrolo-pyrroles (TTDPP) in solution were red shifted up to 25 nm and 60 nm, respectively, relative to Pigment Red 255 (PhDPP), while a new absorption band appeared at longer wavelengths in N-methyl pyrolidone (NMP) and N,N′-dimethylpropylene urea (DMPU) which is ascribed to solvent induced charge transfer (CT) complex. The molecular conformations and absorption spectra of TDPP and TTDPP were characterized by quantum chemical methods in order to better understand the observed behavior.

Theoretical investigations into the charge transfer properties of thiophene α-substituted naphthodithiophene diimides: excellent n-channel and ambipolar organic semiconductors

2017 ◽  
Vol 19 (21) ◽  
pp. 13978-13993 ◽  
Author(s):  
Li-Fei Ji ◽  
Jian-Xun Fan ◽  
Shou-Feng Zhang ◽  
Ai-Min Ren
Keyword(s):  
Charge Transfer ◽  
Charge Transport ◽  
Transport Properties ◽  
Organic Semiconductors ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Chemical Methods ◽  
Quantum Chemical Methods ◽  
Theoretical Investigations ◽  
Transfer Properties

The effects of substituents at the thiophene α-position of NDTI on the electronic structures, stability, molecular packing and the charge transport properties were investigated using quantum chemical methods.

Reconsideration of solvent effects calculated by semiempirical quantum chemical methods

1993 ◽  
Vol 14 (3) ◽  
pp. 371-377 ◽  
Author(s):  
Miroslaw Szafran ◽  
Mati M. Karelson ◽  
Alan R. Katritzky ◽  
Jacek Koput ◽  
Michael C. Zerner
Keyword(s):  
Solvent Effects ◽  
Quantum Chemical ◽  
Chemical Methods ◽  
Quantum Chemical Methods

scholarly journals A New Benchmark Set for Excitation Energy of Charge Transfer States: Systematic Investigation of Coupled-Cluster Type Methods

2020 ◽  
Author(s):  
Balázs Kozma ◽  
Attila Tajti ◽  
Baptiste Demoulin ◽  
Róbert Izsák ◽  
Marcel Nooijen ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Excitation Energy ◽  
Systematic Investigation ◽  
Coupled Cluster ◽  
Excitation Energies ◽  
Chemical Methods ◽  
Valence States ◽  
Quantum Chemical Methods ◽  
Material Physics ◽  
Cluster Methods

There are numerous publications on benchmarking quantum chemistry methods for excited states. These studies rarely include Charge Transfer (CT) states although many interesting phenomena in e.g. biochemistry and material physics involve transfer of electron between fragments of the system. Therefore, it is timely to test the accuracy of quantum chemical methods for CT states, as well. In this study we first suggest a set benchmark systems consisting of dimers having low-energy CT states. On this set, the excitation energy has been calculated with coupled cluster methods including triple excitations (CC3, CCSDT-3, CCSD(T)(a)* ), as well as with methods including full or approximate doubles (CCSD, STEOM-CCSD, CC2, ADC(2), EOM-CCSD(2)). The results show that the popular CC2 and ADC(2) methods are much more inaccurate for CT states than for valence states. On the other hand, CCSD seems to have similar systematic overestimation of the excitation energies for both valence and CT states. Concerning triples methods, the new CCSD(T)(a)* method including non-iterative triple excitations preforms very well for all type of states, delivering essentially CCSDT quality results.<br>

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