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.

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 Thiophene-forming one-pot synthesis of three thienyl-bridged oligophenothiazines and their electronic properties

2016 ◽  
Vol 12 ◽  
pp. 2055-2064 ◽  
Author(s):  
Dominik Urselmann ◽  
Konstantin Deilhof ◽  
Bernhard Mayer ◽  
Thomas J J Müller
Keyword(s):  
Cyclic Voltammetry ◽  
Helical Structure ◽  
Quantum Yields ◽  
Absorption Bands ◽  
One Pot ◽  
Fluorescence Quantum Yields ◽  
Oxidation Potentials ◽  
Td Dft ◽  
Lower Oxidation ◽  
Stokes Shifts

The pseudo five-component Sonogashira–Glaser cyclization synthesis of symmetrically 2,5-diaryl-substituted thiophenes is excellently suited to access thienyl-bridged oligophenothiazines in a one-pot fashion. Three thienyl-bridged systems were intensively studied by UV–vis and fluorescence spectroscopy as well as by cyclic voltammetry. The oxidation proceeds with lower oxidation potentials and consistently reversible oxidations can be identified. The Stokes shifts are large and substantial fluorescence quantum yields can be measured. Computational chemistry indicates lowest energy conformers with sigmoidal and helical structure, similar to oligophenothiazines. TD-DFT and even semiempirical ZINDO calculations reproduce the trends of longest wavelengths absorption bands and allow the assignment of these transitions to possess largely charge-transfer character from the adjacent phenothiazinyl moieties to the central thienyl unit.

Synthesis, Electronic Spectra and Solvent-Induced Reversible Dissociation of Diphosphine(hexafluoroacetylacetonato)copper(I) Complexes

2003 ◽  
Vol 58 (10) ◽  
pp. 950-954 ◽  
Author(s):  
Valeri Pawlowski ◽  
Andreas Strasser ◽  
Arnd Vogler
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Electronic Spectra ◽  
Ion Pairs ◽  
Excitation Spectra ◽  
Polar Solvents ◽  
Long Wavelength ◽  
Reversible Dissociation ◽  
Ligand Charge Transfer

The complexes CuI(P-P)(hfac) with P-P = 1,2-bis(diphenylphosphino)ethane (diphos), 1,3-bis-(diphenylphosphino)propane (prophos), 2,2’-bis(diphenylphosphino)-1,1’-binaphthyl (binap) and hfac = hexafluoroacetylacetonate were synthesized and spectroscopically characterized. In the solid state or in solutions of non-polar solvents these compounds are yellow owing to a long-wavelength (hfac− →P-P) ligand-to-ligand charge transfer absorption. In coordinating solvents such as CH3CN the complexes undergo a reversible dissociation according to the equation: Cu(P-P)(hfac) + n CH3CN ⇌ [Cu(P-P)(CH3CN)n]+hfac−.While the complexes are not luminescent the ion pairs [Cu(P-P)(CH3CN)n]+hfac− are emissive at 77 K. The cations and the anions show separate emissions as indicated by the excitation spectra.

Stabilization of mixed valencies in Cu, Zn-based oxides

2005 ◽  
Vol 891 ◽  
Author(s):  
Anne Le Nestour ◽  
Manuel Gaudon ◽  
Mona Tréguer-Delapierre ◽  
Ronn Andriessen ◽  
Alain Demourgues
Keyword(s):  
Solid Solution ◽  
Solid State ◽  
Solid State Synthesis ◽  
Zinc Aluminate ◽  
Absorption Bands ◽  
Absorption Properties ◽  
Nir Absorption ◽  
Uv Visible ◽  
Intense Absorption ◽  
Copper Cations

ABSTRACTCu and Zn-based oxides have been developed for the last decades because of their remarkable electronic properties and their relevant UV-Visible-NIR absorption properties. Cu in oxides can adopt various oxidation states (+I, +II, +III) stabilized in various environments (h, Td, D4h, C4v, D2h, Oh). Divalent copper cations can occupy Td or Oh sites in zinc aluminate spinel network. Solid state routes lead to homogeneous phases with Zn1−xCuxAl2O4 compositions. Depending on the inversion rate in the spinel matrix, various absorption bands have been identified in the UV-Visible-CNIR spectrum. The synthesis of the zinc-aluminate spinel solid solution Zn1−xCuxAl2O4 by an esterification route led to monocrystalline nanosized oxides. Two intense absorption bands at 300 and 500 nm can be attributed to charge transfer phenomena between oxygen and Cu2+ cations in tetrahedral and octahedral coordinations. Two other less intense absorption bands centred at 800 nm and 1500 nm are also appearing when the copper rate in the spinel increases but their relative intensity are not in good agreement with those observed in the case of the solid-state synthesis. In the case of the esterification route, the absorption band at 800 nm is much more intense than in the case of the solid-state synthesis. It can only be explained either by a deviation to the centrosymmetric character of octahedral sites or by the occurence of a non negligible amount of monovalent copper cations which give electronic transitions in this energy range. A magnetic study correlated to EPR measurements confirms the occurence of a mixed valence state for copper cations in the solid solution Zn1−xCuxAl2O4. EPR spectra at T=4K show for the small concentration of Cu2+ (x<0.10) a strong anisotropic signal due to the presence of Cu2+ ions in a distorted octahedral symmetry (gx=2.07, gy= 2.15 gz=2.23). Moreover the hyperfine structure, identified on EPR spectra tend to disappear as the compounds are annealed under air because the content of paramagnetic centers Cu2+ (3d9) as well as their interactions become significant. Furthermore, the color changes drastically with the Cu+ (3d10) content. Finally the structural features and UV-Visible-NIR absorption properties of copper-zinc aluminates will be discussed and compared to Cu-doped ZnO.

Z-scheme CdS/Co9S8-RGO for photocatalytic hydrogen production

2020 ◽  
Vol 7 (14) ◽  
pp. 2692-2701 ◽  
Author(s):  
Shuangshuang Kai ◽  
Baojuan Xi ◽  
Haibo Li ◽  
Shenglin Xiong
Keyword(s):  
Charge Transfer ◽  
Solid State ◽  
Hydrogen Production ◽  
Hydrothermal Method ◽  
Evolution Rate ◽  
One Pot ◽  
Photocatalytic Hydrogen Production ◽  
Efficient Charge

All-solid-state Z-scheme CdS/Co9S8-RGO heterostructures are synthesized by a facile one-pot hydrothermal method followed by annealing, which exhibit a H2 evolution rate up to 4.82 mmol h−1 g−1 and a remarkable stability due to an efficient charge transfer and separation.

scholarly journals Spectral Properties of Dyes with Interfragmental Charge Transfer: Solvatochromism and Solvatofluorochromism of 2-(3-Coumaroyl)-benzopyrylium Perchlorates

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Edward V. Sanin ◽  
Alexander I. Novikov ◽  
Alexander D. Roshal
Keyword(s):  
Charge Transfer ◽  
Spectral Properties ◽  
Spectral Characteristics ◽  
Quantum Yields ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Solvent Parameters ◽  
Wavelength Absorption ◽  
Solvent Molecules ◽  
The Stability

The paper deals with the spectral properties of dyes with interfragmental charge transfer, in particular, derivatives of 2-(3-coumaroyl)benzopyrylium (CBP) perchlorates. The positions of long-wavelength absorption and emission bands, quantum yields, and lifetimes of fluorescence were measured, mostly in aprotic solvents. Regression analysis of the relationship between the spectral characteristics of CBP and the main solvent parameters (polarity, polarisability, nucleophilicity, and electrophilicity) was carried out. It was found that the characteristics of CBP depend mainly on two solvent parameters—polarity and/or nucleophilicity. An increase in these parameters results in a hypsochromic shift of absorption bands and a decrease of lifetimes and fluorescence intensity. The positions of the emission bands can demonstrate either hypsochromism or bathochromism, depending on the nature of the substituents. The solvatofluorochromic effects are not as strong as the solvatochromic ones. We believe that the spectral behaviour of CBP can be explained by cation depolarisation and by a decrease in the stability of nucleophilic complexes with solvent molecules that is associated with interfragmental charge transfer following excitation, relaxation, and radiative deactivation of the excited state.

scholarly journals One-Pot Microwave-Assisted Synthesis of Water-Soluble Pyran-2,4,5-triol Glucose Amine Schiff Base Derivative: XRD/HSA Interactions, Crystal Structure, Spectral, Thermal and a DFT/TD-DFT

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 117
Author(s):  
Yousef Hijji ◽  
Rajeesha Rajan ◽  
Hamdi Ben Yahia ◽  
Said Mansour ◽  
Abdelkader Zarrouk ◽  
...  
Keyword(s):  
Schiff Base ◽  
Molecular Orbital ◽  
Density Functional ◽  
Condensation Reaction ◽  
3D Structure ◽  
Water Soluble ◽  
Microwave Assisted Synthesis ◽  
One Pot ◽  
Microwave Assisted ◽  
Td Dft

The(3R,4R,6R)-3-(((E)-2-hydroxybenzylidene)amino)-6-(hydroxymethyl)tetrahydro-2H-pyran-2,4,5-triol water-soluble Glucose amine Schiff base (GASB-1) product was made available by condensation of 2-hydroxybenzaldehyde with (3R,6R)-3-amino-6-(hydroxymethyl)-tetra-hydro-2H-pyran-2,4,5-triol under mono-mode microwave heating. A one-pot 5-minute microwave-assisted reaction was required to complete the condensation reaction with 90% yield and without having byproducts. The 3D structure of GASB-1 was solved from single crystal X-ray diffraction data and computed by DFT/6-311G(d,p). The Hirshfeld surface analysis (HSA), molecular electronic potential (MEP), Mulliken atomic charge (MAC), and natural population analysis (NPA) were performed. The IR and UV-Vis spectra were matched to their density functional theory (DFT) relatives and the thermal behavior was resolved in an open-room condition via thermogravimetry/Derivative thermogravimetry (TG/DTG) and differential scanning calorimetry (DSC). The highest occupied molecular orbital/lowest unoccupied molecular orbital (HOMO/LUMO), density of state (DOS), and time-dependence TD-DFT computations were correlated to the experimental electron transfer in water and acrylonitrile solvents.

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