Two Excited State Structures of Donor-Acceptor Substituted "Proton Sponge"

2005 ◽  
Vol 277-279 ◽  
pp. 1060-0 ◽  
Author(s):  
A. Szemik Hojniak ◽  
I. Deperasińska ◽  
W.J. Buma ◽  
G. Balkowski ◽  
A.F. Pozharsky ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Ground State ◽  
Experimental Spectrum ◽  
Proton Sponge ◽  
Strong Electron ◽  
Acceptor Group ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Ab Initio Hf

Photoexcitation of “proton sponge” 1,8-bis (dimethylamino) naphthalene (DMAN) leads to charge transfer (CT) emission. This work demonstrates that substitution of DMAN with a strong electron acceptor group (CN) results in CN-DMAN and leads to a stronger orbital decoupling between the Donor and Acceptor groups and to a more effective CT process (λF = 630 nm). The theoretical absorption spectrum calculated for CN-DMAN using the ZINDO method on its ground state ab initio [HF/6-31G(d)] optimized geometry reproduces a better experimental spectrum than that calculated using the RCIS method. It also shows that AM1 excited state (1La) optimization reveals two quasi-degenerated states with anti-quinoidal (A) and quinoidal (B) structures and the CT nature. Both structures may contribute more or less equally to the fluorescence of CN-DMAN in a solution.

scholarly journals Thermochromic aggregation-induced dual phosphorescence via temperature-dependent sp3-linked donor-acceptor electronic coupling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tao Wang ◽  
Zhubin Hu ◽  
Xiancheng Nie ◽  
Linkun Huang ◽  
Miao Hui ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Electronic Coupling ◽  
Temperature Dependent ◽  
Molecular Systems ◽  
Donor And Acceptor ◽  
Theoretical Investigations ◽  
Donor Acceptor ◽  
And Control ◽  
Two Temperature

AbstractAggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient room temperature phosphorescence (RTP) in bulk by restricting molecular motions. Here, we show that by utilizing triphenylamine (TPA) as an electronic donor that connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Distinct dual phosphorescence bands emitting from largely localized donor and acceptor triplet emitting states could be recorded at lowered temperatures; at room temperature, only a merged RTP band is present. Theoretical investigations reveal that the two temperature-dependent phosphorescence bands both originate from local/global minima from the lowest triplet excited state (T1). The reported molecular construct serves as an intermediary case between a fully conjugated donor-acceptor system and a donor/acceptor binary mix, which may provide important clues on the design and control of high-freedom molecular systems with complex excited-state dynamics.

scholarly journals 8-(Pyridin-2-yl)quinolin-7-ol as a Platform for Conjugated Proton Cranes: A DFT Structural Design

Micromachines ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 901 ◽  
Author(s):  
Anton Georgiev ◽  
Liudmil Antonov
Keyword(s):  
Excited State ◽  
Structural Design ◽  
Density Functional ◽  
Intramolecular Proton Transfer ◽  
State Density ◽  
Strong Electron ◽  
Functional Theory ◽  
Substituted Pyridines ◽  
Donor Acceptor ◽  
Enol Tautomer

Theoretical design of conjugated proton cranes, based on 7-hydroxyquinoline as a tautomeric sub-unit, has been attempted by using ground and excited state density functional theory (DFT) calculations in various environments. The proton crane action request existence of a single enol tautomer in ground state, which under excitation goes to the excited keto tautomer through a series of consecutive excited-state intramolecular proton transfer (ESIPT) steps with the participation of the crane sub-unit. A series of substituted pyridines was used as crane sub-units and the corresponding donor-acceptor interactions were evaluated. The results suggest that the introduction of strong electron donor substituents in the pyridine ring creates optimal conditions for 8-(pyridin-2-yl)quinolin-7-ols to act as proton cranes.

scholarly journals Halogen-Bond Assisted Photoinduced Electron Transfer

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4361
Author(s):  
Bogdan Dereka ◽  
Ina Fureraj ◽  
Arnulf Rosspeintner ◽  
Eric Vauthey
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Ground State ◽  
Halogen Bond ◽  
Quenching Rate ◽  
Excited Complex ◽  
Diffusion Controlled ◽  
Donor Acceptor ◽  
Quenching Rate Constant ◽  
Excited State Population

The formation of a halogen-bond (XB) complex in the excited state was recently reported with a quadrupolar acceptor–donor–acceptor dye in two iodine-based liquids (J. Phys. Chem. Lett. 2017, 8, 3927–3932). The ultrafast decay of this excited complex to the ground state was ascribed to an electron transfer quenching by the XB donors. We examined the mechanism of this process by investigating the quenching dynamics of the dye in the S1 state using the same two iodo-compounds diluted in inert solvents. The results were compared with those obtained with a non-halogenated electron acceptor, fumaronitrile. Whereas quenching by fumaronitrile was found to be diffusion controlled, that by the two XB compounds is slower, despite a larger driving force for electron transfer. A Smoluchowski–Collins–Kimball analysis of the excited-state population decays reveals that both the intrinsic quenching rate constant and the quenching radius are significantly smaller with the XB compounds. These results point to much stronger orientational constraint for quenching with the XB compounds, indicating that electron transfer occurs upon formation of the halogen bond.

scholarly journals Donor-Acceptor Substituted Benzo-, Naphtho- and Phenanthro-Fused Norbornadienes

Molecules ◽  
2020 ◽  
Vol 25 (2) ◽  
pp. 322 ◽  
Author(s):  
Mads Mansø ◽  
Lorette Fernandez ◽  
Zhihang Wang ◽  
Kasper Moth-Poulsen ◽  
Mogens Brøndsted Nielsen
Keyword(s):  
Visible Region ◽  
Energy Difference ◽  
Sonogashira Coupling ◽  
Solar Thermal Energy ◽  
Absorption Properties ◽  
Structural Modifications ◽  
Acceptor Group ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
Selection Of

The photochromic norbornadiene/quadricyclane (NBD/QC) couple has found interest as a molecular solar thermal energy (MOST) system for storage of solar energy. To increase the energy difference between the two isomers, we present here the synthesis of a selection of benzo-fused NBD derivatives that contain an aromatic unit, benzene, naphthalene or phenanthrene, fused to one of the NBD double bonds, while the carbon atoms of the other double bond are functionalized with donor and acceptor groups. The synthesis protocols involve functionalization of benzo-fused NBDs with bromo/chloro substituents followed by a subjection of these intermediates to a cyanation reaction (introducing a cyano acceptor group) followed by a Sonogashira coupling (introducing an arylethynyl donor group, -C≡CC6H4NMe2 or -C≡CC6H4OMe). While the derivatives have good absorption properties in the visible region (redshifted relative to parent system) in the context of MOST applications, they lack the ability to undergo NBD-to-QC photoisomerization, even in the presence of a photosensitizer. It seems that loss of aromaticity of the fused aromatics is too significant to allow photoisomerization to occur. The concept of destroying aromaticity of a neighboring moiety as a way to enhance the energy density of the NBD/QC couple thus needs further structural modifications, in the quest for optimum MOST systems.

Modulation of band gap and p- versus n-semiconductor character of ADA dyes by core and acceptor group variation

2016 ◽  
Vol 3 (5) ◽  
pp. 545-555 ◽  
Author(s):  
Agnieszka Nowak-Król ◽  
Reinhard Wagener ◽  
Felix Kraus ◽  
Amaresh Mishra ◽  
Peter Bäuerle ◽  
...  
Keyword(s):  
Band Gap ◽  
Building Blocks ◽  
Acceptor Group ◽  
Donor And Acceptor ◽  
Type Semiconductor ◽  
Group Variation ◽  
Donor Acceptor ◽  
Semiconductor Character

By variation of donor and acceptor building blocks in acceptor–donor–acceptor dyes a transition from p- to n-type semiconductor has been achieved.

THE ABSORPTION SPECTRUM OF BO2

1961 ◽  
Vol 39 (12) ◽  
pp. 1738-1768 ◽  
Author(s):  
J. W. C. Johns
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
Detailed Analysis ◽  
Ground State ◽  
Flash Photolysis ◽  
Electronic Transitions ◽  
Molecular Constants ◽  
Boron Trichloride ◽  
Symmetric Molecule ◽  
First Excited State

The boron flame bands have been observed in absorption during the flash photolysis of mixtures of boron trichloride and oxygen. Detailed analysis of the spectrum has shown that the bands arise from two electronic transitions in the linear symmetric molecule BO2, [Formula: see text] and A2Πu−X2Πg. The main molecular constants, in cm−1 except for r0, are summarized below:[Formula: see text]Both 2Π states show the Renner effect. In the ground state the Renner parameter, εω2, was found to be −92.2, whereas in the first excited state it is much smaller, −13.1 cm−1.

scholarly journals Thermochromic AIE Dual Phosphorescence via Temperature-Dependent sp3-Linked Donor-Acceptor Electronic Coupling

2020 ◽  
Author(s):  
Tao Wang ◽  
Zhubin Hu ◽  
Xiancheng Nie ◽  
Linkun Huang ◽  
Hui Miao ◽  
...  
Keyword(s):  
Excited State ◽  
Room Temperature ◽  
Electronic Coupling ◽  
Triplet States ◽  
Molecular Motions ◽  
Temperature Dependent ◽  
Molecular Systems ◽  
Donor And Acceptor ◽  
Donor Acceptor ◽  
And Control

<p>Aggregation-induced emission (AIE) has proven to be a viable strategy to achieve highly efficient RTP in bulk by restricting molecular motions. Here we show that by utilizing triphenylamine (TPA) as an electronic donor which connects to an acceptor via an sp3 linker, six TPA-based AIE-active RTP luminophores were obtained. Both the TPA AIE-gen and the <i>sp</i><sup>3</sup>-linkage can suppress aggregation-caused quenching. Consequently, dual phosphorescence bands emitting from localized donor and acceptor triplet states, respectively, could be recorded at lowered temperatures; at room temperature, only a single RTP band corresponding to the lowest triplet state is present, presumably due to thermally assisted electronic coupling between the two states. The reported molecular construct serves as an “intermediary case” between a fully conjugated donor-acceptor system and a do-nor/acceptor binary mix, which may provide important clues on the design and control of molecular systems with complex excited-state dynamics.<br></p>

scholarly journals Chromophore-radical excited state antiferromagnetic exchange controls the sign of photoinduced ground state spin polarization

2021 ◽  
Author(s):  
Martin L. Kirk ◽  
David A. Shultz ◽  
Patrick Hewitt ◽  
Daniel E. Stasiw ◽  
Ju Chen ◽  
...  
Keyword(s):  
Excited State ◽  
Spin Polarization ◽  
Ground State ◽  
Electron Spin Polarization ◽  
Organic Radical ◽  
Antiferromagnetic Exchange ◽  
Ground State Spin ◽  
Donor Acceptor ◽  
State Spin ◽  
Ground State Electron

A change in the sign of the ground state electron spin polarization (ESP) is reported in complexes where an organic radical (nitronylnitroxide, NN) is covalently attached to a donor–acceptor chromophore via two different meta-phenylene bridges.

Accurate description of hybridized local and charge-transfer excited-state in donor–acceptor molecules using density functional theory

RSC Advances ◽  
2016 ◽  
Vol 6 (110) ◽  
pp. 108404-108410 ◽  
Author(s):  
Y. Y. Pan ◽  
J. Huang ◽  
Z. M. Wang ◽  
S. T. Zhang ◽  
D. W. Yu ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Excited State ◽  
Charge Transfer ◽  
Ground State ◽  
Density Functional ◽  
Accurate Description ◽  
Functional Theory ◽  
Donor Acceptor ◽  
Acceptor Molecules

The ωB97X was the most reliable functional for the accurate description of HLCT state at ground state and excited state.

Absorption spectrum of the Mg2 molecule

1970 ◽  
Vol 48 (7) ◽  
pp. 901-914 ◽  
Author(s):  
W. J. Balfour ◽  
A. E. Douglas
Keyword(s):  
Absorption Spectrum ◽  
Excited State ◽  
High Resolution ◽  
Potential Energy ◽  
Dissociation Energy ◽  
Ground State ◽  
Potential Energy Curve ◽  
Energy Curve ◽  
Vibrational Constants

The absorption spectrum of the Mg2 molecule, which occurs in a furnace containing Mg vapor, has been photographed with a high resolution spectrograph. The rotational structures of the bands have been analyzed and the rotational and vibrational constants of the two states determined. The bands are found to arise from a 1Σ–1Σ transition between a very lightly bonded ground state and a more stable excited state. The R.K.R. potential energy curve of the ground state, which has a dissociation energy of 399 cm−1, has been determined. The more important constants of the ground state are ωe = 51.12 cm−1, ωexe = 1.64 cm−1, re = 3.890 Å and those of the upper state are ωe = 190.61 cm−1, ωexe = 1.14 cm−1, re = 3.082 Å.

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