Excited-state vibrational relaxation and deactivation dynamics of trans-4-(N,N-dimethylamino)-4′-nitrostilbene in nonpolar solvents studied by ultrafast time-resolved broadband fluorescence spectroscopy

Chiu, Chih-Chung; Chen, Wei‐Chung; Cheng, Po‐Yuan

doi:10.1016/j.jphotochem.2015.05.023

Cited by 19 publications

(11 citation statements)

References 46 publications

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“…The other conical regions on the S 1 surface, CI-S 1 /S 0 -trans, CI-S 1 /S 0 -twist-t and CI-S 1 /S 0 -cis, stay away from the accessible region of DANS started from trans-S 1 -FC. The mechanisms for trans-DANS presented in this work are consistent with the experimentally observed ~0.1 singlet-triplet branching ratio in nonpolar solvents [68]. For DANS excited to cis-S 1 -FC, two singlet pathways, cis-S 1 -FC → CI-S 1 /S 0 -twist-c → transor cis-S 0 and cis-S 1 -FC → CI-S 1 /S 0 -DHP → DHP-S 0 , decay along the steeply descending S 1 surface and thus are the dominate pathways.…”

Section: Discussionsupporting

confidence: 89%

“…The investigation on CIs and ISCs within low-lying electronic states of DANS is of crucial importance in unveiling the nature of nonadiabatic decay accompanied with trans ↔ cis isomerization and ring-closing reactions [67,68]. In previous studies, crossing regions were avoided and singlet-triplet quasi-degenerations were disclosed in one-dimensional PECs towards α C=C [37]; however, the geometries and properties for possible CIs and ISCs involved in the photoisomerization and ring-closing of DANS are still unknown.…”

Section: Conical Intersections and Intersystem Crossingsmentioning

confidence: 99%

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Photorelaxation Pathways of 4-(N,N-Dimethylamino)-4′-nitrostilbene Upon S1 Excitation Revealed by Conical Intersection and Intersystem Crossing Networks

Xue

Lei

et al. 2020

Molecules

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Multi-state n-electron valence state second order perturbation theory (MS-NEVPT2) was utilized to reveal the photorelaxation pathways of 4-(N,N-dimethylamino)-4′-nitrostilbene (DANS) upon S1 excitation. Within the interwoven networks of five S1/S0 and three T2/T1 conical intersections (CIs), and three S1/T2, one S1/T1 and one S0/T1 intersystem crossings (ISCs), those competing nonadiabatic decay pathways play different roles in trans-to-cis and cis-to-trans processes, respectively. After being excited to the Franck–Condon (FC) region of the S1 state, trans-S1-FC firstly encounters an ultrafast conversion to quinoid form. Subsequently, the relaxation mainly proceeds along the triplet pathway, trans-S1-FC → ISC-S1/T2-trans → CI-T2/T1-trans → ISC-S0/T1-twist → trans- or cis-S0. The singlet relaxation pathway mediated by CI-S1/S0-twist-c is hindered by the prominent energy barrier on S1 surface and by the reason that CI-S1/S0-trans and CI-S1/S0-twist-t are both not energetically accessible upon S1 excitation. On the other hand, the cis-S1-FC lies at the top of steeply decreasing potential energy surfaces (PESs) towards the CI-S1/S0-twist-c and CI-S1/S0-DHP regions; therefore, the initial twisting directions of DN and DAP moieties determine the branching ratio between αC=C twisting (cis-S1-FC → CI-S1/S0-twist-c → trans- or cis-S0) and DHP formation relaxation pathways (cis-S1-FC → CI-S1/S0-DHP → DHP-S0) on the S1 surface. Moreover, the DHP formation could also take place via the triplet relaxation pathway, cis-S1-FC → ISC-S1/T1-cis → DHP-T1 → DHP-S0, however, which may be hindered by insufficient spin-orbit coupling (SOC) strength. The other triplet pathways for cis-S1-FC mediated by ISC-S1/T2-cis are negligible due to the energy or geometry incompatibility of possible consecutive stepwise S1 → T2 → T1 or S1 → T2 → S1 processes. The present study reveals photoisomerization dynamic pathways via conical intersection and intersystem crossing networks and provides nice physical insight into experimental investigation of DANS.

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Section: Discussionsupporting

confidence: 89%

Section: Conical Intersections and Intersystem Crossingsmentioning

confidence: 99%

Photorelaxation Pathways of 4-(N,N-Dimethylamino)-4′-nitrostilbene Upon S1 Excitation Revealed by Conical Intersection and Intersystem Crossing Networks

Xue

Lei

et al. 2020

Molecules

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“…To corroborate the experimental Raman spectra of DCM with the possible structural changes during the ICT, we performed TDDFT simulations to find the locally optimized geometries and corresponding Raman spectra. Most of the (TD)DFT studies on DCM or similar push-pull emitters have focused on the evaluation of the absorption and emission spectra which are consistent with the experimental results [27][28][29][30][59][60][61]. Investigation of the vibrational spectrum changes of a molecule during the specific excited state processes may provide important clues to further development for the DFT methods of higher accuracy.…”

Section: Twisted Ict State Of Dcmmentioning

confidence: 87%

Twisted Intramolecular Charge Transfer State of a “Push-Pull” Emitter

Lee

Jen

Pang

2020

IJMS

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The excited state Raman spectra of 4-dicyanomethylene-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) in the locally-excited (LE) and the intramolecular charge transfer (ICT) states have been separately measured by time-resolved stimulated Raman spectroscopy. In a polar dimethylsulfoxide solution, the ultrafast ICT of DCM with a time constant of 1.0 ps was observed in addition to the vibrational relaxation in the ICT state of 4–7 ps. On the other hand, the energy of the ICT state of DCM becomes higher than that of the LE state in a less polar chloroform solution, where the initially-photoexcited ICT state with the LE state shows the ultrafast internal conversion to the LE state with a time constant of 300 fs. The excited-state Raman spectra of the LE and ICT state of DCM showed several major vibrational modes of DCM in the LE and ICT conformer states coexisting in the excited state. Comparing to the time-dependent density functional theory simulations and the experimental results of similar push-pull type molecules, a twisted geometry of the dimethylamino group is suggested for the structure of DCM in the S1/ICT state.

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“…The plot of compounds 3a and 3h in the absence and presence of DNA demonstrate significant changes in an average lifetime because viscosity difference of compounds solution in the presence of DNA occurs. Results suggest that compound 3a has more binding affinity as compared to compound 3h …”

Section: Results and Discussionmentioning

confidence: 99%

Design and Synthesis of Carbothioamide/Carboxamide-Based Pyrazoline Analogs as Potential Anticancer Agents: Apoptosis, Molecular Docking, ADME Assay, and DNA Binding Studies

et al. 2022

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To discover anticancer drugs with novel structures and expand our research scope, pyrazoline derivatives ( 3a – 3l ) were designed and synthesized through cyclization of chalcones with thiosemicarbazide/semicarbazide in CH 3 COOH as a solvent. All newly synthesized pyrazoline derivatives were fully characterized using several spectroscopic experiments such as 1 H, 13 C NMR, FT-IR spectroscopy, and mass analysis. By HPLC , the purity of all analogs was found above 95% and both lead compounds ( 3a and 3h ) were also validated by HRMS . Anticancer activity of synthesized pyrazoline derivatives ( 3a – 3l ) was investigated by the MTT assay against the human lung cancer cell (A549), human cervical cancer cell (HeLa), and human primary normal lung cells (HFL-1). Staurosporine (STS) was used as a standard drug. The anticancer results showed that two potent analogs 3a and 3h exhibit excellent activity against A549 (IC 50 = 13.49 ± 0.17 and 22.54 ± 0.25 μM) and HeLa cells (IC 50 = 17.52 ± 0.09 and 24.14 ± 0.86 μM) and low toxicity against the HFL-1 (IC 50 = 114.50 ± 0.01 and 173.20 ± 10 μM). The flow cytometry was further used to confirm the anticancer activity of potent derivatives against the A549 cancer cell line. DNA binding interaction of anticancer agents 3a and 3h with Ct-DNA has been carried out by absorption, fluorescence, EtBr (dye displacement assay), circular dichroism, cyclic voltammetry and time-resolved fluorescence, which showed noncovalent binding mode of interaction. Anticancer activity of both lead compounds ( 3a and 3h ) may be attributed to DNA binding. The evaluation of the antioxidant potential of pyrazoline analogs 3a and 3h by 2,2-diphenyl-1-picrylhydrazyl free radical showed promising antioxidant activity with IC 50 values of 0.132 ± 0.012 and 0.215 ± 0.025 μg/mL, respectively. In silico molecular docking of pyrazoline derivatives was also performed using autodock vina software against the DNA hexamer with PDB ID: 1Z3F and ADMET properties to explore their best hits.

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Excited-state vibrational relaxation and deactivation dynamics of trans-4-(N,N-dimethylamino)-4′-nitrostilbene in nonpolar solvents studied by ultrafast time-resolved broadband fluorescence spectroscopy

Cited by 19 publications

References 46 publications

Photorelaxation Pathways of 4-(N,N-Dimethylamino)-4′-nitrostilbene Upon S1 Excitation Revealed by Conical Intersection and Intersystem Crossing Networks

Photorelaxation Pathways of 4-(N,N-Dimethylamino)-4′-nitrostilbene Upon S1 Excitation Revealed by Conical Intersection and Intersystem Crossing Networks

Twisted Intramolecular Charge Transfer State of a “Push-Pull” Emitter

Design and Synthesis of Carbothioamide/Carboxamide-Based Pyrazoline Analogs as Potential Anticancer Agents: Apoptosis, Molecular Docking, ADME Assay, and DNA Binding Studies

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