Solvent effect on the conical intersection of 4-cyclopentadienylidene-1,4-dihydropyridine (CPDHP)

Alfalah, Sherin; Deeb, Omar; Zilberg, Shmuel; Haas, Yehuda

doi:10.1016/j.cplett.2008.05.024

Cited by 13 publications

(20 citation statements)

References 17 publications

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“…The BRTSin this solvent lies in fact on the excited state, and the CoIn becomes an avoided crossing. These results are depicted pictorially in Figure 2, taken from [53].…”

Section: (4)mentioning

confidence: 94%

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Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases

Haas

2014

Advances in Chemistry

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The current status of the role of conical intersections (CoIns) in molecular photochemistry is reviewed with a special emphasis on the procedures used to locate them. Due to space limitations, the extensive literature of the subject is given by referring the reader to representative references, whereas the author group’s work is described in detail. The basic properties of CoIns are outlined and contrasted with those of transition states in thermal reactions. Location of CoIns using the method of Longuet-Higgins sign-inverting loops is described in detail. The concept of “anchors”—valence bond structures that represent stable molecules and other stationary points on the potential energy surface—is introduced and its use in constructing loops is described. The authors’ work in the field is outlined by discussing some specific examples in detail. Mathematical aspects and details are left out. The main significance of the method is that it explains a large body of photochemical reactions (for instance, ultrafast ones) and is particularly suitable for practicing chemists, using concepts such as reaction coordinates and transition states in the search.

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“…The BRTSin this solvent lies in fact on the excited state, and the CoIn becomes an avoided crossing. These results are depicted pictorially in Figure 2, taken from [53].…”

Section: (4)mentioning

confidence: 94%

“…In the more polar solvents (MTHF and MeCN) the BR structure lies on S 1 ; there is no biradical transition state and the CoIn vanishes [53].…”

Section: Future Research Directionsmentioning

confidence: 99%

Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases

Haas

2014

Advances in Chemistry

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“…One TS is a biradical covalent form without polar contribution, whereas the second TS has a dominant polar contribution and can be defined as zwitterion . This kind of dual reaction routes was discovered for different molecules with C=C polar bond …”

Section: Introductionmentioning

confidence: 93%

Design of Light‐Induced Molecular Switcher for the Driver of the Quantum Cellular Automata (QCA) Based on the Transition through the Intramolecular Charge Transfer (ICT) Structure

Zilberg

2020

Israel Journal of Chemistry

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The design of light‐induced switcher for the molecular QCA driver was discussed. The driver‐cell with two connected chromophores was proposed as a basic model of the molecular light‐induced trigger. One of the chromophores will conjugate with a left diagonal and the second chromophore will conjugate with a right diagonal. Some differences between two chromophores can allow selective controlling of the switch to the left or to the right. The following three‐steps mechanism for QCA switcher was suggested – light‐induced transition through ICT area (a), initiation of the driver‘s polarization (b) and the beginning of the signal transition to the other cells (c). The principal physical characteristics of the driver‘s trigger was proposed, and the corresponding chemical implementation was discussed. Three kinds of processes leading to ICT were discussed as mechanisms suggested for potential switchers: 1) Irradiation leading to the ICT excited state; 2) Chemical reaction with ICT transition state; 3) Excited State Intramolecular Proton Transfer (ESIPT). The common features of these processes are the non‐radiative transition to the initial state after excitation, with the back transition going through the highly polar charge transfer (CT) area.

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“…3 The molecule is a model molecule that was used to explore solvent and electric field effects on conical intersection (CI). 1,4 This molecule belongs to a family of molecules such as merocyanines 5 and 1-fluoro-2,4-hexadiene, 6 whose CIs were considered to be controlled by the solvent.…”

Section: Introductionmentioning

confidence: 99%

The Photophysics of a Polar Molecule in a Nonpolar Cryogenic Glass - The Effects of Dimerization on (1-Butyl-4-(1H-inden-1-ylidene)-1,4-dihydropyridine (BIDP)

2010

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The first excited state of BIDP was shown in a previous communication to exhibit an ultrafast decay in fluid nonpolar, nonprotic solutions due to the presence of a S(1)/S(0) conical intersection (CI). In frozen polar and nonpolar glasses a strong fluorescence was observed, rationalized by the hindering of the internal torsion required to reach the geometry of the CI. Complete analysis of the data was hampered by some unusual observations in nonpolar glasses. In this paper we show that they can be explained by assuming dimer formation, with a formation constant of K(eq) = (4 ± 3) × 10(5) M(-1) at 83 K and ΔH(dim) = 7 ± 2 kcal/mol. A complete analysis of the spectra is presented, and fluorescence quantum yields of the monomer and dimer are reported. Efficient self-quenching is found, with a Stern Volmer constant, K(SV) = (1.5 ± 0.1) × 10(6) M(-1), assigned to static quenching. The dimer absorption spectrum was extracted from the data and is compared to Kasha's exciton model and to quantum chemical (QC) calculations. The basic features of exciton splitting are reproduced by quantum mechanical calculations, but complete quantitative agreement of the QC computations with the experimental results is not attained. The previous analysis of the monomer spectra using the displaced harmonic oscillator model is extended to the more demanding conditions prevailing at cryogenic temperatures. The derived ΔH(dim) is in good agreement with other dimers formation enthalpies and with the quantum mechanical calculation presented. The new analysis corrects τ(f) in MCHIP to 2.9 × 10(-13) s, somewhat smaller than the value reported in polar solvent in a previous communication, thereby strengthening the assumption that polarity can reduce the efficiency of CI.

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Solvent effect on the conical intersection of 4-cyclopentadienylidene-1,4-dihydropyridine (CPDHP)

Cited by 13 publications

References 17 publications

Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases

Conical Intersections Leading to Chemical Reactions in the Gas and Liquid Phases

Design of Light‐Induced Molecular Switcher for the Driver of the Quantum Cellular Automata (QCA) Based on the Transition through the Intramolecular Charge Transfer (ICT) Structure

The Photophysics of a Polar Molecule in a Nonpolar Cryogenic Glass - The Effects of Dimerization on (1-Butyl-4-(1H-inden-1-ylidene)-1,4-dihydropyridine (BIDP)

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