Photo and Collision Induced Isomerization of a Cyclic Retinal Derivative: An Ion Mobility Study

Coughlan, Neville J. A.; Scholz, Michael S.; Hansen, Christopher S.; Trevitt, Adam J.; Adamson, Brian D.; Bieske, Evan J.

doi:10.1007/s13361-016-1427-8

Cited by 12 publications

(25 citation statements)

References 29 publications

(46 reference statements)

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Section: Methodsmentioning

confidence: 99%

“…These results are consistent with the 1 HNMR characterizations described above.I nanext set of measurements each isomer was isolated and subjected to collisional activation. [27] At higher collision energies ag as-phase quasiequilibrium is established whereby the more stable isomer is more abundant. [28] Relative abundances of E-6 and Z-6 as af unction of electric field in the collision zone are shown in Figure 3b and c, respectively.R egardless of the initially selected isomer (E-6 or Z-6), at the quasi-equilibrium conditions Z-6 is more abundant than E-6,providing evidence for the greater stability of the Z-6 isomer in the gas phase.…”

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confidence: 99%

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A Strong cis‐Effect in an Imidazole‐Imidazolium‐Substituted Alkene

et al. 2017

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Abstract:We report the first example of an alkene with two carbon-bound substituents (imidazole and imidazolium rings) where the Z-isomer has agreater thermodynamic stability than the E-isomer which persists in both the gas phase and in solution. Theoretical calculations,s olution fluorescence spectroscopyand gas-phase ion mobility mass spectrometry studies confirm the preference for the Z-isomer,the stability of which is traced to an on-covalent interaction between the imidazole lone pair and the imidazolium ring.The greater thermodynamic stability of E-stilbene 1 (and Edisubstituted alkenes in general) over the Z-isomer, and the thermal/photoisomerism between the two forms,are concepts taught to virtually every chemistry student. Cases where the cis-orZ-isomer has greater thermodynamic stability are rare, mostly limited to di-halo (e.g. 2)ordimethoxy alkenes (e.g. 3), monohalo-propenes and 2-cyanopropene with strong electron-withdrawing atoms/groups are directly bound to the alkene.The phenomenon has been coined the "cis-effect" and the underlying rationale for the effect has been the subject of study over the last fifty years.[1] Allyl anions also adopt a Zconfiguration, particularly when coordinated to am etal counter-cation, however calculations suggest that the Zconfiguration is also preferred in the gas-phase anion. [2] Ford ifluoroethylene the Z-isomer is calculated to be more stable than the E-isomer by 4.5 kJ mol À1 at the CCSD-(T) level, while the effect is somewhat weaker in the other cases.[1i] Them ost recent proposals suggest the origin of the cis-effect in difluoroethylene arises from agreater correlation energy of the Z-isomer in combination with steric attractions between the s-and p-type lone pairs on Fatoms present in the Z-isomer.[1j]Here we report on the first example of anon-cyclic alkene bearing two carbon-atom-bound groups (a benzimidazole and benzimidazolium ring) where the Z-isomer is more thermodynamically stable than the E-isomer.Itisdemonstrated that non-covalent interactions between the benzimidazole and benzimidazolium ring is the most important factor in stabilizing the Z-isomer.All geometry optimizations were carried out in the gasphase with the B3LYP density functional [3] and 6-311+ ++ +G-(d,p) basis set [4] within Gaussian 09.[5] Stationary points were characterized as minima by calculating the Hessian matrix analytically at this level of theory.For comparison, geometries were optimized with B3LYP-D3(BJ), [6] yielding deviations of less than 0.005 in calculated bond distances to the B3LYP geometry.Molecular orbitals (MO) and natural bond orbitals (NBO) were calculated at the B3LYP/6-311+ ++ +G(d,p) level of theory.N BOs were calculated with the NBO 5.9 program. [7] Single-point energies were calculated at the B3LYP/6-311+ ++ +G(d,p) gas phase geometries.D FT (including TD-DFT) and HF calculations were carried out within Gaussian 09, [5] with solvent effects employing aP CM approach [8] with Tr uhlarsS MD model with acetonitrile.[9] DLPNO-CCSD(T) [10] calculations with the...

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Section: Methodsmentioning

confidence: 99%

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confidence: 99%

A Strong cis‐Effect in an Imidazole‐Imidazolium‐Substituted Alkene

et al. 2017

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“…Coughlan et al have shown that in solution the RPSB degrades in a process which also involves a Diels-Alder cyclization and forms a cyclic retinal derivative of mass 238 amu. PISA measurements on this cyclic retinal derivative showed it to contain two main isomers which can be reversibly interconverted through collisional heating or absorption of light (λ max 420 nm) [49].…”

Section: Fragmentation Via Cyclizationmentioning

confidence: 94%

Gas-phase studies of the retinal protonated Schiff base chromophore

Toker

Andersen

2021

Eur. Phys. J. D

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Gas-phase studies of the retinal protonated Schiff base chromophore are reviewed. The use of action spectroscopy has solidified the understanding of the spectral-tuning mechanisms of this important chromophore. Ion-mobility spectrometry and gas phase femtosecond pump-probe spectroscopy studies indicate that several of the remarkable photo-isomerization properties of the chromophore such as its specificity and ultrafast nature are intrinsic properties of the chromophore. With a firm understanding of the properties of the isolated retinal chromophore in terms of spectroscopy and dynamics, the influence of the protein is becoming better understood.

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“…38,39 For the gas-phase isomerization measurements, the IMMS was used in tandem mode, with a pulsed electrostatic ion gate situated midway along the drift region selecting the target isomer ions, which were excited immediately after the gate either by a 5 ns pulse of light from an optical parametric oscillator (OPO, EKSPLA NT342B) or through energetic collisions with buffer gas molecules in a short 3 mm collision zone (slammer) where the electric field could be varied. 37 Resulting isomers were separated in the second stage of the drift region. The photoisomerization measurements were run at 40 Hz with alternate ion packets exposed to the output of the pulsed OPO (operating at 20 Hz), so that laser-on and laser-off ATDs were recorded, the difference between which revealed the effect of light on the drifting ions.…”

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confidence: 99%

Photo- and Collision-Induced Isomerization of a Charge-Tagged Norbornadiene–Quadricyclane System

Jacovella

Carrascosa

Buntine

et al. 2020

J. Phys. Chem. Lett.

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Molecular photoswitches based on the norbornadiene–quadricylane (NBD–QC) couple have been proposed as key elements of molecular solar thermal energy storage schemes. To characterize the intrinsic properties of such systems, reversible isomerization of a charge-tagged NBD–QC carboxylate couple is investigated in a tandem ion mobility mass spectrometer, using light to induce intramolecular [2 + 2] cycloaddition of NBD carboxylate to form the QC carboxylate and driving the back reaction with molecular collisions. The NBD carboxylate photoisomerization action spectrum recorded by monitoring the QC carboxylate photoisomer extends from 290 to 360 nm with a maximum at 315 nm, and in the longer wavelength region resembles the NBD carboxylate absorption spectrum recorded in solution. Key structural and photochemical properties of the NBD–QC carboxylate system, including the gas-phase absorption spectrum and the energy storage capacity, are determined through computational studies using density functional theory.

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Photo and Collision Induced Isomerization of a Cyclic Retinal Derivative: An Ion Mobility Study

Cited by 12 publications

References 29 publications

A Strong cis‐Effect in an Imidazole‐Imidazolium‐Substituted Alkene

A Strong cis‐Effect in an Imidazole‐Imidazolium‐Substituted Alkene

Gas-phase studies of the retinal protonated Schiff base chromophore

Photo- and Collision-Induced Isomerization of a Charge-Tagged Norbornadiene–Quadricyclane System

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