Microsolvation of the 5-hydroxyindole cation (5HI+) with nonpolar and quadrupolar ligands: Infrared photodissociation spectra of 5HI+-Ln clusters with L = Ar and N2 (n ≤ 3)

Klyne, Johanna; Dopfer, Otto

doi:10.1016/j.jms.2017.03.010

Cited by 17 publications

(27 citation statements)

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“…47,48 Calculated harmonic vibrational frequencies are linearly scaled by a factor of 0.957 derived previously from fitting the free OH stretching frequency of cationic s/a5HI + . 22 Yet, this scaling factor yields OH stretch frequencies of W (n 1/3 = 3635/ 3733 cm À1 ) systematically lower by B20 cm À1 than the experimental values (n 1/3 = 3657/3756 cm À1 ). 49 For selected 5HIH + -W clusters, anharmonic spectra are calculated at the B3LYP-D3/ aug-cc-pVDZ level as implemented in GAUSSIAN09.…”

Section: Experimental and Computational Techniquesmentioning

confidence: 74%

“…27,[31][32][33][34] This hybrid density functional with additive dispersion correction has proven to yield reliable results for related aromatic clusters. 11,22,23,[35][36][37][38][39] For example, the binding energies computed for the monohydrates of the benzene and naphthalene cations (D 0 = 3209 and 2773 cm À1 ) compare favorably with the experimental values (D 0 = 3290 AE 120 and 2800 AE 300 cm À1 ). 40,41 Similarly, the calculated binding energy of W 2 (D 0 = 1108 cm À1 ) matches the measured value (D 0 = 1105 AE 10 cm À1 ).…”

Section: Experimental and Computational Techniquesmentioning

confidence: 79%

“…IRPD spectra are measured in the XH stretch range (X = N and O, 2600-3800 cm À1 ) with a quadrupole-octopole-quadrupole tandem mass spectrometer described elsewhere. [18][19][20][21][22][23][24][25][26] Briefly, protonated clusters are generated in an electron ionization source coupled to a pulsed molecular beam expansion. Solid 5HI (Sigma-Aldrich, 97%) is heated to 145 1C and the resulting vapor is seeded in Ar or N 2 carrier gas (8-9 bar) containing water.…”

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

“…Collision-induced dissociation in the octopole confirms the composition of mass-selected parent clusters. 22,23 The protonation sites in 5HIH + have already been examined in a previous study. 17 The 5HIH + protomers offer two competing H-bonding sites for W molecules, namely, their NH and OH functional groups.…”

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

“…Comparison to neutral and cationic s/a5HI-W clusters previously studied at the same level (B3LYP-D3/aug-cc-pVTZ) yields the effects of protonation. 22,23 Total binding energies (D 0 ) are derived by subtracting the zeropoint corrected energies of the corresponding monomers from that of the cluster: D 0 = E 0 (5HIH + -W n ) À E 0 (5HIH + ) À nÁE 0 (W). Binding energies of the Ar/N 2 tag in 5HIH + -W-Ar/N 2 are calculated in a similar way.…”

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

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Microhydration of protonated 5-hydroxyindole revealed by infrared spectroscopy

Klyne

Dopfer

2019

Phys. Chem. Chem. Phys.

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Section: Experimental and Computational Techniquesmentioning

confidence: 74%

Section: Experimental and Computational Techniquesmentioning

confidence: 79%

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

Section: Experimental and Computational Techniquesmentioning

confidence: 99%

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Microhydration of protonated 5-hydroxyindole revealed by infrared spectroscopy

Klyne

Dopfer

2019

Phys. Chem. Chem. Phys.

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Aromatic Charge Resonance Interaction Probed by Infrared Spectroscopy

2018

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Charge resonance is as trong attractive intermolecular force in aromatic dimer radical ions.D espite its importance,this fundamental interaction has not been characterized at high resolution by spectroscopyo fi solated dimers.W e employv ibrational infrared spectroscopyo fc old aromatic pyrrole dimer cations to precisely probe the charge distribution by measuring the frequency of the isolated N À Hstretch mode (n NH ). We observe al inear correlation between n NH and the partial charge qo nt he pyrrole molecule in different environments.S ubtle effects of symmetry reduction, such as substitution of functional groups (here pyrrole replaced by Nmethylpyrrole) or asymmetric solvation (here by an inert N 2 ligand), shift the charge distribution towardt he moiety with lower ionization energy.T his general approach provides ap recise experimental probe of the asymmetry of the charge distribution in such aromatic homo-and heterodimer cations.The intermolecular interactions of aromatic p electrons are important for chemical and biological recognition. [1] Radical ions of arenes are involved in chemical reaction mechanisms, charge transport of modern (bio-)organic materials (organic electronics), and radiation damage in DNAand proteins. [2] In addition to p H-bonding,c ation/anion-p,a nd p-p stacking interactions, [3] the charge-resonance (CR) interaction is af undamental and very strong force in charged arene dimers. [4] Forc ations,t his stabilization arises from sharing the positive charge between two identical or different molecules with the same or comparable ionization energies in a p-stacked dimer.I nahomodimer cation (A 2 + ), the positive charge is equally shared between both molecules, while in ah eterodimer (AB + )t he partner with the lower ionization energy (IE) carries more positive charge.I nt he simplest description, the CR interaction in A 2 + causes as plitting between the two electronic states described by Y AE = Y(A + )Y(A) AE Y(A)Y(A + ); the symmetric Y + ground state is stable and the destabilized antisymmetric Y À state is repulsive.The splitting between both electronic states is twice the stabilization energy of the ground state (ca. 50-100 kJ mol À1 ). Thei nteraction is strongest for A 2 + homodim-ers,a nd decreases in AB + as the difference in the IEs of the two molecules increases (DIE = IE A ÀIE B ). This description of the CR interaction in arene dimer ions is similar to the one employed for odd electron chemical bonds in radical ions (hemibonds) [5] and exciton splitting in delocalized electronic excitation in neutral dimers. [6] In the condensed phase, p-stacked dimer cations of aromatic and polycyclic aromatic hydrocarbons were first detected by electron spin resonance [7] and optical absorption spectroscopy of the intense and broad CR transition connecting the two Y AE states. [7d, 8] Thelatter electronic transition occurs in the low-energy part of the optical spectrum (in the red to near-infrared near 1 mm) and provides adirect measure for the CR splitting.Inthe gas phase,the binding e...

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