Electron-induced chemistry in imidazole clusters embedded in helium nanodroplets

Abstract

Electron-induced chemistry in imidazole (IMI) clusters embedded in helium nanodroplets (with an average size of 2×10 5 He atoms) has been investigated with highresoluton time-of-flight mass spectrometry. The formation of both, negative and positive, ions was monitored as a function of the cluster size n. In both ion spectra a clear series of peaks with IMI cluster sizes up to at least 25 are observed. While the anions are formed by collisions of IMI n with He *− , the cations are formed through ionization of IMI n by He + as the measured onset for the cation formation is observed at 24.6 eV (ionization energy of He). The most abundant series of anions are dehydrogenated anions IMI n-1 (IMI−H) − , while other anion series are IMI clusters involving CN and C 2 H 4 moieties. The formation of cations is dominated by the protonated cluster ions IMI n H + , while the intensity of parent cluster cations IMI n + is also observed preferentially for the small cluster size n.The observation of series of cluster cations [IMI n CH 3 ] + suggests either CH 3 + cation to be solvated by n neutral IMI molecules, or the electron-induced chemistry has led to the formation of protonated methyl-imidazole solvated by (n−1) neutral IMI molecules.Keywords: Imidazole, imidazole clusters, helium nanodroplets, electron attachment, electron-induced processesRunning Title: Electron-induced chemistry in imidazole doped HND.

Probing the electronic structure and spectroscopy of pyrrolyl and imidazolyl radicals using high-resolution photoelectron imaging of cryogenically cooled anions

“…[19][20][21][22][23][24][25][26][27][28][29] Another five-membered-ring heterocycle, imidazole (C 3 H 4 N 2 ), which is similar to pyrrole but contains two separated nitrogen atoms, has been found in the side chain of the amino acid, histidine, and has been studied as an important PANH building block. [30][31][32][33] The radical intermediates of pyrrole (pyrrolyl, C 4 H 4 N) and imidazole (imidazolyl, C 3 H 3 N 2 ) by rupture of a C-H or N-H bond play key roles in atmospheric chemistry, combustion, biochemistry and many other chemical processes due to their high reactivity. Pyrrolyl has three isomeric forms: a 1-pyrrolyl radical (or simply pyrrolyl) that arises by N-H bond fission in pyrrole and 2-and 3-pyrrolyl radicals that come from C-H bond fission in the a and b sites, respectively.…”

Complexes of gold and imidazole formed in helium nanodroplets

“…An aromatic molecule, imidazole forms the basis for a wide range of organic molecules such as the DNA bases guanine and adenine, histidines, histamines, and N-heterocyclic carbene (NHC) complexes to name a few. 18 We produce neutral Au m Im n complexes in superfluid helium nanodroplets which are then ionized. Using mass spectrometry to study the Au m Im n + products, we identify a number of seemingly “magic” combinations of m and n , i.e.…”

Electric deflection of imidazole dimers and trimers in helium nanodroplets: Dipole moments, structure, and fragmentation

“…Previously published mass spectra 14 suggest that ~5%-10% of imidazole cluster ionization products in helium nanodroplets are detected as (IM)n + , therefore the absence of any trimer signal implies that in this case the (IM)D + signal originates primarily from dimers. Furthermore, the (IM)2 + peak is much weaker than (IM)D + , therefore the latter is the dominant dimer ionization channel.…”

“…The dominant products of electron-impact ionization of bare IM clusters are a series of (IM)nH + peaks, 13 while clusters embedded in helium nanodroplets yield both (IM)nH + and a weaker (IM)n + series. 14 By applying the experimental approach described in this paper, we are able to identify the provenance of some of the small detected cluster ions.…”