Laboratory study on the fullerene–PAH-derived cluster cations in the gas phase

2019 ◽  
Vol 490 (3) ◽  
pp. 3498-3507
Author(s):  
Junfeng Zhen ◽  
Weiwei Zhang ◽  
Yuanyuan Yang ◽  
Qingfeng Zhu
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Reaction Pathway ◽  
Theoretical Calculations ◽  
Large Fraction ◽  
Quadrupole Ion Trap ◽  
Fullerene C60 ◽  
Molecule Reaction ◽  
Flight Mass Spectrometry ◽  
Polycyclic Aromatic

ABSTRACT It is possible that fullerene–polycyclic aromatic hydrocarbon (PAH) clusters or associations of fullerenes with PAHs contain a large fraction of interstellar fullerenes in the interstellar medium. Herein, we report the formation and photofragmentation behaviour of fullerene–PAH derivatives, fullerene/9-vinylanthracene (C16H12) and fullerene/9-methylanthracene (C15H12) cluster cations. Experiments are carried out using a quadrupole ion trap in combination with time-of-flight mass spectrometry in the gas phase. The results show that fullerene (C60)/9-vinylanthracene (e.g. [(C16H12)3C60]+), fullerene (C56 and C58)/9-vinylanthracene (e.g. [(C16H12)4C56]+ and [(C16H12)4C58]+), fullerene (C60)/9-methylanthracene (e.g. [(C15H12)3C60]+), and fullerene (C56 and C58)/9-methylanthracene (e.g. [(C15H12)4C56]+ and [(C15H12)4C58]+) cluster cations, i.e. large fullerene-derived molecules, are formed in the gas phase through the ion–molecule reaction pathway. With irradiation, all fullerene–PAH-derived cluster cations lose their monomolecular groups without other fragmentation channels (e.g. dehydrogenation). The structure of newly formed fullerene–PAH-derived cluster cations and the bond energy for these adduction formation pathways are investigated with theoretical calculations. The obtained results provide a general molecular growth route towards large fullerene–PAH derivatives (e.g. large fullerene-derived molecules) with functional PAHs in a bottom-up formation process and insights into the effect of functional groups (e.g. vinyl, –C2H3, and methyl, –CH3) on their formation and photoevolution behaviours. In addition, the fullerene–PAH-derived clusters (from 83 to 170 atoms in total, or ∼2 nm in size) offer a good model of carbon dust grains, and the relevance to the nanometre-sized carbon dust grain in space is briefly discussed.

scholarly journals Formation and photochemistry of covalently bonded large functional PAH clusters

2019 ◽  
Vol 628 ◽  
pp. A57 ◽  
Author(s):  
Junfeng Zhen ◽  
Yuanyuan Yang ◽  
Weiwei Zhang ◽  
Qingfeng Zhu
Keyword(s):  
Gas Phase ◽  
Functional Group ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Formation Processes ◽  
Flight Mass Spectrometry ◽  
Covalently Bonded ◽  
Different Types ◽  
Polycyclic Aromatic ◽  
Vinyl Group

Polycyclic aromatic hydrocarbon (PAH) molecules belong to a large and diverse chemical family in the interstellar medium (ISM). We study the formation and photochemistry of covalently bonded large functional PAH clusters, dicoronylene (DC, C48H20)/9-vinylanthracene (C16H12) and dicoronylene/9-methylanthracene (C15H12) cluster cations, in the gas phase, and we offer an approach to the evolution of different types of large (covalently bonded) PAH clusters in the ISM. The experiments, which we combined with a quadrupole ion trap and time-of-flight mass spectrometry, show that large functional PAH cluster cations can form by gas-phase condensation through molecular-ion reactions. One group of functional PAH cluster cations contain the vinyl group (−CHCH2), that is, from C16H12DDC+ (e.g., C16H12C48H19+, m/z = 799) to (C16H12)2DDC+ (e.g., (C16H12)2C48H18+, m/z = 1002). The other group of functional PAH cluster cations contain the methyl group (−CH3), that is, from C15H12DDC+ (e.g., C15H12C48H19+, m/z = 787) to (C15H12)2DDC+ (e.g., (C15H12)2C48H18+, m/z = 990). With laser irradiation, the DC/9-vinylanthracene and DC/9-methylanthracene cluster cations show a very complicated dissociation process (e.g., dehydrogenation, −CH3 or −CHCH2 unit losses). We investigate the structure of newly formed PAH cluster cations, the bond energy, and the photodissociation energy for these reaction pathways with quantumchemical calculations. The obtained results provide a general molecular growth route toward large PAH cluster cations (e.g., functional PAH clusters) in a bottom-up formation process and the insight of the functional group (e.g., vinyl, −C2H3 and methyl, −CH3) effect on their evolutionary behavior. In addition, the studies of DC/9-vinylanthracene and DC/9-methylanthracene clusters (94–123 atoms, ∼2 nm in size) also provide a possible way of interpreting the formation processes of nanometer-sized grains in the ISM, especially when functional PAHs are included.

scholarly journals Laboratory formation of large molecules in the gas phase

2019 ◽  
Vol 623 ◽  
pp. A102 ◽  
Author(s):  
Junfeng Zhen
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Molecular Clusters ◽  
Large Molecules ◽  
Flight Mass Spectrometry ◽  
Molecular Precursor ◽  
Dust Grain ◽  
Strong Radiation ◽  
Graphene Cluster

We report the experimental study on the formation process of large molecules (e.g. a family group of molecular clusters and graphene) in the gas phase. The experiment was carried out using a quadrupole ion trap in combination with time-of-flight mass spectrometry. As the initial molecular precursor, dicoronylene (DC, C48H20)/anthracene (C14H10) cluster cations, the results show that large PAH cluster cations (e.g., (C14H10)C48Hn+, n = [1–19] and (C14H10)C62Hm+, m = [1–25]) and PAH-graphene cluster cations (e.g., (C14H10)nC48+, n = 0, 1, 2, 3 and (C14H10)mC62+, m = 0, 1, 2) are formed by gas-phase condensation under laser irradiation conditions. We infer that these results present in here provide a formation route for interstellar large molecules under the influence of a strong radiation field in the ISM. The relevance of newly formed species to the nanometer-sized dust grain in space is briefly discussed.

Reactivity Trends in the Gas Phase Addition of Acetylene to N-protonated Aryl Radical Cations

2020 ◽  
Author(s):  
Oisin Shiels ◽  
P. D. Kelly ◽  
Cameron C. Bright ◽  
Berwyck L. J. Poad ◽  
Stephen Blanksby ◽  
...  
Keyword(s):  
Gas Phase ◽  
Ion Trap ◽  
Radical Cations ◽  
Rate Coefficients ◽  
Similar Process ◽  
Ion Molecule Reactions ◽  
Aromatic Radicals ◽  
Polycyclic Aromatic ◽  
Gas Phase Ion ◽  
Type Radical

<div> <div> <div> <p>A key step in gas-phase polycyclic aromatic hydrocarbon (PAH) formation involves the addition of acetylene (or other alkyne) to σ-type aromatic radicals, with successive additions yielding more complex PAHs. A similar process can happen for N- containing aromatics. In cold diffuse environments, such as the interstellar medium, rates of radical addition may be enhanced when the σ-type radical is charged. This paper investigates the gas-phase ion-molecule reactions of acetylene with nine aromatic distonic σ-type radical cations derived from pyridinium (Pyr), anilinium (Anl) and benzonitrilium (Bzn) ions. Three isomers are studied in each case (radical sites at the ortho, meta and para positions). Using a room temperature ion trap, second-order rate coefficients, product branching ratios and reaction efficiencies are reported. </p> </div> </div> </div>

Gas Phase Reactions of Trimethylborate with the [M − H]− Ions of Nucleotides and Their Non-Covalent Homo- and Heterodimer Complexes

2003 ◽  
Vol 56 (5) ◽  
pp. 389 ◽  
Author(s):  
Ana K. Vrkic ◽  
Richard A. J. O'Hair
Keyword(s):  
Gas Phase ◽  
Mass Spectrometer ◽  
Ion Trap ◽  
Quadrupole Ion Trap ◽  
Methanol Molecule ◽  
Collision Induced Dissociation ◽  
Base Loss ◽  
Gas Phase Reactions ◽  
Ion Trap Mass Spectrometer ◽  
Neutral Base

Trimethylborate (TMB) reacts with deprotonated monomer, homo-, and heterodimer ions of nucleotides (2′-deoxyadenosine-5′-monophosphate [dAMP], 2′-deoxycytidine-5′-monophosphate [dCMP], 2′-deoxyguanosine-5′-monophosphate [dGMP], and 2′-deoxythymidine-5′-monophosphate [dTMP]) in a quadrupole ion trap mass spectrometer by addition with concomitant elimination of one or two methanol molecules (monomers), one or three methanol molecules (homodimers), and three methanol molecules (heterodimers). The mode of reaction appears to influence the observed rates, with the loss of only one methanol molecule corresponding to the fastest rate. There appears to be a structure–reactivity correlation for the monomers, with the [dGMP – H]– ions (which adopt a syn conformation of the guanine moiety) reacting fastest with TMB through the loss of only one methanol molecule. No such structure–reactivity trends are observed for the homo- and heterodimers. In addition, the collision-induced dissociation (CID) reactions of the [(dXMP)n − H]– (n = 1 or 2) as well as the [dXMP + dYMP – H + (CH3O)3B – 3(CH3OH)]– ions (where nucleotides X, Y = A, C, G, or T) were studied. The latter fragment to form [dXMP – H + BPO4]– and [dXMP – 3H + BPO3]– ions (where X = A, C, G, or T), while [dXMP – H]– ions fragment by neutral base loss. The homo- and heterodimers fragment to form [dXMP – H]– and [dXMP + HPO3]– ions, and the relative abundances of the [dXMP – H]– monomer ions from the heterodimers led to the following acidity order: dGMP ≈ dTMP > dCMP > dAMP.

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