Probing the Electronic Stability of Multiply Charged Anions: Sulfonated Pyrene Tri- and Tetraanions

Abstract

The strong intramolecular Coulomb repulsion in multiply charged anions (MCAs) creates a potential barrier that provides dynamic stability to MCAs and allows electronically metastable species to be observed. The 1-hydroxy-3,6,8-pyrene-trisulfonate {[Py(OH)(SO(3))(3)](3-) or HPTS(3-)} was recently observed as a long-lived metastable MCA with a large negative electron binding energy of -0.66 eV. Here we use Penning trap mass spectrometry to monitor the spontaneous decay of HPTS(3-) --> HPTS(*2-) + e(-) and have determined the half-life of HPTS(3-) to be 0.1 s. To explore the limit of electronic metastability, we tried to make the related quadruply charged pyrene-1,3,6,8-tetrasulfonate {[Py(SO(3))(4)](4-)}. However, only its decay product, the triply charged radical anion [Py(SO(3))(4)](*3-), as well as the triply charged ion-pairs [Py(SO(3))(4)H](3-) and [Py(SO(3))(4)Na](3-), was observed, suggesting that the tremendous intramolecular Coulomb repulsion makes the [Py(SO(3))(4)](4-) anion extremely short-lived. Photoelectron spectroscopy data showed that [Py(SO(3))(4)](*3-) is an electronically stable species with electron binding energies of +0.5 eV, whereas [Py(SO(3))(4)H](3-) and [Py(SO(3))(4)Na](3-) possess electron binding energies of 0.0 and -0.1 eV, respectively. Ab initio calculations confirmed the stability of these triply charged species and further predicted a large negative electron binding energy (-2.78 eV) for [Py(SO(3))(4)](4-), consistent with its short lifetime.

Perspective: Electrospray photoelectron spectroscopy: From multiply-charged anions to ultracold anions

“…2(b)). 38,[81][82][83][84] The strong intramolecular Coulomb repulsion not only influences the energetics and stability of MCAs, but it is also expected to strongly influence the electron emission dynamics, which can be investigated using PE imaging by measuring the photoelectron angular distribution. [85][86][87] The first PE imaging on MCAs was done on a series of linear aliphatic dicar-…”

A multi-agent quantum Monte Carlo model for charge transport: Application to organic field-effect transistors

“…2(b)). 38,[81][82][83][84] The strong intramolecular Coulomb repulsion not only influences the energetics and stability of MCAs, but it is also expected to strongly influence the electron emission dynamics, which can be investigated using PE imaging by measuring the photoelectron angular distribution. [85][86][87] The first PE imaging on MCAs was done on a series of linear aliphatic dicar- [88][89][90] which were expected to display strong anisotropy in the PE angular distribution.…”

“…98,99 The Kappes group has investigated electron tunneling in several meta-stable MCAs using mass spectrometry and photodetachment. 84,[100][101][102] MCAs can be pumped to an excited state, from which fast electron tunneling can occur. Such resonant tunneling was first observed in the copper phthalocyanine tetrasulfonate tetraanion.…”

Resonant tunneling through the repulsive Coulomb barrier of a quadruply charged molecular anion

“…The RCB provides dynamic stability to MCAs and allows long-lived metastable MCAs with negative electron binding energies to be observed [9][10][11][12]. Metastable MCAs can undergo spontaneous electron emission from their ground states by tunneling through the RCB, analogous to α-decay for radioactive nuclei [11][12][13][14][15][16].…”

“…Metastable MCAs can undergo spontaneous electron emission from their ground states by tunneling through the RCB, analogous to α-decay for radioactive nuclei [11][12][13][14][15][16]. Such decay has been studied using ion trap mass spectrometry, yielding tunneling lifetimes on the order of seconds for a number of metastable MCAs at room temperature [11,12,16].…”