Effect of cation complexation on the structure of a conformationally flexible multiply charged anion: stabilization of excess charge in the Na+ x adenosine 5'-triphosphate dianion ion-pair complex.

We report a computational study of the conformationally and tautomerically flexible cation-dianion complex of Na(+) with doubly deprotonated adenosine 5'-triphosphate (ATP) using a hierarchical selection method. The method uses molecular dynamics to generate initial conformeric structures, followed by a classification process that groups conformers into five "families" to ensure that a representative sample of structures is retained for further analysis, while very similar conformational structures are eliminated. Hierarchical ab initio calculations (DFT and MP2) of typical conformers of the families are then performed to identify the lowest-energy conformeric structures.

Characterizing the intrinsic stability of gas-phase clusters of transition metal complex dianions with alkali metal counterions: counterion perturbation of multiply charged anions.

The authors report the gas-phase generation and characterization of a series of cation-dianion clusters, e.g., M(+).

Counter-ion perturbation of the fragmentation pathways of multiply charged anions: evidence for exit channel complexes on the fragmentation potential energy surfaces.

We report the first low-energy collisional excitation measurements and density functional theory calculations to characterize the ground state potential energy surfaces of contact ion-pair complexes that contain multiply charged anions (MCAs). Excitation of K+.Pt(CN)(4) (2-) and K+.

Stabilization of excess charge in isolated adenosine 5'-triphosphate and adenosine 5'-diphosphate multiply and singly charged anions.

Multiply charged anions (MCAs) represent highly energetic species in the gas phase but can be stabilized through formation of molecular clusters with solvent molecules or counterions. We explore the intramolecular stabilization of excess negative charge in gas-phase MCAs by probing the intrinsic stability of the [adenosine 5'-triphosphate-2H](2-) ([ATP-2H](2-)), [adenosine 5'-diphosphate-2H](2-) ([ADP-2H](2-)), and H(3)P(3)O(10)(2-) dianions and their protonated monoanionic analogues. The relative activation barriers for decay of the dianions via electron detachment or ionic fragmentation are investigated using resonance excitation of ions isolated within a quadrupole trap.