Bruce S. Ault

Bio: Bruce S. Ault is an academic researcher from University of Cincinnati. The author has contributed to research in topics: Matrix isolation & Infrared spectroscopy. The author has an hindex of 30, co-authored 269 publications receiving 4190 citations. Previous affiliations of Bruce S. Ault include University of Virginia.

Matrix Isolation Study of the Thermal and Photochemical Reaction of OVCl3 with NH3: Spectroscopic and Theoretical Characterization of Cl2V(O)NH2

Abstract: Initial and secondary intermediates in the reaction of OVCl3 with NH3 have been characterized by matrix isolation infrared spectroscopy and density functional calculations. Twin jet co-deposition of these two reagents led to a series of infrared absorptions that are assigned to the 1:1 molecular complex between these two species. Irradiation of these matrices with light of λ > 300 nm led to complete destruction of the complex, and the growth of a number of new bands. These are assigned to the Cl2V(O)NH2 species, as well as to HCl arising from destruction of the complex. Identification of these species was supported by extensive isotopic labeling (15N and 2H), as well as by B3LYP/6-311G+(2d,3p) density functional calculations. Good agreement was observed between the experimental and the computed frequencies. Similar experiments with (CH3)3N led, at best, to a very small degree of complex formation.

Infrared matrix isolation and theoretical study of the initial intermediates in the reaction of ozone with cis-2-butene.

Abstract: Matrix isolation studies combined with infrared spectroscopy of the twin jet codeposition of ozone and cis-2-butene into argon matrices have led to the first observation of several early intermedia...

Photoinduced C−N Bond Cleavage in 2-Azido-1,3-diphenyl-propan-1-one Derivatives: Photorelease of Hydrazoic Acid

Abstract: Photolysis of 3-azido-1,3-diphenyl-propan-1-one (1a) in toluene yields 1,3-diphenyl-propen-1-one (2), whereas irradiation of 3-azido-2,2-dimethyl-1,3-diphenyl-propan-1-one (1b) results in the formation of mainly 2,2-dimethyl-1,3-diphenyl-propan-1-one. Laser flash photolysis (308 nm) of 1a,b in acetonitrile reveals a transient absorption (λmax = ∼310 nm) due to the formation of radicals 4a and 4b, respectively, which have lifetimes of ∼14 μs at ambient temperature. TD−DFT calculations (B3LYP/6-31+G(d)) reveal that the first and second excited states of the triplet ketone (T1K (n,π*) and T2K (π,π*)) in azide 1a are almost degenerate, at ∼74 and 76 kcal/mol above the ground state (S0), respectively. Similarly, azide 1b has T1K and T2K 75 and 82 kcal/mol above S0, respectively. The calculated transition state for cleaving the C−N bond is located 71 and 74 kcal/mol above S0 in azides 1a and 1b, respectively. The calculated bond dissociation energies for breaking the C−N bond are 55 and 58 kcal/mol for azides 1...

Matrix Isolation Study of the Reaction of CrCl2O2 with NH3: Synthesis and Characterization of ClCr(O)2NH2

Abstract: Initial and secondary intermediates in the reaction of CrCl2O2 with NH3 have been characterized by matrix isolation infrared spectroscopy and density functional calculations. Twin-jet co-deposition of these two reagents led to a series of infrared absorptions that are assigned to the 1:1 molecular complex between these two species. The shift of ν2 of NH3 in the complex was +218 cm-1, indicating that CrCl2O2 is a moderately strong Lewis acid. Irradiation of these matrices with light of λ > 300 nm led to complete destruction of the complex and the growth of a number of new bands. These are assigned to the ClCr(O)2NH2 species, as well as to HCl arising from destruction of the complex. Identification of these species was supported by isotopic labeling (15N and 2H), as well as by B3LYP/6-311G+(2d,3p) density functional calculations. Good agreement was observed between the experimental and computed frequencies.

The density functional formalism, its applications and prospects

Abstract: A scheme that reduces the calculations of ground-state properties of systems of interacting particles exactly to the solution of single-particle Hartree-type equations has obvious advantages. It is not surprising, then, that the density functional formalism, which provides a way of doing this, has received much attention in the past two decades. The quality of the energy surfaces calculated using a simple local-density approximation for exchange and correlation exceeds by far the original expectations. In this work, the authors survey the formalism and some of its applications (in particular to atoms and small molecules) and discuss the reasons for the successes and failures of the local-density approximation and some of its modifications.

The Halogen Bond

Abstract: The halogen bond occurs when there is evidence of a net attractive interaction between an electrophilic region associated with a halogen atom in a molecular entity and a nucleophilic region in another, or the same, molecular entity. In this fairly extensive review, after a brief history of the interaction, we will provide the reader with a snapshot of where the research on the halogen bond is now, and, perhaps, where it is going. The specific advantages brought up by a design based on the use of the halogen bond will be demonstrated in quite different fields spanning from material sciences to biomolecular recognition and drug design.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Abstract: Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Photoremovable Protecting Groups in Chemistry and Biology: Reaction Mechanisms and Efficacy

Abstract: The review covers the knowledge on photoremovable protecting groups and includes all relevant chromophores studied in the time period of 2000–2012; the most relevant earlier works are also discussed.