Neutral, Ion Gas-Phase Energetics and Structural Properties of Hydroxybenzophenones

Abstract

We have carried out a study of the energetics, structural, and physical properties of o-, m-, and p-hydroxybenzophenone neutral molecules, C(13)H(10)O(2), and their corresponding anions. In particular, the standard enthalpies of formation in the gas phase at 298.15 K for all of these species were determined. A reliable experimental estimation of the enthalpy associated with intramolecular hydrogen bonding in chelated species was experimentally obtained. The gas-phase acidities (GA) of benzophenones, substituted phenols, and several aliphatic alcohols are compared with the corresponding aqueous acidities (pK(a)), covering a range of 278 kJ.mol(-1) in GA and 11.4 in pK(a). A computational study of the various species shed light on structural effects and further confirmed the self-consistency of the experimental results.

It Is Important to Compute Intramolecular Hydrogen Bonding in Drug Design?

“…Laurence [141] described in detail the hydrogen bond basicities of functional groups relevant to medicinal chemistry. Recently, the empirical appreciation of the bond strength according to the pK a (H 2 O) equalization principle was used for the prediction of H bond strengths from the acid−base parameters of the interacting partners [142,143].…”

Substituent Effects on the Basicity of Patriscabrin A and Lettucenin A: Evolution Favors the Aromatic?

“…35 These quantities were computed using the B3LYP functional, 36,37 as it is known to reproduce the experimental results well (in addition to being in good agreement with those reported at the CCSD(T) and G2 levels 38,39 ) for intrinsic acid/base properties. 40,41 Supplementary geometrical, frequency, and energy calculations were also performed with the M06-2X method to investigate the robustness of our chosen method (see the Supporting Information (SI)); 42 our overall qualitative conclusions persist with this method. We calculated basicities (B NP ) of natural products and analogues (NP) using a proton-transfer reaction between each NP and water (eq 1).…”

“…The optimized structural coordinates and harmonic vibrational frequency data reported in this work have been obtained using the Gaussian 09 suite of programs (G09) . These quantities were computed using the B3LYP functional, , as it is known to reproduce the experimental results well (in addition to being in good agreement with those reported at the CCSD­(T) and G2 levels , ) for intrinsic acid/base properties. , Supplementary geometrical, frequency, and energy calculations were also performed with the M06-2X method to investigate the robustness of our chosen method (see the Supporting Information (SI)); our overall qualitative conclusions persist with this method.…”

Acidities of closo-1-COOH-1,7-C2B10H11 and Amino Acids Based on Icosahedral Carbaboranes

“…Finally, one of the most complex difficulties, within an acid− base context, is the prediction of liquid-phase behavior as compared to gas-phase behavior, which can be tackled with the exploration of correlating gas-phase and liquid-phase acidities, as shown from previous works in the literature. 28 ■ ASSOCIATED CONTENT * S Supporting Information…”