Reactivity Sites in Dopamine Depend on its Intramolecular Hydrogen Bond

Abstract

In this work, three conformers of dopamine were theoretically analyzed, two of them forming an intramolecular hydrogen bond between OH groups in the catechol moiety, the third one without this interaction. The used theoretical method was based on the Kohn-Sham method within the hybrid exchange-correlation functionals without empirical parameters, PBE0. The molecular geometry obtained by this method was contrasted with that obtained from the second-order many-body perturbation theory (MP2) method and the 6-31+G(d), 6-311+G(d) and 6-311++G(d,p) basis sets. Global reactivity descriptors were predicted by using only the PBE0/6-311++G(d,p) method. This method revealed that dopamine is not a good acceptor of electrons. Thus, in one charge transfer process, this compound prefers donating electrons, as observed experimentally. All global chemical predictors do not show important changes regardless of the presence of an intramolecular hydrogen bond. However, in the case of local reactivity predictors, oxygen atoms of the catechol moiety exhibit changes when this contact is present. This conclusion was confirmed when 8 catechol derivatives were analyzed with the same procedure applied over the dopamine. Additionally, the carbon atoms opposite to the carbon atoms linked to oxygen atoms, in the catechol moiety, present the biggest changes when these systems donate one electron. Consequently, the electron involved during the charge transfer process of these systems will be detached from the region defined between these two carbon atoms.

A simulation of free radicals induced oxidation of dopamine in aqueous solution

“…In both mechanisms we find that the electron is always removed from the π orbital of the catechol group with no σ electron density being lost neither from the O1-H1 nor the O2-H2 bond. Particularly, the electron leaves the C1 or C2 atoms, depending on which one is closer to the radical, which is also reported by García-Hernández and Garza [35]. Another common property of all reactions is that they always start a few femtoseconds after beginning of the simulations as well as that they are finished within less than one picosecond.…”

Naphthoquinone-Dopamine Linked Colorimetric and Fluorescence Chemosensor for Selective Detection of Sn2+ Ion in Aqueous Medium and Its Bio-Imaging Applications

“…Therefore, according to the IUPAC rule of the hydrogen bond, the obtained HB in 2CND perfectly coordinates with the high electrophilic character of Sn 2+ with enlarged fluorescence emission intensity, where the two atoms maintain the donor−acceptor properties with high electronegativity. 50 Consequently, owing to the high electronegativity of fluorophores, the obtained HB at the proper direction, and the strong electrophilic nature of Sn 2+ than the other metal ions, the chemosensor 2CND displayed better selectivity and higher emission intensity toward Sn 2+ than the other transition-metal ions studied. The fluorescence emission of 2CND with an added amount of Sn 2+ under a xenon lamp (75 W) are shown as an inset in Figure 2.…”

“…In the dopamine unit of 2CND , where the HB is existing on the −OH group, the other −OH group may be available in the opposite direction; thus, the interaction of O–H····O is strongly hindered within the molecule. Therefore, according to the IUPAC rule of the hydrogen bond, the obtained HB in 2CND perfectly coordinates with the high electrophilic character of Sn 2+ with enlarged fluorescence emission intensity, where the two atoms maintain the donor–acceptor properties with high electronegativity . Consequently, owing to the high electronegativity of fluorophores, the obtained HB at the proper direction, and the strong electrophilic nature of Sn 2+ than the other metal ions, the chemosensor 2CND displayed better selectivity and higher emission intensity toward Sn 2+ than the other transition-metal ions studied.…”

Electron Donor–Acceptor Properties of Different Muscarinic Ligands: On the Road to Control Schizophrenia

“…With these parameters, it is possible to determine the electron donor–acceptor MAP (DAM) (see Figure ). These chemical descriptors have been used successfully in many different chemical systems. ,− …”