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In this study, we investigated the potential of palladium tetrakis (imidazole) phthalocyanine (PdPc(Imz) 4 ) for use as an organic semiconductor for improving the photovoltaic performance. In order to get more information about the prevailing model of the conduction mechanism (correlated barrier hopping (CBH)) for PdPc(Imz) 4 , electrical impedance measurements were performed at different temperatures and the obtained data were simulated by the Kohlraush Williams Watt (KWW) approach. Theoretical studies (density functional theory (DFT)) were performed and molecular electrostatic potential (MEP) maps were also extracted to understand the relationship between the molecular structures and the molecular electronic structure of PdPc(Imz) 4 and its semiconductor properties. Furthermore, studies on the AC electrical process as a function of temperature highlighted a hopping charge transport according to an equivalent electrical circuit composed of a parallel constant-phase element (CPE), capacitance in the grain boundary layer ( C g ), and resistance of the grain boundary ( R g ). To improve interpretation of the results, an in-depth analysis of the behavior of the electric transport was conducted. As a result, the correlated barrier hopping (CBH) conduction mechanism was shown to be the most suitable predominant conduction mechanism., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

A unified CO 2 -amine reaction mechanism applicable to absorption in aqueous or nonaqueous solutions and to adsorption on immobilized amines in the presence of both dry and humid conditions is proposed. Key findings supported by theoretical calculations and experimental evidence are as follows: (1) The formation of the 1,3-zwitterion, RH 2 N + -COO - , is highly unlikely because not only the associated four-membered mechanism has a high energy barrier, but also it is not consistent with the orbital symmetry requirements for chemical reactions. (2) The nucleophilic attack of CO 2 by amines requires the catalytic assistance of a Bro̷nsted base through a six-membered mechanism to achieve proton transfer/exchange. An important consequence of this concerted mechanism is that the N and H atoms added to the C=O double bond do not originate from a single amine group. Using ethylenediamine for illustration, detailed description of the reaction pathway is reported using the reactive internal reaction coordinate as a new tool to visualize the reaction path. (3) In the presence of protic amines, the formation of ammonium bicarbonate/carbonate does not take place through the widely accepted hydration of carbamate/carbamic acid. Instead, water behaves as a nucleophile that attacks CO 2 with catalytic assistance by amine groups, and carbamate/carbamic acid decomposes back to amine and CO 2 . (4) Generalization of the catalytic assistance concept to any Bro̷nsted base established through theoretical calculations was supported by infrared measurements. A unified six-membered mechanism was proposed to describe all possible interactions of CO 2 with amines and water, each playing the role of a nucleophile and/or Bro̷nsted base, depending on the actual conditions., Competing Interests: The authors declare no competing financial interest.