The Tunisian Association of Heterocyclic Chemistry and its Applications STCHA has already organized four congresses: a) JICHA 1-2016; b) CMCH 1-2017; c) CMCH 2-2018; d) CMCH 3-2019 through Abstracts, Proceedings, Plenary Conferences, Oral Communications and Poster Communications.The various papers of this fifth STCHA Congress "Second International Conference on Heterocyclic Chemistry and its Applications: JICHA 2-2020" are presented in an innovative way through Review Articles and Audio-visual Lectures. This First Virtual Congress of STCHA is organized on June 22 & 23, 2020 at the Technopole of Borj Cedria - Tunisia. Volume IV of the JICHA 2-2020 Congress Book gathers Review Articles from Maghrebian specialists in theoretical and crystallographic studies.