**4. Comparative structural study of the eight imidazole derivatives**

**Section 3** presented the single crystal X-ray structure analyses of eight closely related organic imidazole compounds. All the eight structures have the imidazole core essentially as the basic skeleton, with different groups (DMDPIMH: dCH3, dCH3, dC6H5, dC6H5, with H2O, DMPPTI: dCH3, dCH3, dC6H5, dC6H4dCH3, FPDMMPI: dCH3, dCH3, dC6H4dF, dC6H4dCH3, DMPDMPIHH: dCH3, dCH3, dC6H5, dC6H3d2(CH3), with 0.5H2O, DMPFPDMI: dCH3, dCH3, dC6H4dF, dC6H3d2(CH3), FPMOPDMI: dCH3, dCH3, dC6H4dF, dC6H4dOdCH3, DMOPFPDMI: dCH3, dCH3, dC6H4dF, dC6H3d2(OdCH3), FPTPI: dC6H5, dC6H5, dC6H4dF, dC6H5) as different substituents. The structure elucidation of the compounds has revealed a few features, such as (1) the hydrogen bonds: OdH … N, OdH … O, CdH … N; and (2) the interactions CdH … π.

**C**d**H** … **π interactions:** Weak acids and soft bases interact. A particular hydrogen bond between two such systems is called a CdH … π interaction. The interactions between aromatic acceptors and CdH aliphatic donors and those between aromatic acceptors and CdH donors are the two most prominent. The non-covalent connections that surround these systems are referred to in chemistry as "π interactions" or "π effects" [9].

**Related structures:** On September 11, 2022, the terms **imidazole** and **1***H***-imidazole** on IUCr Journals Crystallography Journals Online (https://journals.iucr.org/) returned 6276 and 290 articles, respectively, matching the searches. The IUCr Journals' paper reference codes: tk2693 (4,5-dimethyl-1,2-diphenyl-1*H*-imidazole monohydrate), rk2234 (4,5-dimethyl-2-phenyl-1-(p-tolyl)-1*H*-imidazole), si2269 (2-(4-fluorophenyl)-4,5-dimethyl-1-(4- methylphenyl)-1*H*-imidazole), hg2722 (1-(3,5-dimethylphenyl)-4,5-dimethyl-2-phenyl-1*H*-imidazole hemihydrate), hg5018 (1-(3,5-dimethylphenyl)-2-(4-fluorophenyl)-4,5-dimethyl-1*H*-imidazole), wn2396 (2-(4-fluorophenyl)-1-(4-methoxyphenyl)-4,5-dimethyl-1*H*-imidazole), hg5156 (1-(3,5-dimethoxyphenyl)-2-(4-fluorophenyl)-4,5-dimethyl-1*H*-imidazole), and tk2707 (2-(4-fluorophenyl)-1,4,5-triphenyl-1H-imidazole), affirm that the geometry of the five-membered imidazole cores are very like in all the described structures.

**Database survey:** The search using the CCDC ConQuest (Version 2022.2.0) in the Cambridge Structural Database (CSD, Version 5.43, update November 2021) [23] for the compound name **imidazole** gave 21,489 hits, and for the compound name **1***H***imidazole** gave 9198 hits. A single query on 2D diagram search using the CCDC ConQuest (Version 2022.2.0) gave 142 hits for DMDPIMH (including the CSD Refcode: SUYRUA), 45 hits for DMPPTI (including the CSD Refcode: VABBUX), 5 hits for FPDMMPI (including the CSD Refcode: QUZLED), 25 hits for DMPDMPIHH (including the CSD Refcode: VUZSOZ), one hit for DMPFPDMI (with the CSD Refcode: URALEF), two hits for FPMOPDMI (including the CSD Refcode: YUQBUI), three hits for DMOPFPDMI (including the CSD Refcode: GAPGEL), and six hits for FPTPI (including the CSD Refcode: KUZFUH).
