**3.2 Structural analysis of 4,5-dimethyl-2-phenyl-1-(p-tolyl)-1***H***-imidazole (DMPPTI)**

This section depicts the structure details of DMPPTI [11]. The crystal structure was solved by direct methods using the program SIR2002 [22]. The program SHELXL97 [19] refines the final crystal structure model.

This compound belongs to the monoclinic crystal system with the space group P21/ n. Molecular formula: C18H18N2; molecular weight: 262.34; crystal data: a = 9.6971 (3) Å; b = 7.5458 (2) Å; c = 19.8407 (7) Å; β = 96.604 (3)°; V = 1442.16 (8) Å3 ; Z = 4;

#### **Figure 3.**

*The crystal packing with hydrogen bonds [21], viewed along the c-axis.*

Dx = 1.208 Mg m<sup>3</sup> ; F(000) = 560; final R[F2 > 2σ(F<sup>2</sup> )] = 0.049 and wR(F<sup>2</sup> ) = 0.138 for 2529 reflections observed with I > 2σ(I).

With CdH = 0.95 to 0.98 Å; Uiso(H) = kUeq(C), k = 1.5 for dCH3 and 1.2 for the other H atoms, all the hydrogen atoms were arranged geometrically and allowed to drive on their parent atoms.

In (**Figure 4**), with the maximum deviation = 0.004 (1) Å for N3, the imidazole ring is planar. This ring makes dihedral angles of 68.91 (8)°, and 20.43 (9)° with the (C11dC16) and (C21dC26) rings, respectively. 73.62 (8)° is the dihedral angle among the (C11dC16) and (C21dC26) rings. The C12dH12⋯N3<sup>i</sup> and

C16dH16⋯N3ii intermolecular nonclassical hydrogen bonds stabilize the packing (**Figure 5**). Symmetry codes are: (i) x + 2, y + 1, z and (ii) x + 2, y + 2, z.

The ORTEP-3 for Windows drew the thermal displacement ellipsoid plot with a 30% probability level [20] (**Figure 4**). The crystal packing using the PLATON [21] was viewed along the a-axis (**Figure 5**).
