*2.2. Crystal Structure Determination*

Single crystals were obtained by the slow evaporation of the ethanol solution of the isoflavone **5** at ambient temperature. A single crystal of the dimensions 0.393 × 0.305 × 0.134 mm<sup>3</sup> was selected and x-ray data were collected at 223 K on a Bruker D8 Venture equipped (Bruker, Madison, EI, USA) with IµS micro-focus sealed tube Mo Kα (λ = 0.71073 Å) and a PHOTON 100 CMOS detector. Bruker SAINT was utilized for the cell refinement and data reduction [36]. The structure was solved by direct methods and refined by full-matrix least-squares on *F* <sup>2</sup> using SHELXTL [37]. Detailed refining methods followed previously reported methods [35], and the outcomes of the crystallographic data collection, structural determination and refinement are summarized in Table 1 (CCDC deposition number 2027508). All relevant information which include bond distances, angles, fractional coordinates, and the equivalent isotropic displacement parameters can be obtained free of charge from the CCDC (Cambridge Crystallographic Data Centre), 12 Union Road, Cambridge CB2 1EZ, UK; Fax: +44 1223 336033; E-mail: deposit@ccdc.cam.ac.uk.


**Table 1.** Crystal data and structure refinement for compound **5**.
