Mini 1240

All compounds’
melting points were measured using Gallan-Kamp equipment and are uncorrected.
TLC was used to assess the purity of the compounds. A Shimadzu 470
IR-spectrophotometer was used to record the infrared (IR) spectra
(KBr). ¹H NMR spectra were recorded on a 500 MHz spectrometer
using CDCl₃ or DMSO-d₆ as a
solvent and tetramethylsilane (TMS) as an internal reference (chemical
shifts were given in ppm (δ) and coupling constants (J values) in Hertz (Hz)). The splitting patterns were designated
as singlet (s), doublet (d), doublet of doublets (dd), triplet (t),
quartet (q), or multiplet (m). The spectra of UV–vis were measured
using a Shimadzu mini1240. The fluorescence emission spectra are performed
at room temperature using a Hitachi F-7100 FL Spectrophotometer. The
Gaussian 09 program is used for quantum chemical calculations³⁴ via the density functional theory method with
the B3LYP functional in a gaseous phase^{35 (link)} and the 6-311++G (d,p) basis set. To conduct open circuit potential
linear and Tafel plot polarization tests in electrochemical studies,
the 352/252 model corrosion measuring technique is utilized in conjunction
with an EG&G potentiostat/galvanostat, model 273A, that operates
on IBM software. Scanning electron microscope (SEM) analysis was performed
at the unit of electronic microscopy (JEOL, JSM5400LV) at Assuit University.

The phlorotannin content was estimated by determining the total phenolic content (TPC) of the extracts using a modified version of the method performed by Farvin & Jacobsen [7 (link)]. The liquid extracts were diluted 10 times before analysis. To 100 μL of diluted sample 0.75 mL Folin Ciolcalteu phenol reagent (10% v/v in water) was added and mixed. After 5 min, 0.75 mL sodium-carbonate solution (7.5% Na₂CO₃ w/v in water) was added and mixed. The reaction was incubated for 90 minutes in room temperature in the dark. The absorbance was measured at 725 nm by a UV-vis spectrophotometer (Shimadzu UV mini−1240, Duisburg, Germany). Gallic-acid (GA, 2,3,4-trihydrobenzoic acid) was used for quantification (calibration curve: 0–250 μg mL⁻¹). The results are expressed as grams of gallic acid equivalents (GAE) in 100 g dw (g GAE 100 g⁻¹ dw, n = 3).