Journal Information

Journal ID (publisher-id): chemical

Title: Journal of the Korean Chemical Society

Translated Title (ko): 대한화학회지

ISSN (print): 1017-2548

ISSN (electronic): 2234-8530

Publisher: Korean Chemical Society대한화학회

Article Information

Copyright statement: Copyright © 2021, Korean Chemical Society

Copyright: 2021

Date received: 07 February 2021

Date accepted: 03 March 2021

Publication date (print): 20 June 2021

Volume: 65

Issue: 3

Pages: s203-s207

Publisher ID: jkcs-65-s203

Synthesis, Characterization and in vitro Antibacterial Studies on Mixed Ligand Complexes of Iron(III) Based on 1,10-phenanthroline

Getinet Tamiru Tigineh[*]

Getu Sitotaw

Amogne Workie[†]

Atakilt Abebe

Bahir Dar University, Science College, Chemistry Department, P.O. Box; 79, Bahir Dar, Ethiopia.

[†] Institute of Chemistry, Academia Sinica, 128, Sec. Academia Rd., Nangang, Taipei 115, Taiwan.

Author notes:

Correspondence to: [*] E-mail: getenet.tamiru@bdu.edu.et; getsh2007@gmail.com

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Experimental▼

Chemicals

1,10-phenanthroline monohydrate (>99%, BDH Chemical Ltd., Poole, England), guanine (99%, ACROS), FeCl3 (>97%), silver nitrate (>99%), sodium hydroxide (>97%), acetone (>98%), chloroform (>99%), sulfuric acid (>95%)] (Sigma Aldrich), methanol (Absolut) (Hi Media Laboratories Ltd., India), KBr (for IR spectroscopy Uvasol®), dichloromethane (>99.5%), Mueller Hinton agar, and barium chloride (BLULUX Laboratories Ltd., India), and nitric acid (T.V. Industrial Estate, India) were used.

Instruments and Methods

Melting points were determined using STONE, STAFFORDSHIRE, ST15 OSA, UK, digital melting point apparatus. Molar conductivities of 10-4 M solutions of the solid complex in double distilled water were measured using Jenway 4200 conductivity meter. Elemental analyses were performed using a PERKIN ELMER 2400 CHN elemental analyzer. The electronic absorption spectra in the (200-800 nm) range were obtained in double distilled water on a Shimadzu UV-1700 UV-Visible spectrophotometer. FTIR spectra were recorded on a Perkin-Elmer frontier promotion cod ILC38B6PD7 spectrometer (4000-450 cm-1) in KBr pellets. HR-ESI spectra was conducted on dual ionization ESCi® (ESI/APCi) source options Waters LCT Premier XE (Waters Corp., Manchester, UK) at Academia Sinica, Institute of Chemistry, Taiwan. Iron content was determined by PerkinElmer, Optima 7300V HF Version ICP-OES spectrometer, digesting 1.6 mg of each complex in concentrated nitric acid and diluting them using double distilled water. The current-voltage measurements were performed using CHI 760d Electrochemical Workstation (Texas, USA) connected to a personal computer with a conventional three-electrode system. Carbon paste electrode (CPE) as a working electrode, platinum coil as a counter electrode, and Ag/AgCl (3M KCl) as a reference electrode were used. Cyclic voltammograms of 2.0 mM aqueous solution of the complexes at the carbon paste electrode (CPE) were recorded within the potential window of 0.2 to 1.1 V. Chloride ions were determined thermo-gravimetrically using the AgCl precipitate obtained from the mixture of 10 mL solution of 11 mg of each complex in distilled water with excess AgNO3 solution.

TableS1.

IR spectra data of ligands and complexes

Ligands and complexes Frequency, cm-1
ν(O-H) ν(NH2) ν(C-H) ν(C=O) δ(NH2) scissoring ν(C=N) ν(C=C) ν(C-N)
1,10-phenanthroline monohydrate 3430(s) - 3043(vw) - - 1588(m) 1622(m) 1295(vw)
Guanine - 3320, 3118(m,d) 2695(vw) 1698(s) 1673(s) 1476(m) 1552(w) 1261endo(m), 1215exo(m)
[Fe(L1)2(H2O)2]Cl3 3395(s,b) - 3042(vw) - - 1543(w) 1623(w) 1254(vw)
[Fe(L1)2(L2)(H2O)]Cl2 3460(b)* 3344, 3108(w,b) 2696(vw) 1700(s) 1673(s) 1451(m) 1553(w) 1263(m), 1217(m)

Key: s = strong; m = medium; w = weak; vw = very weak; d=doublet; b = broad, *overlap with the ν(NH2)

FigureS1.

FTIR spectra of ligands and complex.

jkcs-65-s203-f001.tif
TableS2.

Electronic spectral data of the salt, ligands, and complexes

Compounds λmax(nm) Assignments
1,10-Phenanthroline 225 π → π* (C=C)
266 n → π* (C=N)
Guanine 245 π → π* (C=C)
272 n → π* (C=N)
FeCl3 300 LMCT
511,553,631 2T2g→2A2g, 2T2g→2T1g, 2T2g→2Eg
[Fe(L1)2(H2O)2]Cl3 221 π → π* (C=C)
268 n → π* (C=N)
353 LMCT
480, 512, 670 2T2g→2A2g, 2T2g→2T1g, 2T2g→2Eg
[Fe(L1)2(L2)(H2O)]Cl2 270 n → π* (C=N)
420, 516, 739 2T2g→2A2g, 2T2g→2T1g, 2T2g→2Eg
FigureS2.

UV-Vis spectra of metal salt, ligands, and complexes.

jkcs-65-s203-f002.tif
FigureS3.

ESI-Mass spectra of complexes.

jkcs-65-s203-f003.tif
FigureS4.

Cyclic voltammogram of 2.0 mM solution of Fe(III) complexes with 1.0 M KCl supporting electrolyte at a scan rate of 100 mVs-1.

jkcs-65-s203-f004.tif
TableS3.

Antibacterial activities of the metal salt, complexes, and commercially available antibiotic

Compound Inhibition zone (mm)
Gram-positive Gram-negative
S.aures S.epi E.coli K.pne
FeCl3 0.00±00 4.60±0.01 3.30±0.11 0.00±00
[Fe(L1)2(H2O)2]Cl3 26.86±0.23 29.70±0.10 12.30±0.40 8.90±0.11
[Fe(L1)2(L2)(H2O)]Cl2 13.17±0.30 14.22±0.21 30.99±0.01 25.20±0.30
Erythromycin 28.70±0.58 29.97±0.50 10.90±0.11 7.30±0.38
TableS4.

MIC assay of [Fe(L1)2(L2)(H2O)]Cl2 against four bacterial pathogens

Microorganism Minimum concentration of microorganism growth (in μg/mL)
75 150 300 500 600
Staphylococcus aureus + + + − −
Staphylococcus epidermidis + + + − −
Escherichia coli + − − − −
Klebsiella Pneumonia + − − − −

Note: +: bacteria growth and −: no bacteria growth.