A new Cd(II) complex with the ligand 4′-chloro-2,2′6′,2′′-terpyridine (Cltpy), [Cd(Cltpy)(I)2], has been synthesized and characterized by CHN elemental analysis, 1H-NMR, 13C-NMR, and IR spectroscopy and structurally analyzed by X-ray single-crystal diffraction. The single-crystal X-ray analyses show that the coordination number in complex is five with three terpyridine (Cltpy) N-donor atoms and two iodine atoms. The antibacterial activities of Cltpy and its Cd(II) complex are tested against different bacteria.
Terpyridine molecules with three nitrogen atoms acting as tridentate ligands to coordinate with various transition metal ions have been extensively studied [
Structure of Cltpy ligand.
All chemicals were reagent grade and used without further purification. Elemental analyses (CHN) were performed using a Carlo ERBA model EA 1108 analyzer. FT-IR spectra were collected on a Shimadzu prestige 21 spectrophotometer in the range of 4000–400 cm−1 using KBr pellets. 1H and 13C NMR spectra were recorded with a Bruker spectrometer at 250 MHz in D6-DMSO.
4′-chloro-2,2′:6′,2′′-terpyridine (0.268 g, 1 mmol) was placed in one arm of a branched tube, cadmium(II) acetat (0.264 g, 1 mmol) and potassium iodide (0.332 g, 2 mmol) in the other. Methanol was carefully added to fill both arms, the tube was then sealed, and the ligand-containing arm was immersed in a bath at 60°C, while the other remained at ambient temperature. After two days, the light brown crystals that had deposited in the cooler arm were filtered off, then washed with diethylether, and air dried. Yield: 71%. Analysis: found: C: 28.38, H: 1.51, N: 6.59%. Calculated for C15H10CdClI2N3: C: 28.42, H: 1.59, N, 6.63%.
In vitro activity test was carried out using the growth inhibitory zone (well method) [
Data collection for X-ray crystal structure determination was performed on a STOE IPDS I/II diffractometer using graphite-monochromated Mo-K
Crystallographic data of [Cd(Cltpy)I2 complex.
Identification code | Cd (terpy-Cl) I2 (7) |
---|---|
Empirical formula | C15 H10 Cd Cl I2 N3 |
Formula weight | 633.91 |
Colour | light brown |
Temperature | 293(2) K |
Wavelength | 0.71073 A |
Crystal system | Monoclinic |
Space group | P2(1)/c |
Unit cell dimensions | |
Volume | 1817.0(3) Å3 |
Z | 4 |
Density (calculated) | 2.317 g cm−3 |
Absorption coefficient | 4.745 mm−1 |
1168 | |
Crystal size | |
Theta range for data collection | 1.78 to 25.02° |
Index ranges | |
Reflections collected | 9236 |
Independent reflections | 3184 |
Absorption correction | Empirical |
Max. and min. transmission | 0.5774 and 0.3606 |
Refinement method | Full-matrix |
least-squares on | |
Data/restraints/parameters | 3184/0/199 |
Goodness-of-fit on | 1.063 |
Final | |
Largest diff. peak, hole | 0.802 and −0.708e· Å−3 |
The reaction of CdX2 (X: nitrate and acetate) with 4′-chloro-2,2′:6′,2′′-terpyridine (Cltpy) and potassium iodide yielded crystalline material formulated as [Cd(Cltpy)(I)2]. The IR spectra display characteristic absorption bands for the tpyCl ligands. The relatively weak absorption bands at around 3042–3065 cm−1 are due to the C–H modes involving the aromatic ring hydrogen atoms. The absorption bands with variable intensity in the frequency range 1400–1620 cm−1 correspond to aromatic ring vibrations of the tpyCl ligand [
The 1H-NMR spectra of DMSO solutions of complex at room temperature show two triplets, a singlet, and a multiplet for the aromatic protons of Cltpy ligand. The 13C-NMR spectra of DMSO solutions of these compounds show eight distinct bands assigned to the aromatic carbon atoms of the pyridine rings of the Cltpy ligand.
The solid-state structure of compound was determined by single-crystal X-ray diffraction. Crystal and structure refinement data of the compound are given in Table
Selected bond lengths/Å and angles/°.
[Cd(Cltpy)I2] | |||
---|---|---|---|
Cd1–N1 | 2.373(5) | 135.19(11) | |
Cd1–N2 | 2.331(5) | 106.17(11) | |
Cd1–N3 | 2.381(5) | 101.35(12) | |
Cd1–I1 | 2.7311(8) | 101.13(13) | |
Cd1–I2 | 2.7523(7) | 101.33(13) | |
99.34(13) | |||
| 69.24(17) | 130.94(18) | |
| 68.81(18) | 118.63(2) | |
Molecular structure of [Cd(Cltpy)I2] including the atom numbering scheme. All hydrogen atoms have been omitted for clarity.
The complex structure was described in detail. Five coordinate complexes with chelating ligands can exhibit either square pyramidal or trigonal bipyramidal geometries, and the particular case is influenced by both steric and electronic factors. The variation of five coordinate species between square pyramidal and trigonal bipyramidal is quantified using
The new [Cd(Cltpy)(I)2] complex reported herein takes on a slightly distorted square pyramidal structure as evidenced by the
This complex has some intermolecular interactions. Intermolecular interactions in crystal of [Cd(Cltpy)I2] complex are shown in Table
Intermolecular interactions in crystals of [Cd(Cltpy)I2] complex.
A | H | B | B-H |
---|---|---|---|
I2 | 2.937 | 3.620(2) | 166.16 |
I2 | 3.130 | 3.435(2) | 161.15 |
I2 | 3.163 | 3.308(2) | 135.50 |
C2(N1C1–C5) | 3.472(3) | ||
Centroid | 3.818(2) | ||
Centroid | 4.275(2) |
(a) The unit cell of [Cd(Cltpy)I2]. (b) Close-up view of the aromatic
The unit cell of complex is shown in Figure
The antibacterial activities of Cltpy and its Cd(II) complex are shown in Table
Antibacterial activities (zone of growth inhibition and minimal inhibitory concentrations) of Cltpy ligand and Cd (II) complex and gentamicin (as a standard compound).
Method | Main compounds | Microorganisms | |||||
Growth Inhibitory zone [mm] | Cltpy | 10 | 15 | 20 | 30 | 25 | 15 |
Complex | 10 | 20 | 20 | 10 | 12 | 10 | |
Standard | Gentamicin | 20 | 25 | 15 | 13 | 32 | 20 |
Minimum inhibitory concentration (mg/mL) (MIC) | L | 100 | 100 | 50 | 6.25 | 12.5 | 100 |
Complex | 100 | 50 | 50 | 100 | 100 | 100 | |
Against
New multidentate ligand, 4′-chloro-2,2′:6′,2′′-terpyridine (Cltpy), has been used for preparation of an inorganic complex. A new Cd(II) complex [Cd(Cltpy)I2] has been synthesized and characterized by CHN elemental analysis, 1H-NMR, 13C-NMR, and IR spectroscopy, and structurally analyzed by X-ray single-crystal diffraction. The single-crystal X-ray analyses show that the coordination number in this complex is five with three terpyridine (Cltpy) N-donor atoms and two iodine atoms. The antibacterial activities of Cltpy and its Cd(II) complex are tested against different bacteria. The complex has good activity against all tested bacteria. Against
CCDC reference number 799987 contains the additional crystallographic data for this paper. These data can be obtained free of charge at
This work was supported by the Payame Noor University, Khoy in Iran and Facultad de Quimica, Universidade de Vigo, Vigo Pontevedra in Spain.