A new inorganic-organic hybrid compound, [{Cu(phen)2}2(H4W12O40)], was synthesized, and its crystal structure was determined. The Keggin anion H4W12O404− was grafted with two coordination units {Cu(phen)2}, forming an electrically neutral molecule. The antibacterial activity of several polyoxometalate compounds with different anionic structures including the new compound was studied. The results show that the compound
Polyoxometalates (POMs) have been shown to exhibit biological activities
This work is about the synthesis of a new polyoxometalate derivative, [Cu2(phen)4(H4W12O40)], and study on the antibacterial activity of several polyoxometalate compounds with different anionic structures including the new compound.
All reagents were purchased commercially and used without further purification. Elemental analyses (C, H, and N) were performed on a Perkin–Elmer 2400 CHN elemental analyzer and that of W and Cu on an ICP–AES analyzer. The IR spectrum was obtained on an Magna-560 FT/IR spectrometer with KBr pellets in the 400–4000 cm−1 region. TG analysis was carried out on a DTG-60H thermal analyzer in flowing N2 with a heating rate of 10°C·min−1. SEM images were recorded on Hitachi S-3400N (Hitachi High-Technologies Europe GmbH, Krefeld, Germany).
Synthesis of [Cu2(phen)4(H4W12O40)] was modified from our previous report [
Compounds
The X-ray diffraction data of compound
Crystal data and structure refinements for compound
Formula | C48H32Cu2N8O40W12 |
---|---|
Fw | 3710 |
Crystal system | Monoclinic |
Space group | P21/c |
|
26.1828(15) |
|
11.84219(7) |
|
23.3996(13) |
|
90.00 |
|
113.74(2) |
|
90.00 |
|
6641.2(7) |
|
4 |
|
3.711 |
F(000) | 6600 |
|
21.419 |
Rint | 0.0932 |
Refine number of reflns/parameters/restraints | 13661/991/54 |
R_factor_all/[ |
0.0871/0.0456 |
wR_factor_ref/[ |
0.0857/0.0745 |
Goodness of fit | 0.954 |
Cu-O and Cu-N bond lengths (Å) in
Bond | Length | Bond | Length |
---|---|---|---|
Cu1 N1 | 2.214(11) | Cu2 N5 | 1.960(12) |
Cu1 N2 | 1.990(10) | Cu2 N9 | 2.038(12) |
Cu1 N3 | 1.996(13) | Cu2 N7 | 1.965(12) |
Cu1 N4 | 1.991(11) | Cu2 N8 | 2.168(12) |
Cu1 O7 | 2.045(10) | Cu2 O38 | 2.217(8) |
All the isolated bacterial strains were achieved by colony formation on selective salt agar plates containing 6 mg/mL oxacillin. All bacterial strains were stored at −80°C and routinely grown at 37°C.
Antibacterial activities of compounds
Type | Code | Compound | Concentration | Bacterial strains |
---|---|---|---|---|
I | 1 | [{Cu(phen)2}2(H4W12O40)] | 1 mg/mL | FA2 |
2 | [Cu(phen)(H2O)(Mo3O10)] | 1 mg/mL | ABC3, FA2, FA3, YB57, USA300 | |
II | 3 | K5PW11TiO40·14H2O | 1 mg/mL | YB57, USA300 |
III | 4 | Na7CeW10O35·26H2O | 1 mg/mL | SA5, SA1, SP, USA300 |
IV | 5 | K13[La(SiW11O39)2]·26H2O | 1 mg/mL | YB57, USA300 |
6 | K13[Ce(SiW11O39)2]·26H2O | 1 mg/mL | SA5, SA1, SP, USA300 |
Scanning electron microscopy (SEM) was performed to assess the activity of different polyoxometalates on the bacterial strains
The asymmetric unit of compound
Ball-stick representation of the decorated Keggin anion in
Two Cu2+ ions are all five-coordinated. Cu1 ion displays in a square prism geometry, and the geometry of Cu2 ion is better to be described as triangle bipyramid. The donor atoms bonding to Cu ions come from two phen molecules with chelating coordination mode and the Keggin anion, forming a complex fragment {Cu(phen)2}2+ (Figure
The IR spectrum (Figure
The compounds
SEM technique was used to explore the interaction of polyoxometalates with the bacterial strains. SEM images (Figure
SEM images of
The bioactivity of polyoxometalates has been known for many years but still has large space to explore. The results of this work on the antibacterial activity of polyoxometalates including the new compound show that antibacterial activity of the compounds is more relative with their component element than with anionic structure, which means that exploration of antibacterial materials should focus on the choice of elements.
In this work, the compounds with Ce elements have better antibacterial activity. So, synthesizing compounds with other lanthanide elements and other compounds with cerium element and examining their antibacterial activity as well as exploring the reaction mechanism of Ce compounds need further investigations.
The data used to support the findings of this study are included within the article.
The authors declare no conflicts of interest.
Jingmin Gu and Lei Zhang contributed equally to this article.
This work was supported by the National Natural Science Foundation of China (No. 81501423) and Norman Bethune Program of Jilin University (No. 2015223). We also like to give our special thanks to Dr. Sadeeq ur Rahman from College of Veterinary Sciences & Animal Husbandry, Abdul Wali Khan University, Mardan, Pakistan, for generously providing
Figure S1: coordination geometries of Cu ions; Figure S2: stacking representation of