Natural diatomite without purification except washing with distilled water was used. Diatomite samples were exposed to chemical analysis and characterized with different techniques as described elsewhere . It contains ~ 83.6% SiO2 and 4.24 Al2O3, 1.07 % Fe2O3, 6.17% CaO, and others oxides 4.86 % and it is free from TiO2, Na2O, K2O and MgO. Cu-MOF was prepared as described previously . Absolute ethanol and other chemicals were supplied from Sigma Aldrich without further purification.
Synthesis of Cu-MOF/Diatomite
1.0 g Cu-MOF which prepared previously  and 2.0 g diatomite were dissolved in 150 ml anhydrous ethanol separately to prepare solution A and solution B. After mixing the two solutions, the mixture was sonicated for 2 h and transferred to a flask equipped with condensed reflux at 100 °C for 12 h. The suspension was centrifugally washed three times with absolute ethanol and dried under vacuum at 70 °C overnight to obtain a Cu-MOF/Diatomite powder.
The Characterization Techniques
X-ray diffraction (XRD) analysis
X-ray diffraction (XRD) patterns were performed with power D8 ADVANCE diffractometer (Germany) using CuKa radiation (1.542°A, 40 KV, 40mA) in the 2Ө range of 4–80. The acquisition parameters were as: a step size of 0.02 and a step time of 0.4s.
Fourier transforms infrared (FTIR) spectroscopy
FTIR spectra of the samples were obtained using a KBr disk and FTIR 6500 spectrometer (JASCO, Japan) in the range of 400-4000cm-1
The thermal analysis
The thermal analysis (TGA, DTA) were performed by USA Berkin – Elmer thermogravimeter samples of approximately 10 mg was heated from 50oC to 800oC with heating rate 10/min under a nitrogen atmosphere, and the flow of nitrogen was 50 ml/min.
Transmission Electron Microscope (TEM)
To identify the morphology and the particle size of the prepared samples was examined by using a transmission electron microscope (TEM) quanta FEG working at 100 keV.
Antibacterial activity assays
Antimicrobial activity of selected compounds were evaluated against pathogenic Gram-positive bacteria (Bacillus subtilis ATCC6633 and Staphylococcus aureus ATCC29213), Gram-negative bacterium (Escherichia coli ATCC 25922 and Salmonella enterica ATCC 25566), yeast fungi (Candida albicans NRRL-Y477 and Candida tropicalis
ATCC750) and fungus (Aspergillus niger NRC53) by the agar diffusion technique.
Bacteria were obtained from the American Type Culture Collection and Northern Regional Research laboratories while the fungal isolates were obtained from the culture collection of the Department of Chemistry of Natural and Microbial Products, National Research Center, Cairo, Egypt. The microorganisms were passage at least twice to ensure purity and viability. The bacteria were maintained on nutrient agar medium and fungi were maintained on potato dextrose agar medium. About 50 mg of the prepared powder samples were applied on the inoculated agar plates and incubated for 24 h at 37 oC for bacteria and 72 h at 28 oC for fungi. The antimicrobial effect was evaluated by measuring the inhibition zone diameter around samples in (mm).