Grafting of multiwalled carbon nanotubes with pyrazole derivatives: characterization, antimicrobial activity and molecular docking study

Figures & data

Scheme 1 Synthesis of 4-phenyldiazenyl-1H-pyrazole-3,5-diamine 1a-c.

Scheme 2 Synthesis of 5-amino-4-benzylidene-2,4-dihydro-3H-pyrazol-3-ones 2a-c.

Scheme 3 Grafting of 4-phenyldiazenyl-1H-pyrazole-3,5-diamine, 1(a-c), and 5-amino-4-benzylidene-2,4-dihydro-3H-pyrazol-3-one, 2(a-c), onto MWCNTs-COOH.

Table 1 Antimicrobial activity of the synthesized pyrazole, 1(a-c), and pyrazolone, 2(a-c) derivatives and grafted CNTs, CNTs-1(a-c) and CNTs-2(a-c).

Samples code	Gram positive bacteria		Gram negative bacteria	Fungi
	Staphylococcus aureus (SA)	Bacillus subtilis (BS)	Escherichia coli (EC)	Aspergillusniger (AS)	Candida albicans (CA)
1a	8	11	NA	NA	9
CNTs-1a	NA	NA	NA	NA	NA
1b	NA	NA	NA	NA	11
CNTs-1b	9	NA	19	NA	16
1c	14	8	NA	NA	11
CNTs-1c	23	9	18	NA	18
2a	11	8	NA	NA	12
CNTs-2a	12	8	13	6	12
2b	NA	10	8	NA	10
CNTs-2b	12	20	12	7	NA
2c	14	9	8	NA	NA
CNTs-2c	14	9	8	NA	NA
CNTs	NA	NA	NA	NA	NA
Trimethoprim/sulphamethoxazole	20	21	19	26	18
Chloramphenicol	30	24	29	29	25
DMSO	NA	NA	NA	NA	NA

Abbreviations: CNTs, carbon nanotubes; DMSO, dimethyl sulfoxide; NA, not detected.

Table 2 The results obtained from docking study of 1c, 2b, CNTs-1c and CNTs-2b using MOE 2009 software

Sample code	Docking energy kcal/mol	Amino acids residue involved in docking interaction	No of hydrogen bond	Length of hydrοgen bonds Å
1c	−9.0211	Thr181	2	3.52 Å H-acceptor
		Ser113		1.91 Å H-acceptor
2b	−6.5027	Thr181	1	2.15 Å H-acceptor
CNTs-1c	−32.2912	Tyr 218	3	2.54 Å H-acceptor
		Lys 214		2.47 Å H-acceptor
		Arg 74		1.84 Å H-acceptor
CNTs-2b	−25.3870	Lys 214	2	2.09 Å H-acceptor
		Gln 254		1.87 Å H-acceptor

Abbreviation: CNTs, carbon nanotubes.

Figure 1 FTIR spectra of CNTs and CNTs-1(a-c).

Abbreviations: CNTs, carbon nanotubes; FTIR, Fourier transform infrared spectroscopy.

Figure 2 FTIR spectra of CNTs and CNTs-2(a-c).

Abbreviations: CNTs, carbon nanotubes; FTIR, Fourier transform infrared spectroscopy.

Figure 3 (A) The selected region of scanning electron microscope (SEM) image of CNTs grafted with 5-amino-4-benzylidene-2,4-dihydro-3H-pyrazol-3-one (CNTs-2a); (B) the corresponding EDX spectrum of CNTs-2a.

Abbreviation: CNTs, carbon nanotubes.

Figure 4 TEM micrographs of (A) CNTs, (B) CNTs-1aand (C) CNTs-2a.

Abbreviations: CNTs, carbon nanotubes; TEM, transmission electron microscopy.

Figure 5 XRD patterns of CNTs and grafted CNTs with pyrazole derivatives, CNTs-1(a-c).

Abbreviations: CNTs, carbon nanotubes; XRD, X-ray diffractogram.

Figure 6 XRD patterns of CNTs and grafted CNTs with pyrazolone derivaties, CNTs-2(a-c).

Abbreviations: CNTs, carbon nanotubes; XRD, X-ray diffractogram.

Figure 7 TGA (A) and DTGA (B) curves of CNTs, CNTs(1a), CNTs(1b) and CNTs(1c).

Abbreviations: CNTs, carbon nanotubes; DTGA, derivative of thermogravematric analysis; TGA, thermogravematric analysis.

Figure 8 TGA (A) and DTGA (B) curves of CNTs, CNTs(2a), CNTs(2b) and CNTs(2c).

Abbreviations: CNTs, carbon nanotubes; DTGA, thermogravematric analysis; TGA, derivative of thermogravematric analysis. 

Figure 9 2D the active site of 1UBY.

Figure 10 2D Lignad interaction of neat CNTs with the active site of 1UBY.

Abbreviation: CNTs, carbon nanotubes.

Figure 11 2D Lignad interaction of 1c with the active site of 1UBY.

Figure 12 2D Lignad interaction of CNTs-1c with the active site of 1UBY.

Abbreviation: CNTs, carbon nanotubes.

Figure 13 2D Ligand interaction of 2b with the active site of 1UBY.