2. EXPERIMENTAL Synthesis of 1-(2-(2,4,5-triphenyl-1H-imidazol-1-yl) ethyl)piperazines (84-98)

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1 29 2. EXPERIMENTAL 2.1. PREPARATION OF THE CATALYST Sulphated yttria (SO4 2- /Y2O3) was prepared by sol-gel method using the known procedure. 147 The catalyst with 5 wt% of SO4 2 loaded yttrium oxide (Y2O3) was prepared by the sol-gel method. To the dispersion of 2.7 g of Y2O3 in 100 ml ethanol, 3.2 ml of 1 M H2SO4 was added drop wise with vigorous stirring. The resulting colloidal suspension was stirred for 4 h. The gel obtained was filtered, washed and dried in an air oven at 100 C for 12 h. The addition of BaCl2 to the filtrate gave no precipitate which indicates that all the sulphate ions were completely loaded on the gel. This catalyst contained 5 wt% of SO4 2- /Y2O PREPARATION OF COMPOUNDS Synthesis of 1-(2-(2,4,5-triphenyl-1H-imidazol-1-yl) ethyl)piperazines (84-98) In a 50 ml round bottom flask, benzil (1 mmol), aromatic aldehyde (1 mmol), aminoethylpiperazine (1 mmol) and ammonium acetate (2 mmol) were introduced in the presence of sulphated yttria (50 mg) in ethanol (20 ml). Then the reaction mixture was stirred at 80 C for the stipulated period of time. The progress of the reaction was monitored by TLC. After completion of the reaction, volume of the reaction mixture was reduced, diluted with cold water and extracted with ethyl acetate. The organic layer obtained was dried over anhydrous Na2SO4 and then solvent was removed under reduced pressure. The crude products, thus obtained were subjected to purification by column chromatography using silica gel ( mesh size) and 20% methanol in ethyl acetate as eluent to yield 1-(2- (2,4,5-triphenyl-1H-imidazol-1-yl) ethyl)piperazines (84-98).

2 30 The above general method was adopted for the synthesis of the following compounds. 1-(2-(2,4,5-triphenyl-1H-imidazol-1-yl)ethyl)piperazine (84) 1-(2-(4,5-diphenyl-2-(p-tolyl)-1H-imidazol-1-yl)ethyl)piperazine (85) 1-(2-(2-(4-bromophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (86) 1-(2-(2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (87) 1-(2-(2-(4-fluorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (88) 1-(2-(2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (89) 1-(2-(2-(4-methoxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (90) 4-(4,5-diphenyl-1-(2-(piperazin-1-yl)ethyl)-1H-imidazol-2-yl)-N,N-dimethylaniline (91) 1-(2-(2-(3-fluorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (92) 1-(2-(2-(3-bromo-4-fluorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (93) 2-bromo-4-(4,5-diphenyl-1-(2-(piperazin-1-yl)ethyl)-1H-imidazol-2-yl)phenol (94) 1-(2-(2-(3,4-dichlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (95) 1-(2-(2-(2,3-dichlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (96) 1-(2-(2-(3,5-dimethoxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)ethyl)piperazine (97) 1-(2-(4,5-diphenyl-2-(3,4,5-trimethoxyphenyl)-1H-imidazol-1-yl)ethyl)piperazine (98) Synthesis of 1-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1- yl)ethyl)piperazines (99-111) In a 50 ml round bottom flask, butane-2,3-dione (1 mmol), aromatic aldehyde (1 mmol), aminoethylpiperazine (1 mmol) and ammonium acetate (2 mmol) were introduced in the presence of sulphated yttria (50 mg) in ethanol (20 ml). Then the reaction mixture was stirred at 80 C for the stipulated period of time. The progress of the reaction was monitored by TLC. After completion of the reaction, volume of the reaction mixture was reduced, diluted with cold water and extracted with ethyl acetate. Organic layer was dried over anhydrous Na2SO4 and then solvent was removed under reduced pressure. The crude products, thus obtained were subjected to purification by column chromatography using silica gel

3 31 ( mesh size) and 20% methanol in ethyl acetate as eluent to yield 1-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)ethyl)piperazine derivatives (99-111). The above general method was adopted for the synthesis of the following compounds. 1-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)ethyl)piperazine (99) 1-(2-(4,5-dimethyl-2-(p-tolyl)-1H-imidazol-1-yl)ethyl)piperazine (100) 4-(4,5-dimethyl-1-(2-(piperazin-1-yl)ethyl)-1H-imidazol-2-yl)-N,N-dimethylaniline 101) 1-(2-(2-(4-fluorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine (102) 1-(2-(2-(4-chlorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine (103) 1-(2-(2-(2,4-dichlorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine (104) 1-(2-(4,5-dimethyl-2-(4-nitrophenyl)-1H-imidazol-1-yl)ethyl)piperazine (105) 1-(2-(2-(3-bromo-4-fluorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine(106) 2-bromo-4-(4,5-dimethyl-1-(2-(piperazin-1-yl)ethyl)-1H-imidazol-2-yl)phenol (107) 1-(2-(2-(3,4-dimethoxyphenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine (108) 1-(2-(4,5-dimethyl-2-(3,4,5-trimethoxyphenyl)-1H-imidazol-1-yl)ethyl)piperazine (109) 1-(2-(2-(benzo[d][1,3]dioxol-5-yl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)piperazine (110) 1-(2-(4,5-dimethyl-2-(thiophen-2-yl)-1H-imidazol-1-yl)ethyl)piperazine (111) Synthesis of 4-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl) ethyl)morpholines ( ) In a 50 ml round bottom flask, butane-2,3-dione (1 mmol), aromatic aldehyde (1 mmol), 2-morpholinoethanamine (1 mmol) and ammonium acetate (2 mmol) were introduced in the presence of sulphated yttria (50 mg) in ethanol (20 ml). Then the reaction mixture was stirred at 80 C for the stipulated period of time. The progress of the reaction was monitored by TLC. After completion of the reaction, volume of the reaction mixture was reduced, diluted with cold water and extracted with ethyl acetate. The organic layer obtained was dried over anhydrous Na2SO4 and then solvent was removed under reduced pressure. The crude products, thus

4 32 obtained were subjected to purification by column chromatography using silica gel ( mesh size) and 20% ethyl acetate in hexane as eluent to yield 4-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1- yl)ethyl)morpholines ( ). The above general method was adopted for the synthesis of the following compounds. 4-(2-(4,5-dimethyl-2-phenyl-1H-imidazol-1-yl)ethyl)morpholine (112) 4-(2-(4,5-dimethyl-2-(p-tolyl)-1H-imidazol-1-yl)ethyl)morpholine (113) 4-(2-(2-(4-bromophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (114) 4-(2-(2-(4-chlorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (115) 4-(2-(2-(4-fluorophenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (116) 4-(2-(2-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (117) 4-(4,5-dimethyl-1-(2-morpholinoethyl)-1H-imidazol-2-yl)-N,N-dimethylaniline (118) 2-bromo-4-(4,5-dimethyl-1-(2-morpholinoethyl)-1H-imidazol-2-yl)phenol (119) 4-(2-(2-(3,4-dimethoxyphenyl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (120) 4-(2-(4,5-dimethyl-2-(3,4,5-trimethoxyphenyl)-1H-imidazol-1-yl)ethyl)morpholine (121) 4-(2-(2-(benzo[d][1,3]dioxol-5-yl)-4,5-dimethyl-1H-imidazol-1-yl)ethyl)morpholine (122) 4-(2-(4,5-dimethyl-2-(thiophen-2-yl)-1H-imidazol-1-yl)ethyl)morpholine (123) Synthesis of 4-((2,4,5-triphenyl-1H-imidazol-1-yl) methyl)pyridines ( ) In a 50 ml round bottom flask, benzil (1 mmol), aromatic aldehyde (1 mmol), pyridin-4-yl methanamine (1 mmol) and ammonium acetate (2 mmol) were introduced in the presence of sulphated yttria (50 mg) in ethanol (20 ml). Then the reaction mixture was stirred at 80 C for the stipulated period of time. The progress of the reaction was monitored by TLC. After completion of the reaction, volume of the reaction mixture was reduced, diluted with cold water and extracted with ethyl acetate. Organic layer obtained was dried over anhydrous Na2SO4 and then solvent was

5 33 removed under reduced pressure. The crude products, thus obtained were subjected to purification by column chromatography using silica gel ( mesh size) and 20% ethyl acetate in hexane as eluent to yield 4-((2,4,5-triphenyl-1H-imidazol-1-yl)methyl) pyridines ( ). The above general method was adopted for the synthesis of the following compounds. 4-((2,4,5-triphenyl-1H-imidazol-1-yl)methyl)pyridine (124) 4-((2-(4-fluorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)pyridine (125) 4-((2-(4-chlorophenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)pyridine (126) 4-((4,5-diphenyl-2-(p-tolyl)-1H-imidazol-1-yl)methyl)pyridine (127) 4-((2-(4-methoxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)pyridine (128) 4-(4,5-diphenyl-1-(pyridin-4-ylmethyl)-1H-imidazol-2-yl)-N,N-dimethylaniline (129) 4-((2-(3,5-dimethoxyphenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)pyridine (130 4-((2-(benzo[d][1,3]dioxol-5-yl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)pyridine (131) 2.3. SPECTRAL MEASUREMENTS The 1 H and 13 C NMR spectra of the synthesized compounds in CDCl3 were recorded on a Bruker Avance 400 or 500 MHz NMR spectrometer. The 1 H and 13 C NMR were recorded to TMS as an internal standard and the central line of CDCl3. IR spectra were recorded by using a JASCO FT/IR-5300 spectrometer. High-resolution mass spectra (HRMS) were recorded using electro spray ionization on a Bruker Maxis machine. LC-Mass spectra were recorded on a VG7070H Mass spectrometer using EI technique, or a Shimadzu-LCMS-2010A mass spectrometer instrument. Samples were prepared by dissolving about 1 mg of compound in 2 ml of spectral grade methanol. Column chromatography was performed on silica gel ( mesh).

6 SINGLE CRYSTAL XRD STUDIES Suitable crystals of the reported compounds were grown by slow evaporation technique using methanol as solvent. Diffraction data were collected on a Bruker, 2004 APEX 2 diffractometer using graphite-monochromated MoKα radiation (K = Å) at 293 K. The structure was solved by direct methods and successive Fourier difference syntheses (SHELXS-97) 148 and refined by a full matrix least square procedure on F 2 with anisotropic thermal parameters. All non-hydrogen atoms were refined (SHELXL-97) 149 and placed in chemically acceptable positions POWDER X-RAY DIFFRACTION Powder X-Ray diffraction (XRD) patterns of catalysts were obtained using a model D/Max 2550 V with Cu anticathode radiation. The diffractograms were recorded in 2θ range between 10 and 80 in steps of 0.02 with count time of 20 s at each point. Average crystallite size was determined according to the Debye- Scherrer equation. D = K / cos Where D is the crystal size of the catalyst, is the X-ray wavelength (0.154 nm), is the full width half maximum (FWHM) of the peak, K = 0.89 and θ is the diffraction angle SCANNING ELECTRON MICROSCOPY The morphology of the catalyst was examined using Model ULTRA-55 scanning electron microscope (FE-SEM). Samples were mounted on a gold platform placed in the scanning electron microscope for taking images at various magnifications.

7 TRANSMISSION ELECTRON MICROSCOPY A small quantity of catalyst suspension was dropped onto copper grids with holey carbon film. The grids were dried under natural conditions and examined. TEM images were taken using the 200 kv Ultra High Resolution Transmission Electron Microscope JEOL-2010, having high resolution Optical microscope, Leica microscope THEORETICAL STUDIES The theoretical calculations were performed at DFT level on Pentium IV/3.02 personal computer using Gaussian 03W 150 program package, invoking gradient geometry optimization. The molecular geometry of the compounds were optimized by using the DFT method with a hybrid functional B3LYP [Becke s-three hybrid exchange (B3) and Lee-Yang-Parr (LYP) correlation functional] and the 6-31G(d,p) basis set. All the calculations were performed with Gaussian 03W package of programs. The optimized structure, bond parameters, nonlinear optics (NLO), natural bond orbital (NBO), HOMO LUMO and molecular electrostatic potential (MEP) calculations were done at the same level of theory and plotted using Gauss view 05 program ANTIMICROBIAL STUDIES 151, Antibacterial studies The following Gram positive and Gram negative bacterial strains have been used for the study 1) Staphylococcus aureus (Gram positive) 2) Escherichia Coli (Gram negative) 3) Pseudomonas aeruginosa (Gram negative) 4) Salmonella typhi (Gram negative) 5) Bacillus subtilis (Gram positive)

8 36 Preparation of the test inoculum: a) Sub-culture (Preparation of seeded broth) The strains Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Bacillus subtilis were inoculated in conical flasks containing 100 ml of sterile nutrient broth. These conical flasks were incubated 37 ± 2 C for 24 h. This was used as seeded broth. b) Incubation of nutrient agar petridishes The dilutions were studied by inoculating 0.2 ml of each dilution on to the solidified nutrient agar medium by spread plate method after incubation at 37 ± 2 C for 24 h. The numbers of wellformed colonies on the plates were counted. The seeded broth was then suitably diluted to have microorganisms per milliliter or cfu/ml. This was designated as the working stock and used for the antibacterial studies. Preparation of solutions of test compounds The solutions of test compounds were prepared by dissolving the same in dimethyl sulfoxide (DMSO) in a specific gravity bottle and stored in refrigerator. The solution was removed from the refrigerator 1h prior to use. The test compounds were prepared at a concentration of 200 µg/ml. Similarly, the standard solutions of Ciprofloxacin and Amphotericin B were used respectively at a concentration of 200 µg/ml for finding the minimum inhibitory concentration. Preparation of culture media The following media were used for the bacterial growth. a) Nutrient agar medium b) Nutrient broth medium

9 37 The media were sterilized by autoclaving at a pressure of 15 lb/sq at 121 C for 20 min. a) Nutrient agar medium (Hi-media) The nutrient agar medium was prepared by dissolving 28 g of nutrient agar (procured from Hi-media, Mumbai) in 1000 ml of distilled water. Formula Peptone : 1% ; Sodium chloride : 0.5% Beef extract : 1% Agar : 2% p H : 7.4 ± 0.2 b) Nutrient broth medium (Hi-media) The nutrient broth medium was prepared by dissolving 13 g of nutrient broth (Procured Hi-media, Mumbai) in 1000 ml of distilled water. Formula Peptone : 1% Sodium chloride : 0.5% Beef extract : 1% p H : 7.4 ± 0.2 Determination of antibacterial activity by Disc Diffusion Method Nutrient agar plates were prepared under sterile condition and incubated overnight to detect contamination. About 0.2 ml of working stock culture was transferred into separate nutrient agar

10 38 plates and spreaded thoroughly using a glass spreader. Whatmann No.1 discs (6 mm in diameter) were impregnated with the test compounds dissolved in DMSO (200 µg/ml) for about half an hour. Commercially available drug disc (Ciprofloxacin 10 µg/disc) was used as positive reference standard. Negative controls were also prepared by impregnating the disc of same size on the inoculated agar plates and incubated at 37 ± 2 C for about h. Antibacterial activity was evaluated by measuring the zone of inhibition against the test organism Antifungal studies The following fungal strains were used for the study 1. Candida albicans 2. Rhizopus sp. 3. Aspergillus niger 4. Aspergillus flavus 5. Penicillium chrysogenum Preparation of culture media Sabouraud s dextrose agar (SDA) medium was used for the growth of fungi and testing was done in Sabourauds dextrose broth (SDB) medium. The sub-culture and the viable count were carried out by the same procedure used for antibacterial studies except the temperature, which should be maintained at 28 ± 2 C for about 72 h. Similarly for disc diffusion method, the petri dishes were incubated at 28 ± 2 C for about 72 h. The same concentration of the test compound, solvent and Amphotericin B (standard) prepared previously were used for the antifungal studies.