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ABSTRACT. The aim of the present work was to discover various synthetic route of biological active halogenated symmetric double Schiff bases of 1,1'-bis(4-aminophenyl)cyclohexane, their spectral and microbial study. Symmetric double Schiff base ligands of halogenated benzaldehyde and 1,1'-bis(4-aminophenyl)cyclohexane were synthesized by conventional and green chemistry approach. The purity of Schiff bases was checked by Thin Layer Chromatography (TLC). The structures of these ligands were elucidated by UV, FTIR, 1 HNMR and MS; and assayed for their antibacterial activity against Escherichia coli (E. coli), Bacillus megaterium (B.mega), Proteus vulgaris (P. vulgaris, Staphylococcus aureus (S. aureus) and Aspergillus niger (A. niger)The minimum inhibition concentrations (MIC) of the compounds were studied by cup plate method. Schiff bases revealed moderate antimicrobial activity and good antifungal activity against chosen standard drugs and microorganisms.

The density, viscosity and ultrasonic speed (2MHz) of chloroform and symmetric double Schiff bases have been investigated at 308.15K. Various acoustical parameters such as specific acoustical impedance (Z), adiabatic compressibility (Кa), Rao’s molarsound function (Rm), Vander Waals constant (b), internal pressure (π), free volume (Vf), intermolecular free path length (Lf), classical absorption coefficient (α/f2)Cl) and viscous relaxation time (τ) were determined using ultrasonic speed (U), viscosity (η) and density (ρ) data of Schiff bases solutions and correlated with concentration. Increasing linear or nonlinear trends of (Z, Rm, b, τ and (α/f2)Cl) and decreasing trend of Кa, Lf,, π and Vf with increasing concentration of Schiff bases suggested presence of strong molecular interactions in the solutions and solvophilic nature of the Schiff bases, which is further supported by the positive values of solvation number. The nature and position of substituent also affected the strength of molecular interactions.

The density, viscosity and ultrasonic speed (2MHz)

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ABSTRACT. Symmetric double Schiff bases of 1,1'-bis(4-amino phenyl)cyclohexane and substituted aromatic benzaldehydes were synthesized by thermal and microwave irradiated green chemistry techniques. The purity of Schiff bases was checked by TLC. The structure of Schiff bases were supported by UV, FTIR, 1 HNMR and MS techniques. The antibacterial and antifungal activities of Schiff bases were checked against gram positive and gram negative microbes. Schiff bases showed moderate antibacterial activity but they showed good comparable antifungal activity against chosen microbes and standard drugs.

Symmetric double Schiff bases of 1,1’- bis (4-amino phenyl) cyclohexane and substituted aromatic benzaldehydes were synthesized by thermal and microwave irradiated green chemistry techniques. The purity of Schiff bases was checked by TLC. The structure of Schiff bases were supported by UV, FTIR, 1HNMR and MS techniques. The antibacterial and antifungal activities of Schiff bases were checked against gram positive and gram negative microbes. Schiff bases showed moderate antibacterial activity but they showed good comparable antifungal activity against chosen microbes and standard drugs.

The density (ρ), viscosity (η) and ultrasonic speed (U) (2MHz) of THF solutions of symmetric double Schiff bases (SDSB-1,SDSB-2 and SDSB-3) were determined at 303.15, 308.15 and 313.15 K. Various acoustical parameters such as specific acoustical impedance (Z), isentropic compressibility ( s ), Rao's molar sound function (R m ), Van der Waals constant (b), internal pressure (π), free volume (V f ), intermolecular free path length (L f ), viscous relaxation time (τ) and classical absorption coefficient (α/f 2 ) Cl ), were determined using ρ, η and U data. The results are interpreted in terms of molecular interactions occurring in the solutions at different temperatures and concentrations. Linear increase of ρ, η U, Z, R m , b, (α/f 2 ) Cl and τ with increasing C, linear decrease of К S , L f and π with increasing T, V f increased linearly with C and T except SDSB-3 supported existence of strong molecular interactions in the solutions and confirming solvophilic nature of the Schiff bases. The structure, nature and size of the solutes and solvent, concentration and temperature affected molecular interactions.