Various substituted 3-{6-fluoro-7-(substituted)-1,3-benzothiazol-2-yl-1 -[(4-acetyl-5-methyl-5-phenyl-4,5-dihydro-1,3,4-oxadiazol-2-yl)methyl]-2 -thioxo-2,3-dihydroquinazoline-4 (1H) -one and 3-{(6-fluoro -7- (substituted) - 1,3 -benzothiazol-2-yl-1-({4-acetyl-5-[4-(dimethylamino)phenyl]-4,5-dihydro -1,3,4-oxadiazol-2-yl}methyl) -2- thioxo -2,3- dihydroquinazolin -4 (1H)-one. containing different functional groups have been synthesized by condensing anthranilic acids with substituted 2-aminobenzothiazoles in dry pyridine and then by condensing with ethylchloroacetate in presence of dry acetone and K₂CO₃. The identity of compounds were confirmed on the basis of their spectral (UV, IR, ¹H NMR and MASS) data. Further, they have been screened for their antimicrobial activities.
 

 Mixed ligand complexes of VO(IV) and ZrO(IV) with pyrrole-2- carboxaldehyde thiosemicarbazone (PCTS) as primary and salicylaldehyde as secondary ligand have been synthesized and characterized on the basis of analytical, magnetic and spectral studies. Analytical data proposed l:l:l (M-L-L') stoichiometric composition for the synthesized complexes [where M= VO(IV)/ ZrO(IV), L=PCTS and L'H= salicylaldehyde]. Electronic spectra of VO(IV) complexes suggested distorted octahedral geometry for them. IR spectra of the ligands and complexes showed bidentate nature of the ligands. The complexes are non -electrolytes. ZrO(IV) complexes possess hepta coordinated structure.

Complexes of the type,R₃SnCl.L(where R= -C₆H₅ and L= Et₂NH, Pr₂NH and Bz₂NH) were obtained. Complexes of the type, R₂SnCl₂.2L (where R=-CH₃ and L=Et₂NH, Pr₂NH, Bz₂NH and (CH₂CH₂OH)₂NH; R=-C₄H₉ and L= Et₂NH and Pr₂NH and where R= C₆H₅ and L= Bz₂NH) were formed. Complexes of the type, R₂SnCl₂.L(where R= -C₆H₅ and L= Et₂NH and Pr₂NH; and where R= -CH₃ and L= MePhNH) were also formed. Complexes of the type, ROSnCl₃.2L (where R=-CH₃, -C₂H₅ and t- C₄H₉ and L= Et₂NH, Pr₂NH and Bz₂NH; and also where R= -CH₃ and -C₂H₅ with (CH₂CH₂OH)₂NH and MePhNH) were prepared. Complex of the type, ROSnCl₃.L (where R= t-C₄H₉ and L= MePhNH) was also isolated. Infrared spectral studies were carried out.

Various acoustic parameters like isentropic compressibility (bs) intermolecular free length (L_f) apparent molar volume (f), apparent molar compressibility (f_k), molar compressibility (w), molar sound velocity (R), acoustic impedance (z) of KCl in 10%, 20%, 30% and dioxan+water at 303.15K have been determined from ultrasonic velocity (V), density (r) and relative viscosity (hr) of the solution. These parameters are related with the molar concentration of the solution and reflects the distortion of the structure of the solvent (i.e. dioxan + water) when the solute is added to it.

Various acoustic parameters like isentropic compressibility (bs) intermolecular free length (L_f) apparent molar volume (f), apparent molar compressibility (f_k), molar compressibility (w), molar sound velocity (R), acoustic impedance (z) of KCl in 10%, 20%, 30% and dioxan+water at 303.15K have been determined from ultrasonic velocity (V), density (r) and relative viscosity (hr) of the solution. These parameters are related with the molar concentration of the solution and reflects the distortion of the structure of the solvent (i.e. dioxan + water) when the solute is added to it.

The thermodynamic parameters and excess molar volumes have been calculated from the experimental value of densities and viscosities of binary mixtures of propyl acetate with pentan-1-ol at ( 298.15, 303.15, 308.15 and 313.15 ) K. All the mixtures exhibited endothermic enthalpies which decreased with increasing concentration of propyl acetate . The variations of the excess molar volumes and thermodynamic properties of these mixtures with concentration of propyl acetate and alkan-1-ol, These effects have been interpreted on the basis of molecular interactions. The excess molar volumes are fitted to Redlich - Kister equation. excess properties considered, and yielded acceptable results.
 

Complexes of the type, R₂SnCl₂.2L (where R= -CH₃ and L=n-Butylamine or monoethanolamine), R₂SnCl₂.L (where R= -C₄H₉ or -C₆H₅ and L=n-Butylamine), ROSnCl₃.2L (where R= -CH₃ or -C₂H₅ and L=n-Butylamine or monoethanolamine) and ROSnCl₃.L (where R= t-Butyl and L=n-Butylamine) and ROSnCl₃.2L (where R= t-Butyl and L=monoethanolamine) have been prepared. Infrared spectral studies have been carried out to suggest possible structures of the complexes.

The Kinetics of the oxidation of acetophenoneoxime by pyridinium fluorochromate has been studied in acetic acid medium. The reaction has unit dependence on each of the PFC [H⁺] and first order with respect to substrate. The effect of temperature, solvent and neutral salt has been studied. The rate increases with increase in concentration of hydrogen ions, the activation energy and other thermodynamic parameters are determined and a possible mechanism has been proposed.
 

Reaction of Amoxicillin & Alanine with certain biologically active metal ions, in binary & ternary systems have been traced conductometrically & spectrophotometrically. Formation of M : Ala : Amox, 1:1 & l:2 complexes and M : Ala : Amp. l:1:1 complex is indicated, structures of the isolated mixed complexes with the metal : Alanine : Amoxicillin in l:l:l molar ratio have been ascertained on the basis of analytical data and physico-chemical properties. The results of the study appear to support the hypothesis that formation of metal bridged drug­receptor complex is formed during antihiotic activity of the drug.