www.scholarsresearchlibrary.com t Available online a Scholars Research Library Archives of Applied Science Research, 2015, 7 (1):10-14 (http://scholarsresearchlibrary.com/archive.html) ISSN 0975-508X CODEN (USA) AASRC9 10 Scholars Research Library Density, viscosity and ultrasonic speed of halogenated symmetric double Schiff bases in DMF solutions at 308.15K B. J. Gangani and P. H. Parsania* Department of Chemistry, Saurashtra University, Rajkot, Gujarat, India _____________________________________________________________________________________________ ABSTRACT The density ( ), viscosity ( ) and ultrasonic speed (U) (2MHz) of DMF solutions of halogenated symmetric double Schiff bases were determined at 308.15K. Various acoustical parameters such as specific acoustical impedance (Z), adiabatic compressibility (К a ), Rao’s molar sound function (R m ), Vander Waals constant (b), internal pressure ( ), free volume (V f ), intermolecular free path length (L f ), classical absorption coefficient ( /f 2 ) Cl ), and viscous relaxation time ( )were determined using , and U data. Linear increase of U, Z, R, b, V f , ( /f 2 ) Cl and , and linear decrease of К a , L f and with increasing concentration of Schiff bases supported solvophilic nature of the Schiff bases and further supplemented by solvation number. The position and nature of substituent also affected molecular interactions. Keywords: Halogenated Schiff bases, ultrasonic speed, density, viscosity, acoustical parameters, molecular interactions _____________________________________________________________________________________________ INTRODUCTION Schiff bases are widely used as analytical reagents, fine chemicals, medical substrates and ligands for metal complexes [1]. Schiff bases are well known due to their impressive applications such as the preparation of dyes, liquid crystals, and powerful corrosion inhibitors [2]. Symmetric double Schiff bases are also used as starting materials of drugs in pharmaceutical industries due to their antitumor, anticancer, anti-inflammatory and antibacterial activities [3]. Ultrasonic technique has become a powerful tool for studying pharmacokinetics of drug and their molecular behavior in the solutions [4]. This is because of its ability of characterizing physico-chemical behavior of liquid solution. The study of properties of pure solvents and their solutions find direct applications in chemical, pharmaceutical, polymer and bio-chemical industries [5-6]. Therefore by measuring density of liquids and their ultrasonic speed many acoustical parameters can be determined [7, 8]. Ultrasonic speed and related thermodynamic parameters useful for characterizing thermodynamic and physico-chemical aspects of binary liquid mixtures such as molecular association or dissociation due to various forces [9]. Density, viscosity and ultrasonic speed, data provide umpteen’s information about the molecular interaction between ions, dipoles, hydrogen bonding, Vanderwaals forces as well as multipolar and dispersive forces [10]. The ultrasonic speed in a solution is fundamentally related to the binding forces between the atoms or molecules and has been successfully employed in understanding the nature of molecular interactions in pure solvents and their solutions. The change in ultrasonic speed and related parameters enlighten the structural changes associated with the liquid mixtures having strongly interacting components as well as weakly interacting components [11]. Molecular interaction studies can be carried out by both spectroscopic and non-spectroscopic techniques [12]. The physical and chemical properties of polymers in solutions was studied by number of researchers [13,14] and they correlated the