Synthesis Of Bis-Thiourea Derivatives And Studies On Its Application As Chemical Sensor

Three new bis-thiourea derivatives namely 1,2-bis(4-chlorobenzoylthiourea)-propane (S I), 1,4- bis(4-chlorobenzoylthiourea)-butane (S2) and 1,2-bis(4-chlorobenzoy1thiourea)-ethane (S3) were successfully synthesized by the reaction of the mixture of 4-chlorobenzoylchloride and ammonium thiocyanate with selected diamine compounds namely 1,2-diaminopropane, 1,4- diaminobutane and 1,2- diaminoethane. FTIR spectra of all the compounds show the presence of u (N-H), u (GO), u (C=S), u (C-N) stretching frequencies at 3173-3297 cm-', 1630-1672 cm", 843-846 cm-' and 1092-1094 cm-' respectively. Proton NMR spectra show the presence of three important chemical shifts in all the compounds : amino proton 6H (Nl) 11.33-1 1.38 ppm, 6H (N2) 10.77-10.86 ppm and 6H (aromatic proton) at 7.49-7.90 ppm. While "C NMR spetra show that the thiono, C=S and ketone, C=O chemical shifts at 180.06-1 81.18 ppm and 165.0- 167.29 ppm respectively. Solid-state ammonium ion sensors based on photocured poly(n-butyl acrylate) membrane with immobilized newly synthesized compounds were successfully used for the determination of ammonium ion. The sensor membrane does not require any plasticizer and the S1- and S2- based membrane electrodes gave near Nernstian responses (57.3 mV per decade and 50.6 mV per decade respectively) throughout the ammonium in concentration range of lo-' to loJ M with detection limits approaching 10" M ammonium ion. However, the S3- based electrode has a typical Nernstian response with a slope of of 35.6 mV per decade in the concentration range of 1 to 1 o-' M.