The synthesis, sensor and biological properties of two novel rhodanine derivative molecules

Herein, two different rhodanine derivative molecules (E)-2-(5-(4-(((2,5-dichlorophenyl)sulfonyl)oxy)benzylidene)-4-oxo-2-thioxothiazolidin-3-yl)acetic acid (3) and (E)-2-(5-(4-(((4-bromophenyl)sulfonyl)oxy)benzylidene)-4-oxo-2-thioxothiazolidin-3-yl)acetic acid (4) have been synthesized for the first time. The characterization of these molecules was carried out using various spectroscopic techniques such as ¹H–, ¹³C– NMR, FT–IR and Q–TOF. Sensor properties of the newly synthesized rhodanine derivative molecules were investigated in detail using potentiometric methods. For this purpose, different polymer membrane sensors in which these two molecules were used as ionophores in the design were prepared. Potentiometric performance properties were compared among these prepared sensors, using mixtures in which the most ideal potentiometric behavior of both molecules was observed. Among the two sensors, Sensor IX exhibited much higher selectivity against Cu²⁺ ions compared to Sensor II. The sensors had linear and Nernstian responses in the concentration range of 1.0 × 10⁻¹–1.0 × 10⁻⁵ mol L⁻¹. The detection limits of the sensors prepared with ionophore 3 and 4 were found to be 9.77 × 10⁻⁶ mol L⁻¹ and 9.36 × 10⁻⁶ mol L⁻¹, respectively, indicating that both sensors have comparable limit of detection values. While the sensor prepared with 4 had a very fast response time of 5 s, the sensor prepared with 3 exhibited a response time of approximately 10 s. The sensors prepared with both molecules worked in a wide pH range (4.0–10.0) without being affected by pH changes. Both sensors were subsequently applied to various real samples, and very high recoveries were obtained. Based on these data, it can be stated that the newly synthesized rhodanine derivatives can be used as ionophores. However, there are particular differences in terms of selectivity and other potentiometric performance criteria between the two synthesized molecules. Lastly, the anti-microbial effects of these new molecules on six different bacteria were studied, and it was determined that the synthesized molecules inhibit the growth of some bacterial species to a certain extent.