Our environment is becoming more polluted due to the commercial applications of toxic chemicals and heavy metal cations. So, for the sensing of heavy metal cations in aqueous solution N,N′-(cyclohexane-1,2-diyl)bis(2,5-dimethoxybenzenesulfonamide) CDBDMBS (3a) and N,N′-(1,2-phenylene)bis(2,5-dimethoxybenzenesulfonamide) PBDMBS (3b) were synthesized in this work. Spectroscopic techniques, such as UV/Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (¹H-NMR & ¹³C-NMR) spectroscopy, and single crystal X-ray diffraction studies, were carried out for their structure elucidation. After that, a simple, cheap and reliable electrochemical technique was carried out in order to check the affinity of our newly designed chelating agents towards various heavy metal cations (Ag⁺, As³⁺, Au³⁺, Ce²⁺, Cr³⁺, Ga³⁺, Hg²⁺, Pb²⁺ and Y³⁺) using a Keithley electrometer. For this purpose CDBDMBS and PBDMBS were fabricated with conducting Nafion binder on a glassy carbon electrode (GCE) for the development of sensitive and selective electrochemical sensors to probe the heavy metal cations in a phosphate buffer phase (pH = 7.0) in a short response time, qualitatively and quantitatively. It was found that CDBDMBS was very selective with good affinity for gallium cations after a comparative study between CDBDMBS/Nafion/GCE and PBDMBS/Nafion/GCE. Gallium is one of the various heavy metal cations in our ecosystem as an environmental pollutant. The analytical performance of CDBDMBS/Nafion/GCE was found to be very interesting in terms of sensitivity, stability, linear dynamic range and improved electrochemical performance towards Ga³⁺ ions. The calibration plot is linear (r² = 0.9006) over a large concentration range of Ga³⁺ ions (1.0 nM to 0.01 M) in addition to the sensitivity, limit of detection (at a SNR of 3) and limit of quantification that are found to be 3.955 × 10⁻³ μA μM⁻¹ cm⁻², 0.02 nM and 0.08 nM, respectively. This novel approach introduces a new and well organized system for the development of efficient sensors for toxic cationic electrochemicals in environmental and healthcare fields on a large scale. Therefore, this newly designed CDBDMBS/Nafion/GCE presents a cost effective compound that can be used as a feasible substitute for the detection and removal of Ga³⁺ions from water samples efficiently.