The electron transport properties of an electrostatic gated single molecular transistor are investigated by using self-consistent semi-empirical method. The charge transport characteristics of the molecular device are analysed through the current-voltage I _SD−V _SD characteristics transmission characteristics T (E), and molecular projected self-consistent Hamiltonian states analysis. It is revealed that the gate bias V _G can effectively tune the transport properties to greater extent. The mechanisms governing the gate bias tuned transport properties in this device were discussed. The proposed device also exhibits gate modulated negative differential resistance feature, which is exploited in realising basic logic gates. Thus, by using source-drain resistance R as a function of V _G, the application of using gated thiophene based molecular device to realise a set of five basic logic gates at particular V _SD is shown. The significant feature of the proposed device is the possibility of realising different logic gates with just one molecular transistor using computationally inexpensive semi-empirical method.