Provided herein is a method of synthesis of Au(III)-NHC complexes, a pharmaceutical composition comprises thereof. Also provided herein are the methods for the treatment and prevention of cancer/tumor in patients in need thereof by the administration of the Au(III)-NHC complexes. Also provided is method of detecting thiol in a biological system. The Au(III)-NHC complexes possess anticancer activity such as the induction of cell death, inhibition of cellular proliferation, inhibition of thioredoxin reductase activity, and inhibition of tumor growth in vivo.