The present disclosure provides terminally activated monofunctional POZ derivatives having a range of functional active groups allowing conjugation of the monofunctional POZ derivatives to a variety of target molecules under a wide range of reaction conditions to produce a hydrolytically stable target molecule-POZ conjugate. Furthermore, the present disclosure provides novel methods of synthesis for the disclosed terminally activated monofunctional POZ derivatives and hydrolytically stable target molecule-POZ conjugates created using the disclosed terminally activated monofunctional POZ derivatives.