A Single‐Pot Template Reaction Towards a Manganese‐Based T 1 Contrast Agent

Manganese‐based contrast agents (MnCAs) have emerged as suitable alternatives to gadolinium‐based contrast agents (GdCAs). However, due to their kinetic lability and laborious synthetic procedures, only a few MnCAs have found clinical MRI application. In this work, we have employed a highly innovative single‐pot template synthetic strategy to develop a MnCA, MnL Me , and studied the most important physicochemical properties in vitro. MnL Me displays optimized r 1 relaxivities at both medium (20 and 64 MHz) and high magnetic fields (300 and 400 MHz) and an enhanced r 1 b =21.1 mM −1  s −1 (20 MHz, 298 K, pH 7.4) upon binding to BSA ( K a =4.2×10 3  M −1 ). In vivo studies show that MnL Me is cleared intact into the bladder through renal excretion and has a prolonged blood half‐life compared to the commercial GdCA Magnevist. MnL Me shows great promise as a novel MRI contrast agent.