Herein, we report the synthesis of two enantiomeric DOTAZA esters and a related DOT3AZA ester. These compounds are tunable analogues of the well-known chelator DOTA and can be easily functionalized through click chemistry of the side-chain azide groups. Like DOTA, DOTAZA forms complexes with various di- and trivalent metals, as demonstrated in the synthesis and structural analysis of CuDOTAZA and the preparation of GdDOTAZA.

Herein, we present the synthesis and structural analysis of metal complexes of enantiomerically pure 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraazidoethylacetic acid (DOTAZA). DOTAZA is a new tunable analog of DOTA, a clinically approved chelator for various pharmaceutically relevant metal ions. In this work, we investigate the complexation chemistry of DOTAZA and report the crystal structures of a number of complexes with pharmaceutically relevant metal ions such as Gd3+ [magnetic resonance imaging (MRI)], Eu3+ (luminescence spectroscopy), Y3+ [positron emission tomography (PET)], In3+ [single‐photon‐emission computed tomography (SPECT)], and Na+. These structures provide useful information for imaging applications and demonstrate the potential of DOTAZA to form stable complexes. Owing to its clickable azide functionalities, it may be used for the development of tailored imaging reagents that retain the positive complexation chemistry of the parent compound DOTA.

Organic acids, typically derived from an oil-based value chain, are frequently used as corrosion inhibitors in industrial metal working fluids. The criteria for selection of these corrosion inhibitors have changed in the last decades, and are today not only performance-driven, but influenced by ecological considerations, toxicity and regulatory standards. We present scalable semisynthetic approaches to organic corrosion inhibitors based on phosphonic acids from renewable resources. They have been evaluated by chip filter assay, potentiodynamic polarization measurements, electrochemical impedance measurements and gravimetry for corrosion protection of iron and steel in an aqueous environment at slightly alkaline pH. The efficacy of several phosphonic acids tested was found to be strongly dependent on structural features influencing molecular self-assembly of protective layers, and the solubility of salts formed with di- and trivalent cations from the media or formed during corrosion. A carboxyphosphonic acid (derived from castor oil) was found to have remarkable anticorrosive effects in all media tested. We attribute the anticorrosion properties of this carboxyphosphonic acid to the formation of particularly stable protective layers on the metal surface. It might thus serve as a commercially attractive substitute for current acidic corrosion inhibitors, derived from renewable resources.

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Amino alcohols, typically derived from an oil-based value chain, are frequently used as alkaline additives for neutralization of acidic corrosion inhibitors in industrial metal working fluids. The criterions for selection of these additives have changed in the last decades and are nowadays not only performance driven, but influenced by ecological considerations, toxicity and regulatory standards. We present amino acids as functional, nontoxic, non-hazardous, non-volatile, chemically stable and cheap alkaline additives for common acidic corrosion inhibitors. The resulting mixtures have been evaluated for Co, Ni and Cu-leaching and were analyzed by chip-filter assay, potentiodynamic polarization measurements, electrochemical impedance measurements and gravimetry for corrosion protection of iron and steel in aqueous environment at slightly alkaline pH. Of several amino acids tested, Glu and Tau were found to synergistically interact with several acidic corrosion inhibitors of the carboxylic acid and the phosphonic acid type. Glu had a particularly positive impact on the protective properties of phosphonic acids with low hard water compatibility and served as an antiscalant. Tau had also a positive effect on the anticorrosive properties of several acidic corrosion inhibitors and lead to low levels of Co and Ni-leaching. Glu and Tau might thus serve as commercially and ecologically attractive substitutes for current alkaline additives to acidic corrosion inhibitors.