Synthesis, characterization and DFT studies of novel –CH2– capped and non-capped salan complexes

Biomimetics for purple acid phosphatases: A historical perspective

Biomimetics hold potential for varied applications in biotechnology and medicine but have also attracted particular interest as benchmarks for the functional study of their more complex biological counterparts, e.g. metalloenzymes. While many of the synthetic systems adequately mimic some structural and functional aspects of their biological counterparts the catalytic efficiencies displayed are mostly far inferior due to the smaller size and the associated lower complexity. Nonetheless they play an important role in bioinorganic chemistry. Numerous examples of biologically inspired and informed artificial catalysts have been reported, designed to mimic a plethora of chemical transformations, and relevant examples are highlighted in reviews and scientific reports. Herein, we discuss biomimetics of the metallohydrolase purple acid phosphatase (PAP), examples of which have been used to showcase synergistic research advances for both the biological and synthetic systems. In particular, we focus on the seminal contribution of our colleague Prof. Ademir Neves, and his group, pioneers in the design and optimization of suitable ligands that mimic the active site of PAP.

Rigid, strained, and flexible: a DFT study of a backbone-affected monohydride formation of salen and salan complexes

The monohydride formation of some palladium(II)-sulfosalen and sulfosalan catalysts was studied by DFT methods. The coordination of the hydrogen molecule to the metal center and the following heterolytic dissociation of the coordinated hydrogen could occur in a two-step or a concerted process resulting in a monohydride complex and having a protonated dissociated phenolate arm. The effect of the backbone frame of the ligands (the molecular unit between two nitrogen atoms) strongly determines the energetics and the type of the hydride formation. Rigid, strained, and flexible molecular structures were studied covering a wide range of planar and spherical types of backbones. Besides the previously studied Direct 1 and Direct 2 mechanisms, three other mechanisms of direct monohydride formation were found. Known and fictive structures were studied to predict kinetically and thermodynamically preferred pathways as well as complexes for this type of reaction.

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