AUTHOR=Diez-Castellnou Marta , Salassa Giovanni , Mancin Fabrizio , Scrimin Paolo 

TITLE=The Zn(II)-1,4,7-Trimethyl-1,4,7-Triazacyclononane Complex: A Monometallic Catalyst Active in Two Protonation States

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00469

DOI=10.3389/fchem.2019.00469

ISSN=2296-2646

ABSTRACT=<p>In this paper, the unusual reactivity of the complex Zn(II)-1,4,7-trimethyl-1, 4,7-triazacyclononane (<bold>2</bold>) in the transesterification of the RNA-model substrate, <italic>HPNP</italic> (<bold>3</bold>), is reported. The dependence of the reactivity (k<sub>2</sub>) with pH does not follow the characteristic bell-shape profile typical of complexes with penta-coordinated metal centers. By the contrary, two reactive species, featuring different deprotonation states, are present, with the tri-aqua complex being more reactive than the mono-hydroxy-diaqua one. Apparently, such a difference arises from the total complex charge which plays an important role in the stability of the transition state/s of the reactions. Relevant insight on the reaction mechanism were hence obtained.</p>