Coordination Chemistry of a Controlled Burst of Zn2+ in Bulk Aqueous and Nanosized Water Droplets with a Zincon Chelator
journal contributionposted on 06.12.2019, 14:36 by Cheryle N. Beuning, Noah E. Barkley, Prem N. Basa, Shawn C. Burdette, Nancy E. Levinger, Debbie C. Crans
The light-induced photolysis of [Zn(NTAdeCage)]− generates a temporally controlled burst of Zn2+, which is rapidly chelated in situ by the free ligand Zincon2–. The [Zn(Zincon)]2– coordination progress is monitored using absorption spectroscopy in bulk aqueous buffer and reverse micelle environments. The [Zn(NTAdeCage)]− photocage and free ligand Zincon2– have different reverse micelle locations that affect the [Zn(Zincon)]2– formation at the nanoscale compared to the bulk aqueous buffer. The formation of [Zn(Zincon)]2– in a bulk aqueous buffer is more efficient despite the released Zn2+ and Zincon2– being physically closer within reverse micelles. The observed reduction of complex formation is attributed to the interfacial partitioning of Zincon2–, distinct from the Zn2+ photocage in the water pool, requiring diffusion for the species to meet to form [Zn(Zincon)]2–. This work introduces a proof-of-concept methodology to experimentally measure fast chelation reactions in confined spaces and thus provides an approach to exploring cellular responses.