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Access Type

WSU Access

Date of Award

January 2018

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Jeremy Kodanko

Abstract

ABSTRACT

DESIGN OF RUTHENIUM(II) POLYPYRIDYL COMPLEXES FOR EFFECTIVELY CAGING NITRILES

AND AROMATIC HETEROCYCLES

by

AO LI

May 2018

Advisor: Dr. Jeremy Kodanko

Major: Chemistry

Degree: Doctor of Philosophy

Ru(II) polypyridyl complexes have been frequently employed in the caging and photorelease of biologically active compounds. Traditional photocaging groups derived from Ru(II) have been largely based on bi- or tridentate ancillary ligands, and those bearing ancillary ligands with high-denticities are yet to be developed. Exploring Ru(II) polypyridyl complexes possessing ancillary ligands with high-denticities provides insight into the photophysical and photochemical properties of ruthenium complexes, which creates novel prospects in the design of ruthenium complexes applicable towards photoactivated drug delivery and energy conversion.In this thesis, we present a series of Ru(II)-based photocages derived from tetradentate ancillary ligands TPA and cyTPA that have been developed as effective photocaging groups for nitriles and aromatic heterocycles. All complexes exhibit excellent stability in the dark and selectively release the caged nitriles and aromatic heterocycles upon irradiation with light. My findings contribute to showing that Ru(TPA) is appropriate as a photochemical agent to offer precise control over biological activity without undesired toxicity. In addition, the results in this thesis reveal a transtype effect that significantly promotes ligand photodissociation in Ru(II) polypyridyl complexes,where a complex presents a highly mixed 3MCLT/3pp* excited state as the lowest triplet state to achieve an efficient photoinduced ligand exchange. Such an unusual manner offers a clearer understanding of the mechanisms of ligand photodissociation, which can be used to design

ruthenium complexes for the applications that require efficient ligand dissociation, such as drug delivery. Furthermore, in order to control CYP activity and to achieve photoactivated CYP inhibition, a series of new Ru(II)-caged CYP inhibitors that effectively liberate CYP inhibitors upon irradiation with low-energy light are described in this thesis. The complexes show strong absorption in the visible range but remain stable in the dark. Photoreleased CYP inhibitors are demonstrated to be capable of undergoing a Type II binding to inactivate CYP activity, and the photo byproducts are non-toxic and well-tolerated by cells. Taken together, this thesis addressed the necessity of the development of Ru(II)-based photocaging groups with high-denticity ancillary ligands for caging nitriles and aromatic heterocycles, and the thesis also established the design and synthesis of Ru(II)-caged CYP inhibitors for controlling CYP activity spatiotemporally with lowenergy ight.

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