Chemistry and Chemical Biology ETDs

Publication Date

Fall 12-15-2017

Abstract

A series of square-planar metal (diimine)(dichalcogenolene) chromophoric complexes have been synthesized, characterized and studied spectroscopically. Studies conducted on diimineplatinum(II) dichalcogenolene complexes (LPtL’) using time resolved spectroscopic techniques such as transient absorption and emission, reveal a charge-separated excited state of the type dichalcogenolene → diimine charge-transfer (LL’CT) [(dichalcogenolene•+)Pt(diimine•-) with an open shell donor-acceptor biradical character. Long-live excited state lifetimes were observed for these complexes upon visible photoexcitation of the LL’CT or MMLL’CT band. A direct linear relationship is observed to exist between photoluminescence rates, calculated SOC matrix elements, and 13C-NMR chemical shifts.

A series of M(diimine)(dichalcogenolene) complexes were tested against the electric field of widely used organic solvents such as acetone, acetonitrile, dimethylsulfoxide (DMSO), dichloromethane (DCM), chloroform, tetrahydrofuran (THF), dichloroethane (DCE), dimethylformamide (DMF), toluene and benzene. First and foremost, it was observed that an increase of the polarity of the solvent remarkably stabilizes the occupied orbitals (HOMO) and destabilizes the virtual orbitals of the complexes. Thus, the HOMO-LUMO gap is observed to increase, and the LL’CT band is blue shifted. The observed trend in the increasing energy of the LL’CT band as the solvent polarity increases can be explained based on the charge distribution in the ground state. A linear relationship was observed when the energy of the LL’CT band maxima was plotted versus the solvent parameter, E*MLCT. This same trend was also observed when the energy of the LL’CT band maxima was plotted against the calculated dipole moment.

Project Sponsors

NIH, NSF

Language

English

Keywords

chromophore, diimineplatinum(II) dichalcogenolene, donor-acceptor biradical character, excited state lifetimes

Document Type

Dissertation

Degree Name

Chemistry and Chemical Biology

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Committee Member (Chair)

Professor Martin. L. Kirk

Second Committee Member

Dr. Yang Qin

Third Committee Member

Dr. C. Feng

Fourth Committee Member

Dr. R. Giri

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