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Investigations of the Electronic and Molecular Structures of Luminescent Pt(II) and Pt(IV) Complexes with Triimine Ligands
Author Info
Shingade, Vikas M
Permalink:
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460447231
Abstract Details
Year and Degree
2016, PhD, University of Cincinnati, Arts and Sciences: Chemistry.
Abstract
The work presented in this dissertation focuses on platinum(II) and platinum(IV) complexes with the 2,6-bis(N-methylbenzimidazol-2'-yl)pyridine (mbzimpy) pincer ligand. The complexes have the general formulae Pt(mbzimpy)X
+
(X: Cl, Br, CCPh, Ph and CH
3
) and Pt(mbzimpy)X
3
+
) (X: Cl, Br). The second chapter details the investigations of electronic structures of Pt(mbzimpy)X
+
complexes using cyclic voltammetry, UV-visible and emission spectroscopies. The Pt(tpy)X
+
analogs (tpy= 2,2’;6’2”-terpyridine) have also been examined for comparison. Pt(L)X
+
complexes (L: mbzimpy or tpy) undergo two chemically reversible one-electron reduction processes at cathodic potentials. In the case of Pt(mbzimpy)X
+
, these processes occur at slightly more negative potentials. Furthermore, these processes are shifted cathodically along the Cl〈CCPh〈Ph〈CH
3
series of ancillary ligands. The absorption spectra of Pt(L)X
+
exhibit ligand-centered (
1
LC) transitions (ε ≈ 10
4
M
-1
cm
-1
) in the UV region and metal-to-ligand-charge transfer (
1
MLCT) transitions (ε ≈ 10
3
M
-1
cm
-1
) in the visible region. The corresponding visible band in Pt(L)(CCPh)
+
has been assigned to the
1
(LLCT/MLCT) mixed state (LLCT: ligand-to-ligand-charge transfer). The preceding
1
LC and
1
MLCT transitions of Pt(mbzimpy)X
+
occur at longer wavelengths than found for the corresponding Pt(tpy)X
+
analogs. The
1
MLCT band of Pt(L)X
+
is shifted to the red along Cl〈Ph〈CH
3
series. The low energy
1
LC states of Pt(mbzimpy)X
+
occur at virtually the same wavelength, whereas they undergo a distinct shift to the blue along Cl〈Ph〈CH
3
series in the case of Pt(tpy)X
+
. The latter effect has been qualitatively explained by invoking π
*
(L)/6p
z
(Pt) orbital mixing. The frozen solutions of all the compounds exhibit structured emission beginning at λ
max
in the 470-560 nm range. This emission is assigned to the
3
LC state which is stabilized due to configurational interaction with the higher-lying
3
MLCT state. In the case of Pt(L)CCPh
+
, the emission, however, originates from a
3
(LLCT/MLCT) mixed state. Chapter 3 describes an investigation of the aggregation of Pt(mbzimpy)(CH
3
)
+
and Pt(tpy)(CH
3
)
+
in DMSO-d
6
using 2D
1
H-
1
H NOESY, as well as concentration-dependent
1
H NMR and UV-visible absorption spectroscopies. A detailed analysis of NMR and UV-visible spectra leads to the conclusion that both compounds form head-to-tail dimers in DMSO solution. Further, it is evident that the forces stabilizing these dimers are dominated by ligand..ligand interactions. The intermolecular interactions stabilizing dimers of Pt(mbzimpy)(CH
3
)
+
are decidedly stronger than those of the terpyridyl analog. Chapter 4 details the first successful isolation and characterization of Pt(mbzimpy)X
3
+
(X = Cl and Br ) salts. Electrochemical studies show that these complexes undergo an irreversible reduction accompanied by loss of axial halide ligands. Pt(mbzimpy)Cl
3
+
is slightly more stable to reduction than the corresponding bromo complex. No emission was observed from the bromo derivative, whereas 77K frozen solutions of Pt(mbzimpy)Cl
3
+
shows extremely weak emission near 690nm. The latter emission is tentatively assigned as originating from a lowest
3
LF state.
Committee
William Connick, Ph.D. (Committee Chair)
Hairong Guan, Ph.D. (Committee Member)
James Mack, Ph.D. (Committee Member)
Pages
171 p.
Subject Headings
Inorganic Chemistry
Keywords
Platinum
;
terpyridine
;
benzimidazole
;
luminescence
;
electronic structure
;
electronic absorption
Recommended Citations
Refworks
EndNote
RIS
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Citations
Shingade, V. M. (2016).
Investigations of the Electronic and Molecular Structures of Luminescent Pt(II) and Pt(IV) Complexes with Triimine Ligands
[Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460447231
APA Style (7th edition)
Shingade, Vikas.
Investigations of the Electronic and Molecular Structures of Luminescent Pt(II) and Pt(IV) Complexes with Triimine Ligands.
2016. University of Cincinnati, Doctoral dissertation.
OhioLINK Electronic Theses and Dissertations Center
, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460447231.
MLA Style (8th edition)
Shingade, Vikas. "Investigations of the Electronic and Molecular Structures of Luminescent Pt(II) and Pt(IV) Complexes with Triimine Ligands." Doctoral dissertation, University of Cincinnati, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1460447231
Chicago Manual of Style (17th edition)
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Document number:
ucin1460447231
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© 2016, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.