Description
TitleCucurbit[7]uril host-vologen guest complexes
Date Created2011
Other Date2011-10 (degree)
Extentxxvi, 172 p. : ill.
DescriptionIn this thesis, we demonstrated that a molecular host, cucurbit[7]uril, provides an
alternative method of adsorbing molecules on semiconductors and shields the guest from
the hetereogenous interface. These novel hybrid systems exhibited photophysical and
electrochemical properties that differ from the properties of layers obtained by directly
attaching the chromophore to the semiconductor through binding groups.This thesis describes the host-guest chemistry between cucurbit[7]uril (CB[7]) and
various series of viologen guests. Methylviologen (1,1'-dimethyl-4,4'-bipyridinium dichloride, MV2+), 1-methyl-1'-p-tolyl-4,4'-bipyridinium dichloride (MTV2+), and 1,1'-dip-tolyl-(4,4'-bipyridine)-1,1'-diium dichloride (DTV2+) were encapsulated in the macrocyclic host cucurbit[7]uril, CB[7]. The complexes MV2+@CB[7] and MTV2+@CB[7] were physisorbed to the surface of
TiO2 nanoparticle films. The complexation into CB[7] was monitored by 1H NMR. TiO2 films functionalized with the complexes were studied by FT-IR-ATR and UV-Vis absorption. The electrochemical and spectroelectrochemical properties of MV2+@CB[7]
and MTV2+@CB[7] were studied in solution and in electrochromic windows (ECDs),
where the complexes were bound to TiO2 films cast on FTO. The ECDs prepared from MV2+@CB[7]/TiO2/FTO and MTV2+@CB[7]/TiO2/FTO electrodes showed reversible, sharp and fast color switching upon application of -0.8 V. Viologen derivative DTV2+ exhibited enhanced fluorescence upon encapsulation.
Aqueous solutions of DTV2+ were weakly fluorescent (Φ = 0.02, τ < 20 ps), whereas the
emission of the DTV2+@2CB[7] complex was enhanced by one order of magnitude (Φ =
0.29, τ = 0.7 ns) and was blue-shifted by 35 nm. DTV2+ in polymethylmethacrylate
(PMMA) matrix was fluorescent with a spectrum similar to that observed for the complex
in solution. DFT and CIS calculations suggested that the increased planarity of the
aromatic rings and a quinonoid structure of the S1 state, induced by encapsulation in the
host, can explain the observed emission enhancement. The absorption and emission
spectra of DTV2+@2CB[7] in water exhibited a large Stokes shift (ΔSt ~ 10,000 cm-1) and no fine structure. 1H NMR and UV-Vis titration indicated that the DTV2+@2CB[7] complex is formed in aqueous solutions with a complexation constant of K1W = 1.2×104 M-1, K2W = 1.0×104 M-1 in water, and K1NaCl = 1.1×104 M-1, K2NaCl = 0.8×104 M-1in 0.05 M
NaCl aqueous solution.
NotePh.D.
NoteIncludes bibliographical references
NoteIncludes vita
Noteby Marina Freitag
Genretheses, ETD doctoral
Languageeng
CollectionGraduate School - Newark Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.