THESIS
2020
1 online resource (xxxiv, 183 pages) : illustrations (some color)
Abstract
Stimuli-responsive luminescent materials are attracting tremendous attention for their potential
applications in optical sensors, bioimaging, data recording, molecular switch and so on. To
achieve a stimuli-responsive luminescent material, which must respond to at least one of the
following external stimuli, including light, heat, mechanical force, vapors, pH value, or
magnetic field, in an observable way. Some of them even operate in a multi-stimuli-responsive
mode, showing multi-color emission behaviors.
Usually, they rely heavily on aromatic compounds with intro/intermolecular interactions and
the resulting variation of interactions, such as large ππ interactions, dipole⸳⸳⸳dipole
interactions, D-A interactions, or hydrophobic effect. These weak forces may allow the
transformation...[
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Stimuli-responsive luminescent materials are attracting tremendous attention for their potential
applications in optical sensors, bioimaging, data recording, molecular switch and so on. To
achieve a stimuli-responsive luminescent material, which must respond to at least one of the
following external stimuli, including light, heat, mechanical force, vapors, pH value, or
magnetic field, in an observable way. Some of them even operate in a multi-stimuli-responsive
mode, showing multi-color emission behaviors.
Usually, they rely heavily on aromatic compounds with intro/intermolecular interactions and
the resulting variation of interactions, such as large π...π interactions, dipole⸳⸳⸳dipole
interactions, D-A interactions, or hydrophobic effect. These weak forces may allow the
transformation of aggregation modes or self-assembly architectures, leading to a remarkable
emission behavior change. Thus, stimuli-response behaviors could also be as strong tools to
verify the emission mechanism by constructing the structure-property relationship of the
corresponding luminescence changes.
This thesis mainly focused on the development of stimuli-responsive materials and discovered
the mechanism behind the phenomena as well as some new linking strategies in biology. Firstly,
linear gold(I) complex TPPGPA with conglobate trimer configuration trigged by aurophilic
interactions in the crystalline state was prepared to emit dual phosphorescent white-light
emission, which exhibited multi-stimuli responsive luminescent properties including
thermochromism and mechanochromism. Moreover, the molecular packing mode and
aurophilic interactions regulation were subtly taken as a functional relationship of the
experimental correlation with emission. Interestingly, to simply mix the precursor with TPPGPA with a ratio of 1:1, we could achieve cocrystal with distinct packing. The emission
color changes upon grinding and hydrostatic pressure were also evaluated. Next, we developed
a simple approach to achieve organic luminescent radical ions, which show strong solid-state
emission and superior stability with reversible light-stimuli response property. Mechanism
study reveals that the molecular symmetry breaking in the crystalline state caused molecular
conformation and redox property change, as well as the unique molecular packing, facilitate the
light-stimuli radical generation.
At last, we provide a strategy for metal-free click bioconjugation at diverse levels based on
activated alkynes. This work, even though not very match with the theme of the stimuliresponse
materials but is very meaningful. As a proof-of-concept, the abundant native groups,
including amine, thiol, and hydroxyl groups, can directly react with activated alkynes without
modification in the absence of metal catalysis. Through this strategy, high-efficient
modification and potential functionalization can be achieved for natural polysaccharide,
biocompatible polyethylene glycol (PEG), synthetic polymers, cell-penetrating peptide, protein,
fast whole-cell mapping, and even quick differentiation and staining of Gram-positive bacteria,
etc. Therefore, the current metal-free click bioconjugation strategy based on activated alkynes
is promising for the development of quick fluorescence labeling and functional modification of
many targets and can be widely applied towards the fabrication of complex biomaterials and
future in vivo labeling and detection.
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