Highly Efficient TTA-UC In Self-Assembled Supramolecular Polymers Matrixes Based On Quadruple Hydrogen Bonding And It's Application

The upconversion based on triplet-triplet annihilation is an optical process of converting low-energy photons into high-energy photons.Since it was firstly proposed in 1960 s,it have drawn extensive attention due to its excellent photophysical properties such as high quantumyield,low excitation intensity as well as adjustable excitation/emissionwavelength.Sensitizers and energy matched emitters are critical components of TTA-UC system.Presently,most of the triplet sensitizers are metal complex that have high intersystem crossing(ISC)efficiency because of the participation of heavy metals,but the high prices and limited types restrict their applications in TTA-UC.In contrast,organic photosensitizers are not only inexpensive but structurally easy to modify,having become one of the choices of photosensitizers in TTA-UC.It has always been the focus in TTA-UC research to realize high energy emission with high quantum yield by low incident power andthe recent research suggest that the TTA-UC based on triplet energy migration(TEM)mechanism could obtain high upconversion quantum yield through the reorganization or connection of sensitizers and emitters.Quadruple hydrogen bondcould form supramolecular polymer in a non-polar solvent due to its large complexation constant,which provides an opportunity for TEM.Based on the above,we herein synthesized organic sensitizers and emitters modified with quadruple hydrogen bond,fabricated supramolecular polymer TTA-UC system in non-polar solvents,investigating their upconversion properties.The specific work is as follows:1.Through click-chemical reaction of mercapto-alkynyl groups,successfully synthesized Bodipy Photosensitizers modified with two quadruple hydrogen bonds and two iodine.The photophysical properties test revealed that the compound has a large molar extinction coefficient and a long triplet lifetime.The photooxidation performance test shows that the Bodipy has strong photooxidation ability after being assembled into nanoparticles by microemulsion method and could be used as a photosensitizer in TTA-UC.2.The 9,10-diphenylanthracene(DPA)modified with double quadruple hydrogen bonds was selected as the emitter and the Pd(II)Octaethylporphine was used as the sensitizer for the research of upconversion in supramolecular polymer system.The diffusion ordered spectroscopy(DOSY)and low temperature upconversion tests demonstrated the existence of TEM mechanism in the organic phase of the supramolecular polymer with a high quantum yield.In addition,the upconversion test of the organic phase of the supramolecular polymer at different oxygen concentrations has shown that the system is extremely sensitive to oxygen and could be used as an oxygen sensor to detect oxygen concentrations in the hypoxic region.Finally,using the superior film-forming properties of the supramolecular polymer,the solid phase upconversion in air can be achieved after being coating.By microemulsion method,the supramolecular polymer was assembled into nanoparticles to achieve upconversion in the aqueous phase and was applied to cell imaging.