Design And Synthesis Of Two-photon Absorbed Organic Molecule For Their Photodynamic Therapy And Optical Limiting Applications

Two-photon absorption is distinctly different from traditional one-photon absorption,which not only induces photophysical process(fluorescence or phosphorescence)but also initiates threedimensional selective photochemical reaction(photopolymerization or photo-uncaging).These especial advantages endow two-photon absorbed materials attractive potential in the applications of molecular imaging,material science,chemistry and physics.In recent years,as the commercialization of two-photon microscope and pulsed laser(pump two-photon absorbed materials),two-photon absorbed materials have attracted considerable attenuations in biomedical field.Meanwhile,high intensity pulsed laser also promote the laser blinding weapons,which thus inevitably bring the risk of researchers or sensitive optical devices.In this context,optical limiter is especially important to protect researchers or optical devices from high intensity laser.Consideration of the ease of functionality and low cost,organic molecules with strong two-photon absorption have become a star material in biomedicine and optical limiter.Although lots of strong two-photon absorbed organic molecules have been attained by optimizing structure-properties relationships,the poor watersolubility and attenuation of two-photon absorbed ability in strong polar solvent greatly limited their applications in biomedicine and optical limiter.Therefore,developing organic molecules with strong two-photon absorbed ability in strong polar solvent is critical to expand their applications in biomedicine as well as optical limiting.This paper aims to design strong two-photon absorbed organic molecules in strong polar solvent and exploit their applications in photodynamic therapy and optical limiting.This thesis can be divided into four sections.1.Inner Salt-Shaped Conjugated Small Molecule with Strong Two-Photon Absorption for Mitochondrial-Targeting Photodynamic TherapyTwo-photon photodynamic therapy(TP-PDT)is a very promising therapeutic model in treatments of cancer at depth.However,attaining suitable TP-photosensitizers(TP-PSs)with large TPabsorption cross-sections(?)in strong polar solvent,high singlet oxygen(1O2)quantum yield and subcellular-selectivity remains extremely challenging.Here,we present the simple usage of a synthetic inner salt-shaped molecular architecture to simultaneously endow conjugated small molecule with remarkably enhanced ? in strong polar solvent,high 1O2 quantum yield and mitochondrial-targeting ability.Furthermore,we successfully demonstrate the first example of mitochondrial-targeted and mitochondrial apoptosis-mediated TP-PDT using such inner salt-shaped small molecule.2.Adjusting the Singlet Oxygen Generation by Host-Guest Chemistry for Two-Photon Photodynamic Therapeutic RegulationThe ability to adjust singlet oxygen(1O2)generation of two-photon absorbing photosensitizers(TP-PSs)in deep tissue is highly valuable in expanding the scope of photodynamic therapy applications.Investigating the mechanism and relationship between TP-PSs molecular structure and the 1O2 generation are beneficial to the modulation of 1O2 generation.Here,we designed a new zwitterionic TP-PS compose of positive-charged quaternary ammonium and negative-charged carboxylic group,which exhibited ultra-high two-photon absorption cross sections(?)within the therapeutic window.By experimental investigation,we revealed that quaternary ammonium group in zwitterion plays an important role in the 1O2 generation.Furthermore,we demonstrated the proof-ofconcept application to adjust 1O2 generation by host-guest complexation between a water-soluble pillar[5]arene(WP5)and our zwitterionic TP-PS.Finally,a preliminary study on cell culture showed efficient two-photon induced phototoxicity using such host-guest complex.3.Organic Molecule/Rare Earth Nanomaterial Co-functionalized Graphene Oxide Nanocomposites with Dual Two-photon Absorption for Giant Broadband Optical Limiting against Ultrafast Femtosecond PulsesIn this study,we first introduced the concept of dual two-photon absorption(dual-TPA)by integrating the two types of TPA materials,i.e.,organic molecule with large TPA cross sections and RENP,into GO system in a one-step hydrothermal-processable method.This proposed concept afforded two independent and efficient two-photon induced PET in the final GO-hybrid(GO-Hs)which exhibited nearly 3-folded low OL threshold(where transmittance falls to 50% of transmission)across the red and NIR regions under femtosecond pulses compared to pure GO.Moreover,GO-Hs exhibited almost same decreases(approximately 35%)of output power intensity versus input power density in both 720 and 980 nm compared to that of typical benchmark C60 performed 8-ns pulse of 532-nm laser.This work provided a novel,promising and general approach to design new-generation optical limiters.4.Two-Photon-Induced Blue Emission of Water-soluble Organic Compounds with Remarkably Large Cross Sections and Their Optical Limiting PropertiesHerein we report a very easy way to realize the two-photon-induced deep blue emission of water soluble organic molecule with remarkable high absorption cross section of 4075 GM which is the highest(about 4-fold higher than the previous record)among the currently reported blue emission materials.Furthermore,compared to those very-frequently reported strong electronic push-pull groups,such as N,N-dialkylamino groups,another interesting innovation is that the simple introduction of the carboxylate ion such recognized weaker electronic push-pull groups into a concise symmetric structure can not only realize water-solubility,highlight the promise of the application in biological and environment friendly treatment,but also greatly improve the two-photon absorption cross section.