| Photochromic compound is a chemical that changes structure into another state which has different electron absorption spectra when under UV radiation.Among them,spiropyran（SP）is a class of historic and widely used photochromic compounds whose photochromic process can bring about the molecular conformational change.The photochemical cleavage of the spiro C-O bond leads to the planarization of the two originally orthogonal heterocycles,giving rise to an increase in the extent ofπ-conjugation in the merocyanine（MC）form,which can be recovered under irradiation with longer-wavelength light.Hence,the SP can reversibly interconvert between the orthogonal SP form and conjugated MC form through alternating UV and visible light irradiation,accompanying with the advantage of fine-turning modulation of conformation,polarizability,apparent color and spectroscopic properties.In addition,due to its photo-responsive conformational changes,it also makes a potential building block for stimulus-responsive supramolecular assemblies.In the previous reported work,researchers have mainly focused on organic systems,whose luminescence are assigned as singlet state.Under high-energy UV radiation,these systems confront with serious photobleaching drawback because of the occurrence of photo-degradatio,impurity or oxygen during the structural isomerization process.The unsatisfactory fatigue resistance has severely hindered their applications such as biological imaging for long-playing time-lapse studies or high laser powers required and service life of data storage.Therefore,it is of great significance to develop feasible design strategies to improve their stability and fatigue resistance during the photo-chromic process.To address this challenge,transition metal Pt（Ⅱ）center is introduced into organic systems,triplet-sensitized photo-chromism（TSP）effect can be used to efficiently reduce the cleavage energy of the spiro C-O bond and can be controlled by visible-light photo switching performance.As an important supramolecular building block,organoplatinum（Ⅱ）complexes with unique square-planar structural feature show the strong propensity to form architectures through delicate balance of multiple noncovalent interactions including metal-metal andπ-πstacking interactions,and a minor perturbation of the molecular structure or external environment can induce significant changes in their photophysical properties and responsive behaviors.Hence,the exploration of organoplatinum（Ⅱ）systems with spectroscopic changes can be achieved from the molecular level to supramolecular and nanoscale level.The all-visible-light-controlled chiroptical switches are conceived through the introduction of phosphorescent platinum（Ⅱ）and photo-chromic SP as triplet-sensitizer and photo-regulator building-blocks,respectively,which are interlinked by S/R diaminocyclohexane as chiral genes,and can be well applied to molecular logic gates,anti-counterfeit materials,information storage and encryption fields.The specific contents of this thesis are as follows:In second chapter,we have designed a visible light controlled switch S/R1-SP based on TSP effect by linking cyclometalated platinum（Ⅱ）complexes.There is an effective resonance energy and chirality transfer process from cyclometalated platinum（Ⅱ）complex to MC isomer,which endows S/R1-SP the function of dynamic regulation of luminescence behavior.Based on the above properties,we have applied the switch in molecular logic gates,anti-counterfeit inks and fully visible light rewritable patterns for the development of advanced materials and application research.In third chapter,we have reported the integration of SP and square-planar platinum（Ⅱ）as a photo-controlled switching motif that endows the materials with dynamic assembly-induced optical characteristics.Based on the integrated TSP and FRET tactics,the chiral motif（S,S）/（R,R）-trans-1,2-diaminocyclohexane is selected as the linkage to bridge SP and phosphorescent organoplatinum（Ⅱ）to construct the chiroptical switches S/R2-SP.The dynamic self-assembly can be modulated by delicate balance of multiple noncovalent interactions.It plays a vital role in the manipulation of the kinetic-controlled photochromic reaction,synergetic with FRET process proceeding from organoplatinum（Ⅱ）moiety to open isomer of MC,which leading to the achievement of time-dependent multicolor optical switch.In addition,the chirality of S/R1-MC is also governed by the diaminocyclohexane chiral sense,and the phototriggered chirality transformation is effectively realized from to the open MC moiety and the phosphorescent organoplatinum（Ⅱ）segment via efficient intramolecular FRET progress and multiple intermolecular noncovalent interactions.The photo-controlled chiroptical switches have been successfully achieved to regulate the chiroptical activities on both the molecular and supramolecular level.Based on the above properties,we have completed the application of logic gate and time-resolved information encryption,which provides a new method for building time-resolved information anti-counterfeiting systems.In this thesis,we have synthesized two series of well-designed photo-controlled switches based on spiropyran derived phosphorescent organoplatinum（Ⅱ）complexes.This integrated design strategy simultaneously realize the photo-controlled characteristics of TSP,and efficient intramolecular energy transfer,chirality transfer and supramolecular self-assembly process respectively which endow the S/R1-SP with both excellent photochromic optical and chiroptical behaviors and S/R2-SP with assembly-induced photo-controlled characteristics.Therefore,we have designed different application scenarios such as molecular logic gate,anti-counterfeiting,and information storage encryption according to the dynamic optical control characteristics of optically controlled molecules.The research in this thesis realized regular luminescence behavior and bleaching reaction,as well as the construction of stimuli-responsive assemblies through rational molecular design,which is important for the development of photochromic compounds and metal Pt（Ⅱ）complexes in the exploration of photophysical properties and smart materials. |
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