Platinum(Ⅱ) Arylacetylide Complexes Based Cooperative Supramolecular Polymers And Their Optically Functionalizations

For living organisms,functionalized small molecules in cells self-assemble into long-range-ordered supramolecular polymers via cooperative effects between multiple non-covalent interactions.To simulate the cooperative supramolecular polymerization processes in vitro,supramolecular chemists have developed a series of cooperative polymerization monomers based on artificial systems.In the past decade,platinum(Ⅱ)arylacetylide complexes have attracted more and more attention for the following reasons:Firstly,platinum(Ⅱ)arylacetylide complexes display abundant photophysical and photochemical properties,facilitating to their optically functional applications;Secondly,it is prone to perform structural modifications for platinum(Ⅱ)arylacetylide complexes,facilitating to the introduction of assembly groups.As a result,optically functions can be extended from the molecular to the supramolecular levels,which lay the foundations for applications of supramolecular assemblies in material science,bioscience,and light harvesting system.Herein,platinum(Ⅱ)arylacetylide complexes are linked to chiral amide groups to construct cooperative polymerization monomers.By introducing(hetero)acenes into platinum(Ⅱ)arylacetylide moieties,cooperative supramolecular polymers are endowed with diverse photophysical and photochemical properties.In detail,this dissertation can be divided into four parts:In chapter 2,we have achieved the photo-responsiveness of cooperative supramolecular polymers under orange light via the doping of photo-sensitizer and theπ-extension of acenes.In research project a,a novel BODIPY photo-sensitizer has been prepared,which generate singlet oxygen(1O2)under organe light.When mixed with platinated anthracene-based supramolecular polymer,the endoperoxidation of anthracene unit can be triggered under 590 nm light irradiation.However,this method may possess two drawbacks:not only the photo-responsive wavelength is restricted by absorption of photo-sensitizer,but also the photo-sensitizer may interfere with supramolecular polymerization.Therefore,in research project b,a novel monomer has been designed by replacing anthracene unit of platinated anthracene-based monomer with tetracene unit.Notably,the alteration of acene unit has no significantly impacts on supramolecular polymerization,since the teracene-based monomer still adopts the cooperative nucleation-elongation mechanism.Moreover,the integration of tetracene unit ensure the occurrence of photo-responsive behaviors.Upon exposure to 590 nm light irradiation,the endoperoxidations of supramolecular polymer proceed rapidly.In chapter 3,a novel NIR photo-switch,together with its functionalized assembly monomer,has been contructed via connecting alkynylated pentacene unit to platinated building blocks.Under NIR light irradiation,the model compound shows reversible photo-responsiveness via the endoperoxidation/deoxygenation of pentacene unit.On this basis,the NIR photo-switch has been further integrated into the supramolecular monomer,which adopts cooperative nucleation-elongation mechanism to form helical supramolecular polymers.Notably,the NIR photo-responsiveness can be triggered in the aggregated states.NIR supramolecular assemblies have also attracted considerable attention in the photothermal studies.In chapter 4,we have designed NIR monomers possessing thiadizole or selenadiazole moieties on the peripheral of acenes.Through this design,not only the photostability of acenes can be significantly enhanced,but also spectral properties of monomers can be extended to NIR region due to intramolecular charge transfer.Subsequently,supramolecular polymerization studies confirm that they adopt cooperative nucleation-elongation mechanism during self-aggregation processes.By measuring the thermodynamic parameters of supramolecular polymerizations,the relationships between the structure of heteroacenes and the self-aggregation tendency have been probed.In particular,the integration of selenadiazole moiety enhance the self-aggregation tendency.Subsequently,NIR monomer has been utilized to prepare nanoparticles in aqueous medium via nanoprecipitation method.Under NIR light(730 nm)irradiation,the photothermal conversion efficiency of nanoparticles is determined to be 18.8%,which is comparable to those of gold nanovesicles or nanorods.As mentioned above,the spectral properties of supramolecular monomers can be tuned by altering(hetero)acene units.Hence,in chapter 5,a supramolecular sequential energy transfer(SET)system is constructed via the co-assembling of anthracene(donor),tetracene-(relay acceptor),and naphtho[2,3-c][1,2,5]selenadiazole-based(final acceptor)platinated monomers.Firstly,the energy transfer of binary systems has been studied,which display high energy transfer efficiencies(maximum values:75.0%～95.8%)and high exciton migration rates(1013～1014 L mol-1s-1).On this basis,we have further explored SET of ternary supramolecular copolymeric system.Notably,the overall energy transfer efficiency from donor to final acceptor is higher than those of the state-of-art artificial supramolecular SET systems.Besides,since both donor and relay acceptor show wavelength-dependent endoperoxidation,the SET of ternary supramolecular copolymer can be regulated via light irradiation.In summary,different optically functionalizations can be achieved by introducing functionalized(hetero)acenes.Hence,platinum(Ⅱ)arylacetylides represent a type of"versatile" molecular system.However,the scientific explorations for functionalized cooperative supramolecular polymers on the basis of platinum(Ⅱ)arylacetylides are relatively limited,since platinum(Ⅱ)arylacetylides suitable for the construction of cooperative supramolecular polymers are rare.Meanwhile,the optically functions of(hetero)acenes in platinum(Ⅱ)arylacetylides have not been fully investigated.Hence,in future studies,more functionalized platinum(Ⅱ)arylacetylides are expected to be explored,together with corresponding optically functions.Through the combination of functionalized platinum(Ⅱ)arylacetylides and cooperative polymerization,it is anticipated that more and more functionalized cooperative supramolecular polymers with distinguished optically functions will be constructed in the future.