Study On Synthesis And Low-power Upconversion Properties Of Porphyrin/Anthracene Derivatives

TTA upconversion (TTA-UC) material has attracted much attention because ofpotential applications, such as photovoltaics, photocatalysis, bioimaging, photodynamictherapy (PDT), frequency up-converted lasing, and so forth. In the field of domestic andforeign. the preparation, the relationship between structure and properties and theabsorption effect on conversion of it is one of the cutting-edge research.The main contents and results of this thesis include:1. Synthetic material: To improve the TTA efficiency, a series of metal porphyrin-anthracene derivatives were synthesized，they were named as PdTPP, PtTPP, PdMeTPP,PdBrTPP, DPA, DTACl, DNAMe, DNACl and DNACN, respectively. In the process ofTTA-UC, which are separately treated as sensitizer (PdTPP, PtTPP, PdMeTPP andPdBrTPP) with long triplet-triplet phosphorescence lifetime (τp) and acceptor (DPA,DTACl, DNAMe, DNACl and DNACN) with high fluorescence quantum efficiency (Φf).2. Effect of TTA-UC metal complex: In this research, the conversion phenomenonof PdTPP/DTACl and PtTPP/DTACl was shown. In DMF, as triplet-triplet sensitizerPdTPP have longer phosphorescence life (9.63μs), less non-phosphorescence decay rateconstant (9.75×104s-1) and lagerer phosphorescence quantum yield (0.45%), Underlow-powered excitation at60mW/cm2, green-to-blue upconversion efficiency (Φuc) ofDTACl combined with PdTPP was as high as10.33%, which is higher than7.15%(PtTPP/DTACl), it proves that Palladium porphyrin derivatives are more conducive to improve theconversion efficiency.3. Heavy atom effect: It seems that the positive external heavy atom effect onupconversion efficiency (Φuc) of DPA (9,10-diphenylanthracene) emitter combined withpalladium(II)tetraphenylporphyrins as triplet sensitizer was firstly found to significantlyincreased from12.33%to35.17%under excitation of low power density at30mW/cm2(ex=532nm). Dynamics data showed that the increasing phosphorescence lifetime (p)and phosphorescence quantum yield (Φp) of sensitizer, accompanied with the decreasingnon-phosphorescence decay rate constant (knp), have contribution to the triplet-tripletenergy transfer. Interestingly, the external heavy atom effect was found to be moreefficient than the internal heavy atom effect (12.33%to30.18%) on upconversionefficiency, which has provided a simple approach to increase low-powered upconversionefficiency without the difficulties whose can be arisen by the modification of the sensitizer molecular structure in its inner parts. Moreover, this efficient green-to-blue upconversionhas been demonstrated to have potential application for the hydrogen-generation fromwater under excitation of sun energy.4. A new medium for triplet-triplet annihilated upconversion: We first discoveredthe the oil-in-water (o/w) microemulsion containing acceptor (9,10-dinaphthylanthracene)and sensitizer (Pd(II)tetratolylporphyrin), i.e., upconverted o/w microemulsion, was firstlyreported for the triplet-triplet annihilated upconversion (TTA-UC). The correlationsbetween structure/upconversion performance of three9,10-dinaphthylanthracenes dopedwith Pd(II)tetratolylporphyrin were investigated. Under the excitation of ultralow powerdensity at60mW/cm2(λex=532nm), the upconverted o/w microemulsion emitsgreen-to-blue upconversion and the efficiency (ΦUC) increase is accompanied by thetemperature increase. The maximum ΦUCvalue for the upconverted o/w microemulsionwas obtained as high as33.68%that is comparable to the counterpart in pure organicsolvent. Very importantly, it is no need for the upconverted o/w microemulsion to deaerate,which is of critical importance for the application such as upconversion-poweredphotoelectrochemistry. To the best of our knowledge, the current study represents thesimple approach to obtain high TTA-UC without degassing any more.