Synthesis And Optoelectronic Properties Of Chiral Cyclometalated Platinum Complexes Incorporating Pinene

As both the foundation and pioneer of high and new technology,new materials research,one of the most important and potential field in the 21st Century,have been receiving increasing attentions.Among these,molecular functional materials,especially those with multiple properties,push people's expectation to an even higher level.Due to their structural stability and functional diversity,metal coordination compounds based on molecular building blocks can be widely used in advanced material areas of luminescence,conductivity,ferroelectricity and magnetism.Pinene is a cheap chiral natural product of the terpene class.Owing to the rigidity and steric hindrance of the pinene group,compounds incorporating pinene can induce structural distortion or form helical packing.In the material filed,it was commonly used as a chiral precursor to prepare many outstanding molecular functional materials for ferroelectrics,chiral optics and photovoltaics.On the other hand,benefiting from their good planarity and conjugation effect,cyclometalated platinum complexes exhibit a series of excellent photophysical and photochemical properties,such as luminescence,photo-conductivity and so on.Moreover,the structural isomerization or helical supramolecular self-assemble may be triggered by an external stimulus(pressure,temperature,solvent polarity,etc.).Therefore,cyclometalated platinum complexes can also be good stimulus-response materials.In this paper,chiral cyclometalated platinum complexes with pinene functionalized N^C^N and C^N^N ligands have been designed and synthesized.These complexes present interesting vapochromism,mechanochromism,chiral supramolecular self-assemble and redox properties.The details were shown as follows.In Chapter 1,the research background of this thesis was present,which mainly involve the structure,self-assemble and optoelectronic properties of cyclometalated platinum complexes.In addition,the application of chiral platinum complexes and chiral spectroscopy were also elaborated.In Chapter 2,four new couples of enantiomeric chiral cyclometalated platinum(II)complexes incorporating pinene have been designed and synthesized.Their crystal structures and chiroptical properties(ECD and VCD)have been characterized.Two couples of them show interesting vapochromism,highly selectivity to dichloromethane.In the vapochromic process,the variances of structures,crystallinity,colors and luminescences were produced,also before and after exposing vapor different solid ECD and VCD spectra were exhibited.In one case,the transformation of crystalline phase to amorphous state was induced,and the ordered molecular packing was destroyed while disordered aggregates were formed,which can be verified by the weakened chiral signals of solid ECD and VCD spectra.In the other case,the vapor led the crystalline-to-crystalline change,interestingly that switching behaviors of solid ECD and VCD spectra were induced simultaneously.In Chapter 3,pinene groups were introduced to neutral as well as cationic cyclometalated platinum(II)complexes,and interesting mechanochromic phenomena were exhibited.Before and after grinding,not only variance of crystallinity,colors and luminescences were produced,but also the signals of solid ECD and VCD are weakened as a result of molecules changing from ordered packing to disordered aggregation.In Chapter 4,by utilizing the inherent chirality and steric hindrance of pinene as well as planarity of cyclometalated platinum(II)complexes,monomeric and trimeric cyclometalated platinum(II)complexes with novel structures have been designed and synthesized.The Pt atoms played a key role in the formation of intramolecular helical trimeric structures.Also intermolecular helical packing of the monomeric complex can be formed through Pt…Pt contacting.The chiral enviroments were enhanced through forming intramolecular helical structures or intermolecular helical aggregations evidenced by ECD and CPL activities.More interestingly,the chiroptical properties can be switched reversibly or irreversibly due to deaggregation or decomposition upon increasing the temperature.In Chapter 5,the frontier orbitals and redox properties of cyclometalated platinum(?)complexes can be tuned by incorporating the pinene group.At ambient temperature,a couple of cyclometalated platinum(?)complexes can be oxidized by oxygen,and one couple of enantiomeric chiral cyclometalated platinum(?)complexes was obtained,while the color,luminescence and ECD spectra of complexes have undergone distinct changes.In addition,this couple of cyclometalated platinum(?)complexes was also oxidized by a series of common oxidants,and the oxidation reactions may be quick or sluggish,so the oxidation process was controlled by kinetics.