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The Second-order Nonlinear Optical Property Of The Chelated Polypyridyl Metal Ru(Ⅱ) Complexes

Posted on:2014-09-05Degree:MasterType:Thesis
Country:ChinaCandidate:C H WangFull Text:PDF
GTID:2251330401481783Subject:Physical chemistry
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Chelated polypyridyl metal complexes have occupied an important role in the filed ofphotophysics, electrochemistry and DNA structure probes. They not only introduce thesubstituent groups, but also have good metal-ligand charge transfer character. Therefore, thechelated polypyridyl metal complexes become the NLO candidate material. Polypyridylligands, such as phenanthroline, bipyridyl, terpyridyl, diazafluorene, are a kind of πdelocalization nitrogen heterocyclic chelated ligands. The coordation of the ligands to themetal (chelation effect) make them to stay in the plane, thus enhancing the second-order NLOresponse.The chelated polypyridyl (1,10-phenanthroline and2,2′:6′,2′’-terpyridyl) metal Ru(Ⅱ)complexes were investigated by quantum chemical calculations. The results show that:(1) The dynamic first hyperpolarizabilities of a series of1,10-phenanthroline Ru(Ⅱ)complexes were calculated by coupled perturbed (time-dependent) method and DFT inN,N-Dimethylformamide (DMF) solution (λ=1.907μm). Theβtotvalues for Series acomplexes with two cis CO are less than those of Series b complexes with two trans PPh3.The increase of attracting electron ability and π-conjugation on the1,10-phenanthroline ligandleads to the increase of the correspondingβtotvalues. TDDFT demonstrates that ILCTcontributes to theβtotvalues for the complexes in Series a, while the relatively low-energyMLCT and LLCT are responsible for the complexes in Series b.(2)The static first hyperpolarizabilities for a series of the two-dimensional (2D) pincerRu(Ⅱ) complexes with the substituted Tpy and H2SCS tridentate ligands (Tpy=2,2′:6′,2′’-terpyridyl and H2SCS=2,6-bis(benzylaminothiocarbonyl)phenyl) have beeninvestigated by DFT and analytical third energy derivatives. The introduction of thedonor/acceptor groups affectsβtotvalues of the2D systems, to a certain extent. Incomparison with system1[Ru(H2SCS)(Tpy)]+, introducing the branches with strong electronacceptor group (p-NO2-phenylethynyl) to the Tpy ligand or the branches with strong electrondonor group (p-NH2-phenylethynyl) to the H2SCS ligand can effectively improve theβtotvalues. TDDFT show that theβtotvalues are influenced by ILCT, MLCT, LMCT transitions.Moreover, the proton abstraction plays an important role in tuning the second-order NLOresponse. Particularly, for system5bearing the branches with NO2groups on H2SCS ligand,there is a dramatic enhancement in theβtotvalues for its deprotonated forms. Theβtotvalues of the mono-deprotonated system5-H and the di-deprotonated system5-2H are58.712×10-30esu and761.803×10-30esu, about7.58times and36.4times compared with thedi-protonated system5, respectively. Theβtotvalues in our work have two-dimensionalcharacter due to their large off-diagonal tensor values.
Keywords/Search Tags:chelated polypyridyl metal complexes, second-order NLO properties, protonabstraction switch, DFT
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