| Phthalocyanines are an important class of pigments which have found their applications in various disciplines.Study on the relationship of their structures and properties is of great importance on designing new phthalocyanines with novel properties and material performances.Our research work has been focused on the following respects:1.DFT study of the structures and properties of mono-phthalocyanine metal complexes with different nonperipheral and axial substituents and central metalsDensity Functional Theory(DFT) and time-dependent DFT calculations are carried out to comparatively describe the molecular structures,molecular orbital energy gaps,atomic charges,infrared(IR) and Raman spectra,and the UV-vis spectra of PbPc,PbPc(α-OC2H5)4,and PbPc(α-OC5H11)4.Substitution of bulky alkoxy groups at the nonperipheral positions of phthalocyanine ring adds obvious effect to the molecular structures of phthalocyaninato lead compounds by deflecting the isoindole units in the direction that the isoindole units extend and distorting them in the C4 axis direction due to the steric hindrance.Both the calculated IR and UV-vis absorption spectra of PbPc(α-OC5H11)4 correspond well with the experimental results.Density functional theory(DFT) and time-dependent DFT calculations are carried out to comparatively describe the molecular structures,molecular orbital energy gaps,atomic charges,infrared(IR) spectra,Raman spectra,and electronic absorption spectra of lead phthalocyaninate(PbPc),tin phthalocyaninate(SnPc),germanium phthalocyaninate(GePc),tin(Ⅳ) dichlorophthalocyaninate(PcSnCl2),and germanium(Ⅳ) dichlorophthalocyaninate(PcGeCl2).The calculated structural data and the simulated IR spectrum of PbPc correspond well with the experimental result. The important effects of axial ligands and ionic radius of metal center to the molecular structures,molecular orbital and atomic charges are described,and the metal-sensitive peaks in the IR and Raman spectra are identified by comparative study of the five complexes with different central metals and axial ligands.The electronic natures of all the bands in the absorption spectra are assigned and analyzed comparatively according to the calculated electronic transition contributions.Axial ligands also greatly changed the electronic absorption spectra due to the change of the orbital energy level and the molecular symmetry.2.DFT study of the structures and properties of homoleptic and hemoleptic bis(phthalocyaninato) yttrium and lanthanum double-decker complexes and location of hole and acid proton in mixed (phthalocyaninato)(porphyrinato) yttrium double-deckerDensity Functional Theory(DFT) calculations are carried out to describe the molecular structures,molecular orbitals,atomic charges,UV-vis absorption spectra,IR,and Raman spectra of bis(phthaiocyaninato) rare earth(Ⅲ) complexes M(Pc)2(M = Y,La) as well as their reduced products[M(Pc)2]-(M = Y,La).Good consistency is found between the calculated results and experimental data.Reduction of the neutral M(Pc)2 into[M(Pc)2]- induces the reorganization of their orbitals and charge distribution,and decreases the inter-ring interaction.With the increase of the ionic size from Y to La,the inter-ring distance of both the neutral and reduced double-decker complexes M(Pc)2 and[M(Pc)2]-(M = Y,La) increases,the inter-ring interaction and the splitting of the Q bands decrease,and corresponding bands in the IR and Raman spectra take red shift.The orbital energy level and orbital nature of the frontier orbitals are also described and explained in term of atomic character.The present work,representing the first systemic DFT study on the bis(phthalocyaninato) yttrium and lanthanum complexes,sheds further light on clearly understanding structure and spectroscopic properties of bis(phthalocyaninato) rare earth complexes.The substitutional effect of alkoxy substituents attached at one phthalocyanine ligand on the whole molecule of three heteroleptic bis(phthalocyaninato) yttrium complexes Y(Pc)[Pc(α-OCH3)4](1), Y(Pc)[Pc(α-OCH3)8](2),and Y(Pc)[Pc(β-OCH3)8](3) as well as their reduced products {Y(Pc)[Pc(α-OCH3)4]}-(4),{Y(Pc)[Pc(α-OCH3)8]}-(5),and {Y(Pc)[Pc(β-OCH3)8]}-(6) in term of the molecular structures,molecular orbitals,atomic charges,electronic absorption spectra,IR,and Raman spectra is studied by density functional theory(DFT) calculations.Good consistency is found between the calculated results and experimental data in the electronic absorption spectra,IR,and Raman of 1 and 3.Introduction of electronic-donating methyloxy groups at one phthalocyanine ring of the heteroleptic double-deckers induces structural deformation on both the phthalocyanine ligands,electron transfer between the two phthalocyanine rings, change of orbital energy and composition,shift of electronic absorption bands, and distinguish of the vibrational modes of the unsubstituted phthalocyanine from the substituted phthalocyanine ligand in the IR and Raman spectra in comparison with the unsubstituted homoleptic counterpart Y(Pc)2.The calculation results reveal that incorporation of methyloxy substituents at the non-peripheral positions add more influence on the structure and spectroscopic properties of bis(phthalocyaninato) yttrium double-decker than at the peripheral positions,which also increases with increasing the number of substituents from four to eight.Nevertheless,the substitutional effect due to alkoxy substituents at one phthalocyanine ligand of the double-decker on the unsubstituted phthalocyanine ring as well as the whole molecule and importance of the position and number of alkoxy substituents are discussed in detail.In addition, the effect of reduction of 1-3 into 4-6 on the structure and spectroscopic properties of bis(phthalocyaninato) yttrium compound is also discussed.The systemic DFT study of alkoxy substitutional effect on the heteroleptic bis(phthalocyaninato) yttrium complexes is not only useful towards understanding the structure and spectroscopic properties of bis(phthalocyaninato) rare earth complexes but also helpful in designing and preparing double-deckers with tuneable structure and properties in terms of substitutional effects.The location of the hole and acid proton in neutral non-protonated and protonated mixed(phthalocyaninato)(porphyrinato) yttrium double-decker complex,respectively,is studied on the basis of density functional theory(DFT) calculations on the molecular structures,molecular orbitals,atomic charges,and electronic absorption and infrared spectra of neutral,reduced,and two possible protonated species of mixed(phthalocyaninato)(porphyrinato) yttrium compound,namely(Pc)Y(Por),[(Pc)Y(Por)]-,(HPc)Y(Por),and(Pc)Y(HPor). When the neutral(Pc)Y(Por) is reduced to[(Pc)Y(Por)]-,the calculated results on the molecular structure,atomic charge,and electronic absorption and infrared spectra show that the added electron has more influence on the Pc ring than on Pot counterpart,suggesting the location of hole on the Pc ring in neutral (Pc)Y(Por).Nevertheless,comparison of the calculation results on the structure, orbital composition,charge distribution,and electronic absorption and infrared spectra between(HPc)Y(Por) and(Pc)Y(HPor) leads to the conclusion that the acid proton in protonated mixed(phthalocyaninato)(porphyrinato) yttrium compound should localize on the Por ring rather than Pc ring despite of the localization of the hole on the Pc ring in(Pc)Y(Por).This result is in line with the trend revealed by comparative studies over the X-ray single crystal molecular structures between[MⅢ{ Pc(α-OC5H11)4 }(TCIPP)]and [MⅢH{Pc(α-OC5H114)(TCIPP)](M = Sm,Eu).The present work not only represents the first systemic DFT study on structures and properties of mixed (phthalocyaninato)(porphyrinato) yttrium double-decker complexes,but more importantly sheds further light on clearly understanding the nature of protonated bis(tetrapyrrole) rare earth complexes. 3.Charge transfer properties of bis(phthalocyaninato) rare earth(Ⅲ) complexes:intrinsic ambipolar semiconductor for field effect transistorsDensity functional theory(DFT) calculations are carried out to investigate the effect of oligomer length,halogen substitution,and heteroatom substitution on the organic field effect transistor(OFET) performance of a series of oligothienoacenes(1-5 for oligothienoacene with thiophene units' number from two to six).The appropriate ionization potential and electron affinity,balanced charge injection barrier for both hole and electron relative to the work function potential of Au source-drain electrodes,low hole and electron reorganization energy,and good intrinsic transfer mobility for both hole and electron of both the boron substituted hexathienoacenes 5BH and 5BH-2F-a make these two compounds good potential semiconductors for ambipolar OFET devices,with calculated intrinsic charge transfer mobilities achieving 3.74 and 5.07 cm2 V-1 s-1 for hole,and 4.77 and 5.76 cm2 V-1 s-1 for electron,respectively.The high intrinsic mobilities of 5BH and 5BH-2F-a are rationalized in terms of their frontier orbitals,molecular structure variation upon oxidation and reduction,and electron coupling between two neighboring molecules.All the results indicate that heteroatom substitution of sulfur atoms in oligothienoacenes is a rational way towards good ambipolar OFET semiconducting materials.Density functional theory(DFT) calculations are carried out to study the charge transfer properties of bis(phthalocyaninato) yttrium and lanthanum double-decker complexes M(Pc)2(M = Y,La) for organic field effect transistors (OFET).The results indicate that the intrinsic delocalized hole in M(Pc)2(M = Y, La) induces the high energy level of highest occupied molecular orbital(HOMO) and low energy level of lowest unoccupied molecular orbital(LUMO) in the sandwich double-decker molecules as well as the small ionization potential and large electronic affinity.These factors lead to very small injection barrier relative to Au source-drain electrode of these two double-deckers for both hole and electron and render them as good potential ambipolar semiconductor. Associated with the very small reorganization energy for hole and electron and large transfer integral in crystal,these two complexes M(Pc)2(M = Y,La) display intrinsic charge transfer mobility of 0.034 and 0.17 cm2 v-1 s-1 for hole and 0.031 and 0.088 cm2 v-1 s-1 for electron in crystal according to the calculation results.The high intrinsic mobility for both hole and electron in these double-deckers is rationalized by examining the changes of geometric and electronic structures upon reduction and oxidation and charge transfer integral of different transfer modes in crystal.Charge transfer integrals in all the possible dimers composed of two Y(Pc)2 molecules are systematically studied to simulate the molecular arrangement of bis(phthalocyaninato) rare earth complexes in thin solid films.
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