Theoretical study of one- and two-photon absorption properties of octupolar D-2d and D-3 bipyridyl metal complexes
ABSTRACT The molecular equilibrium structures, electronic structures, and one- and two-photon absorption (TPA) properties of C2v (Zn(II), Fe(II) and Cu(I)) dipolar and D2d (Zn(II) and Cu(I)) and D3 (Zn(II)) octupolar metal complexes featuring different functionalized bipyridyl ligands have been studied by the ZINDO-SOS method. The calculated results show that one- and two-photon absorption properties of metal complexes are strongly influenced by the nature of the ligands (donor end groups and pi linkers) and metal ions as well as by the symmetry of the complexes. The length of the pi-conjugated backbone, the Lewis acidity of the metal ions, and the increase of ligand-to-metal ratio result in a substantial enhancement of the TPA cross sections of metal complexes. Substitution of C=N and N=N for C=C plays an important role in altering the maximum TPA wavelengths and the maximum TPA cross sections of metal complexes. Of them, the C=N substituted metal complexes have relatively large TPA cross sections. Replacing styryl with thienylvinyl makes the one-photon absorption wavelength red shift and at the same time leads to a great decrease of the maximum TPA cross sections of metal complexes. The possible reason is discussed. In the range 500-1250 nm, octupolar metal complexes exhibit intense TPAs and therefore are promising candidates for TPA materials.
SourceAvailable from: Paul Savel[Show abstract] [Hide abstract]
ABSTRACT: We report the synthesis, the photophysical and the two-photon absorption (2PA) properties of a series of octupolar bipyrimidine-based ligands incorporating N-substituted amines as terminal donor groups. The effect of replacing phenylvinylene [capital Pi]-conjugated linkers by fluorenylvinylene ones was also investigated. The linear absorption spectrum of these compounds is dominated by an intensive charge transfer band which is sensitive to the N-substitution and the [capital Pi]-bridge nature. The excitation anisotropy spectrum indicates that this band encompasses multiple S0[rightward arrow]Sn transitions whose occurrence is well rationalized on the basis of the Frenkel exciton model. The 2PA spectrum also corroborates the presence of several electronic transitions. In apolar or moderatly polar medium, excited ligands mainly deactivate through a highly emissive intramolecular charge transfer (ICT) state localized within a single branch of the chromophore. In highly polar medium, the solvent-induced sJournal of Materials Chemistry C 01/2013; DOI:10.1039/C3TC31370K
[Show abstract] [Hide abstract]
ABSTRACT: Symmetric‐type carbazole derivatives show great potential for application in two‐photon absorption (TPA) materials and organic light‐emitting diodes. The absorption spectra and fluorescence emission spectra of three different N‐alkyl symmetric‐type carbazole derivatives were investigated. The density functional theory (DFT) time‐dependent‐DFT//Becke, three‐parameter, Lee–Yang–Parr/6‐31 G* method has been used to theoretically study one‐photon absorption properties. The computational results are in good agreement with the available experimental values. The two‐photon excited fluorescence of the compounds was surveyed by 120 fs pulse at 790 nm Ti: sapphire laser operating at 1 kHz repetition rate. Two‐photon excited fluorescence was obtained in the range of 380–600 nm, and TPA cross‐sections were calculated. The TPA properties of the series of compounds were investigated by the ZINDO/single and double electronic excitation configuration interaction method. The influence of the chemical structure of the compounds on two‐photon optical properties was discussed. The results show how the different changes in one‐photon absorption and TPA properties on the basis of lengthening the conjugated bridge and the different carbazole N‐alkyl substituents are attributed to the transition dipole moment in the excited process. Copyright © 2011 John Wiley & Sons, Ltd.Journal of Physical Organic Chemistry 05/2012; 25(5). DOI:10.1002/poc.1923 · 1.23 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: We have theoretically investigated two series of cyclometalated Pt(II) complexes, a series [Pt (C, N, N) Cl] and b series [Pt (C, N, Npyrazolyl) Cl]. The geometrical and electronic structures are calculated at the ECP60MWB//6-31G*(H, C, Cl, N, S) basis set level using DFT method; one-photon absorption (OPA) properties are calculated by using both TDDFT and ZINDO methods and two-photon absorption (TPA) properties are obtained with the ZINDO/SOS method. The resonance integrals parameters (β sp and β d) for Pt are adjusted to −1 and −28.5 eV, respectively, to make max OPA wavelength calculated by ZINDO closest to the experimental data and TDDFT results. The calculated results indicate the molecule 2b ([Pt (Cnaphthyl, N, Npyrazolyl) Cl]) has the biggest potential as outstanding TPA materials because (i) the TPA properties of b series are more outstanding in IR wavelength range, the molecules in b series have good transparencies and possess 1-pyrazolyl-NH that is also available for another metal coordination (e.g., dimerization) and chemical interactions; (ii) when C is Cnaphthyl in the C, N, N ligand of cyclometalated Pt(II) complexes, the molecules have the best conjugation effect and the best TPA properties.Science China-Chemistry 07/2012; 55(7). DOI:10.1007/s11426-012-4612-z · 1.52 Impact Factor