Excited States of Phosphorescent Platinum(II) Complexes Containing N∧C∧N-Coordinating Tridentate Ligands:  Spectroscopic Investigations and Time-Dependent Density Functional Theory Calculations

Abstract

The absorption and emission spectra of the Pt(II) complexes containing N wedge C wedge N-coordinating tridentate ligands, platinum(II) 1,3-di(2-pyridyl)benzene chloride [Pt(dpb)Cl] and platinum(II) 3,5-di(2-pyridyl)toluene chloride [Pt(dpt)Cl], together with their corresponding free ligands, 1,3-di(2-pyridyl)benzene (dpbH) and 3,5-di(2-pyridyl)toluene (dptH), have been analyzed by density functional theory (DFT) for the ground state and time-dependent DFT (TDDFT) for the excited states. T(1)(A(1)) and S(1)(B(2)) of the complexes (in C(2)(v) symmetry) were assigned on the basis of the calculated excitation energies as well as comparison of the experimental spectroscopic properties and the calculated states' characteristics. The calculated excitation energies for T(1) and S(1) of the complexes as well as those for T(1) of the free ligands were in good agreement with their observed values within 600 cm(-1). The d-pi* characters of the excited states were evaluated from the change in electron densities between the ground and excited states by Mulliken population analysis; values of 25% for T(1) and 32% for S(1) were obtained for both complexes. The calculated values of d-pi* character were found to be consistent with the reported emission lifetimes as well as the observed emission energy shifts from the corresponding free ligands. Most spectroscopic properties of the complexes and the free ligands, which include solvatochromic shift, Stokes shifts, methyl substitution shifts, and emission spectra profiles, were well explained from the calculation results.

Electronic structures and optical properties of neutral substituted fluorene-based cyclometalated platinum(II)–acetylide complexes: A DFT exploration

“…The geometry structures of the complexes were optimized by employing the Becke's 3-parameter hybrid method and the Lee-Yang-Parr correlation functional (B3LYP) [74][75][76][77][78] with the effective core potential (ECP) basis set of the LanL2DZ [79][80][81] type with an additional f-polarization function (f = 0.18) for the Pt atom and 6-31G (d) [82] basis set for the other atoms. This kind of theoretical approach and calculation level has been proven to be reliable by previous works [83][84][85][86][87].…”

Photophysics and electroluminescence of organometallic compounds with d-electrons

“…It is expected that, unlike the case of PtOEP, the b 2g level of Pt 2+ is located close to the level of ligand, leading to mixing of the two orbitals. In fact, strong mixing of the 5d-and -orbitals is found by the TDDFT calculation for NˆCˆN-Pt(Cl) [13]. As a result we can expect high PL intensity for this compound.…”

“…One is terdentate NˆCˆN-coordinating 1,3-di(pyridyl) benzene ligands Pt(Cl) and the other is NˆNˆC-coordinating 6-phenyl-2, 2 -bipyridine ligands Pt(Cl), which is called NˆCˆN-Pt(Cl) [12] (or Pt(dpb)Cl [13]) and NˆNˆC-Pt(Cl) [12], respectively. These compounds have Cl at one of the four coordinates of Pt.…”

Influence of the Li⋅⋅⋅π Interaction on the H/X⋅⋅⋅π Interactions in HOLi⋅⋅⋅C6H6⋅⋅⋅HOX/XOH (X=F, Cl, Br, I) Complexes

“…There has been an increase in the number of studies on phosphorescent transition‐metal complexes not only from a scientific viewpoint but also from development of emissive dopants for phosphorescent organic light‐emitting diodes (OLEDs). The rapid growth of interest in phosphorescent‐based OLEDs has prompted syntheses and photophysical investigations of a wide variety of phosphorescent complexes 1–5. These complexes possess good properties for performance at high glass‐state transition temperature and thermal stability, are capable of sublimation as well as formation of thin film in vacuum conditions 6–8.…”