Ab-Initio Study of Circular Dichroism and Circularly Polarized Luminescence of Spin-allowed and Spin-forbidden Transitions: From Organic Ketones to Lanthanide Complexes

Abstract

<div><div><div><p>Complete and restricted active space self-consistent field (CAS-/RAS-SCF) wavefunction methods are applied for the calculation of circular dichroism (CD) and circularly polarized luminescence (CPL) of a series of molecules comprising four organic ketones, the chiral Cobalt(III) complex Λ-[Co(en)3]3+ and the Europium(III) complex [Eu(DPA)3]3–. The ab-initio results are in good agreement with the experimental data and previous results obtained with Kohn-Sham density functional theory in the case of the spin-allowed transitions. CD and CPL properties are calculated ab-initio for the first time for the spin-forbidden transitions of both a transition metal and a lanthanide complex.</p></div></div></div>

Beyond Chiral Organic (p-Block) Chromophores for Circularly Polarized Luminescence: The Success of d-Block and f-Block Chiral Complexes

“…Any contribution arising from the coupling between the electric dipole (ED) and electric quadrupole (EQ) moments is neglected in the rotatory strength equation since the consideration of an isotropic medium implies the orientation average (Gendron et al, 2019 ). The comparison of CPL intensities of different compounds showing different quantum yields requires some normalization of the rotatory strength by the global emission contribution which is ruled by the dipole strength ( D ij ) depicted in Equation (3), where is the electric transition quadrupole moment (Gendron et al, 2019 ).…”

“…Despite the many examples reported to date, the relationship between the structure of the complex and the value of g lum , which is of fundamental importance for molecular programming, remains challenging. This weakness mainly relies on the difficulties of performing theoretical CPL studies accessible to synthetic coordination chemists (Gendron et al, 2019 ). The potential applications of CPL arising from chiral Ln 3+ systems is of considerable importance in biology and biochemistry because they have shown to be very sensitive to small changes in the molecular structure which can be detected as a change in the CPL emission.…”

How the Ligand Field in Lanthanide Coordination Complexes Determines Magnetic Susceptibility Anisotropy, Paramagnetic NMR Shift, and Relaxation Behavior

“… 20 − 22 Despite this, many other spectral phenomena defy explanation, and “ J mixing” is often cited as a “catch-all”, highlighting limitations in current understanding. 12 , 14 , 23 …”

EuIII functionalized silica nanoparticles encapsulating chiral CrIII complexes with simultaneous unpolarized red and polarized NIR-I luminescence

“…The rotatory strength (R), which is the probability of absorbing (or emitting) a circularly polarized photon from an initial state to a final state, is usually expressed in 10 À40 cgs units. 62,63 The computed values for R are 229 Â 10 À40 cgs and 107 Â 10 À40 cgs (in absolute values) for the respective transitions. Those R values, are four to five orders of magnitude larger compared to the spin-forbidden transitions on chiral Co(III) and Cr(III) complexes.…”