π–π-Induced aggregation and single-crystal fluorescence anisotropy of 5,6,10b-triazaacephenanthrylene

Abstract

The influence of π–π overlap in centrosymmetric dimers on the aggregation type, single-crystal absorption and fluorescence anisotropy of the new heterocyclic system 5,6,10b-tri­aza­acephenanthrylene is presented.

Unveiling the Impact of Aggregation on Optical Anisotropy of Triazaacephenanthrylene Single Crystals. A Combined Quantum Crystallography and Conceptual Density Functional Theory Approach

“…This has a profound impact on the properties of the obtained material, as we have proven in our recent work. 23 …”

“…It is known that the absorption anisotropy can be explained by the relative orientations of the largest transition dipole moments (TDMs) of the molecules building the crystal. In our previous paper 23 we have determined the direction of the transition dipole moments for the monomer and dimer of TAAP. All TDMs were found in the plane of the chromophore approximately along the [1̅10] direction, except for one in the dimer and one in the monomer, which were perpendicular to the molecular plane.…”

“…Lack of conventional π···π interactions between fused ring systems can explain the unusual fluorescence observed alongside the direction perpendicular to the formed dimers. The general empirical rule 23 states that increasing π-overlap causes fluorescence quenching. The example of TAAP forces us to re-examine this rule and pay more attention to the character of the overlapping rings.…”

Linear Extrapolation of the Analyte-Specific Light Scattering and Fluorescence Depolarization in Turbid Samples

“…Although the anisotropy spectrum r (λ) and depolarization P (λ) are two interconvertible parameters as shown with eqs and , their popularity differs in fluorescence and light-scattering literature works. Anisotropy is more popular in fluorescence spectroscopy literature, − whereas depolarization is more commonly used in the light scattering literature. , Experimentally, fluorescence anisotropy or depolarization is measured by exciting the fluorophores with vertically linearly polarized light (V) and then detecting the intensity of Stokes’ shifted emission that is vertically ( I VV (λ)) and horizontally polarized ( I VH (λ)). The variable G (λ) in eqs and is for correcting the polarization bias in the instrument response, and it is commonly referred to as G -factor or G -factor spectrum …”

Experimental and DFT Study of the Photoluminescent Green Emission Band of Halogenated (−F, −Cl, and −Br) Imines

“…However, they have been also observed in rare earth oxides and these are associated with f → f transitions [14]. The introduction of functional groups in I crystals causes a PL signal increase of the characteristic emission peaks of I [15] by mesomeric and inductive effects, as the electron density of the aromatic ring is increased with the π→π* and n → π* electronic transitions, etc., along with hyperconjugation [16]. In summary, the objective of this paper is systematically synthesize four crystals and modify them by adding the − X halogen atom and to characterize the morphological, structural, and optical relationships associated with the change of − X atoms.…”