Structure–Property Relationship in π-Conjugated Bipyridine Derivatives: Effect of Acceptor and Donor Moieties on Molecular Behavior

Abstract

Here, we reported the photophysical studies, single-crystal X-ray crystallography, and density functional theory (DFT) calculations of two bipyridine derivative molecules. In addition, thermal gravimetric analysis and cyclic voltammetry studies were also performed for both compounds. According to crystallographic data, the π-conjugated molecules have high-quality crystal structures as a result of intramolecular and intermolecular hydrogen bonds occurring through the molecules of the compound. It was determined that when the functional groups (F– and CH3O−) were introduced to the para positions, the molecules adopted slipped stacking (J-aggregate) and antiparallel cofacial stacking (H-aggregate). It was observed that these two bipyridine derivatives disclose the relationship between molecular conformation-molecular packing modes and photophysical behavior of organic solids. The results of DFT calculations supported the structural, spectroscopic, and photophysical data and confirmed the compositions of frontier molecular orbitals in both molecules.

Structure–Property Relationship in Amber Color Light-Emitting Electrochemical Cell with TFSI Counteranion: Enhancing Device Performance by Different Substituents on N∧N Ligand

“…Four novel cationic Ir­(III) complexes were typically synthesized by cleavage of the [Ir­(Meppy) 2 (μ-Cl) 2 ]/[Ir­(Meppy) 2 (μ-Cl) 2 ] dimer with ancillary N ∧ N ligands in ethylene glycol, and then an excess of ammonium hexafluorophosphate (NH 4 PF 6 ) or lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSI) salt was used for ion metathesis, thus exchanging the [PF 6 ] − or [TFSI] − anion with the chloride ion (Scheme ). N ∧ N ligands, Fpbpy and MeObpy, were synthesized as in our previous study . The synthesized novel complexes are [Ir­(Meppy) 2 (Fpbpy)]­[PF 6 ] ( 1b PF 6 ), [Ir­(Meppy) 2 (Fpbpy)]­[TFSI] ( 1b TFSI), [Ir­(Meppy) 2 (MeObpy)]­[PF 6 ] ( 2b PF 6 ), and [Ir­(Meppy) 2 (MeObpy)]­[TFSI] ( 2b TFSI), where Meppy = 2-( p- methylphenyl)-pyridine ( b ), Fpbpy = 4,4′-bis­(4-fluorophenyl)-2,2′-bipyridine ( 1 ), and MeObpy = 4,4′-bis­(4-methoxy)-2,2′-bipyridine ( 2 ).…”

Computational Investigation of Adsorptive Removal of Pb

“…This is a valid approach for modelling interactions with the adsorption site on the functionalised linkers as demonstrated by previous studies in the literature. [61,62,83] The cluster model used to study adsorption on the UiO-66 defective node (Fig. 7 and accompanying discussion) has been used widely in the literature in the past, [27,30,[84][85][86][87] including in recent work by our group where we report the details of how the cluster model was obtained.…”

Structure–Property Relationship on Aggregation-Induced Enhanced Emission of the Spirobifluorene Derivatives including Herringbone, T, and Helical Aggregation Mode in Solid-Phase: Synthesis, Crystallography, Density Functional Theory, Optical, and Thermal Properties

“…The formation of herringbone and T-type aggregates is beneficial for enhancing fluorescence efficiency, while parallel face-to-face H-type aggregation is disadvantageous. 34 Herringbone and T-type aggregation cause red shifts in the spectra, which shows the improvement of solid-state efficiency, whereas H-aggregation causes severe fluorescence quenching and blue shifts in solid-phase spectra. 35,36 To obtain the aggregation-induced emission effect, a slight structural modification of a given molecule, such as extending π•••π conjugation, incorporating the heteroatom in the conjugated backbone or modification with bulky substituents may have a great effect on its supramolecular structure and photoluminescent behavior.…”

“…This phenomenon is called aggregation-induced emission (AIE), attributed to various factors, including restricted molecular motion, which blocks the nonradiative decay channels, electronic interactions, and planarization of the molecules. − Therefore, these free motions’ restriction occurred by the strong intramolecular π···π stacking interactions in the solid state and the molecular arrangement with the intermolecular interactions, enhancing the molecular rigidity fluorescence emission of the molecules. The formation of herringbone and T-type aggregates is beneficial for enhancing fluorescence efficiency, while parallel face-to-face H - type aggregation is disadvantageous . Herringbone and T -type aggregation cause red shifts in the spectra, which shows the improvement of solid-state efficiency, whereas H-aggregation causes severe fluorescence quenching and blue shifts in solid-phase spectra. , …”