Small substituent groups as geometric controllers for tridentate platinum(ii) complexes to effectively suppress non-radiative decay processes

Photophysical properties of Pt(ii) complexes based on the benzoquinoline (bzq) ligand with OLED implication: a theoretical study

In this study, we investigate photophysical properties of eight inorganic Pt(ii) complexes containing the bzq (benzoquinoline) ligand for OLED applications using high-level density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. We explore the radiative and non-radiative relaxation constants (k r, k nr), spin-orbit coupling (SOC) matrix elements, and spectral properties. To ensure compatibility between the host and guest compounds, we determine the HOMO and LUMO energy levels, as well as the triplet excitation energies of the selected systems, and evaluate their efficiency for OLED devices. Our findings indicate that all systems, except for 2a and 2b, exhibit a small S1-T1 energetic gap (ΔE ≤ 0.60 eV) and promising SOC matrix elements (25-93 cm-1), leading to a significant intersystem crossing (ISC) process. These complexes also show promising radiative relaxation rates (k r = ∼10-4 s-1) and high phosphorescent quantum yields (Φ > 30%). Thus, our results confirm that six out of the eight selected Pt(ii) complexes are promising candidates for use in the emitting layer (EML) of OLED devices as efficient green emitters.

High efficient room temperature phosphorescent materials constructed with methylene molecular configuration

In this work, we have investigated several pure organic room temperature phosphorescent materials with donor-methylene acceptor configurations with relatively different quantum efficiency. The results show that the introduction of methylene functional group in room temperature phosphorescent materials based on donor-acceptor configuration is more favorable for obtaining higher phosphorescent quantum efficiency in crystal phase environment. More importantly, our calculations reveal the root cause of the excellent quantum efficiency performance after the introduction of methylene groups. The results show that the introduction of methylene can inhibit the structural deformation of molecules during the excited state transition process and give them higher interaction. Moreover, in the donor-acceptor configuration, the heavy atom effect is more favorable to the formation of π-x (X = Br) interaction to accelerate the occurrence of intersystem crossing and achieve a higher intersystem crossing rate. Therefore, the donor-methylene-acceptor molecule is expected to improve the quantum efficiency of room temperature phosphorescence, and the addition of heavy atoms is more conducive to prolong the life of room temperature phosphorescence. This work provides a useful reference for rational design of room temperature phosphorescent materials with high efficiency and long life.

Room-temperature luminescence from Pd(II) and Pt(II) complexes: from mechanochromic crystals to flexible polymer matrices

A series of Pd(II) (PdLOMe, PdLOHex) and Pt(II) (PtLOMe, PtLOHex) complexes bearing tetradentate ligands as dianionic luminophores were synthesized. Hence, the cyclometallating chelators were alternatively decorated with two n-hexyloxy (LOHex) or two methoxy (LOMe) moieties to promote crystallization and processability. The new compounds were unambiguously characterized by means of multiple NMR spectroscopies and mass spectrometry as well as by single crystal X-ray diffractometric analysis (PtLOMe and PdLOMe). Steady state and time-resolved photoluminescence spectroscopic studies were carried out in crystalline phases, in fluid solutions at room temperature, in frozen glassy matrices at 77 K and in a flexible polymeric matrix (PMMA). PtLOMe presents an intriguing mechanochromism resulting from the responsive metal-metal interactions involving adjacent monomeric units. Incorporation of the Pd(II) complexes into the polymeric matrix boosts their photophysical properties by stiffening of the coordination environment while reducing non-radiative deactivation pathways mediated by dissociative metal-centred states, which also become thermally inaccessible at 77 K.

Characterizing the Binding Sites for GK Domain of DLG1 and DLG4 via Molecular Dynamics Simulation

Discs-large (DLG) is a member that belongs to the membrane-associated guanylate kinase (MAGUK) family. The GK domain of DLGs has evolved into a protein–protein interaction module that could bind with kinds of proteins to regulate diverse cellular functions. Previous reports have demonstrated the GK domain of DLGs functioned as a phosphor-peptide-binding module by resolving the crystal structures. Here we investigated into the interactions of DLG1 and DLG4 with their reported phosphor-peptides by molecular dynamics simulations. Post-dynamics analysis showed that DLG1/4 formed extensive interactions with phosphorylated ligands, including hydrophobic and hydrogen bonding interactions. Among them, the highly conserved residues among the DLGs in phosphor-site and β5 sheet were crucial for the binding according to the energy decomposition calculations. Additionally, the binding interactions between DLG4 and reported unphosphorylated peptides including MAP1A and designed GK inhibitory (GKI-QSF) peptides were analyzed. We found the key residues that played important roles in DLG4/unphosphorylated peptide systems were very similar as in DLG4/phosphor-peptide systems. Moreover, the molecular dynamic simulation for the complex of DLG1 and GKI-QSF was carried out and predicted that the GKI-QSF could bind with DLG1 with similar Kd value compared to DLG4/GKI-QSF, which was verified by using ITC assay (Kd = 1.20 ± 0.29 μM). Our study might be helpful for the better understanding of the structural and biological function of DLGs GK domain and encourage the discovery of new binders.