In order to design new Ag(I)-based materials for thermally activated delayed fluorescence (TADF), it is vital to develop a detailed understanding of the current best performing materials. The quantitative predictions of the photophysical processes of the Ag(dmp)(P2-nCB) TADF complex are calculated using time-dependent density functional theory (TD-DFT) combined with the path integral approach for dynamics including the Herzberg-Teller effects. All calculated results are in good agreement with the experimentally available data, demonstrating the validity of our applied theoretical approach. Analysis of ETS-NOCV (extended transition state natural orbital for chemical valence) shows that there is a weak bond interaction dominated by electrostatic interactions and accompanied by some covalent components between Ag(I) and dmp ligands due to the introduction of the strongly electron-donating negatively charged P2-nCB ligand, thus giving a small energy separation between the lowest singlet S1 and triplet T1 states of ΔE(S1 - T1) ≈ 532 cm-1. The SOC strongly depends on the geometrical alteration caused by the molecular "promotion" vibrations. Our study has revealed that a few "promotion" vibrational modes, that is, ω46 and ω227, effectively induce the strong SOC between S1 and T1 and speed up the reverse intersystem crossing (RISC) process dramatically. The computed kRISC value is 1.19 × 107 s-1 for the solid phase at 300 K, which are about 5 orders of magnitude larger than the mean phosphorescence rate, kP = 9.56 × 102 s-1, and it is also far larger than ISC k0ISC = 7.84 × 102 s-1 rates from T1 to S0. The S1 state thus can be an efficient thermal repopulation from the T1 state by the RISC pathway. Finally, we also note that the diabatic vibration coupling triplet pair T1/T2 will also be important for efficient and practical RISC. Our investigation will be of great utility toward designing and improving the Ag(I)-based TADF complexes.
A novel thermo-responsive microsphere-sized poly(N-isopropylacrylamide) (PNIPAm) composite hydrogels were prepared by gelation of poly(vinyl alcohol) (PVA) solution containing ultra-fine CaCO 3 , then treated with 2wt% glutaraldehyde solution, sequencely with HCl acid, and PVA matrix with microsphere-sized pores obtained. The internal pores of the dry PVA matrix were filled with PNIPAm hydrogels to give a thermo-responsive composite hydrogels for drug carrier. The composite hydrogel was characterized via scanning electron microscopy (SEM), temperature dependence of equilibrium swelling ratio in water of the composite hydrogels was also investigated. Rhodamine B (RB) was loaded to the composite hydrogels for release study.
The intermolecular weak interaction between GeH4 and X(X=He, Ne, Ar, Kr) has been studied at MP2/aug-cc-pvtz level. Electron density topological properties of the studied systems have been calculated to investigate the critical points of H…X weak bonds. The molecules electrostatic potential (MESP) image is one of the tools for conformational analysis, and the related data suggests the view of the non-electrostatic weak interaction in nature of the GeH4…X(X=Ar, Kr) systems. To help possible experimental identification of the intermolecular weak interactions described in this work, the frequencies analysis and NMR properties were also calculated at MP2/aug-cc-pvtz level.
Abstract The synergistic regulation of the multi‐functional sites on one receptor molecule with different cationic effectors for anion recognition is scarce to be well understood from the experiment and theory. In this work, a new anion receptor with three functional zones including ether hole, biurea and double bipyridine groups ( EUPR ) is designed expecting to enhance the chloride anion recognition together with a rational synthesis path being proposed based on four simple and mature organic reaction steps. The conformational structures of the designed receptor EUPR and the binding behaviors for three kinds of ions (Cl − , Na + , and Ag + ) are deeply investigated by using density functional theoretical calculations. It is found that Cl − binding via the hydrogen bond interaction can be significantly enhanced and synergistically regulated by the two kinds of cations and the corresponding conformational changes of receptor EUPR . Especially, the conformational pre‐organization of receptor caused by the encapsulation of sodium ion into ether hole is benefit to the binding for Cl − in both thermodynamics and kinetics. Na + binding, in turn, can ever be enhanced by chloride anion, whereas it seems that Ag + binding cannot always be enhanced by chloride anion, reflecting an electrical complementary matching and mutual enhancement effect for different counter ions. Moreover, solvent effect calculations indicate that EUPR may be an ideal candidate structure for Cl − recognition by strategy of counter ion enhancement in water. Additionally, a visual study of intermolecular noncovalent interaction (NCI) and molecular electrostatic potential (ESP) are used for the analysis on the nature of interactions between receptor and bound ions.
Differently sized fullerenes are shown to be flexible tools for tuning the oxidation states of gallium, and a fluoridation strategy facilitates the further stabilization of Ga@Ih(1812)-C60.
The solid acid catalyst (ACSA) for the gutter oil esterification to biodiesel was prepared via active carbon as raw material by introducing the-SO 3 H group onto the surface of it. The ACSA were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and elemental analysis (EA), respectively. And the results showed that the-SO 3 H groups were successfully introduced onto the surface of the active carbon and the containing of the-SO 3 H groups are higher than 0.017g per gram of ACSA.
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