Synthesis, Spectra, and Theoretical Investigations of 1,3,5-Triazines Compounds as Ultraviolet Rays Absorber Based on Time-Dependent Density Functional Calculations and three-Dimensional Quantitative Structure-Property Relationship

Incorporation of Cu-TATAB metal-organic framework within polyurethane nanocomposite for enhanced thin film microextraction of some chlorinated pesticides

In this research, electrospun nanofibers based on copper-based metal organic framework (MOF)/polyurethane (PU) were prepared in order to achieve an applicable and superior extractive phase. The incorporation of MOF, in the synthesized nanocomposite contributed to the enhanced sorption efficiency. The prepared sorbent was implemented for the thin film microextraction (TFME) of target compounds with subsequent quantification using gas chromatography-mass spectrometry (GC-MS). To obtain the maximum efficiency of the synthesized sorbent, the influential parameters on extraction and desorption steps, including the MOF percentage in nanocomposite, desorption solvent type and its volume, desorption time, solution ionic strength and extraction time were optimized. After method development, the linear dynamic range (0.02-700 μg L-1), limits of detection (LODs) (0.005-0.1 μg L-1) and limits of quantification (LOQs))0.02-0.33 μg L-1(were calculated. The relative standard deviations values for intra-day and inter-day analysis were found to be in the range of 4.3-5.3 % and 6.2-8.1 %, respectively. The developed method was validated for the TFME of model organochlorine (OC) pesticide residues in fish, soil and water samples. the recovery values for the spiked samples at two concentration levels of 5 and 100 µg l-1 were found in the range of 72-110 %.

New Light-Green Thermally Activated Delayed Fluorescence Polymer Based on Dimethylacridine-Triphenyltriazine Light-Emitting Unit and Tetraphenylsilane Moiety as Non-Conjugated Backbone

In the search for solution-processable TADF materials as a light emitting layer for OLED devices, polymers have attracted considerable attention due to their better thermal and morphological properties in the film state with respect to small molecules. In this work, a new polymer (p-TPS-DMAC-TRZ) with thermally activated delayed fluorescence (TADF) light-emitting characteristics was prepared from a conjugation-break unit (TPS) and a well-known TADF core (DAMC-TRZ). This material was designed to preserve the photophysical properties of DAMC-TRZ, while improving other properties, such as thermal stability, promoted by its polymerization with a TPS core. Along with excellent solubility in common organic solvents such as toluene, chloroform and THF, the polymer (M_n = 9500; M_w = 15200) showed high thermal stability (TDT_5% = 481 °C), and a T_g value of 265 °C, parameters higher than the reference small molecule DMAC-TRZ (TDT_5% = 305 °C; T_g = 91 °C). The photoluminescence maximum of the polymer was centered at 508 nm in the solid state, showing a low redshift compared to DMAC-TRZ (500 nm), while also showing a redshift in solution with solvents of increasing polarity. Time-resolved photoluminescence of p-TPS-DMAC-TRZ at 298 K, showed considerable delayed emission in solid state, with two relatively long lifetimes, 0.290 s (0.14) and 2.06 s (0.50), and a short lifetime of 23.6 ns, while at 77 K, the delayed emission was considerably quenched, and two lifetimes in total were observed, 24.6 ns (0.80) and 180 ns (0.20), which was expected from the slower RISC process at lower temperatures, decreasing the efficiency of the delayed emission and demonstrating that p-TPS-DMAC-TRZ has a TADF emission. This is in agreement with room temperature TRPL measurements in solution, where a decrease in both lifetime and delayed contribution to total photoluminescence was observed when oxygen was present. The PLQY of the mCP blend films with 1% p-TPS-DMAC-DMAC-TRZ as a dopant was determined to be equal to 0.62, while in the pure film, it was equal to 0.29, which is lower than that observed for DMAC-TRZ (0.81). Cyclic voltammetry experiments showed similarities between p-TPS-DMAC-TRZ and DAMC-TRZ with HOMO and LUMO energies of -5.14 eV and -2.76 eV, respectively, establishing an electrochemical bandgap value of 2.38 eV. The thin film morphology of p-TPS-DMAC-TRZ and DMAC-TRZ was compared by AFM and FE-SEM, and the results showed that p-TPS-DMAC-TRZ has a smoother surface with fewer defects, such as aggregations. These results show that the design strategy succeeded in improving the thermal and morphological properties in the polymeric material compared to the reference small molecule, while the photophysical properties were mostly maintained, except for the PLQY determined in the pure films. Still, these results show that p-TPS-DMAC-TRZ is a good candidate for use as a light-emitting layer in OLED devices, especially when used as a host-guest mixture in suitable materials such as mCP.

Optoelectronic and charge transport properties of D-n-A type 1,3,5-triazine derivatives: A combined experimental and DFT study

The synthesis of five D-n-A type star-shaped octupolar molecules is presented in the current work. The exploration of the potential applicability of molecules under study in organic optoelectronics as electron or hole transporting materials is carried out by DFT methods. All the molecules have a 1,3,5-triazine core, which acts as an electron acceptor (A). Phenyl ring and pyridine ring act as electron donors (D) in AZ and PZ series of molecules respectively. The donor and acceptor core are connected by -NH bridge (n). The crystal structure of a molecule in the PZ series is elucidated. Thermogravimetric studies are carried out to confirm the thermal stability of molecules. The frontier molecular orbitals of molecules are characterized with the help of cyclic voltammetry. With the assistance of DFT methodologies, the whole research presented in this work focuses on the electronic excitations, reorganization energies, electron affinity, ionization potential and features of frontier molecular orbitals of molecules. The investigation of the variation of optoelectronic properties of molecules with changing patterns of nucleophilic substitution on 1,3,5-triazine core and presence of a hetero (nitrogen) atom in the donor part of the molecule is also accomplished.

Theoretical and experimental studies on the fluorescence properties of aluminum(III), cadmium(II), zinc(II), and copper(II) complexes of substituted 8-hydroxyquinoline

Fifty-five 8-hydroxyquinoline (8-HQ) derivatives are synthesized and the corresponding aluminum(III), cadmium(II), copper(II), and zinc(II) metal complexes are prepared and their fluorescent activities are evaluated. The results indicate that the aluminum complexes have the best fluorescence properties, followed by zinc and cadmium complexes, while almost no fluorescence is observed with the copper complexes. The relationship between the fluorescence properties and complex structure is summarized and a predictive three-dimensional quantitative structure–property relationship model is established using the multifit molecular alignment rule of Sybyl program. With the introduction of groups at the C-2 position or electron-withdrawing groups to the 8-hydroxyquinoline framework, fluorescence wavelength blue shifts are observed with the zinc, aluminum, and cadmium complexes. At the same time, a red shift of the fluorescence emission wavelength is detected for the aluminum and zinc complexes when C-5 of 8-hydroxyquinoline was substituted with halogens or a methyl group. Moreover, the zinc, cadmium, and aluminum complexes with 2,4-dimethyl substituents on the 8-hydroxyquinoline all show good fluorescence properties. The highest occupied molecular orbital and lowest unoccupied molecular orbital energies of the complexes are also calculated and the fluorescence properties of the metal complexes are analyzed from the viewpoint of molecular orbitals.