Dataset Information

Effect of Protonation on Optical and Electrochemical Properties of Thiophene-Phenylene-Based Schiff Bases with Alkoxy Side Groups.

ABSTRACT: Three polyazomethines and their corresponding model compounds were protonated with trifluoroacetic acid, and its effect on their optical (UV-vis absorption and photoluminescence) properties and electrochemical behavior has been studied, in the context of the presence and elongation of alkoxy side groups. Moreover, the effect of environment dielectric constants (i.e., polarity of the solvent) was considered on the doping process. It has been proven that the presence of alkoxy side groups is necessary for protonation to occur, while unsubstituted compounds undergo hydrolysis to constitutive units. Acid doping of imines consisting of alkoxy side chains has resulted in a distinct bathochromic shift (>200 nm) of the low-energy absorption band. Even the length of alkyl chains has not affected the position of shifted bands; it has been observed that azomethines with smaller, methoxy side groups undergo the protonation process much faster than their octyloxy-substituted analogues, due to the absence of steric hindrance. The electrochemical studies of these alkoxy-substituted imines have indicated a better p-type behavior after protonation induced by the capability of the protonated form to easily oxidize in acetonitrile and to generate the native molecules. The environmental polarity has also had impact on the doping process, which took place only in low-polar media.

SUBMITTER: Nitschke P

PROVIDER: S-EPMC8389983 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:We designed and synthesized unsubstituted 4,4'-bibenzo[c]thiophene 4,4'-BBT and its silyl-substituted derivatives 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT with one or two tert-butyldimethylsilyl groups on each thiophene ring, as new π-building blocks in emitters, photosensitizers and semiconductors for organic optoelectronic devices. The characterization of 4,4'-BBT, 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT was successfully determined by FTIR, 1H and 13C NMR measurements, high-resolution mass spectrometry (HRMS) analysis, photoabsorption and fluorescence spectroscopy, cyclic voltammetry (CV) and density functional theory (DFT) calculations. Moreover, a single-crystal X-ray structural analysis was successfully made for 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT. The photoabsorption and fluorescence maxima (λ abs max and λ fl max) of the three 4,4'-bibenzo[c]thiophene derivatives in toluene exhibit bathochromic shifts in the order of 4,4'-BBT (359 nm and 410 nm) < 1,1'-Si-4,4'-BBT (366 nm and 420 nm) < 1,1',3,3'-Si-4,4'-BBT (371 nm and 451 nm). The HOMO and LUMO energy levels rise in the order of 4,4'-BBT (-5.55 eV and -2.39 eV) < 1,1'-Si-4,4'-BBT (-5.45 eV and -2.34 eV) < 1,1',3,3'-Si-4,4'-BBT (-5.34 eV and -2.30 eV), but the rise of the HOMO energy level is larger than that of the LUMO energy level, resulting in the bathochromic shift of the photoabsorption band from 4,4'-BBT to 1,1',3,3'-Si-4,4'-BBT. The fluorescence quantum yields (Φ fl) of 4,4'-BBT, 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT in toluene are 0.41, 0.41 and 0.36, respectively. It is worth mentioning that in the solid state 1,1'-Si-4,4'-BBT and 1,1',3,3'-Si-4,4'-BBT show relatively high Φ fl-solid values of 0.22 and 0.25, respectively, whereas 4,4'-BBT exhibits poor solid-state fluorescence properties (Φ fl-solid < 0.02). This work provides an efficient synthetic method for the 4,4'-bibenzo[c]thiophene derivatives and their photophysical properties in the solution and solid state, electrochemical properties and X-ray crystal structures.

Project description:Two Schiff bases, (E)-4-((2-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPOCB) and (E)-4-((4-chlorobenzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (4AAPPCB), have been synthesized and grown as single crystals. Single-crystal X-ray diffraction analysis was employed to determine the crystal structure of the compounds, and the results suggest that the compounds crystallized into an orthorhombic crystal system having P212121 and Pbca space groups, respectively. Further, the crystallinity of the compounds was analyzed by the PXRD technique. The UV-vis-NIR spectra of the compounds demonstrate excellent transmittance in the entire visible region. The lower cutoff wavelengths of the compounds were determined to be 338 and 333 nm, respectively; additionally, optical band gaps of the compounds found were 4.60 and 4.35 eV. FTIR and NMR (1H and 13C) spectral techniques were utilized to analyze the molecular structure of the compounds. The compounds emit photoluminescence with broad emission bands with centers at 401 and 418 nm. The thermal stability and phase transitions were assessed through thermogravimetric methods. The phase transition prior to melting was indicated by the endothermic event at around 190 °C in the DTA curves of both crystals, and the same was observed in the DSC curves. The second harmonic efficiencies of the powdered compounds I and II were found to be 3.52 and 1.13 times better than that of the standard reference KDP. The 4AAPOCB and 4AAPPCB compounds showed isotropic polarizability amplitudes of 46.02 × 10-24 and 46.52 × 10-24 esu, respectively. The calculation of linear polarizability and NLO second-order polarizability (β) along with other optical parameters was performed for optimized geometries. The nonzero amplitudes of the average β values for compounds 4AAPOCB and 4AAPPCB were found to be 14.74 × 10-30 and 8.10 × 10-30 esu, respectively, which show a decent potential of the synthesized molecules for NLO applications. The calculated β amplitudes were further explained based on calculated electronic parameters like molecular electrostatic potentials, frontier molecular orbitals, molecular orbital energies, transition energies, oscillator strengths, and unit spherical representation of NLO polarizability. The current analysis emphasizes the significance of synthesized compounds as prospective candidates for optical and NLO applications through the use of experiments and quantum computations.

Dataset Information

Effect of Protonation on Optical and Electrochemical Properties of Thiophene-Phenylene-Based Schiff Bases with Alkoxy Side Groups.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets