Search results for "Phosphore"
showing 10 items of 114 documents
Combined Theoretical and Experimental Study of the Photophysics of Asulam
2013
The photophysics of the neutral molecular form of the herbicide asulam has been described in a joint experimental and theoretical, at the CASPT2 level, study. The unique π → π* aromatic electronic transition (f, ca. 0.5) shows a weak red-shift as the polarity of the solvent is increased, whereas the fluorescence band undergoes larger red-shifts. Solvatochromic data point to higher dipole moment in the excited state than in the ground state (μ(g)μ(e)). The observed increase in pKa in the excited state (pKa* - pKa, ca. 3) is consistent with the results of the Kamlet-Abboud-Taft and Catalán et al. multiparametric approaches. Fluorescence quantum yield varies with the solvent, higher in water (…
A theoretical insight into the photophysics of psoralen
2006
Psoralen photophysics has been studied on quantum chemistry grounds using the multiconfigurational second-order perturbation method CASPT2. Absorption and emission spectra of the system have been rationalized by computing the energies and properties of the low-lying singlet and triplet excited states. The S1 ππ* state has been determined to be responsible of the lowest absorption and fluorescence bands and to initially carry the population in the photophysical processes related to the phototherapeutic properties of psoralen derivatives. The low-lying T1 ππ* state is, on the other hand, protagonist of the phosphorescence, and its prevalent role in the reactivity of psoralen is suggested to b…
Gold(I)-doped films: new routes for efficient room temperature phosphorescent materials
2021
The synthesis of four novel gold(I)-phosphane complexes coordinated to 9-phenanthrene chromophore has been carried out through the reaction of 9-phenanthreneboronic acid and the corresponding AuClPR3 (PR3 = PPh3 for triphenylphosphane (1a); 1,4-bis(diphenylphosphanyl)butane or dppb (2b); bis(diphenylphosphanyl)acetylene or dppa (2c); (AuCl)2(diphos) (diphos = bis(diphenylphosphanyl)methane or dppm (3)) sources. The X-ray crystal structures of compounds 1a and 2b show the existence of MOF-like intermolecular assemblies that contain empty inner cavities in the absence of aurophilic contacts. In contrast, the formation of a tetranuclear complex with intramolecular aurophilic interactions was e…
Tailoring the Emission of Fluorinated Bipyridine-Chelated Iridium Complexes
2018
New functionalized tris(2′,6′-difluoro-2,3′-bipyridinato-N,C4′)iridium(III) ((dfpypy)3Irs) complexes, including small molecules and their dendrimer embedded analogoues, were synthesized and characterized. It is demonstrated that both the fac-(dfpypy)3Ir-based polyphenylene dendrimers and (triisopropylsilyl)ethynyl (TIPSE)-substituted (dfpypy)3Ir complexes induce large bathochromic shifts (∼50 nm) of emission bands compared with fac-(dfpypy)3Ir. This is due to the pronounced 3π–π* character of emissive excited states and the extended conjugation. A further remarkable feature is the small bathochromic shift of the emissions of fac-tris(2-phenylpyridine)iridium (fac-(ppy)3Ir)-based polyphenyle…
Pulsed-current versus constant-voltage light-emitting electrochemical cells with trifluoromethyl-substituted cationic iridium(iii) complexes
2013
We report on five cationic iridium(III) complexes with cyclometalating 2-(3′-trifluoromethylphenyl)pyridine and a diimine, [(C⁁N)2Ir(N⁁N)](PF6), N⁁N = 4,4′-R2-2,2′-dipyridyl or 4,7-R2-1,10-phenanthroline (R = H, Me, tert-Bu, Ph), and characterize three of them by crystal structure analysis. The complexes undergo oxidation of the Ir–aryl fragment at 1.13–1.16 V (against ferrocene couple) and reduction of the N⁁N ligand at −1.66 V to −1.86 V, and have a redox gap of 2.84–2.99 V. The complexes exhibit bluish-green to green-yellow phosphorescence in an argon-saturated dichloromethane solution at room temperature with a maximum at 486–520 nm, quantum yield of 61–67%, and an excited-state lifetim…
Novel 2D boron nitride with optimal direct band gap: A theoretical prediction
2022
Abstract A novel structurally stable 2D-boron nitride material, namely di-BN, is predicted by means of the first-principles simulations. This monolayer BN system is composed of the azo (N-N) and diboron (B-B) groups. Its in-plane stiffness is close to the monolayer h-BN. Usually, the boron nitride materials are semiconductors with large band gaps. However, the monolayer di-BN possesses a moderate direct band gap of 1.622 eV obtained from our HSE06 calculation. Although the GW correction enlarges the band gap to 2.446 eV, this value is still in the range of the visible light. The detailed investigation of its band arrangement reveals that this material is able to product hydrogen molecules i…
Photophysical properties of the triangular [Au(HNCOH)]3 complex and its dimer
2020
Rate constants for radiative and non-radiative transitions of the [Au(HNCOH)]3 complex and its dimer were calculated within the Herzberg–Teller approximation based on quantum mechanical principles. A high triplet quantum yield was estimated for the monomer. Internal conversion (IC) was found to be the major competing process to the intersystem crossing (ISC) from the lowest excited singlet state (S1) to the lowest triplet state (T1). ISC and IC from the spin-mixed 1 state also dominate the triplet relaxation process resulting in a negligible phosphorescence quantum yield for the monomer. The IC and ISC rate constants of the dimer are considerably smaller due to much lower Franck–Condon fact…
Photophysics and photochemistry with Earth-abundant metals - fundamentals and concepts.
2020
Recent exciting developments in the area of mononuclear photoactive complexes with Earth-abundant metal ions (Cu, Zr, Fe, Cr) for potential eco-friendly applications in (phosphorescent) organic light emitting diodes, in imaging and sensing systems, in dye-sensitized solar cells and as photocatalysts are presented. Challenges, in particular the extension of excited state lifetimes, and recent conceptual breakthroughs in substituting precious and rare-Earth metal ions (e.g. Ru, Ir, Pt, Au, Eu) in these applications by abundant ions are outlined with selected examples. Relevant fundamentals of photophysics and photochemistry are discussed first, followed by conceptual and instructive case stud…
White hybrid organic-inorganic light-emitting diode using ZnO as the air-stable cathode
2009
An efficient white light emitting hybrid organic−inorganic device utilizing air-stable metal oxides as anode and cathode and a polyfluorene mixed with a phosphorescent iridium complex as the emitting material is presented.
Metallophthalocyanines as optical active dopants in borate glass
2021
Abstract B2O3 – phthalocyanine composites (B2O3@MPc) were synthesized at 410 °C by sintering boron trioxide doped with base metal-free phthalocyanine (H2Pc) and/or its complexes of Mg, Zn, Gd (Pc = C32H16N8, phthalocyanine ligand, M = metal ion). The glassy products were characterized by scanning electron microscopy (SEM, EDS) and diffuse reflectance spectroscopy (DRS) which confirmed the incorporation of the respective phthalocyanines into the amorphous borate matrix. FTIR results suggested a possible impact of the phthalocyanine dopants on the final solid structure of the glassy matrix. The UV-excited composites emitted a pronounced blue phosphorescence featured by a two-step quenching pr…