- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Heteroleptic Copper(I) Complexes Prepared from Phenanthroline and Bis-Phosphine Ligands: Rationalization of the Photophysical and Electrochemical Properties
摘要： The electronic and structural properties of ten heteroleptic [Cu(NN)(PP)]+ complexes have been investigated. NN indicates 1,10-phenanthroline (phen) or 4,7-diphenyl-1,10-phenanthroline (Bphen); each of these ligands is combined with five PP bis-phosphine chelators, i.e., bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)benzene (dppb), and bis[(2-diphenylphosphino)phenyl] ether (POP). All complexes are mononuclear, apart from those based on dppm, which are dinuclear. Experimental data—also taken from the literature and including electrochemical properties, X-ray crystal structures, UV?vis absorption spectra in CH2Cl2, luminescence spectra and lifetimes in solution, in PMMA, and as powders—have been rationalized with the support of density functional theory calculations. Temperature dependent studies (78?358 K) have been performed for selected complexes to assess thermally activated delayed fluorescence. The main findings are (i) dependence of the ground-state geometry on the crystallization conditions, with the same complex often yielding different crystal structures; (ii) simple model compounds with imposed C2v symmetry ([Cu(phen)(PX3)2]+; X = H or CH3) are capable of modeling structural parameters as a function of the P?Cu?P bite angle, which plays a key role in dictating the overall structure of [Cu(NN)(PP)]+ complexes; (iii) as the P?Cu?P angle increases, the energy of the metal-to-ligand charge transfer absorption bands linearly increases; (iv) the former correlation does not hold for emission spectra, which are red-shifted for the weaker luminophores; (v) the larger the number of intramolecular π-interactions within the complex in the ground state, the higher the luminescence quantum yield, underpinning a geometry locking effect that limits the structural flattening of the excited state. This work provides a general framework to rationalize the structure?property relationships of [Cu(NN)(PP)]+, a class of compounds of increasing relevance for electroluminescent devices, photoredox catalysis, and solar-to-fuels conversion, which so far have been investigated in an unsystematic fashion, eluding a comprehensive understanding.
关键词： electrochemical properties,bis-phosphine ligands,photophysical properties,phenanthroline,thermally activated delayed fluorescence,density functional theory,heteroleptic copper(I) complexes
更新于2025-09-09 09:28:46
-
Vinyl-Linked Cyanocarbazole-Based Emitters: Effect of Conjugation and Terminal Chromophores on the Photophysical and Electroluminescent Properties
摘要： A series of carbazole-based dyes functionalized with different auxochromes via vinyl linker have been synthesized and characterized. A progressive shift in the absorption maximum is observed as the conjugation and electron-donating nature of chromophore increases. Dyes containing electron-releasing terminal groups such as triphenylamine and carbazole exhibited positive emission solvatochromism attributable to an induced intramolecular charge transfer from triphenylamine/carbazole donor to cyano acceptor. The superior electroluminescence performance of disubstituted dyes demonstrates the role of an additional cyanocarbazole in achieving balanced charge transport compared to monosubstituted analogues. In addition, the electroluminescence performance of the dyes exhibited trends attributable to the electron richness of the linker/terminal chromophore. Thus, the carbazole-based derivatives displayed better electroluminescence efficiency than the analogous fluorene derivatives. Similarly, 2,7-substituted carbazole derivative exhibited better performance than the 3,6-substituted carbazole derivative. A doped electroluminescent device containing 3 wt % tricarbazole derivative showed blue emission with a high external quantum efficiency of 5.3% at a practical brightness of 1000 cd/m2.
关键词： OLED,vinyl linker,carbazole,electroluminescent properties,photophysical properties
更新于2025-09-09 09:28:46
-
Lewis-Acid-Catalyzed BODIPY Boron Functionalization Using Trimethylsilyl Nucleophiles
摘要： A novel and straightforward strategy for boron functionalization in boron dipyrromethenes (BODIPYs) is developed. In particular, this synthetic strategy provides new possibilities for the synthesis of sp2 N-substituted (B-NCS and -NCO), benzotriazole- and trifluoroacetamide-substituted BODIPYs that were hitherto unknown. These new BODIPYs display an array of highly desirable photophysical properties (0.04 < Φ f < 0.86), paving the road for further investigations in material applications.
关键词： photophysical properties,boron functionalization,trimethylsilyl nucleophiles,Lewis acid catalysis,BODIPY
更新于2025-09-09 09:28:46
-
Estimating the Individual Spectroscopic Properties of Three Unique Eu <sup>III</sup> Sites in a Coordination Polymer
摘要： We isolated a coordination polymer with the formula [Eu3(3,5-dcba)9(H2O)(dmf)3]·2dmf, with three unique EuIII coordination sites in the asymmetric unit, with the EuIII ions bridged by 3,5-dichlorobenzoato (3,5-dcba) ligands. The coordination polymer crystallized in the triclinic space group P1? with unit cell dimensions a = 12.4899(15), b = 16.326(2), and c = 25.059(3) ?, α = 84.271(3)°, β = 84.832(3)°, and γ = 68.585(3)° and V = 4725.2(10) ?3. The characteristic 5D0 → 7FJ (J = 0?4) EuIII transitions were observed upon ligand-centered excitation. Emission lifetimes of 0.825 ± 0.085 and 1.586 ± 0.057 ms were observed and were attributed to the sites with coordination of water or dimethylformamide (dmf) molecules to each ion, respectively. Through a combination of spectroscopy and calculations, we determined the photophysical properties of each unique EuIII site. Energy-transfer rates ligand → EuIII were determined for each unique site using the overlapped polyhedra method. The rates depend on the coordinated water molecules and the different donor?acceptor distances. The two sites without coordinated water molecules and shortest donor?acceptor distance display the fastest energy-transfer rate ligand → EuIII, whereas the site with coordinated water molecules and longest donor?acceptor distance displays the slowest energy-transfer rate. Donor?acceptor distances were estimated computationally and were confirmed by calculating the frontier orbitals in the asymmetric units of the polymer using density functional theory.
关键词： coordination polymer,photophysical properties,energy-transfer rates,density functional theory,EuIII
更新于2025-09-09 09:28:46
-
Excited-State Switching between Ligand-Centered and Charge Transfer Modulated by Metal–Carbon Bonds in Cyclopentadienyl Iridium Complexes
摘要： Three series of pentamethylcyclopentadienyl (Cp*) Ir(III) complexes with different bidentate ligands were synthesized and structurally characterized, [Cp*Ir(tpy)L]n+ (tpy = 2-tolylpyridinato; n = 0 or 1), [Cp*Ir(piq)L]n+ (piq = 1-phenylisoquinolinato; n = 0 or 1), and [Cp*Ir(bpy)L]m+ (bpy = 2,2′-bipyridine; m = 1 or 2), featuring a range of monodentate carbon-donor ligands within each series [L = 2,6-dimethylphenylisocyanide; 3,5-dimethylimidazol-2-ylidene (NHC); methyl)]. The spectroscopic and photophysical properties of these molecules and those of the photocatalyst [Cp*Ir(bpy)H]+ were examined to establish electronic structure?photophysical property relationships that engender productive photochemical reactivity of this hydride and its methyl analogue. The Ir(III) chromophores containing ancillary CNAr ligands exhibited features anticipated for predominantly ligand-centered (LC) excited states, and analogues bearing the NHC ancillary exhibited properties consistent with LC excited states containing a small admixture of metal-to-ligand charge-transfer (MLCT) character. However, the molecules featuring anionic and strongly σ-donating methyl or hydride ligands exhibited photophysical properties consistent with a high degree of CT character. Density functional theory calculations suggest that the lowest energy triplet states in these complexes are composed of a mixture of MLCT and ligand-to-ligand CT originating from both the Cp* and methyl or hydride ancillary ligands. The high degree of CT character in the triplet excited states of methyliridium complexes bearing C^N-cyclometalated ligands offer a striking contrast to the photophysical properties of pseudo-octahedral structures fac-Ir(C^N)3 or Ir(C^N)2(acac) that have lowest-energy triplet excited states characterized as primarily LC character with a more moderate MLCT admixture.
关键词： cyclopentadienyl iridium complexes,charge transfer,photophysical properties,Iridium(III) complexes,ligand-centered excited states
更新于2025-09-09 09:28:46
-
Synthesis, structural characterization and photophysical properties of 7-cyanohexahelicene
摘要： 7-Cyanoexahelicene has been prepared in racemic form through a short photochemical synthetic approach and its enantiomeric separation was studied and allowed to obtain (P)- and (M)-enantiomers in 100% ee and > 98.5% ee, respectively. The optical rotatory dispersion and electronic circular dichroism (ECD) spectra of the resolved ones were measured. Other optical properties such as UV and photoluminescence as well as the electrochemical behavior were also examined in solutions.
关键词： Optical resolution,Chirality,Couplings,Photophysical properties,gap energy,Helicenes,Photooxidation
更新于2025-09-04 15:30:14
-
Importance of Chromophore Rigidity on the Efficiency of Blue Thermally Activated Delayed Fluorescence Emitters
摘要： Four new symmetrical donor?acceptor?donor (D?A?D)-type molecules are reported with diphenylamine (DPA) or 10,11-dihydro-5H-dibenz[b,f ]azepine (Az) as electron donors and 9,9-dimethylthioxanthene-S,S-dioxide (TXO2) as the electron acceptor. The donors are attached at different positions on the acceptor core: either para or meta to the sulfone unit. This series provides new insights into the effects of chromophore rigidity/flexibility on the efficiency of thermally activated delayed fluorescence (TADF). The molecules have been characterized by X-ray crystallography, by in-depth photophysical studies, and by theoretical calculations. The clear differences observed in the photophysical properties when using DPA or Az as a donor are shown to originate from different geometries of the donor unit which, in turn, influence the geometry of the nitrogen lone pair and the donating strength of the corresponding fragment. Thus, a para-substituted Az derivative demonstrated blue TADF in polar media, while the compounds with more flexible DPA units did not show delayed fluorescence. To obtain deep-blue emitters, weaker donating units are needed. A more flexible donor unit leads to increased local excited state (donor) LE emission and reduced TADF. However, a certain amount of flexibility has to be present to ensure deep-blue TADF.
关键词： chromophore rigidity,blue emitters,donor-acceptor-donor,photophysical properties,thermally activated delayed fluorescence
更新于2025-09-04 15:30:14
-
Indolizine-Cyanine Dyes: Near Infrared Emissive Cyanine Dyes with Increased Stokes Shifts
摘要： Molecular engineering strategies designed to red-shift cyanine dye absorptions and emissions further into the near infrared (NIR) spectral region are explored. Through the use of a novel donor group, indolizine, with varying cyanine bridge lengths, dye absorptions and emissions were shifted deeper into the NIR region than common indoline-cyanines. Stokes shifts resulting from intramolecular steric interactions of up to ~60 nm in many cases were observed and explained computationally. Molecular brightnesses of up to 5,800 deep into the NIR region were observed. Structure-property relationships are explored for the 6 indolizine-cyanine dyes with varying cyanine bridge length and indolizine substituents showing broad absorption and emission tunability. The dyes are characterized by crystallography, and the photophysical properties are probed by varying solvent for absorption and emission studies. Computational data show involvement of the entire indolizine π-system during light absorption, which suggests these systems can be tunable even further into the NIR region through select derivatizations.
关键词： Photophysical Properties,Stokes Shifts,Near Infrared Emissive,Molecular Brightness,Indolizine-Cyanine Dyes
更新于2025-09-04 15:30:14
-
Life sensors: current advances in oxygen sensing by lanthanide complexes
摘要： Aerobes, such as animals, plants, fungi, and several bacteria, depend upon oxygen to live. Consequently, oxygen sensing comprises an emerging technique in many research fields, ranging from medicine to marine science. In the last few years, lanthanide-based oxygen sensors have seen significant progress in the field of optical sensing technology owing to their long luminescence lifetimes and sharp luminescence bands. These sensors provide an alternative to expensive transition metal-based sensors, such as platinum and ruthenium complexes. This review covers the development and design of lanthanide-based oxygen sensors, along with their photophysical properties related to oxygen sensing. These lanthanide complexes achieve oxygen sensing through the excited state quenching of the intermediate triplet state of the antenna chromophore, which suggests that the sensitivity to pO2 arises from the rate of forward intramolecular energy transfer from the antenna triplet state to the accepting Ln3+ ion being competitive with bimolecular quenching by oxygen. As Tb(III) complexes are highly oxygen sensitive, they are favored to be good oxygen sensors, while the sensitivity of Eu(III), Dy(III), Nd(III), and Gd(III) complexes is low.
关键词： oxygen sensing,lanthanide complexes,Tb(III) complexes,optical sensing technology,photophysical properties
更新于2025-09-04 15:30:14