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This work explores the syntheses, structures, photophysical properties, and photostability of benzodipyrenes (BDPs). BDPs were synthesized through an InCl3‐AgNTf2‐catalyzed, four‐fold alkyne benzannulation reaction. The structures of BDP 4 a and its corresponding endoperoxide product were unambiguously confirmed by X‐ray crystallography. The BDPs reported here can also be recognized as peri‐ and cata‐benzannulated pentacenes with a non‐functionalized central ring. Unlike the previous reported pentacene‐based polycyclic aromatic hydrocarbons, the absorbances of the BDPs were blueshifted by ca. 40 nm relative to pentacene, even after extension of π‐conjugation. The newly synthesized BDP products exhibit relatively good stability with half‐lives as high as 4612 min in THF. Benzodipyrenes (BDPs) were synthesized through a four‐fold alkyne benzannulation reaction in good yields. The BDP products exhibit good relative photostabilities with half‐lives up to 4612 min in THF. [ABSTRACT FROM AUTHOR]

The lanthanides(III) complexes [Ln(bza)3(H2O)n]⋅mH2O, [Ln(ppa)3(H2O)n]⋅mH2O and [Ln(abse)3(H2O)n]⋅mH2O where Ln=Eu3+, Gd3+ or Tb3+ were synthesized using sodium benzoate (Nabza), sodium phenylseleninate (Naabse) and sodium phenylphosphinate (Nappa) in order to verify the influence on coordination modes and the luminescence parameters when the carbon is exchanged by phosphorus or selenium in those ligands. The complexes׳ stoichiometries were determined by lanthanide(III) titration, microanalysis and TGA. The coordination modes were determined as bidentate bridging and chelate by the FT-IR. The triplet state energies of the ligands were obtained by two different approaches giving a difference of about ~2000 cm-1 between them. The [Eu(abse)3(H2O)] complex shows the higher degree of covalence which was verified by the centroid of 5D0→7F0 transition (17,248 cm-1). On the other hand the [Ln(abse)3(H2O)n]⋅mH2O complexes have an inefficient antenna effect verified by the low values of absolute emission quantum yields. The [Ln(ppa)3(H2O)n]⋅mH2O complexes have higher emission decay lifetime values among the complexes which is a result of the ability of this ligand to form coordination polymers avoiding water molecules in the first coordination sphere. The [Eu(ppa)3] complex has the highest point symmetry around europium(III) among the synthesized complexes, followed by the [Eu(bza)3(H2O)2]⋅3/2(H2O) and [Eu(abse)3(H2O)] complexes where europium(III) show similar point symmetries. As one may expect, the triplet state energy position would change the transfer and/or back energy transfer rates from ligand to metal. The calculation of these rates show that the back energy transfer rates are more affected than the transfer ones by changing the triplet state energy in the range of ~2000 cm-1. The changes in the energy transfer rates from triplet state to europium(III) levels are not sufficient to significantly modify the population of the europium(III) 5D0,1 levels and therefore the emission quantum yield. [ABSTRACT FROM AUTHOR]

Eu III and Yb III complexes with the carbazole-dipicolinato ligand dpaCbz 2- , namely K 3 [Eu(dpaCbz) 3 ] and K 3 [Yb(dpaCbz) 3 ], were isolated. The Eu III complex displayed metal-centred emission upon one-photon excitation with a sensitized emission efficiency Φ L Ln of 1.8±0.3 %, corresponding to an intrinsic emission efficiency Φ Ln Ln of 46% and a sensitization efficiency of η sens 3.9%, with an emission lifetime of the emissive state τ of 1.087±0.005 ms. The Yb III complex displayed Φ L Ln of 0.010±0.001 %, and a τ of 2.32±0.06 μs. The Eu III -centred emission was sensitized as well upon two-photon excitation and a two-photon absorption cross-section σ 2PA of 63 GM at 750 nm was determined for the complex. The one- or two-photon sensitized emission intensity of the Eu III complex changes by more than two-fold when the solvent viscosity is varied in the range 0.5 - 200 cP and the emission is independent of dissolved oxygen. The Yb III complex displays a change in emission intensity as well. However, in this case, a dependence of the emission intensity on dissolved oxygen content was observed., Competing Interests: Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

The newly synthesized Eu III and Yb III complexes with the new carbazole-based ligands CPAD 2- and CPAP 4- display the characteristic long-lived metal-centered emission upon one- and two-photon excitation. The Eu III complexes show the expected narrow emission bands in the red region, with emission lifetimes between 0.382 and 1.464 ms and quantum yields between 2.7% and 35.8%, while the Yb III complexes show the expected emission in the NIR region, with emission lifetimes between 0.52 and 37.86 μs and quantum yields between 0.028% and 1.12%. Two-photon absorption cross sections (σ 2PA ) as high as 857 GM were measured for the two ligands. The complexes showed a strong dependence of the one- and two-photon sensitized emission intensity on solvent viscosity in the range of 0.5-200 cP in the visible and NIR region.

We isolated a coordination polymer with the formula [Eu 3 (3,5-dcba) 9 (H 2 O)(dmf) 3 ]·2dmf, with three unique Eu III coordination sites in the asymmetric unit, with the Eu III ions bridged by 3,5-dichlorobenzoato (3,5-dcba) ligands. The coordination polymer crystallized in the triclinic space group P1̅ with unit cell dimensions a = 12.4899(15), b = 16.326(2), and c = 25.059(3) Å, α = 84.271(3)°, β = 84.832(3)°, and γ = 68.585(3)° and V = 4725.2(10) Å 3 . The characteristic 5 D 0 → 7 F J ( J = 0-4) Eu III 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 Eu III site. Energy-transfer rates ligand → Eu III 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 → Eu III , 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.

In this work, Mn doped AIZS/ZnS (Mn:AIZS/ZnS) nanocrystals (NCs) have been synthesized in an approach using heat-up and drop-wise addition of precursors. On the basis of the characterization of these doped NCs on their optical properties and materials, it is found that: (1) as more Mn atoms are doped into NCs, the doped NCs present photoluminescence (PL) red-shift and quantum yield quenching; (2) the doped NCs possess a short PL lifetime in tens of microseconds and a long PL lifetime in hundreds of microseconds, and the short lived PL is more dominant than the long lived one; and (3) the doped NCs present a reversible PL thermal quenching in a range from room temperature to 170°C. Possible PL mechanisms of these NCs were discussed by analyzing their time-resolved PL spectra and thermal stability.

The syntheses, structures, and luminescence properties of a series of copper(I) halide coordination polymers, prepared with mono- and bidentate N-heteroaromatic ligands, are reported. These metal-organic coordination networks form [Cu 2 I 2 L] n for bidentate ligands (where L = pyrazine (1), quinazoline (2)) and [CuIL] n for monodentate ligands (where L = 3-benzoylpyridine (3) and 4-benzoylpyridine(4)). Both sets of compounds exhibit a double-stranded stair-Cu 2 I 2 -polymer, or "ladder" structure with the ligand coordinating to the metal in a bidentate (bridging two stairs) or monodentate mode. The copper bromide analogues for the bidentate ligands were also targeted, [Cu 2 Br 2 L] n for L = pyrazine (5) with the same stair structure, as well as compositions of [CuBr(L)] n for L = pyrazine (6) and quinazoline (7), which have a different structure type, where the -Cu-Br- forms a single-stranded "zigzag" chain. These copper halide polymers were found to be luminescent at room temperature, with emission peaks ranging from ∼550 to 680 nm with small shifts at low temperature. The structure (stair or chain), the halide (I or Br), as well as the ligand play an important role in determining the position and intensity of emission. Lifetime measurements at room and low temperatures confirm the presence of thermally activated delayed fluorescence, or singlet harvesting for compounds 1, 2, and 7. We also investigated the nonlinear optical properties and found that, of this series, [CuBr(quinazoline)] n shows a very strong second harmonic generating response that is ∼150 times greater than that of α-SiO 2 .